WSL2-Linux-Kernel/mm/hugetlb.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Generic hugetlb support.
* (C) Nadia Yvette Chambers, April 2004
*/
#include <linux/list.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/seq_file.h>
#include <linux/sysctl.h>
#include <linux/highmem.h>
mmu-notifiers: core With KVM/GFP/XPMEM there isn't just the primary CPU MMU pointing to pages. There are secondary MMUs (with secondary sptes and secondary tlbs) too. sptes in the kvm case are shadow pagetables, but when I say spte in mmu-notifier context, I mean "secondary pte". In GRU case there's no actual secondary pte and there's only a secondary tlb because the GRU secondary MMU has no knowledge about sptes and every secondary tlb miss event in the MMU always generates a page fault that has to be resolved by the CPU (this is not the case of KVM where the a secondary tlb miss will walk sptes in hardware and it will refill the secondary tlb transparently to software if the corresponding spte is present). The same way zap_page_range has to invalidate the pte before freeing the page, the spte (and secondary tlb) must also be invalidated before any page is freed and reused. Currently we take a page_count pin on every page mapped by sptes, but that means the pages can't be swapped whenever they're mapped by any spte because they're part of the guest working set. Furthermore a spte unmap event can immediately lead to a page to be freed when the pin is released (so requiring the same complex and relatively slow tlb_gather smp safe logic we have in zap_page_range and that can be avoided completely if the spte unmap event doesn't require an unpin of the page previously mapped in the secondary MMU). The mmu notifiers allow kvm/GRU/XPMEM to attach to the tsk->mm and know when the VM is swapping or freeing or doing anything on the primary MMU so that the secondary MMU code can drop sptes before the pages are freed, avoiding all page pinning and allowing 100% reliable swapping of guest physical address space. Furthermore it avoids the code that teardown the mappings of the secondary MMU, to implement a logic like tlb_gather in zap_page_range that would require many IPI to flush other cpu tlbs, for each fixed number of spte unmapped. To make an example: if what happens on the primary MMU is a protection downgrade (from writeable to wrprotect) the secondary MMU mappings will be invalidated, and the next secondary-mmu-page-fault will call get_user_pages and trigger a do_wp_page through get_user_pages if it called get_user_pages with write=1, and it'll re-establishing an updated spte or secondary-tlb-mapping on the copied page. Or it will setup a readonly spte or readonly tlb mapping if it's a guest-read, if it calls get_user_pages with write=0. This is just an example. This allows to map any page pointed by any pte (and in turn visible in the primary CPU MMU), into a secondary MMU (be it a pure tlb like GRU, or an full MMU with both sptes and secondary-tlb like the shadow-pagetable layer with kvm), or a remote DMA in software like XPMEM (hence needing of schedule in XPMEM code to send the invalidate to the remote node, while no need to schedule in kvm/gru as it's an immediate event like invalidating primary-mmu pte). At least for KVM without this patch it's impossible to swap guests reliably. And having this feature and removing the page pin allows several other optimizations that simplify life considerably. Dependencies: 1) mm_take_all_locks() to register the mmu notifier when the whole VM isn't doing anything with "mm". This allows mmu notifier users to keep track if the VM is in the middle of the invalidate_range_begin/end critical section with an atomic counter incraese in range_begin and decreased in range_end. No secondary MMU page fault is allowed to map any spte or secondary tlb reference, while the VM is in the middle of range_begin/end as any page returned by get_user_pages in that critical section could later immediately be freed without any further ->invalidate_page notification (invalidate_range_begin/end works on ranges and ->invalidate_page isn't called immediately before freeing the page). To stop all page freeing and pagetable overwrites the mmap_sem must be taken in write mode and all other anon_vma/i_mmap locks must be taken too. 2) It'd be a waste to add branches in the VM if nobody could possibly run KVM/GRU/XPMEM on the kernel, so mmu notifiers will only enabled if CONFIG_KVM=m/y. In the current kernel kvm won't yet take advantage of mmu notifiers, but this already allows to compile a KVM external module against a kernel with mmu notifiers enabled and from the next pull from kvm.git we'll start using them. And GRU/XPMEM will also be able to continue the development by enabling KVM=m in their config, until they submit all GRU/XPMEM GPLv2 code to the mainline kernel. Then they can also enable MMU_NOTIFIERS in the same way KVM does it (even if KVM=n). This guarantees nobody selects MMU_NOTIFIER=y if KVM and GRU and XPMEM are all =n. The mmu_notifier_register call can fail because mm_take_all_locks may be interrupted by a signal and return -EINTR. Because mmu_notifier_reigster is used when a driver startup, a failure can be gracefully handled. Here an example of the change applied to kvm to register the mmu notifiers. Usually when a driver startups other allocations are required anyway and -ENOMEM failure paths exists already. struct kvm *kvm_arch_create_vm(void) { struct kvm *kvm = kzalloc(sizeof(struct kvm), GFP_KERNEL); + int err; if (!kvm) return ERR_PTR(-ENOMEM); INIT_LIST_HEAD(&kvm->arch.active_mmu_pages); + kvm->arch.mmu_notifier.ops = &kvm_mmu_notifier_ops; + err = mmu_notifier_register(&kvm->arch.mmu_notifier, current->mm); + if (err) { + kfree(kvm); + return ERR_PTR(err); + } + return kvm; } mmu_notifier_unregister returns void and it's reliable. The patch also adds a few needed but missing includes that would prevent kernel to compile after these changes on non-x86 archs (x86 didn't need them by luck). [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: fix mm/filemap_xip.c build] [akpm@linux-foundation.org: fix mm/mmu_notifier.c build] Signed-off-by: Andrea Arcangeli <andrea@qumranet.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Christoph Lameter <cl@linux-foundation.org> Cc: Jack Steiner <steiner@sgi.com> Cc: Robin Holt <holt@sgi.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Kanoj Sarcar <kanojsarcar@yahoo.com> Cc: Roland Dreier <rdreier@cisco.com> Cc: Steve Wise <swise@opengridcomputing.com> Cc: Avi Kivity <avi@qumranet.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Anthony Liguori <aliguori@us.ibm.com> Cc: Chris Wright <chrisw@redhat.com> Cc: Marcelo Tosatti <marcelo@kvack.org> Cc: Eric Dumazet <dada1@cosmosbay.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Izik Eidus <izike@qumranet.com> Cc: Anthony Liguori <aliguori@us.ibm.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-29 02:46:29 +04:00
#include <linux/mmu_notifier.h>
#include <linux/nodemask.h>
#include <linux/pagemap.h>
#include <linux/mempolicy.h>
#include <linux/compiler.h>
#include <linux/cpuset.h>
[PATCH] hugepage: serialize hugepage allocation and instantiation Currently, no lock or mutex is held between allocating a hugepage and inserting it into the pagetables / page cache. When we do go to insert the page into pagetables or page cache, we recheck and may free the newly allocated hugepage. However, since the number of hugepages in the system is strictly limited, and it's usualy to want to use all of them, this can still lead to spurious allocation failures. For example, suppose two processes are both mapping (MAP_SHARED) the same hugepage file, large enough to consume the entire available hugepage pool. If they race instantiating the last page in the mapping, they will both attempt to allocate the last available hugepage. One will fail, of course, returning OOM from the fault and thus causing the process to be killed, despite the fact that the entire mapping can, in fact, be instantiated. The patch fixes this race by the simple method of adding a (sleeping) mutex to serialize the hugepage fault path between allocation and insertion into pagetables and/or page cache. It would be possible to avoid the serialization by catching the allocation failures, waiting on some condition, then rechecking to see if someone else has instantiated the page for us. Given the likely frequency of hugepage instantiations, it seems very doubtful it's worth the extra complexity. This patch causes no regression on the libhugetlbfs testsuite, and one test, which can trigger this race now passes where it previously failed. Actually, the test still sometimes fails, though less often and only as a shmat() failure, rather processes getting OOM killed by the VM. The dodgy heuristic tests in fs/hugetlbfs/inode.c for whether there's enough hugepage space aren't protected by the new mutex, and would be ugly to do so, so there's still a race there. Another patch to replace those tests with something saner for this reason as well as others coming... Signed-off-by: David Gibson <dwg@au1.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 11:08:53 +03:00
#include <linux/mutex.h>
memblock: replace BOOTMEM_ALLOC_* with MEMBLOCK variants Drop BOOTMEM_ALLOC_ACCESSIBLE and BOOTMEM_ALLOC_ANYWHERE in favor of identical MEMBLOCK definitions. Link: http://lkml.kernel.org/r/1536927045-23536-29-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Zankel <chris@zankel.net> Cc: "David S. Miller" <davem@davemloft.net> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Ingo Molnar <mingo@redhat.com> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Jonas Bonn <jonas@southpole.se> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Ley Foon Tan <lftan@altera.com> Cc: Mark Salter <msalter@redhat.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Palmer Dabbelt <palmer@sifive.com> Cc: Paul Burton <paul.burton@mips.com> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Serge Semin <fancer.lancer@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-31 01:09:44 +03:00
#include <linux/memblock.h>
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
#include <linux/sysfs.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 11:04:11 +03:00
#include <linux/slab.h>
mm/hugetlb: make hugetlb migration callback CMA aware new_non_cma_page() in gup.c requires to allocate the new page that is not on the CMA area. new_non_cma_page() implements it by using allocation scope APIs. However, there is a work-around for hugetlb. Normal hugetlb page allocation API for migration is alloc_huge_page_nodemask(). It consists of two steps. First is dequeing from the pool. Second is, if there is no available page on the queue, allocating by using the page allocator. new_non_cma_page() can't use this API since first step (deque) isn't aware of scope API to exclude CMA area. So, new_non_cma_page() exports hugetlb internal function for the second step, alloc_migrate_huge_page(), to global scope and uses it directly. This is suboptimal since hugetlb pages on the queue cannot be utilized. This patch tries to fix this situation by making the deque function on hugetlb CMA aware. In the deque function, CMA memory is skipped if PF_MEMALLOC_NOCMA flag is found. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Roman Gushchin <guro@fb.com> Link: http://lkml.kernel.org/r/1596180906-8442-2-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 04:37:38 +03:00
#include <linux/sched/mm.h>
hugetlbfs: check for pgoff value overflow A vma with vm_pgoff large enough to overflow a loff_t type when converted to a byte offset can be passed via the remap_file_pages system call. The hugetlbfs mmap routine uses the byte offset to calculate reservations and file size. A sequence such as: mmap(0x20a00000, 0x600000, 0, 0x66033, -1, 0); remap_file_pages(0x20a00000, 0x600000, 0, 0x20000000000000, 0); will result in the following when task exits/file closed, kernel BUG at mm/hugetlb.c:749! Call Trace: hugetlbfs_evict_inode+0x2f/0x40 evict+0xcb/0x190 __dentry_kill+0xcb/0x150 __fput+0x164/0x1e0 task_work_run+0x84/0xa0 exit_to_usermode_loop+0x7d/0x80 do_syscall_64+0x18b/0x190 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 The overflowed pgoff value causes hugetlbfs to try to set up a mapping with a negative range (end < start) that leaves invalid state which causes the BUG. The previous overflow fix to this code was incomplete and did not take the remap_file_pages system call into account. [mike.kravetz@oracle.com: v3] Link: http://lkml.kernel.org/r/20180309002726.7248-1-mike.kravetz@oracle.com [akpm@linux-foundation.org: include mmdebug.h] [akpm@linux-foundation.org: fix -ve left shift count on sh] Link: http://lkml.kernel.org/r/20180308210502.15952-1-mike.kravetz@oracle.com Fixes: 045c7a3f53d9 ("hugetlbfs: fix offset overflow in hugetlbfs mmap") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Nic Losby <blurbdust@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Yisheng Xie <xieyisheng1@huawei.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-03-23 02:17:13 +03:00
#include <linux/mmdebug.h>
#include <linux/sched/signal.h>
hugetlb, rmap: add reverse mapping for hugepage This patch adds reverse mapping feature for hugepage by introducing mapcount for shared/private-mapped hugepage and anon_vma for private-mapped hugepage. While hugepage is not currently swappable, reverse mapping can be useful for memory error handler. Without this patch, memory error handler cannot identify processes using the bad hugepage nor unmap it from them. That is: - for shared hugepage: we can collect processes using a hugepage through pagecache, but can not unmap the hugepage because of the lack of mapcount. - for privately mapped hugepage: we can neither collect processes nor unmap the hugepage. This patch solves these problems. This patch include the bug fix given by commit 23be7468e8, so reverts it. Dependency: "hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h" ChangeLog since May 24. - create hugetlb_inline.h and move is_vm_hugetlb_index() in it. - move functions setting up anon_vma for hugepage into mm/rmap.c. ChangeLog since May 13. - rebased to 2.6.34 - fix logic error (in case that private mapping and shared mapping coexist) - move is_vm_hugetlb_page() into include/linux/mm.h to use this function from linear_page_index() - define and use linear_hugepage_index() instead of compound_order() - use page_move_anon_rmap() in hugetlb_cow() - copy exclusive switch of __set_page_anon_rmap() into hugepage counterpart. - revert commit 24be7468 completely Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Acked-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andi Kleen <ak@linux.intel.com>
2010-05-28 04:29:16 +04:00
#include <linux/rmap.h>
#include <linux/string_helpers.h>
#include <linux/swap.h>
#include <linux/swapops.h>
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
#include <linux/jhash.h>
mm: replace all open encodings for NUMA_NO_NODE Patch series "Replace all open encodings for NUMA_NO_NODE", v3. All these places for replacement were found by running the following grep patterns on the entire kernel code. Please let me know if this might have missed some instances. This might also have replaced some false positives. I will appreciate suggestions, inputs and review. 1. git grep "nid == -1" 2. git grep "node == -1" 3. git grep "nid = -1" 4. git grep "node = -1" This patch (of 2): At present there are multiple places where invalid node number is encoded as -1. Even though implicitly understood it is always better to have macros in there. Replace these open encodings for an invalid node number with the global macro NUMA_NO_NODE. This helps remove NUMA related assumptions like 'invalid node' from various places redirecting them to a common definition. Link: http://lkml.kernel.org/r/1545127933-10711-2-git-send-email-anshuman.khandual@arm.com Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> [ixgbe] Acked-by: Jens Axboe <axboe@kernel.dk> [mtip32xx] Acked-by: Vinod Koul <vkoul@kernel.org> [dmaengine.c] Acked-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc] Acked-by: Doug Ledford <dledford@redhat.com> [drivers/infiniband] Cc: Joseph Qi <jiangqi903@gmail.com> Cc: Hans Verkuil <hverkuil@xs4all.nl> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-06 02:42:58 +03:00
#include <linux/numa.h>
mm/hugetlb: defer freeing of huge pages if in non-task context The following lockdep splat was observed when a certain hugetlbfs test was run: ================================ WARNING: inconsistent lock state 4.18.0-159.el8.x86_64+debug #1 Tainted: G W --------- - - -------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. swapper/30/0 [HC0[0]:SC1[1]:HE1:SE0] takes: ffffffff9acdc038 (hugetlb_lock){+.?.}, at: free_huge_page+0x36f/0xaa0 {SOFTIRQ-ON-W} state was registered at: lock_acquire+0x14f/0x3b0 _raw_spin_lock+0x30/0x70 __nr_hugepages_store_common+0x11b/0xb30 hugetlb_sysctl_handler_common+0x209/0x2d0 proc_sys_call_handler+0x37f/0x450 vfs_write+0x157/0x460 ksys_write+0xb8/0x170 do_syscall_64+0xa5/0x4d0 entry_SYSCALL_64_after_hwframe+0x6a/0xdf irq event stamp: 691296 hardirqs last enabled at (691296): [<ffffffff99bb034b>] _raw_spin_unlock_irqrestore+0x4b/0x60 hardirqs last disabled at (691295): [<ffffffff99bb0ad2>] _raw_spin_lock_irqsave+0x22/0x81 softirqs last enabled at (691284): [<ffffffff97ff0c63>] irq_enter+0xc3/0xe0 softirqs last disabled at (691285): [<ffffffff97ff0ebe>] irq_exit+0x23e/0x2b0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(hugetlb_lock); <Interrupt> lock(hugetlb_lock); *** DEADLOCK *** : Call Trace: <IRQ> __lock_acquire+0x146b/0x48c0 lock_acquire+0x14f/0x3b0 _raw_spin_lock+0x30/0x70 free_huge_page+0x36f/0xaa0 bio_check_pages_dirty+0x2fc/0x5c0 clone_endio+0x17f/0x670 [dm_mod] blk_update_request+0x276/0xe50 scsi_end_request+0x7b/0x6a0 scsi_io_completion+0x1c6/0x1570 blk_done_softirq+0x22e/0x350 __do_softirq+0x23d/0xad8 irq_exit+0x23e/0x2b0 do_IRQ+0x11a/0x200 common_interrupt+0xf/0xf </IRQ> Both the hugetbl_lock and the subpool lock can be acquired in free_huge_page(). One way to solve the problem is to make both locks irq-safe. However, Mike Kravetz had learned that the hugetlb_lock is held for a linear scan of ALL hugetlb pages during a cgroup reparentling operation. So it is just too long to have irq disabled unless we can break hugetbl_lock down into finer-grained locks with shorter lock hold times. Another alternative is to defer the freeing to a workqueue job. This patch implements the deferred freeing by adding a free_hpage_workfn() work function to do the actual freeing. The free_huge_page() call in a non-task context saves the page to be freed in the hpage_freelist linked list in a lockless manner using the llist APIs. The generic workqueue is used to process the work, but a dedicated workqueue can be used instead if it is desirable to have the huge page freed ASAP. Thanks to Kirill Tkhai <ktkhai@virtuozzo.com> for suggesting the use of llist APIs which simplfy the code. Link: http://lkml.kernel.org/r/20191217170331.30893-1-longman@redhat.com Signed-off-by: Waiman Long <longman@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-01-05 00:00:15 +03:00
#include <linux/llist.h>
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
#include <linux/cma.h>
mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY On UFFDIO_COPY, if we fail to copy the page contents while holding the hugetlb_fault_mutex, we will drop the mutex and return to the caller after allocating a page that consumed a reservation. In this case there may be a fault that double consumes the reservation. To handle this, we free the allocated page, fix the reservations, and allocate a temporary hugetlb page and return that to the caller. When the caller does the copy outside of the lock, we again check the cache, and allocate a page consuming the reservation, and copy over the contents. Test: Hacked the code locally such that resv_huge_pages underflows produce a warning and the copy_huge_page_from_user() always fails, then: ./tools/testing/selftests/vm/userfaultfd hugetlb_shared 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success ./tools/testing/selftests/vm/userfaultfd hugetlb 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success Both tests succeed and produce no warnings. After the test runs number of free/resv hugepages is correct. [yuehaibing@huawei.com: remove set but not used variable 'vm_alloc_shared'] Link: https://lkml.kernel.org/r/20210601141610.28332-1-yuehaibing@huawei.com [almasrymina@google.com: fix allocation error check and copy func name] Link: https://lkml.kernel.org/r/20210605010626.1459873-1-almasrymina@google.com Link: https://lkml.kernel.org/r/20210528005029.88088-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: YueHaibing <yuehaibing@huawei.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:19 +03:00
#include <linux/migrate.h>
hugetlb: clean up potential spectre issue warnings Recently introduced code allows numa nodes to be specified on the kernel command line for hugetlb allocations or CMA reservations. The node values are user specified and used as indicies into arrays. This generated the following smatch warnings: mm/hugetlb.c:4170 hugepages_setup() warn: potential spectre issue 'default_hugepages_in_node' [w] mm/hugetlb.c:4172 hugepages_setup() warn: potential spectre issue 'parsed_hstate->max_huge_pages_node' [w] mm/hugetlb.c:6898 cmdline_parse_hugetlb_cma() warn: potential spectre issue 'hugetlb_cma_size_in_node' [w] (local cap) Clean up by using array_index_nospec to sanitize array indicies. The routine cmdline_parse_hugetlb_cma has the same overflow/truncation issue addressed in [1]. That is also fixed with this change. [1] https://lore.kernel.org/linux-mm/20220209134018.8242-1-liuyuntao10@huawei.com/ As Michal pointed out, this is unlikely to be exploitable because it is __init code. But the patch suppresses the warnings. [mike.kravetz@oracle.com: v2] Link: https://lkml.kernel.org/r/20220218212946.35441-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20220217234218.192885-1-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Liu Yuntao <liuyuntao10@huawei.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-03-23 00:45:20 +03:00
#include <linux/nospec.h>
#include <asm/page.h>
mm: remove unneeded includes of <asm/pgalloc.h> Patch series "mm: cleanup usage of <asm/pgalloc.h>" Most architectures have very similar versions of pXd_alloc_one() and pXd_free_one() for intermediate levels of page table. These patches add generic versions of these functions in <asm-generic/pgalloc.h> and enable use of the generic functions where appropriate. In addition, functions declared and defined in <asm/pgalloc.h> headers are used mostly by core mm and early mm initialization in arch and there is no actual reason to have the <asm/pgalloc.h> included all over the place. The first patch in this series removes unneeded includes of <asm/pgalloc.h> In the end it didn't work out as neatly as I hoped and moving pXd_alloc_track() definitions to <asm-generic/pgalloc.h> would require unnecessary changes to arches that have custom page table allocations, so I've decided to move lib/ioremap.c to mm/ and make pgalloc-track.h local to mm/. This patch (of 8): In most cases <asm/pgalloc.h> header is required only for allocations of page table memory. Most of the .c files that include that header do not use symbols declared in <asm/pgalloc.h> and do not require that header. As for the other header files that used to include <asm/pgalloc.h>, it is possible to move that include into the .c file that actually uses symbols from <asm/pgalloc.h> and drop the include from the header file. The process was somewhat automated using sed -i -E '/[<"]asm\/pgalloc\.h/d' \ $(grep -L -w -f /tmp/xx \ $(git grep -E -l '[<"]asm/pgalloc\.h')) where /tmp/xx contains all the symbols defined in arch/*/include/asm/pgalloc.h. [rppt@linux.ibm.com: fix powerpc warning] Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Pekka Enberg <penberg@kernel.org> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> [m68k] Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Joerg Roedel <joro@8bytes.org> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com> Cc: Stafford Horne <shorne@gmail.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Joerg Roedel <jroedel@suse.de> Cc: Matthew Wilcox <willy@infradead.org> Link: http://lkml.kernel.org/r/20200627143453.31835-1-rppt@kernel.org Link: http://lkml.kernel.org/r/20200627143453.31835-2-rppt@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-07 09:22:28 +03:00
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <linux/io.h>
#include <linux/hugetlb.h>
#include <linux/hugetlb_cgroup.h>
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
#include <linux/node.h>
mm, hugetlb: do not rely on overcommit limit during migration hugepage migration relies on __alloc_buddy_huge_page to get a new page. This has 2 main disadvantages. 1) it doesn't allow to migrate any huge page if the pool is used completely which is not an exceptional case as the pool is static and unused memory is just wasted. 2) it leads to a weird semantic when migration between two numa nodes might increase the pool size of the destination NUMA node while the page is in use. The issue is caused by per NUMA node surplus pages tracking (see free_huge_page). Address both issues by changing the way how we allocate and account pages allocated for migration. Those should temporal by definition. So we mark them that way (we will abuse page flags in the 3rd page) and update free_huge_page to free such pages to the page allocator. Page migration path then just transfers the temporal status from the new page to the old one which will be freed on the last reference. The global surplus count will never change during this path but we still have to be careful when migrating a per-node suprlus page. This is now handled in move_hugetlb_state which is called from the migration path and it copies the hugetlb specific page state and fixes up the accounting when needed Rename __alloc_buddy_huge_page to __alloc_surplus_huge_page to better reflect its purpose. The new allocation routine for the migration path is __alloc_migrate_huge_page. The user visible effect of this patch is that migrated pages are really temporal and they travel between NUMA nodes as per the migration request: Before migration /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 After /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 with the previous implementation, both nodes would have nr_hugepages:1 until the page is freed. Link: http://lkml.kernel.org/r/20180103093213.26329-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:48 +03:00
#include <linux/page_owner.h>
#include "internal.h"
mm: hugetlb: free the vmemmap pages associated with each HugeTLB page Every HugeTLB has more than one struct page structure. We __know__ that we only use the first 4 (__NR_USED_SUBPAGE) struct page structures to store metadata associated with each HugeTLB. There are a lot of struct page structures associated with each HugeTLB page. For tail pages, the value of compound_head is the same. So we can reuse first page of tail page structures. We map the virtual addresses of the remaining pages of tail page structures to the first tail page struct, and then free these page frames. Therefore, we need to reserve two pages as vmemmap areas. When we allocate a HugeTLB page from the buddy, we can free some vmemmap pages associated with each HugeTLB page. It is more appropriate to do it in the prep_new_huge_page(). The free_vmemmap_pages_per_hpage(), which indicates how many vmemmap pages associated with a HugeTLB page can be freed, returns zero for now, which means the feature is disabled. We will enable it once all the infrastructure is there. [willy@infradead.org: fix documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-5-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-5-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Oscar Salvador <osalvador@suse.de> Tested-by: Chen Huang <chenhuang5@huawei.com> Tested-by: Bodeddula Balasubramaniam <bodeddub@amazon.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:13 +03:00
#include "hugetlb_vmemmap.h"
int hugetlb_max_hstate __read_mostly;
unsigned int default_hstate_idx;
struct hstate hstates[HUGE_MAX_HSTATE];
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
#ifdef CONFIG_CMA
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
static struct cma *hugetlb_cma[MAX_NUMNODES];
hugetlb: support node specified when using cma for gigantic hugepages Now the size of CMA area for gigantic hugepages runtime allocation is balanced for all online nodes, but we also want to specify the size of CMA per-node, or only one node in some cases, which are similar with patch [1]. For example, on some multi-nodes systems, each node's memory can be different, allocating the same size of CMA for each node is not suitable for the low-memory nodes. Meanwhile some workloads like DPDK mentioned by Zhenguo in patch [1] only need hugepages in one node. On the other hand, we have some machines with multiple types of memory, like DRAM and PMEM (persistent memory). On this system, we may want to specify all the hugepages only on DRAM node, or specify the proportion of DRAM node and PMEM node, to tuning the performance of the workloads. Thus this patch adds node format for 'hugetlb_cma' parameter to support specifying the size of CMA per-node. An example is as follows: hugetlb_cma=0:5G,2:5G which means allocating 5G size of CMA area on node 0 and node 2 respectively. And the users should use the node specific sysfs file to allocate the gigantic hugepages if specified the CMA size on that node. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com [1] Link: https://lkml.kernel.org/r/bb790775ca60bb8f4b26956bb3f6988f74e075c7.1634261144.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:46 +03:00
static unsigned long hugetlb_cma_size_in_node[MAX_NUMNODES] __initdata;
hugetlb: be sure to free demoted CMA pages to CMA When huge page demotion is fully implemented, gigantic pages can be demoted to a smaller huge page size. For example, on x86 a 1G page can be demoted to 512 2M pages. However, gigantic pages can potentially be allocated from CMA. If a gigantic page which was allocated from CMA is demoted, the corresponding demoted pages needs to be returned to CMA. Use the new interface cma_pages_valid() to determine if a non-gigantic hugetlb page should be freed to CMA. Also, clear mapping field of these pages as expected by cma_release. This also requires a change to CMA region creation for gigantic pages. CMA uses a per-region bit map to track allocations. When setting up the region, you specify how many pages each bit represents. Currently, only gigantic pages are allocated/freed from CMA so the region is set up such that one bit represents a gigantic page size allocation. With demote, a gigantic page (allocation) could be split into smaller size pages. And, these smaller size pages will be freed to CMA. So, since the per-region bit map needs to be set up to represent the smallest allocation/free size, it now needs to be set to the smallest huge page size which can be freed to CMA. Unfortunately, we set up the CMA region for huge pages before we set up huge pages sizes (hstates). So, technically we do not know the smallest huge page size as this can change via command line options and architecture specific code. Therefore, at region setup time we use HUGETLB_PAGE_ORDER as the smallest possible huge page size that can be given back to CMA. It is possible that this value is sub-optimal for some architectures/config options. If needed, this can be addressed in follow on work. Link: https://lkml.kernel.org/r/20211007181918.136982-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:27 +03:00
static bool hugetlb_cma_page(struct page *page, unsigned int order)
{
return cma_pages_valid(hugetlb_cma[page_to_nid(page)], page,
1 << order);
}
#else
static bool hugetlb_cma_page(struct page *page, unsigned int order)
{
return false;
}
#endif
static unsigned long hugetlb_cma_size __initdata;
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
/*
* Minimum page order among possible hugepage sizes, set to a proper value
* at boot time.
*/
static unsigned int minimum_order __read_mostly = UINT_MAX;
__initdata LIST_HEAD(huge_boot_pages);
/* for command line parsing */
static struct hstate * __initdata parsed_hstate;
static unsigned long __initdata default_hstate_max_huge_pages;
mm/hugetlb: introduce hugetlb_bad_size() When any unsupported hugepage size is specified, 'hugepagesz=' and 'hugepages=' should be ignored during command line parsing until any supported hugepage size is found. But currently incorrect number of hugepages are allocated when unsupported size is specified as it fails to ignore the 'hugepages=' command. Test case: Note that this is specific to x86 architecture. Boot the kernel with command line option 'hugepagesz=256M hugepages=X'. After boot, dmesg output shows that X number of hugepages of the size 2M is pre-allocated instead of 0. So, to handle such command line options, introduce new routine hugetlb_bad_size. The routine hugetlb_bad_size sets the global variable parsed_valid_hugepagesz. We are using parsed_valid_hugepagesz to save the state when unsupported hugepagesize is found so that we can ignore the 'hugepages=' parameters after that and then reset the variable when supported hugepage size is found. The routine hugetlb_bad_size can be called while setting 'hugepagesz=' parameter in an architecture specific code. Signed-off-by: Vaishali Thakkar <vaishali.thakkar@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com> Cc: Dominik Dingel <dingel@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: James Hogan <james.hogan@imgtec.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-20 03:11:04 +03:00
static bool __initdata parsed_valid_hugepagesz = true;
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
static bool __initdata parsed_default_hugepagesz;
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
static unsigned int default_hugepages_in_node[MAX_NUMNODES] __initdata;
[PATCH] hugepage: serialize hugepage allocation and instantiation Currently, no lock or mutex is held between allocating a hugepage and inserting it into the pagetables / page cache. When we do go to insert the page into pagetables or page cache, we recheck and may free the newly allocated hugepage. However, since the number of hugepages in the system is strictly limited, and it's usualy to want to use all of them, this can still lead to spurious allocation failures. For example, suppose two processes are both mapping (MAP_SHARED) the same hugepage file, large enough to consume the entire available hugepage pool. If they race instantiating the last page in the mapping, they will both attempt to allocate the last available hugepage. One will fail, of course, returning OOM from the fault and thus causing the process to be killed, despite the fact that the entire mapping can, in fact, be instantiated. The patch fixes this race by the simple method of adding a (sleeping) mutex to serialize the hugepage fault path between allocation and insertion into pagetables and/or page cache. It would be possible to avoid the serialization by catching the allocation failures, waiting on some condition, then rechecking to see if someone else has instantiated the page for us. Given the likely frequency of hugepage instantiations, it seems very doubtful it's worth the extra complexity. This patch causes no regression on the libhugetlbfs testsuite, and one test, which can trigger this race now passes where it previously failed. Actually, the test still sometimes fails, though less often and only as a shmat() failure, rather processes getting OOM killed by the VM. The dodgy heuristic tests in fs/hugetlbfs/inode.c for whether there's enough hugepage space aren't protected by the new mutex, and would be ugly to do so, so there's still a race there. Another patch to replace those tests with something saner for this reason as well as others coming... Signed-off-by: David Gibson <dwg@au1.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 11:08:53 +03:00
/*
mm: migrate: make core migration code aware of hugepage Currently hugepage migration is available only for soft offlining, but it's also useful for some other users of page migration (clearly because users of hugepage can enjoy the benefit of mempolicy and memory hotplug.) So this patchset tries to extend such users to support hugepage migration. The target of this patchset is to enable hugepage migration for NUMA related system calls (migrate_pages(2), move_pages(2), and mbind(2)), and memory hotplug. This patchset does not add hugepage migration for memory compaction, because users of memory compaction mainly expect to construct thp by arranging raw pages, and there's little or no need to compact hugepages. CMA, another user of page migration, can have benefit from hugepage migration, but is not enabled to support it for now (just because of lack of testing and expertise in CMA.) Hugepage migration of non pmd-based hugepage (for example 1GB hugepage in x86_64, or hugepages in architectures like ia64) is not enabled for now (again, because of lack of testing.) As for how these are achived, I extended the API (migrate_pages()) to handle hugepage (with patch 1 and 2) and adjusted code of each caller to check and collect movable hugepages (with patch 3-7). Remaining 2 patches are kind of miscellaneous ones to avoid unexpected behavior. Patch 8 is about making sure that we only migrate pmd-based hugepages. And patch 9 is about choosing appropriate zone for hugepage allocation. My test is mainly functional one, simply kicking hugepage migration via each entry point and confirm that migration is done correctly. Test code is available here: git://github.com/Naoya-Horiguchi/test_hugepage_migration_extension.git And I always run libhugetlbfs test when changing hugetlbfs's code. With this patchset, no regression was found in the test. This patch (of 9): Before enabling each user of page migration to support hugepage, this patch enables the list of pages for migration to link not only LRU pages, but also hugepages. As a result, putback_movable_pages() and migrate_pages() can handle both of LRU pages and hugepages. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Acked-by: Hillf Danton <dhillf@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:21:59 +04:00
* Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
* free_huge_pages, and surplus_huge_pages.
[PATCH] hugepage: serialize hugepage allocation and instantiation Currently, no lock or mutex is held between allocating a hugepage and inserting it into the pagetables / page cache. When we do go to insert the page into pagetables or page cache, we recheck and may free the newly allocated hugepage. However, since the number of hugepages in the system is strictly limited, and it's usualy to want to use all of them, this can still lead to spurious allocation failures. For example, suppose two processes are both mapping (MAP_SHARED) the same hugepage file, large enough to consume the entire available hugepage pool. If they race instantiating the last page in the mapping, they will both attempt to allocate the last available hugepage. One will fail, of course, returning OOM from the fault and thus causing the process to be killed, despite the fact that the entire mapping can, in fact, be instantiated. The patch fixes this race by the simple method of adding a (sleeping) mutex to serialize the hugepage fault path between allocation and insertion into pagetables and/or page cache. It would be possible to avoid the serialization by catching the allocation failures, waiting on some condition, then rechecking to see if someone else has instantiated the page for us. Given the likely frequency of hugepage instantiations, it seems very doubtful it's worth the extra complexity. This patch causes no regression on the libhugetlbfs testsuite, and one test, which can trigger this race now passes where it previously failed. Actually, the test still sometimes fails, though less often and only as a shmat() failure, rather processes getting OOM killed by the VM. The dodgy heuristic tests in fs/hugetlbfs/inode.c for whether there's enough hugepage space aren't protected by the new mutex, and would be ugly to do so, so there's still a race there. Another patch to replace those tests with something saner for this reason as well as others coming... Signed-off-by: David Gibson <dwg@au1.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 11:08:53 +03:00
*/
DEFINE_SPINLOCK(hugetlb_lock);
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
/*
* Serializes faults on the same logical page. This is used to
* prevent spurious OOMs when the hugepage pool is fully utilized.
*/
static int num_fault_mutexes;
struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp;
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
/* Forward declaration */
static int hugetlb_acct_memory(struct hstate *h, long delta);
static inline bool subpool_is_free(struct hugepage_subpool *spool)
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
{
if (spool->count)
return false;
if (spool->max_hpages != -1)
return spool->used_hpages == 0;
if (spool->min_hpages != -1)
return spool->rsv_hpages == spool->min_hpages;
return true;
}
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
static inline void unlock_or_release_subpool(struct hugepage_subpool *spool,
unsigned long irq_flags)
{
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irqrestore(&spool->lock, irq_flags);
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
/* If no pages are used, and no other handles to the subpool
* remain, give up any reservations based on minimum size and
* free the subpool */
if (subpool_is_free(spool)) {
if (spool->min_hpages != -1)
hugetlb_acct_memory(spool->hstate,
-spool->min_hpages);
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
kfree(spool);
}
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
}
struct hugepage_subpool *hugepage_new_subpool(struct hstate *h, long max_hpages,
long min_hpages)
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
{
struct hugepage_subpool *spool;
hugetlbfs: add minimum size tracking fields to subpool structure hugetlbfs allocates huge pages from the global pool as needed. Even if the global pool contains a sufficient number pages for the filesystem size at mount time, those global pages could be grabbed for some other use. As a result, filesystem huge page allocations may fail due to lack of pages. Applications such as a database want to use huge pages for performance reasons. hugetlbfs filesystem semantics with ownership and modes work well to manage access to a pool of huge pages. However, the application would like some reasonable assurance that allocations will not fail due to a lack of huge pages. At application startup time, the application would like to configure itself to use a specific number of huge pages. Before starting, the application can check to make sure that enough huge pages exist in the system global pools. However, there are no guarantees that those pages will be available when needed by the application. What the application wants is exclusive use of a subset of huge pages. Add a new hugetlbfs mount option 'min_size=<value>' to indicate that the specified number of pages will be available for use by the filesystem. At mount time, this number of huge pages will be reserved for exclusive use of the filesystem. If there is not a sufficient number of free pages, the mount will fail. As pages are allocated to and freeed from the filesystem, the number of reserved pages is adjusted so that the specified minimum is maintained. This patch (of 4): Add a field to the subpool structure to indicate the minimimum number of huge pages to always be used by this subpool. This minimum count includes allocated pages as well as reserved pages. If the minimum number of pages for the subpool have not been allocated, pages are reserved up to this minimum. An additional field (rsv_hpages) is used to track the number of pages reserved to meet this minimum size. The hstate pointer in the subpool is convenient to have when reserving and unreserving the pages. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-16 02:13:36 +03:00
spool = kzalloc(sizeof(*spool), GFP_KERNEL);
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
if (!spool)
return NULL;
spin_lock_init(&spool->lock);
spool->count = 1;
spool->max_hpages = max_hpages;
spool->hstate = h;
spool->min_hpages = min_hpages;
if (min_hpages != -1 && hugetlb_acct_memory(h, min_hpages)) {
kfree(spool);
return NULL;
}
spool->rsv_hpages = min_hpages;
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
return spool;
}
void hugepage_put_subpool(struct hugepage_subpool *spool)
{
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
unsigned long flags;
spin_lock_irqsave(&spool->lock, flags);
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
BUG_ON(!spool->count);
spool->count--;
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
unlock_or_release_subpool(spool, flags);
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
}
/*
* Subpool accounting for allocating and reserving pages.
* Return -ENOMEM if there are not enough resources to satisfy the
* request. Otherwise, return the number of pages by which the
* global pools must be adjusted (upward). The returned value may
* only be different than the passed value (delta) in the case where
* a subpool minimum size must be maintained.
*/
static long hugepage_subpool_get_pages(struct hugepage_subpool *spool,
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
long delta)
{
long ret = delta;
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
if (!spool)
return ret;
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&spool->lock);
if (spool->max_hpages != -1) { /* maximum size accounting */
if ((spool->used_hpages + delta) <= spool->max_hpages)
spool->used_hpages += delta;
else {
ret = -ENOMEM;
goto unlock_ret;
}
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
}
2016-05-20 03:11:01 +03:00
/* minimum size accounting */
if (spool->min_hpages != -1 && spool->rsv_hpages) {
if (delta > spool->rsv_hpages) {
/*
* Asking for more reserves than those already taken on
* behalf of subpool. Return difference.
*/
ret = delta - spool->rsv_hpages;
spool->rsv_hpages = 0;
} else {
ret = 0; /* reserves already accounted for */
spool->rsv_hpages -= delta;
}
}
unlock_ret:
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&spool->lock);
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
return ret;
}
/*
* Subpool accounting for freeing and unreserving pages.
* Return the number of global page reservations that must be dropped.
* The return value may only be different than the passed value (delta)
* in the case where a subpool minimum size must be maintained.
*/
static long hugepage_subpool_put_pages(struct hugepage_subpool *spool,
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
long delta)
{
long ret = delta;
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
unsigned long flags;
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
if (!spool)
return delta;
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irqsave(&spool->lock, flags);
if (spool->max_hpages != -1) /* maximum size accounting */
spool->used_hpages -= delta;
2016-05-20 03:11:01 +03:00
/* minimum size accounting */
if (spool->min_hpages != -1 && spool->used_hpages < spool->min_hpages) {
if (spool->rsv_hpages + delta <= spool->min_hpages)
ret = 0;
else
ret = spool->rsv_hpages + delta - spool->min_hpages;
spool->rsv_hpages += delta;
if (spool->rsv_hpages > spool->min_hpages)
spool->rsv_hpages = spool->min_hpages;
}
/*
* If hugetlbfs_put_super couldn't free spool due to an outstanding
* quota reference, free it now.
*/
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
unlock_or_release_subpool(spool, flags);
return ret;
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
}
static inline struct hugepage_subpool *subpool_inode(struct inode *inode)
{
return HUGETLBFS_SB(inode->i_sb)->spool;
}
static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
{
return subpool_inode(file_inode(vma->vm_file));
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
}
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
/* Helper that removes a struct file_region from the resv_map cache and returns
* it for use.
*/
static struct file_region *
get_file_region_entry_from_cache(struct resv_map *resv, long from, long to)
{
struct file_region *nrg = NULL;
VM_BUG_ON(resv->region_cache_count <= 0);
resv->region_cache_count--;
nrg = list_first_entry(&resv->region_cache, struct file_region, link);
list_del(&nrg->link);
nrg->from = from;
nrg->to = to;
return nrg;
}
static void copy_hugetlb_cgroup_uncharge_info(struct file_region *nrg,
struct file_region *rg)
{
#ifdef CONFIG_CGROUP_HUGETLB
nrg->reservation_counter = rg->reservation_counter;
nrg->css = rg->css;
if (rg->css)
css_get(rg->css);
#endif
}
/* Helper that records hugetlb_cgroup uncharge info. */
static void record_hugetlb_cgroup_uncharge_info(struct hugetlb_cgroup *h_cg,
struct hstate *h,
struct resv_map *resv,
struct file_region *nrg)
{
#ifdef CONFIG_CGROUP_HUGETLB
if (h_cg) {
nrg->reservation_counter =
&h_cg->rsvd_hugepage[hstate_index(h)];
nrg->css = &h_cg->css;
hugetlb_cgroup: fix imbalanced css_get and css_put pair for shared mappings The current implementation of hugetlb_cgroup for shared mappings could have different behavior. Consider the following two scenarios: 1.Assume initial css reference count of hugetlb_cgroup is 1: 1.1 Call hugetlb_reserve_pages with from = 1, to = 2. So css reference count is 2 associated with 1 file_region. 1.2 Call hugetlb_reserve_pages with from = 2, to = 3. So css reference count is 3 associated with 2 file_region. 1.3 coalesce_file_region will coalesce these two file_regions into one. So css reference count is 3 associated with 1 file_region now. 2.Assume initial css reference count of hugetlb_cgroup is 1 again: 2.1 Call hugetlb_reserve_pages with from = 1, to = 3. So css reference count is 2 associated with 1 file_region. Therefore, we might have one file_region while holding one or more css reference counts. This inconsistency could lead to imbalanced css_get() and css_put() pair. If we do css_put one by one (i.g. hole punch case), scenario 2 would put one more css reference. If we do css_put all together (i.g. truncate case), scenario 1 will leak one css reference. The imbalanced css_get() and css_put() pair would result in a non-zero reference when we try to destroy the hugetlb cgroup. The hugetlb cgroup directory is removed __but__ associated resource is not freed. This might result in OOM or can not create a new hugetlb cgroup in a busy workload ultimately. In order to fix this, we have to make sure that one file_region must hold exactly one css reference. So in coalesce_file_region case, we should release one css reference before coalescence. Also only put css reference when the entire file_region is removed. The last thing to note is that the caller of region_add() will only hold one reference to h_cg->css for the whole contiguous reservation region. But this area might be scattered when there are already some file_regions reside in it. As a result, many file_regions may share only one h_cg->css reference. In order to ensure that one file_region must hold exactly one css reference, we should do css_get() for each file_region and release the reference held by caller when they are done. [linmiaohe@huawei.com: fix imbalanced css_get and css_put pair for shared mappings] Link: https://lkml.kernel.org/r/20210316023002.53921-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210301120540.37076-1-linmiaohe@huawei.com Fixes: 075a61d07a8e ("hugetlb_cgroup: add accounting for shared mappings") Reported-by: kernel test robot <lkp@intel.com> (auto build test ERROR) Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Wanpeng Li <liwp.linux@gmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-25 07:37:17 +03:00
/*
* The caller will hold exactly one h_cg->css reference for the
* whole contiguous reservation region. But this area might be
* scattered when there are already some file_regions reside in
* it. As a result, many file_regions may share only one css
* reference. In order to ensure that one file_region must hold
* exactly one h_cg->css reference, we should do css_get for
* each file_region and leave the reference held by caller
* untouched.
*/
css_get(&h_cg->css);
if (!resv->pages_per_hpage)
resv->pages_per_hpage = pages_per_huge_page(h);
/* pages_per_hpage should be the same for all entries in
* a resv_map.
*/
VM_BUG_ON(resv->pages_per_hpage != pages_per_huge_page(h));
} else {
nrg->reservation_counter = NULL;
nrg->css = NULL;
}
#endif
}
hugetlb_cgroup: fix imbalanced css_get and css_put pair for shared mappings The current implementation of hugetlb_cgroup for shared mappings could have different behavior. Consider the following two scenarios: 1.Assume initial css reference count of hugetlb_cgroup is 1: 1.1 Call hugetlb_reserve_pages with from = 1, to = 2. So css reference count is 2 associated with 1 file_region. 1.2 Call hugetlb_reserve_pages with from = 2, to = 3. So css reference count is 3 associated with 2 file_region. 1.3 coalesce_file_region will coalesce these two file_regions into one. So css reference count is 3 associated with 1 file_region now. 2.Assume initial css reference count of hugetlb_cgroup is 1 again: 2.1 Call hugetlb_reserve_pages with from = 1, to = 3. So css reference count is 2 associated with 1 file_region. Therefore, we might have one file_region while holding one or more css reference counts. This inconsistency could lead to imbalanced css_get() and css_put() pair. If we do css_put one by one (i.g. hole punch case), scenario 2 would put one more css reference. If we do css_put all together (i.g. truncate case), scenario 1 will leak one css reference. The imbalanced css_get() and css_put() pair would result in a non-zero reference when we try to destroy the hugetlb cgroup. The hugetlb cgroup directory is removed __but__ associated resource is not freed. This might result in OOM or can not create a new hugetlb cgroup in a busy workload ultimately. In order to fix this, we have to make sure that one file_region must hold exactly one css reference. So in coalesce_file_region case, we should release one css reference before coalescence. Also only put css reference when the entire file_region is removed. The last thing to note is that the caller of region_add() will only hold one reference to h_cg->css for the whole contiguous reservation region. But this area might be scattered when there are already some file_regions reside in it. As a result, many file_regions may share only one h_cg->css reference. In order to ensure that one file_region must hold exactly one css reference, we should do css_get() for each file_region and release the reference held by caller when they are done. [linmiaohe@huawei.com: fix imbalanced css_get and css_put pair for shared mappings] Link: https://lkml.kernel.org/r/20210316023002.53921-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210301120540.37076-1-linmiaohe@huawei.com Fixes: 075a61d07a8e ("hugetlb_cgroup: add accounting for shared mappings") Reported-by: kernel test robot <lkp@intel.com> (auto build test ERROR) Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Wanpeng Li <liwp.linux@gmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-25 07:37:17 +03:00
static void put_uncharge_info(struct file_region *rg)
{
#ifdef CONFIG_CGROUP_HUGETLB
if (rg->css)
css_put(rg->css);
#endif
}
hugetlb: support file_region coalescing again An earlier patch in this series disabled file_region coalescing in order to hang the hugetlb_cgroup uncharge info on the file_region entries. This patch re-adds support for coalescing of file_region entries. Essentially everytime we add an entry, we call a recursive function that tries to coalesce the added region with the regions next to it. The worst case call depth for this function is 3: one to coalesce with the region next to it, one to coalesce to the region prev, and one to reach the base case. This is an important performance optimization as private mappings add their entries page by page, and we could incur big performance costs for large mappings with lots of file_region entries in their resv_map. [almasrymina@google.com: fix CONFIG_CGROUP_HUGETLB ifdefs] Link: http://lkml.kernel.org/r/20200214204544.231482-1-almasrymina@google.com [almasrymina@google.com: remove check_coalesce_bug debug code] Link: http://lkml.kernel.org/r/20200219233610.13808-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Randy Dunlap <rdunlap@infradead.org> Link: http://lkml.kernel.org/r/20200211213128.73302-7-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:35 +03:00
static bool has_same_uncharge_info(struct file_region *rg,
struct file_region *org)
{
#ifdef CONFIG_CGROUP_HUGETLB
return rg->reservation_counter == org->reservation_counter &&
hugetlb: support file_region coalescing again An earlier patch in this series disabled file_region coalescing in order to hang the hugetlb_cgroup uncharge info on the file_region entries. This patch re-adds support for coalescing of file_region entries. Essentially everytime we add an entry, we call a recursive function that tries to coalesce the added region with the regions next to it. The worst case call depth for this function is 3: one to coalesce with the region next to it, one to coalesce to the region prev, and one to reach the base case. This is an important performance optimization as private mappings add their entries page by page, and we could incur big performance costs for large mappings with lots of file_region entries in their resv_map. [almasrymina@google.com: fix CONFIG_CGROUP_HUGETLB ifdefs] Link: http://lkml.kernel.org/r/20200214204544.231482-1-almasrymina@google.com [almasrymina@google.com: remove check_coalesce_bug debug code] Link: http://lkml.kernel.org/r/20200219233610.13808-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Randy Dunlap <rdunlap@infradead.org> Link: http://lkml.kernel.org/r/20200211213128.73302-7-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:35 +03:00
rg->css == org->css;
#else
return true;
#endif
}
static void coalesce_file_region(struct resv_map *resv, struct file_region *rg)
{
struct file_region *nrg = NULL, *prg = NULL;
prg = list_prev_entry(rg, link);
if (&prg->link != &resv->regions && prg->to == rg->from &&
has_same_uncharge_info(prg, rg)) {
prg->to = rg->to;
list_del(&rg->link);
hugetlb_cgroup: fix imbalanced css_get and css_put pair for shared mappings The current implementation of hugetlb_cgroup for shared mappings could have different behavior. Consider the following two scenarios: 1.Assume initial css reference count of hugetlb_cgroup is 1: 1.1 Call hugetlb_reserve_pages with from = 1, to = 2. So css reference count is 2 associated with 1 file_region. 1.2 Call hugetlb_reserve_pages with from = 2, to = 3. So css reference count is 3 associated with 2 file_region. 1.3 coalesce_file_region will coalesce these two file_regions into one. So css reference count is 3 associated with 1 file_region now. 2.Assume initial css reference count of hugetlb_cgroup is 1 again: 2.1 Call hugetlb_reserve_pages with from = 1, to = 3. So css reference count is 2 associated with 1 file_region. Therefore, we might have one file_region while holding one or more css reference counts. This inconsistency could lead to imbalanced css_get() and css_put() pair. If we do css_put one by one (i.g. hole punch case), scenario 2 would put one more css reference. If we do css_put all together (i.g. truncate case), scenario 1 will leak one css reference. The imbalanced css_get() and css_put() pair would result in a non-zero reference when we try to destroy the hugetlb cgroup. The hugetlb cgroup directory is removed __but__ associated resource is not freed. This might result in OOM or can not create a new hugetlb cgroup in a busy workload ultimately. In order to fix this, we have to make sure that one file_region must hold exactly one css reference. So in coalesce_file_region case, we should release one css reference before coalescence. Also only put css reference when the entire file_region is removed. The last thing to note is that the caller of region_add() will only hold one reference to h_cg->css for the whole contiguous reservation region. But this area might be scattered when there are already some file_regions reside in it. As a result, many file_regions may share only one h_cg->css reference. In order to ensure that one file_region must hold exactly one css reference, we should do css_get() for each file_region and release the reference held by caller when they are done. [linmiaohe@huawei.com: fix imbalanced css_get and css_put pair for shared mappings] Link: https://lkml.kernel.org/r/20210316023002.53921-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210301120540.37076-1-linmiaohe@huawei.com Fixes: 075a61d07a8e ("hugetlb_cgroup: add accounting for shared mappings") Reported-by: kernel test robot <lkp@intel.com> (auto build test ERROR) Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Wanpeng Li <liwp.linux@gmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-25 07:37:17 +03:00
put_uncharge_info(rg);
hugetlb: support file_region coalescing again An earlier patch in this series disabled file_region coalescing in order to hang the hugetlb_cgroup uncharge info on the file_region entries. This patch re-adds support for coalescing of file_region entries. Essentially everytime we add an entry, we call a recursive function that tries to coalesce the added region with the regions next to it. The worst case call depth for this function is 3: one to coalesce with the region next to it, one to coalesce to the region prev, and one to reach the base case. This is an important performance optimization as private mappings add their entries page by page, and we could incur big performance costs for large mappings with lots of file_region entries in their resv_map. [almasrymina@google.com: fix CONFIG_CGROUP_HUGETLB ifdefs] Link: http://lkml.kernel.org/r/20200214204544.231482-1-almasrymina@google.com [almasrymina@google.com: remove check_coalesce_bug debug code] Link: http://lkml.kernel.org/r/20200219233610.13808-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Randy Dunlap <rdunlap@infradead.org> Link: http://lkml.kernel.org/r/20200211213128.73302-7-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:35 +03:00
kfree(rg);
rg = prg;
hugetlb: support file_region coalescing again An earlier patch in this series disabled file_region coalescing in order to hang the hugetlb_cgroup uncharge info on the file_region entries. This patch re-adds support for coalescing of file_region entries. Essentially everytime we add an entry, we call a recursive function that tries to coalesce the added region with the regions next to it. The worst case call depth for this function is 3: one to coalesce with the region next to it, one to coalesce to the region prev, and one to reach the base case. This is an important performance optimization as private mappings add their entries page by page, and we could incur big performance costs for large mappings with lots of file_region entries in their resv_map. [almasrymina@google.com: fix CONFIG_CGROUP_HUGETLB ifdefs] Link: http://lkml.kernel.org/r/20200214204544.231482-1-almasrymina@google.com [almasrymina@google.com: remove check_coalesce_bug debug code] Link: http://lkml.kernel.org/r/20200219233610.13808-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Randy Dunlap <rdunlap@infradead.org> Link: http://lkml.kernel.org/r/20200211213128.73302-7-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:35 +03:00
}
nrg = list_next_entry(rg, link);
if (&nrg->link != &resv->regions && nrg->from == rg->to &&
has_same_uncharge_info(nrg, rg)) {
nrg->from = rg->from;
list_del(&rg->link);
hugetlb_cgroup: fix imbalanced css_get and css_put pair for shared mappings The current implementation of hugetlb_cgroup for shared mappings could have different behavior. Consider the following two scenarios: 1.Assume initial css reference count of hugetlb_cgroup is 1: 1.1 Call hugetlb_reserve_pages with from = 1, to = 2. So css reference count is 2 associated with 1 file_region. 1.2 Call hugetlb_reserve_pages with from = 2, to = 3. So css reference count is 3 associated with 2 file_region. 1.3 coalesce_file_region will coalesce these two file_regions into one. So css reference count is 3 associated with 1 file_region now. 2.Assume initial css reference count of hugetlb_cgroup is 1 again: 2.1 Call hugetlb_reserve_pages with from = 1, to = 3. So css reference count is 2 associated with 1 file_region. Therefore, we might have one file_region while holding one or more css reference counts. This inconsistency could lead to imbalanced css_get() and css_put() pair. If we do css_put one by one (i.g. hole punch case), scenario 2 would put one more css reference. If we do css_put all together (i.g. truncate case), scenario 1 will leak one css reference. The imbalanced css_get() and css_put() pair would result in a non-zero reference when we try to destroy the hugetlb cgroup. The hugetlb cgroup directory is removed __but__ associated resource is not freed. This might result in OOM or can not create a new hugetlb cgroup in a busy workload ultimately. In order to fix this, we have to make sure that one file_region must hold exactly one css reference. So in coalesce_file_region case, we should release one css reference before coalescence. Also only put css reference when the entire file_region is removed. The last thing to note is that the caller of region_add() will only hold one reference to h_cg->css for the whole contiguous reservation region. But this area might be scattered when there are already some file_regions reside in it. As a result, many file_regions may share only one h_cg->css reference. In order to ensure that one file_region must hold exactly one css reference, we should do css_get() for each file_region and release the reference held by caller when they are done. [linmiaohe@huawei.com: fix imbalanced css_get and css_put pair for shared mappings] Link: https://lkml.kernel.org/r/20210316023002.53921-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210301120540.37076-1-linmiaohe@huawei.com Fixes: 075a61d07a8e ("hugetlb_cgroup: add accounting for shared mappings") Reported-by: kernel test robot <lkp@intel.com> (auto build test ERROR) Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Wanpeng Li <liwp.linux@gmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-25 07:37:17 +03:00
put_uncharge_info(rg);
hugetlb: support file_region coalescing again An earlier patch in this series disabled file_region coalescing in order to hang the hugetlb_cgroup uncharge info on the file_region entries. This patch re-adds support for coalescing of file_region entries. Essentially everytime we add an entry, we call a recursive function that tries to coalesce the added region with the regions next to it. The worst case call depth for this function is 3: one to coalesce with the region next to it, one to coalesce to the region prev, and one to reach the base case. This is an important performance optimization as private mappings add their entries page by page, and we could incur big performance costs for large mappings with lots of file_region entries in their resv_map. [almasrymina@google.com: fix CONFIG_CGROUP_HUGETLB ifdefs] Link: http://lkml.kernel.org/r/20200214204544.231482-1-almasrymina@google.com [almasrymina@google.com: remove check_coalesce_bug debug code] Link: http://lkml.kernel.org/r/20200219233610.13808-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Randy Dunlap <rdunlap@infradead.org> Link: http://lkml.kernel.org/r/20200211213128.73302-7-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:35 +03:00
kfree(rg);
}
}
hugetlb: dedup the code to add a new file_region Patch series "mm/hugetlb: Early cow on fork, and a few cleanups", v5. As reported by Gal [1], we still miss the code clip to handle early cow for hugetlb case, which is true. Again, it still feels odd to fork() after using a few huge pages, especially if they're privately mapped to me.. However I do agree with Gal and Jason in that we should still have that since that'll complete the early cow on fork effort at least, and it'll still fix issues where buffers are not well under control and not easy to apply MADV_DONTFORK. The first two patches (1-2) are some cleanups I noticed when reading into the hugetlb reserve map code. I think it's good to have but they're not necessary for fixing the fork issue. The last two patches (3-4) are the real fix. I tested this with a fork() after some vfio-pci assignment, so I'm pretty sure the page copy path could trigger well (page will be accounted right after the fork()), but I didn't do data check since the card I assigned is some random nic. https://github.com/xzpeter/linux/tree/fork-cow-pin-huge [1] https://lore.kernel.org/lkml/27564187-4a08-f187-5a84-3df50009f6ca@amazon.com/ Introduce hugetlb_resv_map_add() helper to add a new file_region rather than duplication the similar code twice in add_reservation_in_range(). Link: https://lkml.kernel.org/r/20210217233547.93892-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210217233547.93892-2-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Gal Pressman <galpress@amazon.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Wei Zhang <wzam@amazon.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jann Horn <jannh@google.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:18 +03:00
static inline long
hugetlb_resv_map_add(struct resv_map *map, struct list_head *rg, long from,
hugetlb: dedup the code to add a new file_region Patch series "mm/hugetlb: Early cow on fork, and a few cleanups", v5. As reported by Gal [1], we still miss the code clip to handle early cow for hugetlb case, which is true. Again, it still feels odd to fork() after using a few huge pages, especially if they're privately mapped to me.. However I do agree with Gal and Jason in that we should still have that since that'll complete the early cow on fork effort at least, and it'll still fix issues where buffers are not well under control and not easy to apply MADV_DONTFORK. The first two patches (1-2) are some cleanups I noticed when reading into the hugetlb reserve map code. I think it's good to have but they're not necessary for fixing the fork issue. The last two patches (3-4) are the real fix. I tested this with a fork() after some vfio-pci assignment, so I'm pretty sure the page copy path could trigger well (page will be accounted right after the fork()), but I didn't do data check since the card I assigned is some random nic. https://github.com/xzpeter/linux/tree/fork-cow-pin-huge [1] https://lore.kernel.org/lkml/27564187-4a08-f187-5a84-3df50009f6ca@amazon.com/ Introduce hugetlb_resv_map_add() helper to add a new file_region rather than duplication the similar code twice in add_reservation_in_range(). Link: https://lkml.kernel.org/r/20210217233547.93892-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210217233547.93892-2-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Gal Pressman <galpress@amazon.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Wei Zhang <wzam@amazon.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jann Horn <jannh@google.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:18 +03:00
long to, struct hstate *h, struct hugetlb_cgroup *cg,
long *regions_needed)
{
struct file_region *nrg;
if (!regions_needed) {
nrg = get_file_region_entry_from_cache(map, from, to);
record_hugetlb_cgroup_uncharge_info(cg, h, map, nrg);
list_add(&nrg->link, rg);
hugetlb: dedup the code to add a new file_region Patch series "mm/hugetlb: Early cow on fork, and a few cleanups", v5. As reported by Gal [1], we still miss the code clip to handle early cow for hugetlb case, which is true. Again, it still feels odd to fork() after using a few huge pages, especially if they're privately mapped to me.. However I do agree with Gal and Jason in that we should still have that since that'll complete the early cow on fork effort at least, and it'll still fix issues where buffers are not well under control and not easy to apply MADV_DONTFORK. The first two patches (1-2) are some cleanups I noticed when reading into the hugetlb reserve map code. I think it's good to have but they're not necessary for fixing the fork issue. The last two patches (3-4) are the real fix. I tested this with a fork() after some vfio-pci assignment, so I'm pretty sure the page copy path could trigger well (page will be accounted right after the fork()), but I didn't do data check since the card I assigned is some random nic. https://github.com/xzpeter/linux/tree/fork-cow-pin-huge [1] https://lore.kernel.org/lkml/27564187-4a08-f187-5a84-3df50009f6ca@amazon.com/ Introduce hugetlb_resv_map_add() helper to add a new file_region rather than duplication the similar code twice in add_reservation_in_range(). Link: https://lkml.kernel.org/r/20210217233547.93892-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210217233547.93892-2-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Gal Pressman <galpress@amazon.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Wei Zhang <wzam@amazon.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jann Horn <jannh@google.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:18 +03:00
coalesce_file_region(map, nrg);
} else
*regions_needed += 1;
return to - from;
}
/*
* Must be called with resv->lock held.
*
* Calling this with regions_needed != NULL will count the number of pages
* to be added but will not modify the linked list. And regions_needed will
* indicate the number of file_regions needed in the cache to carry out to add
* the regions for this range.
*/
static long add_reservation_in_range(struct resv_map *resv, long f, long t,
struct hugetlb_cgroup *h_cg,
struct hstate *h, long *regions_needed)
{
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
long add = 0;
struct list_head *head = &resv->regions;
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
long last_accounted_offset = f;
struct file_region *iter, *trg = NULL;
struct list_head *rg = NULL;
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
if (regions_needed)
*regions_needed = 0;
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
/* In this loop, we essentially handle an entry for the range
* [last_accounted_offset, iter->from), at every iteration, with some
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
* bounds checking.
*/
list_for_each_entry_safe(iter, trg, head, link) {
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
/* Skip irrelevant regions that start before our range. */
if (iter->from < f) {
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
/* If this region ends after the last accounted offset,
* then we need to update last_accounted_offset.
*/
if (iter->to > last_accounted_offset)
last_accounted_offset = iter->to;
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
continue;
}
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
/* When we find a region that starts beyond our range, we've
* finished.
*/
if (iter->from >= t) {
rg = iter->link.prev;
break;
}
/* Add an entry for last_accounted_offset -> iter->from, and
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
* update last_accounted_offset.
*/
if (iter->from > last_accounted_offset)
add += hugetlb_resv_map_add(resv, iter->link.prev,
hugetlb: dedup the code to add a new file_region Patch series "mm/hugetlb: Early cow on fork, and a few cleanups", v5. As reported by Gal [1], we still miss the code clip to handle early cow for hugetlb case, which is true. Again, it still feels odd to fork() after using a few huge pages, especially if they're privately mapped to me.. However I do agree with Gal and Jason in that we should still have that since that'll complete the early cow on fork effort at least, and it'll still fix issues where buffers are not well under control and not easy to apply MADV_DONTFORK. The first two patches (1-2) are some cleanups I noticed when reading into the hugetlb reserve map code. I think it's good to have but they're not necessary for fixing the fork issue. The last two patches (3-4) are the real fix. I tested this with a fork() after some vfio-pci assignment, so I'm pretty sure the page copy path could trigger well (page will be accounted right after the fork()), but I didn't do data check since the card I assigned is some random nic. https://github.com/xzpeter/linux/tree/fork-cow-pin-huge [1] https://lore.kernel.org/lkml/27564187-4a08-f187-5a84-3df50009f6ca@amazon.com/ Introduce hugetlb_resv_map_add() helper to add a new file_region rather than duplication the similar code twice in add_reservation_in_range(). Link: https://lkml.kernel.org/r/20210217233547.93892-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210217233547.93892-2-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Gal Pressman <galpress@amazon.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Wei Zhang <wzam@amazon.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jann Horn <jannh@google.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:18 +03:00
last_accounted_offset,
iter->from, h, h_cg,
hugetlb: dedup the code to add a new file_region Patch series "mm/hugetlb: Early cow on fork, and a few cleanups", v5. As reported by Gal [1], we still miss the code clip to handle early cow for hugetlb case, which is true. Again, it still feels odd to fork() after using a few huge pages, especially if they're privately mapped to me.. However I do agree with Gal and Jason in that we should still have that since that'll complete the early cow on fork effort at least, and it'll still fix issues where buffers are not well under control and not easy to apply MADV_DONTFORK. The first two patches (1-2) are some cleanups I noticed when reading into the hugetlb reserve map code. I think it's good to have but they're not necessary for fixing the fork issue. The last two patches (3-4) are the real fix. I tested this with a fork() after some vfio-pci assignment, so I'm pretty sure the page copy path could trigger well (page will be accounted right after the fork()), but I didn't do data check since the card I assigned is some random nic. https://github.com/xzpeter/linux/tree/fork-cow-pin-huge [1] https://lore.kernel.org/lkml/27564187-4a08-f187-5a84-3df50009f6ca@amazon.com/ Introduce hugetlb_resv_map_add() helper to add a new file_region rather than duplication the similar code twice in add_reservation_in_range(). Link: https://lkml.kernel.org/r/20210217233547.93892-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210217233547.93892-2-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Gal Pressman <galpress@amazon.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Wei Zhang <wzam@amazon.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jann Horn <jannh@google.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:18 +03:00
regions_needed);
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
last_accounted_offset = iter->to;
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
}
/* Handle the case where our range extends beyond
* last_accounted_offset.
*/
if (!rg)
rg = head->prev;
hugetlb: dedup the code to add a new file_region Patch series "mm/hugetlb: Early cow on fork, and a few cleanups", v5. As reported by Gal [1], we still miss the code clip to handle early cow for hugetlb case, which is true. Again, it still feels odd to fork() after using a few huge pages, especially if they're privately mapped to me.. However I do agree with Gal and Jason in that we should still have that since that'll complete the early cow on fork effort at least, and it'll still fix issues where buffers are not well under control and not easy to apply MADV_DONTFORK. The first two patches (1-2) are some cleanups I noticed when reading into the hugetlb reserve map code. I think it's good to have but they're not necessary for fixing the fork issue. The last two patches (3-4) are the real fix. I tested this with a fork() after some vfio-pci assignment, so I'm pretty sure the page copy path could trigger well (page will be accounted right after the fork()), but I didn't do data check since the card I assigned is some random nic. https://github.com/xzpeter/linux/tree/fork-cow-pin-huge [1] https://lore.kernel.org/lkml/27564187-4a08-f187-5a84-3df50009f6ca@amazon.com/ Introduce hugetlb_resv_map_add() helper to add a new file_region rather than duplication the similar code twice in add_reservation_in_range(). Link: https://lkml.kernel.org/r/20210217233547.93892-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210217233547.93892-2-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Gal Pressman <galpress@amazon.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Wei Zhang <wzam@amazon.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jann Horn <jannh@google.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:18 +03:00
if (last_accounted_offset < t)
add += hugetlb_resv_map_add(resv, rg, last_accounted_offset,
t, h, h_cg, regions_needed);
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
return add;
}
/* Must be called with resv->lock acquired. Will drop lock to allocate entries.
*/
static int allocate_file_region_entries(struct resv_map *resv,
int regions_needed)
__must_hold(&resv->lock)
{
struct list_head allocated_regions;
int to_allocate = 0, i = 0;
struct file_region *trg = NULL, *rg = NULL;
VM_BUG_ON(regions_needed < 0);
INIT_LIST_HEAD(&allocated_regions);
/*
* Check for sufficient descriptors in the cache to accommodate
* the number of in progress add operations plus regions_needed.
*
* This is a while loop because when we drop the lock, some other call
* to region_add or region_del may have consumed some region_entries,
* so we keep looping here until we finally have enough entries for
* (adds_in_progress + regions_needed).
*/
while (resv->region_cache_count <
(resv->adds_in_progress + regions_needed)) {
to_allocate = resv->adds_in_progress + regions_needed -
resv->region_cache_count;
/* At this point, we should have enough entries in the cache
* for all the existing adds_in_progress. We should only be
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
* needing to allocate for regions_needed.
*/
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
VM_BUG_ON(resv->region_cache_count < resv->adds_in_progress);
spin_unlock(&resv->lock);
for (i = 0; i < to_allocate; i++) {
trg = kmalloc(sizeof(*trg), GFP_KERNEL);
if (!trg)
goto out_of_memory;
list_add(&trg->link, &allocated_regions);
}
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
spin_lock(&resv->lock);
list_splice(&allocated_regions, &resv->region_cache);
resv->region_cache_count += to_allocate;
}
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
return 0;
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
out_of_memory:
list_for_each_entry_safe(rg, trg, &allocated_regions, link) {
list_del(&rg->link);
kfree(rg);
}
return -ENOMEM;
}
mm/hugetlb: document the reserve map/region tracking routines While working on hugetlbfs fallocate support, I noticed the following race in the existing code. It is unlikely that this race is hit very often in the current code. However, if more functionality to add and remove pages to hugetlbfs mappings (such as fallocate) is added the likelihood of hitting this race will increase. alloc_huge_page and hugetlb_reserve_pages use information from the reserve map to determine if there are enough available huge pages to complete the operation, as well as adjust global reserve and subpool usage counts. The order of operations is as follows: - call region_chg() to determine the expected change based on reserve map - determine if enough resources are available for this operation - adjust global counts based on the expected change - call region_add() to update the reserve map The issue is that reserve map could change between the call to region_chg and region_add. In this case, the counters which were adjusted based on the output of region_chg will not be correct. In order to hit this race today, there must be an existing shared hugetlb mmap created with the MAP_NORESERVE flag. A page fault to allocate a huge page via this mapping must occur at the same another task is mapping the same region without the MAP_NORESERVE flag. The patch set does not prevent the race from happening. Rather, it adds simple functionality to detect when the race has occurred. If a race is detected, then the incorrect counts are adjusted. Review comments pointed out the need for documentation of the existing region/reserve map routines. This patch set also adds documentation in this area. This patch (of 3): This is a documentation only patch and does not modify any code. Descriptions of the routines used for reserve map/region tracking are added. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: David Rientjes <rientjes@google.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-25 02:57:52 +03:00
/*
* Add the huge page range represented by [f, t) to the reserve
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
* map. Regions will be taken from the cache to fill in this range.
* Sufficient regions should exist in the cache due to the previous
* call to region_chg with the same range, but in some cases the cache will not
* have sufficient entries due to races with other code doing region_add or
* region_del. The extra needed entries will be allocated.
*
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
* regions_needed is the out value provided by a previous call to region_chg.
*
* Return the number of new huge pages added to the map. This number is greater
* than or equal to zero. If file_region entries needed to be allocated for
* this operation and we were not able to allocate, it returns -ENOMEM.
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
* region_add of regions of length 1 never allocate file_regions and cannot
* fail; region_chg will always allocate at least 1 entry and a region_add for
* 1 page will only require at most 1 entry.
mm/hugetlb: document the reserve map/region tracking routines While working on hugetlbfs fallocate support, I noticed the following race in the existing code. It is unlikely that this race is hit very often in the current code. However, if more functionality to add and remove pages to hugetlbfs mappings (such as fallocate) is added the likelihood of hitting this race will increase. alloc_huge_page and hugetlb_reserve_pages use information from the reserve map to determine if there are enough available huge pages to complete the operation, as well as adjust global reserve and subpool usage counts. The order of operations is as follows: - call region_chg() to determine the expected change based on reserve map - determine if enough resources are available for this operation - adjust global counts based on the expected change - call region_add() to update the reserve map The issue is that reserve map could change between the call to region_chg and region_add. In this case, the counters which were adjusted based on the output of region_chg will not be correct. In order to hit this race today, there must be an existing shared hugetlb mmap created with the MAP_NORESERVE flag. A page fault to allocate a huge page via this mapping must occur at the same another task is mapping the same region without the MAP_NORESERVE flag. The patch set does not prevent the race from happening. Rather, it adds simple functionality to detect when the race has occurred. If a race is detected, then the incorrect counts are adjusted. Review comments pointed out the need for documentation of the existing region/reserve map routines. This patch set also adds documentation in this area. This patch (of 3): This is a documentation only patch and does not modify any code. Descriptions of the routines used for reserve map/region tracking are added. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: David Rientjes <rientjes@google.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-25 02:57:52 +03:00
*/
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
static long region_add(struct resv_map *resv, long f, long t,
long in_regions_needed, struct hstate *h,
struct hugetlb_cgroup *h_cg)
{
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
long add = 0, actual_regions_needed = 0;
spin_lock(&resv->lock);
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
retry:
/* Count how many regions are actually needed to execute this add. */
add_reservation_in_range(resv, f, t, NULL, NULL,
&actual_regions_needed);
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
/*
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
* Check for sufficient descriptors in the cache to accommodate
* this add operation. Note that actual_regions_needed may be greater
* than in_regions_needed, as the resv_map may have been modified since
* the region_chg call. In this case, we need to make sure that we
* allocate extra entries, such that we have enough for all the
* existing adds_in_progress, plus the excess needed for this
* operation.
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
*/
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
if (actual_regions_needed > in_regions_needed &&
resv->region_cache_count <
resv->adds_in_progress +
(actual_regions_needed - in_regions_needed)) {
/* region_add operation of range 1 should never need to
* allocate file_region entries.
*/
VM_BUG_ON(t - f <= 1);
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
if (allocate_file_region_entries(
resv, actual_regions_needed - in_regions_needed)) {
return -ENOMEM;
}
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
goto retry;
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
}
add = add_reservation_in_range(resv, f, t, h_cg, h, NULL);
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
resv->adds_in_progress -= in_regions_needed;
spin_unlock(&resv->lock);
return add;
}
mm/hugetlb: document the reserve map/region tracking routines While working on hugetlbfs fallocate support, I noticed the following race in the existing code. It is unlikely that this race is hit very often in the current code. However, if more functionality to add and remove pages to hugetlbfs mappings (such as fallocate) is added the likelihood of hitting this race will increase. alloc_huge_page and hugetlb_reserve_pages use information from the reserve map to determine if there are enough available huge pages to complete the operation, as well as adjust global reserve and subpool usage counts. The order of operations is as follows: - call region_chg() to determine the expected change based on reserve map - determine if enough resources are available for this operation - adjust global counts based on the expected change - call region_add() to update the reserve map The issue is that reserve map could change between the call to region_chg and region_add. In this case, the counters which were adjusted based on the output of region_chg will not be correct. In order to hit this race today, there must be an existing shared hugetlb mmap created with the MAP_NORESERVE flag. A page fault to allocate a huge page via this mapping must occur at the same another task is mapping the same region without the MAP_NORESERVE flag. The patch set does not prevent the race from happening. Rather, it adds simple functionality to detect when the race has occurred. If a race is detected, then the incorrect counts are adjusted. Review comments pointed out the need for documentation of the existing region/reserve map routines. This patch set also adds documentation in this area. This patch (of 3): This is a documentation only patch and does not modify any code. Descriptions of the routines used for reserve map/region tracking are added. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: David Rientjes <rientjes@google.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-25 02:57:52 +03:00
/*
* Examine the existing reserve map and determine how many
* huge pages in the specified range [f, t) are NOT currently
* represented. This routine is called before a subsequent
* call to region_add that will actually modify the reserve
* map to add the specified range [f, t). region_chg does
* not change the number of huge pages represented by the
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
* map. A number of new file_region structures is added to the cache as a
* placeholder, for the subsequent region_add call to use. At least 1
* file_region structure is added.
*
* out_regions_needed is the number of regions added to the
* resv->adds_in_progress. This value needs to be provided to a follow up call
* to region_add or region_abort for proper accounting.
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
*
* Returns the number of huge pages that need to be added to the existing
* reservation map for the range [f, t). This number is greater or equal to
* zero. -ENOMEM is returned if a new file_region structure or cache entry
* is needed and can not be allocated.
mm/hugetlb: document the reserve map/region tracking routines While working on hugetlbfs fallocate support, I noticed the following race in the existing code. It is unlikely that this race is hit very often in the current code. However, if more functionality to add and remove pages to hugetlbfs mappings (such as fallocate) is added the likelihood of hitting this race will increase. alloc_huge_page and hugetlb_reserve_pages use information from the reserve map to determine if there are enough available huge pages to complete the operation, as well as adjust global reserve and subpool usage counts. The order of operations is as follows: - call region_chg() to determine the expected change based on reserve map - determine if enough resources are available for this operation - adjust global counts based on the expected change - call region_add() to update the reserve map The issue is that reserve map could change between the call to region_chg and region_add. In this case, the counters which were adjusted based on the output of region_chg will not be correct. In order to hit this race today, there must be an existing shared hugetlb mmap created with the MAP_NORESERVE flag. A page fault to allocate a huge page via this mapping must occur at the same another task is mapping the same region without the MAP_NORESERVE flag. The patch set does not prevent the race from happening. Rather, it adds simple functionality to detect when the race has occurred. If a race is detected, then the incorrect counts are adjusted. Review comments pointed out the need for documentation of the existing region/reserve map routines. This patch set also adds documentation in this area. This patch (of 3): This is a documentation only patch and does not modify any code. Descriptions of the routines used for reserve map/region tracking are added. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: David Rientjes <rientjes@google.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-25 02:57:52 +03:00
*/
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
static long region_chg(struct resv_map *resv, long f, long t,
long *out_regions_needed)
{
long chg = 0;
spin_lock(&resv->lock);
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
/* Count how many hugepages in this range are NOT represented. */
chg = add_reservation_in_range(resv, f, t, NULL, NULL,
out_regions_needed);
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
if (*out_regions_needed == 0)
*out_regions_needed = 1;
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
if (allocate_file_region_entries(resv, *out_regions_needed))
return -ENOMEM;
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
resv->adds_in_progress += *out_regions_needed;
spin_unlock(&resv->lock);
return chg;
}
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
/*
* Abort the in progress add operation. The adds_in_progress field
* of the resv_map keeps track of the operations in progress between
* calls to region_chg and region_add. Operations are sometimes
* aborted after the call to region_chg. In such cases, region_abort
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
* is called to decrement the adds_in_progress counter. regions_needed
* is the value returned by the region_chg call, it is used to decrement
* the adds_in_progress counter.
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
*
* NOTE: The range arguments [f, t) are not needed or used in this
* routine. They are kept to make reading the calling code easier as
* arguments will match the associated region_chg call.
*/
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
static void region_abort(struct resv_map *resv, long f, long t,
long regions_needed)
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
{
spin_lock(&resv->lock);
VM_BUG_ON(!resv->region_cache_count);
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
resv->adds_in_progress -= regions_needed;
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
spin_unlock(&resv->lock);
}
mm/hugetlb: document the reserve map/region tracking routines While working on hugetlbfs fallocate support, I noticed the following race in the existing code. It is unlikely that this race is hit very often in the current code. However, if more functionality to add and remove pages to hugetlbfs mappings (such as fallocate) is added the likelihood of hitting this race will increase. alloc_huge_page and hugetlb_reserve_pages use information from the reserve map to determine if there are enough available huge pages to complete the operation, as well as adjust global reserve and subpool usage counts. The order of operations is as follows: - call region_chg() to determine the expected change based on reserve map - determine if enough resources are available for this operation - adjust global counts based on the expected change - call region_add() to update the reserve map The issue is that reserve map could change between the call to region_chg and region_add. In this case, the counters which were adjusted based on the output of region_chg will not be correct. In order to hit this race today, there must be an existing shared hugetlb mmap created with the MAP_NORESERVE flag. A page fault to allocate a huge page via this mapping must occur at the same another task is mapping the same region without the MAP_NORESERVE flag. The patch set does not prevent the race from happening. Rather, it adds simple functionality to detect when the race has occurred. If a race is detected, then the incorrect counts are adjusted. Review comments pointed out the need for documentation of the existing region/reserve map routines. This patch set also adds documentation in this area. This patch (of 3): This is a documentation only patch and does not modify any code. Descriptions of the routines used for reserve map/region tracking are added. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: David Rientjes <rientjes@google.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-25 02:57:52 +03:00
/*
* Delete the specified range [f, t) from the reserve map. If the
* t parameter is LONG_MAX, this indicates that ALL regions after f
* should be deleted. Locate the regions which intersect [f, t)
* and either trim, delete or split the existing regions.
*
* Returns the number of huge pages deleted from the reserve map.
* In the normal case, the return value is zero or more. In the
* case where a region must be split, a new region descriptor must
* be allocated. If the allocation fails, -ENOMEM will be returned.
* NOTE: If the parameter t == LONG_MAX, then we will never split
* a region and possibly return -ENOMEM. Callers specifying
* t == LONG_MAX do not need to check for -ENOMEM error.
mm/hugetlb: document the reserve map/region tracking routines While working on hugetlbfs fallocate support, I noticed the following race in the existing code. It is unlikely that this race is hit very often in the current code. However, if more functionality to add and remove pages to hugetlbfs mappings (such as fallocate) is added the likelihood of hitting this race will increase. alloc_huge_page and hugetlb_reserve_pages use information from the reserve map to determine if there are enough available huge pages to complete the operation, as well as adjust global reserve and subpool usage counts. The order of operations is as follows: - call region_chg() to determine the expected change based on reserve map - determine if enough resources are available for this operation - adjust global counts based on the expected change - call region_add() to update the reserve map The issue is that reserve map could change between the call to region_chg and region_add. In this case, the counters which were adjusted based on the output of region_chg will not be correct. In order to hit this race today, there must be an existing shared hugetlb mmap created with the MAP_NORESERVE flag. A page fault to allocate a huge page via this mapping must occur at the same another task is mapping the same region without the MAP_NORESERVE flag. The patch set does not prevent the race from happening. Rather, it adds simple functionality to detect when the race has occurred. If a race is detected, then the incorrect counts are adjusted. Review comments pointed out the need for documentation of the existing region/reserve map routines. This patch set also adds documentation in this area. This patch (of 3): This is a documentation only patch and does not modify any code. Descriptions of the routines used for reserve map/region tracking are added. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: David Rientjes <rientjes@google.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-25 02:57:52 +03:00
*/
static long region_del(struct resv_map *resv, long f, long t)
{
struct list_head *head = &resv->regions;
struct file_region *rg, *trg;
struct file_region *nrg = NULL;
long del = 0;
retry:
spin_lock(&resv->lock);
list_for_each_entry_safe(rg, trg, head, link) {
mm/hugetlb.c: fix resv map memory leak for placeholder entries Dmitry Vyukov reported the following memory leak unreferenced object 0xffff88002eaafd88 (size 32): comm "a.out", pid 5063, jiffies 4295774645 (age 15.810s) hex dump (first 32 bytes): 28 e9 4e 63 00 88 ff ff 28 e9 4e 63 00 88 ff ff (.Nc....(.Nc.... 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: kmalloc include/linux/slab.h:458 region_chg+0x2d4/0x6b0 mm/hugetlb.c:398 __vma_reservation_common+0x2c3/0x390 mm/hugetlb.c:1791 vma_needs_reservation mm/hugetlb.c:1813 alloc_huge_page+0x19e/0xc70 mm/hugetlb.c:1845 hugetlb_no_page mm/hugetlb.c:3543 hugetlb_fault+0x7a1/0x1250 mm/hugetlb.c:3717 follow_hugetlb_page+0x339/0xc70 mm/hugetlb.c:3880 __get_user_pages+0x542/0xf30 mm/gup.c:497 populate_vma_page_range+0xde/0x110 mm/gup.c:919 __mm_populate+0x1c7/0x310 mm/gup.c:969 do_mlock+0x291/0x360 mm/mlock.c:637 SYSC_mlock2 mm/mlock.c:658 SyS_mlock2+0x4b/0x70 mm/mlock.c:648 Dmitry identified a potential memory leak in the routine region_chg, where a region descriptor is not free'ed on an error path. However, the root cause for the above memory leak resides in region_del. In this specific case, a "placeholder" entry is created in region_chg. The associated page allocation fails, and the placeholder entry is left in the reserve map. This is "by design" as the entry should be deleted when the map is released. The bug is in the region_del routine which is used to delete entries within a specific range (and when the map is released). region_del did not handle the case where a placeholder entry exactly matched the start of the range range to be deleted. In this case, the entry would not be deleted and leaked. The fix is to take these special placeholder entries into account in region_del. The region_chg error path leak is also fixed. Fixes: feba16e25a57 ("mm/hugetlb: add region_del() to delete a specific range of entries") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: <stable@vger.kernel.org> [4.3+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-12-12 00:40:52 +03:00
/*
* Skip regions before the range to be deleted. file_region
* ranges are normally of the form [from, to). However, there
* may be a "placeholder" entry in the map which is of the form
* (from, to) with from == to. Check for placeholder entries
* at the beginning of the range to be deleted.
*/
if (rg->to <= f && (rg->to != rg->from || rg->to != f))
continue;
mm/hugetlb.c: fix resv map memory leak for placeholder entries Dmitry Vyukov reported the following memory leak unreferenced object 0xffff88002eaafd88 (size 32): comm "a.out", pid 5063, jiffies 4295774645 (age 15.810s) hex dump (first 32 bytes): 28 e9 4e 63 00 88 ff ff 28 e9 4e 63 00 88 ff ff (.Nc....(.Nc.... 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: kmalloc include/linux/slab.h:458 region_chg+0x2d4/0x6b0 mm/hugetlb.c:398 __vma_reservation_common+0x2c3/0x390 mm/hugetlb.c:1791 vma_needs_reservation mm/hugetlb.c:1813 alloc_huge_page+0x19e/0xc70 mm/hugetlb.c:1845 hugetlb_no_page mm/hugetlb.c:3543 hugetlb_fault+0x7a1/0x1250 mm/hugetlb.c:3717 follow_hugetlb_page+0x339/0xc70 mm/hugetlb.c:3880 __get_user_pages+0x542/0xf30 mm/gup.c:497 populate_vma_page_range+0xde/0x110 mm/gup.c:919 __mm_populate+0x1c7/0x310 mm/gup.c:969 do_mlock+0x291/0x360 mm/mlock.c:637 SYSC_mlock2 mm/mlock.c:658 SyS_mlock2+0x4b/0x70 mm/mlock.c:648 Dmitry identified a potential memory leak in the routine region_chg, where a region descriptor is not free'ed on an error path. However, the root cause for the above memory leak resides in region_del. In this specific case, a "placeholder" entry is created in region_chg. The associated page allocation fails, and the placeholder entry is left in the reserve map. This is "by design" as the entry should be deleted when the map is released. The bug is in the region_del routine which is used to delete entries within a specific range (and when the map is released). region_del did not handle the case where a placeholder entry exactly matched the start of the range range to be deleted. In this case, the entry would not be deleted and leaked. The fix is to take these special placeholder entries into account in region_del. The region_chg error path leak is also fixed. Fixes: feba16e25a57 ("mm/hugetlb: add region_del() to delete a specific range of entries") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: <stable@vger.kernel.org> [4.3+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-12-12 00:40:52 +03:00
if (rg->from >= t)
break;
if (f > rg->from && t < rg->to) { /* Must split region */
/*
* Check for an entry in the cache before dropping
* lock and attempting allocation.
*/
if (!nrg &&
resv->region_cache_count > resv->adds_in_progress) {
nrg = list_first_entry(&resv->region_cache,
struct file_region,
link);
list_del(&nrg->link);
resv->region_cache_count--;
}
if (!nrg) {
spin_unlock(&resv->lock);
nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
if (!nrg)
return -ENOMEM;
goto retry;
}
del += t - f;
hugetlb_cgroup: fix reservation accounting Michal Privoznik was using "free page reporting" in QEMU/virtio-balloon with hugetlbfs and hit the warning below. QEMU with free page hinting uses fallocate(FALLOC_FL_PUNCH_HOLE) to discard pages that are reported as free by a VM. The reporting granularity is in pageblock granularity. So when the guest reports 2M chunks, we fallocate(FALLOC_FL_PUNCH_HOLE) one huge page in QEMU. WARNING: CPU: 7 PID: 6636 at mm/page_counter.c:57 page_counter_uncharge+0x4b/0x50 Modules linked in: ... CPU: 7 PID: 6636 Comm: qemu-system-x86 Not tainted 5.9.0 #137 Hardware name: Gigabyte Technology Co., Ltd. X570 AORUS PRO/X570 AORUS PRO, BIOS F21 07/31/2020 RIP: 0010:page_counter_uncharge+0x4b/0x50 ... Call Trace: hugetlb_cgroup_uncharge_file_region+0x4b/0x80 region_del+0x1d3/0x300 hugetlb_unreserve_pages+0x39/0xb0 remove_inode_hugepages+0x1a8/0x3d0 hugetlbfs_fallocate+0x3c4/0x5c0 vfs_fallocate+0x146/0x290 __x64_sys_fallocate+0x3e/0x70 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Investigation of the issue uncovered bugs in hugetlb cgroup reservation accounting. This patch addresses the found issues. Fixes: 075a61d07a8e ("hugetlb_cgroup: add accounting for shared mappings") Reported-by: Michal Privoznik <mprivozn@redhat.com> Co-developed-by: David Hildenbrand <david@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Michal Privoznik <mprivozn@redhat.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Cc: <stable@vger.kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Tejun Heo <tj@kernel.org> Link: https://lkml.kernel.org/r/20201021204426.36069-1-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-11-02 04:07:27 +03:00
hugetlb_cgroup_uncharge_file_region(
hugetlb_cgroup: fix imbalanced css_get and css_put pair for shared mappings The current implementation of hugetlb_cgroup for shared mappings could have different behavior. Consider the following two scenarios: 1.Assume initial css reference count of hugetlb_cgroup is 1: 1.1 Call hugetlb_reserve_pages with from = 1, to = 2. So css reference count is 2 associated with 1 file_region. 1.2 Call hugetlb_reserve_pages with from = 2, to = 3. So css reference count is 3 associated with 2 file_region. 1.3 coalesce_file_region will coalesce these two file_regions into one. So css reference count is 3 associated with 1 file_region now. 2.Assume initial css reference count of hugetlb_cgroup is 1 again: 2.1 Call hugetlb_reserve_pages with from = 1, to = 3. So css reference count is 2 associated with 1 file_region. Therefore, we might have one file_region while holding one or more css reference counts. This inconsistency could lead to imbalanced css_get() and css_put() pair. If we do css_put one by one (i.g. hole punch case), scenario 2 would put one more css reference. If we do css_put all together (i.g. truncate case), scenario 1 will leak one css reference. The imbalanced css_get() and css_put() pair would result in a non-zero reference when we try to destroy the hugetlb cgroup. The hugetlb cgroup directory is removed __but__ associated resource is not freed. This might result in OOM or can not create a new hugetlb cgroup in a busy workload ultimately. In order to fix this, we have to make sure that one file_region must hold exactly one css reference. So in coalesce_file_region case, we should release one css reference before coalescence. Also only put css reference when the entire file_region is removed. The last thing to note is that the caller of region_add() will only hold one reference to h_cg->css for the whole contiguous reservation region. But this area might be scattered when there are already some file_regions reside in it. As a result, many file_regions may share only one h_cg->css reference. In order to ensure that one file_region must hold exactly one css reference, we should do css_get() for each file_region and release the reference held by caller when they are done. [linmiaohe@huawei.com: fix imbalanced css_get and css_put pair for shared mappings] Link: https://lkml.kernel.org/r/20210316023002.53921-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210301120540.37076-1-linmiaohe@huawei.com Fixes: 075a61d07a8e ("hugetlb_cgroup: add accounting for shared mappings") Reported-by: kernel test robot <lkp@intel.com> (auto build test ERROR) Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Wanpeng Li <liwp.linux@gmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-25 07:37:17 +03:00
resv, rg, t - f, false);
/* New entry for end of split region */
nrg->from = t;
nrg->to = rg->to;
copy_hugetlb_cgroup_uncharge_info(nrg, rg);
INIT_LIST_HEAD(&nrg->link);
/* Original entry is trimmed */
rg->to = f;
list_add(&nrg->link, &rg->link);
nrg = NULL;
break;
}
if (f <= rg->from && t >= rg->to) { /* Remove entire region */
del += rg->to - rg->from;
hugetlb_cgroup_uncharge_file_region(resv, rg,
hugetlb_cgroup: fix imbalanced css_get and css_put pair for shared mappings The current implementation of hugetlb_cgroup for shared mappings could have different behavior. Consider the following two scenarios: 1.Assume initial css reference count of hugetlb_cgroup is 1: 1.1 Call hugetlb_reserve_pages with from = 1, to = 2. So css reference count is 2 associated with 1 file_region. 1.2 Call hugetlb_reserve_pages with from = 2, to = 3. So css reference count is 3 associated with 2 file_region. 1.3 coalesce_file_region will coalesce these two file_regions into one. So css reference count is 3 associated with 1 file_region now. 2.Assume initial css reference count of hugetlb_cgroup is 1 again: 2.1 Call hugetlb_reserve_pages with from = 1, to = 3. So css reference count is 2 associated with 1 file_region. Therefore, we might have one file_region while holding one or more css reference counts. This inconsistency could lead to imbalanced css_get() and css_put() pair. If we do css_put one by one (i.g. hole punch case), scenario 2 would put one more css reference. If we do css_put all together (i.g. truncate case), scenario 1 will leak one css reference. The imbalanced css_get() and css_put() pair would result in a non-zero reference when we try to destroy the hugetlb cgroup. The hugetlb cgroup directory is removed __but__ associated resource is not freed. This might result in OOM or can not create a new hugetlb cgroup in a busy workload ultimately. In order to fix this, we have to make sure that one file_region must hold exactly one css reference. So in coalesce_file_region case, we should release one css reference before coalescence. Also only put css reference when the entire file_region is removed. The last thing to note is that the caller of region_add() will only hold one reference to h_cg->css for the whole contiguous reservation region. But this area might be scattered when there are already some file_regions reside in it. As a result, many file_regions may share only one h_cg->css reference. In order to ensure that one file_region must hold exactly one css reference, we should do css_get() for each file_region and release the reference held by caller when they are done. [linmiaohe@huawei.com: fix imbalanced css_get and css_put pair for shared mappings] Link: https://lkml.kernel.org/r/20210316023002.53921-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210301120540.37076-1-linmiaohe@huawei.com Fixes: 075a61d07a8e ("hugetlb_cgroup: add accounting for shared mappings") Reported-by: kernel test robot <lkp@intel.com> (auto build test ERROR) Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Wanpeng Li <liwp.linux@gmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-25 07:37:17 +03:00
rg->to - rg->from, true);
list_del(&rg->link);
kfree(rg);
continue;
}
if (f <= rg->from) { /* Trim beginning of region */
hugetlb_cgroup_uncharge_file_region(resv, rg,
hugetlb_cgroup: fix imbalanced css_get and css_put pair for shared mappings The current implementation of hugetlb_cgroup for shared mappings could have different behavior. Consider the following two scenarios: 1.Assume initial css reference count of hugetlb_cgroup is 1: 1.1 Call hugetlb_reserve_pages with from = 1, to = 2. So css reference count is 2 associated with 1 file_region. 1.2 Call hugetlb_reserve_pages with from = 2, to = 3. So css reference count is 3 associated with 2 file_region. 1.3 coalesce_file_region will coalesce these two file_regions into one. So css reference count is 3 associated with 1 file_region now. 2.Assume initial css reference count of hugetlb_cgroup is 1 again: 2.1 Call hugetlb_reserve_pages with from = 1, to = 3. So css reference count is 2 associated with 1 file_region. Therefore, we might have one file_region while holding one or more css reference counts. This inconsistency could lead to imbalanced css_get() and css_put() pair. If we do css_put one by one (i.g. hole punch case), scenario 2 would put one more css reference. If we do css_put all together (i.g. truncate case), scenario 1 will leak one css reference. The imbalanced css_get() and css_put() pair would result in a non-zero reference when we try to destroy the hugetlb cgroup. The hugetlb cgroup directory is removed __but__ associated resource is not freed. This might result in OOM or can not create a new hugetlb cgroup in a busy workload ultimately. In order to fix this, we have to make sure that one file_region must hold exactly one css reference. So in coalesce_file_region case, we should release one css reference before coalescence. Also only put css reference when the entire file_region is removed. The last thing to note is that the caller of region_add() will only hold one reference to h_cg->css for the whole contiguous reservation region. But this area might be scattered when there are already some file_regions reside in it. As a result, many file_regions may share only one h_cg->css reference. In order to ensure that one file_region must hold exactly one css reference, we should do css_get() for each file_region and release the reference held by caller when they are done. [linmiaohe@huawei.com: fix imbalanced css_get and css_put pair for shared mappings] Link: https://lkml.kernel.org/r/20210316023002.53921-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210301120540.37076-1-linmiaohe@huawei.com Fixes: 075a61d07a8e ("hugetlb_cgroup: add accounting for shared mappings") Reported-by: kernel test robot <lkp@intel.com> (auto build test ERROR) Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Wanpeng Li <liwp.linux@gmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-25 07:37:17 +03:00
t - rg->from, false);
hugetlb_cgroup: fix reservation accounting Michal Privoznik was using "free page reporting" in QEMU/virtio-balloon with hugetlbfs and hit the warning below. QEMU with free page hinting uses fallocate(FALLOC_FL_PUNCH_HOLE) to discard pages that are reported as free by a VM. The reporting granularity is in pageblock granularity. So when the guest reports 2M chunks, we fallocate(FALLOC_FL_PUNCH_HOLE) one huge page in QEMU. WARNING: CPU: 7 PID: 6636 at mm/page_counter.c:57 page_counter_uncharge+0x4b/0x50 Modules linked in: ... CPU: 7 PID: 6636 Comm: qemu-system-x86 Not tainted 5.9.0 #137 Hardware name: Gigabyte Technology Co., Ltd. X570 AORUS PRO/X570 AORUS PRO, BIOS F21 07/31/2020 RIP: 0010:page_counter_uncharge+0x4b/0x50 ... Call Trace: hugetlb_cgroup_uncharge_file_region+0x4b/0x80 region_del+0x1d3/0x300 hugetlb_unreserve_pages+0x39/0xb0 remove_inode_hugepages+0x1a8/0x3d0 hugetlbfs_fallocate+0x3c4/0x5c0 vfs_fallocate+0x146/0x290 __x64_sys_fallocate+0x3e/0x70 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Investigation of the issue uncovered bugs in hugetlb cgroup reservation accounting. This patch addresses the found issues. Fixes: 075a61d07a8e ("hugetlb_cgroup: add accounting for shared mappings") Reported-by: Michal Privoznik <mprivozn@redhat.com> Co-developed-by: David Hildenbrand <david@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Michal Privoznik <mprivozn@redhat.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Cc: <stable@vger.kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Tejun Heo <tj@kernel.org> Link: https://lkml.kernel.org/r/20201021204426.36069-1-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-11-02 04:07:27 +03:00
del += t - rg->from;
rg->from = t;
} else { /* Trim end of region */
hugetlb_cgroup_uncharge_file_region(resv, rg,
hugetlb_cgroup: fix imbalanced css_get and css_put pair for shared mappings The current implementation of hugetlb_cgroup for shared mappings could have different behavior. Consider the following two scenarios: 1.Assume initial css reference count of hugetlb_cgroup is 1: 1.1 Call hugetlb_reserve_pages with from = 1, to = 2. So css reference count is 2 associated with 1 file_region. 1.2 Call hugetlb_reserve_pages with from = 2, to = 3. So css reference count is 3 associated with 2 file_region. 1.3 coalesce_file_region will coalesce these two file_regions into one. So css reference count is 3 associated with 1 file_region now. 2.Assume initial css reference count of hugetlb_cgroup is 1 again: 2.1 Call hugetlb_reserve_pages with from = 1, to = 3. So css reference count is 2 associated with 1 file_region. Therefore, we might have one file_region while holding one or more css reference counts. This inconsistency could lead to imbalanced css_get() and css_put() pair. If we do css_put one by one (i.g. hole punch case), scenario 2 would put one more css reference. If we do css_put all together (i.g. truncate case), scenario 1 will leak one css reference. The imbalanced css_get() and css_put() pair would result in a non-zero reference when we try to destroy the hugetlb cgroup. The hugetlb cgroup directory is removed __but__ associated resource is not freed. This might result in OOM or can not create a new hugetlb cgroup in a busy workload ultimately. In order to fix this, we have to make sure that one file_region must hold exactly one css reference. So in coalesce_file_region case, we should release one css reference before coalescence. Also only put css reference when the entire file_region is removed. The last thing to note is that the caller of region_add() will only hold one reference to h_cg->css for the whole contiguous reservation region. But this area might be scattered when there are already some file_regions reside in it. As a result, many file_regions may share only one h_cg->css reference. In order to ensure that one file_region must hold exactly one css reference, we should do css_get() for each file_region and release the reference held by caller when they are done. [linmiaohe@huawei.com: fix imbalanced css_get and css_put pair for shared mappings] Link: https://lkml.kernel.org/r/20210316023002.53921-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210301120540.37076-1-linmiaohe@huawei.com Fixes: 075a61d07a8e ("hugetlb_cgroup: add accounting for shared mappings") Reported-by: kernel test robot <lkp@intel.com> (auto build test ERROR) Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Wanpeng Li <liwp.linux@gmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-25 07:37:17 +03:00
rg->to - f, false);
hugetlb_cgroup: fix reservation accounting Michal Privoznik was using "free page reporting" in QEMU/virtio-balloon with hugetlbfs and hit the warning below. QEMU with free page hinting uses fallocate(FALLOC_FL_PUNCH_HOLE) to discard pages that are reported as free by a VM. The reporting granularity is in pageblock granularity. So when the guest reports 2M chunks, we fallocate(FALLOC_FL_PUNCH_HOLE) one huge page in QEMU. WARNING: CPU: 7 PID: 6636 at mm/page_counter.c:57 page_counter_uncharge+0x4b/0x50 Modules linked in: ... CPU: 7 PID: 6636 Comm: qemu-system-x86 Not tainted 5.9.0 #137 Hardware name: Gigabyte Technology Co., Ltd. X570 AORUS PRO/X570 AORUS PRO, BIOS F21 07/31/2020 RIP: 0010:page_counter_uncharge+0x4b/0x50 ... Call Trace: hugetlb_cgroup_uncharge_file_region+0x4b/0x80 region_del+0x1d3/0x300 hugetlb_unreserve_pages+0x39/0xb0 remove_inode_hugepages+0x1a8/0x3d0 hugetlbfs_fallocate+0x3c4/0x5c0 vfs_fallocate+0x146/0x290 __x64_sys_fallocate+0x3e/0x70 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Investigation of the issue uncovered bugs in hugetlb cgroup reservation accounting. This patch addresses the found issues. Fixes: 075a61d07a8e ("hugetlb_cgroup: add accounting for shared mappings") Reported-by: Michal Privoznik <mprivozn@redhat.com> Co-developed-by: David Hildenbrand <david@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Michal Privoznik <mprivozn@redhat.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Cc: <stable@vger.kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Tejun Heo <tj@kernel.org> Link: https://lkml.kernel.org/r/20201021204426.36069-1-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-11-02 04:07:27 +03:00
del += rg->to - f;
rg->to = f;
}
}
spin_unlock(&resv->lock);
kfree(nrg);
return del;
}
hugetlbfs: truncate_hugepages() takes a range of pages Modify truncate_hugepages() to take a range of pages (start, end) instead of simply start. If an end value of LLONG_MAX is passed, the current "truncate" functionality is maintained. Existing callers are modified to pass LLONG_MAX as end of range. By keying off end == LLONG_MAX, the routine behaves differently for truncate and hole punch. Page removal is now synchronized with page allocation via faults by using the fault mutex table. The hole punch case can experience the rare region_del error and must handle accordingly. Add the routine hugetlb_fix_reserve_counts to fix up reserve counts in the case where region_del returns an error. Since the routine handles more than just the truncate case, it is renamed to remove_inode_hugepages(). To be consistent, the routine truncate_huge_page() is renamed remove_huge_page(). Downstream of remove_inode_hugepages(), the routine hugetlb_unreserve_pages() is also modified to take a range of pages. hugetlb_unreserve_pages is modified to detect an error from region_del and pass it back to the caller. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:41 +03:00
/*
* A rare out of memory error was encountered which prevented removal of
* the reserve map region for a page. The huge page itself was free'ed
* and removed from the page cache. This routine will adjust the subpool
* usage count, and the global reserve count if needed. By incrementing
* these counts, the reserve map entry which could not be deleted will
* appear as a "reserved" entry instead of simply dangling with incorrect
* counts.
*/
void hugetlb_fix_reserve_counts(struct inode *inode)
hugetlbfs: truncate_hugepages() takes a range of pages Modify truncate_hugepages() to take a range of pages (start, end) instead of simply start. If an end value of LLONG_MAX is passed, the current "truncate" functionality is maintained. Existing callers are modified to pass LLONG_MAX as end of range. By keying off end == LLONG_MAX, the routine behaves differently for truncate and hole punch. Page removal is now synchronized with page allocation via faults by using the fault mutex table. The hole punch case can experience the rare region_del error and must handle accordingly. Add the routine hugetlb_fix_reserve_counts to fix up reserve counts in the case where region_del returns an error. Since the routine handles more than just the truncate case, it is renamed to remove_inode_hugepages(). To be consistent, the routine truncate_huge_page() is renamed remove_huge_page(). Downstream of remove_inode_hugepages(), the routine hugetlb_unreserve_pages() is also modified to take a range of pages. hugetlb_unreserve_pages is modified to detect an error from region_del and pass it back to the caller. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:41 +03:00
{
struct hugepage_subpool *spool = subpool_inode(inode);
long rsv_adjust;
bool reserved = false;
hugetlbfs: truncate_hugepages() takes a range of pages Modify truncate_hugepages() to take a range of pages (start, end) instead of simply start. If an end value of LLONG_MAX is passed, the current "truncate" functionality is maintained. Existing callers are modified to pass LLONG_MAX as end of range. By keying off end == LLONG_MAX, the routine behaves differently for truncate and hole punch. Page removal is now synchronized with page allocation via faults by using the fault mutex table. The hole punch case can experience the rare region_del error and must handle accordingly. Add the routine hugetlb_fix_reserve_counts to fix up reserve counts in the case where region_del returns an error. Since the routine handles more than just the truncate case, it is renamed to remove_inode_hugepages(). To be consistent, the routine truncate_huge_page() is renamed remove_huge_page(). Downstream of remove_inode_hugepages(), the routine hugetlb_unreserve_pages() is also modified to take a range of pages. hugetlb_unreserve_pages is modified to detect an error from region_del and pass it back to the caller. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:41 +03:00
rsv_adjust = hugepage_subpool_get_pages(spool, 1);
if (rsv_adjust > 0) {
hugetlbfs: truncate_hugepages() takes a range of pages Modify truncate_hugepages() to take a range of pages (start, end) instead of simply start. If an end value of LLONG_MAX is passed, the current "truncate" functionality is maintained. Existing callers are modified to pass LLONG_MAX as end of range. By keying off end == LLONG_MAX, the routine behaves differently for truncate and hole punch. Page removal is now synchronized with page allocation via faults by using the fault mutex table. The hole punch case can experience the rare region_del error and must handle accordingly. Add the routine hugetlb_fix_reserve_counts to fix up reserve counts in the case where region_del returns an error. Since the routine handles more than just the truncate case, it is renamed to remove_inode_hugepages(). To be consistent, the routine truncate_huge_page() is renamed remove_huge_page(). Downstream of remove_inode_hugepages(), the routine hugetlb_unreserve_pages() is also modified to take a range of pages. hugetlb_unreserve_pages is modified to detect an error from region_del and pass it back to the caller. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:41 +03:00
struct hstate *h = hstate_inode(inode);
if (!hugetlb_acct_memory(h, 1))
reserved = true;
} else if (!rsv_adjust) {
reserved = true;
hugetlbfs: truncate_hugepages() takes a range of pages Modify truncate_hugepages() to take a range of pages (start, end) instead of simply start. If an end value of LLONG_MAX is passed, the current "truncate" functionality is maintained. Existing callers are modified to pass LLONG_MAX as end of range. By keying off end == LLONG_MAX, the routine behaves differently for truncate and hole punch. Page removal is now synchronized with page allocation via faults by using the fault mutex table. The hole punch case can experience the rare region_del error and must handle accordingly. Add the routine hugetlb_fix_reserve_counts to fix up reserve counts in the case where region_del returns an error. Since the routine handles more than just the truncate case, it is renamed to remove_inode_hugepages(). To be consistent, the routine truncate_huge_page() is renamed remove_huge_page(). Downstream of remove_inode_hugepages(), the routine hugetlb_unreserve_pages() is also modified to take a range of pages. hugetlb_unreserve_pages is modified to detect an error from region_del and pass it back to the caller. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:41 +03:00
}
if (!reserved)
pr_warn("hugetlb: Huge Page Reserved count may go negative.\n");
hugetlbfs: truncate_hugepages() takes a range of pages Modify truncate_hugepages() to take a range of pages (start, end) instead of simply start. If an end value of LLONG_MAX is passed, the current "truncate" functionality is maintained. Existing callers are modified to pass LLONG_MAX as end of range. By keying off end == LLONG_MAX, the routine behaves differently for truncate and hole punch. Page removal is now synchronized with page allocation via faults by using the fault mutex table. The hole punch case can experience the rare region_del error and must handle accordingly. Add the routine hugetlb_fix_reserve_counts to fix up reserve counts in the case where region_del returns an error. Since the routine handles more than just the truncate case, it is renamed to remove_inode_hugepages(). To be consistent, the routine truncate_huge_page() is renamed remove_huge_page(). Downstream of remove_inode_hugepages(), the routine hugetlb_unreserve_pages() is also modified to take a range of pages. hugetlb_unreserve_pages is modified to detect an error from region_del and pass it back to the caller. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:41 +03:00
}
mm/hugetlb: document the reserve map/region tracking routines While working on hugetlbfs fallocate support, I noticed the following race in the existing code. It is unlikely that this race is hit very often in the current code. However, if more functionality to add and remove pages to hugetlbfs mappings (such as fallocate) is added the likelihood of hitting this race will increase. alloc_huge_page and hugetlb_reserve_pages use information from the reserve map to determine if there are enough available huge pages to complete the operation, as well as adjust global reserve and subpool usage counts. The order of operations is as follows: - call region_chg() to determine the expected change based on reserve map - determine if enough resources are available for this operation - adjust global counts based on the expected change - call region_add() to update the reserve map The issue is that reserve map could change between the call to region_chg and region_add. In this case, the counters which were adjusted based on the output of region_chg will not be correct. In order to hit this race today, there must be an existing shared hugetlb mmap created with the MAP_NORESERVE flag. A page fault to allocate a huge page via this mapping must occur at the same another task is mapping the same region without the MAP_NORESERVE flag. The patch set does not prevent the race from happening. Rather, it adds simple functionality to detect when the race has occurred. If a race is detected, then the incorrect counts are adjusted. Review comments pointed out the need for documentation of the existing region/reserve map routines. This patch set also adds documentation in this area. This patch (of 3): This is a documentation only patch and does not modify any code. Descriptions of the routines used for reserve map/region tracking are added. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: David Rientjes <rientjes@google.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-25 02:57:52 +03:00
/*
* Count and return the number of huge pages in the reserve map
* that intersect with the range [f, t).
*/
static long region_count(struct resv_map *resv, long f, long t)
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
{
struct list_head *head = &resv->regions;
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
struct file_region *rg;
long chg = 0;
spin_lock(&resv->lock);
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
/* Locate each segment we overlap with, and count that overlap. */
list_for_each_entry(rg, head, link) {
long seg_from;
long seg_to;
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
if (rg->to <= f)
continue;
if (rg->from >= t)
break;
seg_from = max(rg->from, f);
seg_to = min(rg->to, t);
chg += seg_to - seg_from;
}
spin_unlock(&resv->lock);
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
return chg;
}
/*
* Convert the address within this vma to the page offset within
* the mapping, in pagecache page units; huge pages here.
*/
static pgoff_t vma_hugecache_offset(struct hstate *h,
struct vm_area_struct *vma, unsigned long address)
{
return ((address - vma->vm_start) >> huge_page_shift(h)) +
(vma->vm_pgoff >> huge_page_order(h));
}
hugetlb, rmap: add reverse mapping for hugepage This patch adds reverse mapping feature for hugepage by introducing mapcount for shared/private-mapped hugepage and anon_vma for private-mapped hugepage. While hugepage is not currently swappable, reverse mapping can be useful for memory error handler. Without this patch, memory error handler cannot identify processes using the bad hugepage nor unmap it from them. That is: - for shared hugepage: we can collect processes using a hugepage through pagecache, but can not unmap the hugepage because of the lack of mapcount. - for privately mapped hugepage: we can neither collect processes nor unmap the hugepage. This patch solves these problems. This patch include the bug fix given by commit 23be7468e8, so reverts it. Dependency: "hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h" ChangeLog since May 24. - create hugetlb_inline.h and move is_vm_hugetlb_index() in it. - move functions setting up anon_vma for hugepage into mm/rmap.c. ChangeLog since May 13. - rebased to 2.6.34 - fix logic error (in case that private mapping and shared mapping coexist) - move is_vm_hugetlb_page() into include/linux/mm.h to use this function from linear_page_index() - define and use linear_hugepage_index() instead of compound_order() - use page_move_anon_rmap() in hugetlb_cow() - copy exclusive switch of __set_page_anon_rmap() into hugepage counterpart. - revert commit 24be7468 completely Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Acked-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andi Kleen <ak@linux.intel.com>
2010-05-28 04:29:16 +04:00
pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
unsigned long address)
{
return vma_hugecache_offset(hstate_vma(vma), vma, address);
}
EXPORT_SYMBOL_GPL(linear_hugepage_index);
hugetlb, rmap: add reverse mapping for hugepage This patch adds reverse mapping feature for hugepage by introducing mapcount for shared/private-mapped hugepage and anon_vma for private-mapped hugepage. While hugepage is not currently swappable, reverse mapping can be useful for memory error handler. Without this patch, memory error handler cannot identify processes using the bad hugepage nor unmap it from them. That is: - for shared hugepage: we can collect processes using a hugepage through pagecache, but can not unmap the hugepage because of the lack of mapcount. - for privately mapped hugepage: we can neither collect processes nor unmap the hugepage. This patch solves these problems. This patch include the bug fix given by commit 23be7468e8, so reverts it. Dependency: "hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h" ChangeLog since May 24. - create hugetlb_inline.h and move is_vm_hugetlb_index() in it. - move functions setting up anon_vma for hugepage into mm/rmap.c. ChangeLog since May 13. - rebased to 2.6.34 - fix logic error (in case that private mapping and shared mapping coexist) - move is_vm_hugetlb_page() into include/linux/mm.h to use this function from linear_page_index() - define and use linear_hugepage_index() instead of compound_order() - use page_move_anon_rmap() in hugetlb_cow() - copy exclusive switch of __set_page_anon_rmap() into hugepage counterpart. - revert commit 24be7468 completely Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Acked-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andi Kleen <ak@linux.intel.com>
2010-05-28 04:29:16 +04:00
/*
* Return the size of the pages allocated when backing a VMA. In the majority
* cases this will be same size as used by the page table entries.
*/
unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
{
if (vma->vm_ops && vma->vm_ops->pagesize)
return vma->vm_ops->pagesize(vma);
return PAGE_SIZE;
}
EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
/*
* Return the page size being used by the MMU to back a VMA. In the majority
* of cases, the page size used by the kernel matches the MMU size. On
mm, powerpc: use vma_kernel_pagesize() in vma_mmu_pagesize() Patch series "mm, smaps: MMUPageSize for device-dax", v3. Similar to commit 31383c6865a5 ("mm, hugetlbfs: introduce ->split() to vm_operations_struct") here is another occasion where we want special-case hugetlbfs/hstate enabling to also apply to device-dax. This prompts the question what other hstate conversions we might do beyond ->split() and ->pagesize(), but this appears to be the last of the usages of hstate_vma() in generic/non-hugetlbfs specific code paths. This patch (of 3): The current powerpc definition of vma_mmu_pagesize() open codes looking up the page size via hstate. It is identical to the generic vma_kernel_pagesize() implementation. Now, vma_kernel_pagesize() is growing support for determining the page size of Device-DAX vmas in addition to the existing Hugetlbfs page size determination. Ideally, if the powerpc vma_mmu_pagesize() used vma_kernel_pagesize() it would automatically benefit from any new vma-type support that is added to vma_kernel_pagesize(). However, the powerpc vma_mmu_pagesize() is prevented from calling vma_kernel_pagesize() due to a circular header dependency that requires vma_mmu_pagesize() to be defined before including <linux/hugetlb.h>. Break this circular dependency by defining the default vma_mmu_pagesize() as a __weak symbol to be overridden by the powerpc version. Link: http://lkml.kernel.org/r/151996254179.27922.2213728278535578744.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Jane Chu <jane.chu@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-06 02:24:21 +03:00
* architectures where it differs, an architecture-specific 'strong'
* version of this symbol is required.
*/
mm, powerpc: use vma_kernel_pagesize() in vma_mmu_pagesize() Patch series "mm, smaps: MMUPageSize for device-dax", v3. Similar to commit 31383c6865a5 ("mm, hugetlbfs: introduce ->split() to vm_operations_struct") here is another occasion where we want special-case hugetlbfs/hstate enabling to also apply to device-dax. This prompts the question what other hstate conversions we might do beyond ->split() and ->pagesize(), but this appears to be the last of the usages of hstate_vma() in generic/non-hugetlbfs specific code paths. This patch (of 3): The current powerpc definition of vma_mmu_pagesize() open codes looking up the page size via hstate. It is identical to the generic vma_kernel_pagesize() implementation. Now, vma_kernel_pagesize() is growing support for determining the page size of Device-DAX vmas in addition to the existing Hugetlbfs page size determination. Ideally, if the powerpc vma_mmu_pagesize() used vma_kernel_pagesize() it would automatically benefit from any new vma-type support that is added to vma_kernel_pagesize(). However, the powerpc vma_mmu_pagesize() is prevented from calling vma_kernel_pagesize() due to a circular header dependency that requires vma_mmu_pagesize() to be defined before including <linux/hugetlb.h>. Break this circular dependency by defining the default vma_mmu_pagesize() as a __weak symbol to be overridden by the powerpc version. Link: http://lkml.kernel.org/r/151996254179.27922.2213728278535578744.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Jane Chu <jane.chu@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-06 02:24:21 +03:00
__weak unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
{
return vma_kernel_pagesize(vma);
}
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
/*
* Flags for MAP_PRIVATE reservations. These are stored in the bottom
* bits of the reservation map pointer, which are always clear due to
* alignment.
*/
#define HPAGE_RESV_OWNER (1UL << 0)
#define HPAGE_RESV_UNMAPPED (1UL << 1)
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
/*
* These helpers are used to track how many pages are reserved for
* faults in a MAP_PRIVATE mapping. Only the process that called mmap()
* is guaranteed to have their future faults succeed.
*
* With the exception of reset_vma_resv_huge_pages() which is called at fork(),
* the reserve counters are updated with the hugetlb_lock held. It is safe
* to reset the VMA at fork() time as it is not in use yet and there is no
* chance of the global counters getting corrupted as a result of the values.
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
*
* The private mapping reservation is represented in a subtly different
* manner to a shared mapping. A shared mapping has a region map associated
* with the underlying file, this region map represents the backing file
* pages which have ever had a reservation assigned which this persists even
* after the page is instantiated. A private mapping has a region map
* associated with the original mmap which is attached to all VMAs which
* reference it, this region map represents those offsets which have consumed
* reservation ie. where pages have been instantiated.
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
*/
static unsigned long get_vma_private_data(struct vm_area_struct *vma)
{
return (unsigned long)vma->vm_private_data;
}
static void set_vma_private_data(struct vm_area_struct *vma,
unsigned long value)
{
vma->vm_private_data = (void *)value;
}
hugetlb_cgroup: add reservation accounting for private mappings Normally the pointer to the cgroup to uncharge hangs off the struct page, and gets queried when it's time to free the page. With hugetlb_cgroup reservations, this is not possible. Because it's possible for a page to be reserved by one task and actually faulted in by another task. The best place to put the hugetlb_cgroup pointer to uncharge for reservations is in the resv_map. But, because the resv_map has different semantics for private and shared mappings, the code patch to charge/uncharge shared and private mappings is different. This patch implements charging and uncharging for private mappings. For private mappings, the counter to uncharge is in resv_map->reservation_counter. On initializing the resv_map this is set to NULL. On reservation of a region in private mapping, the tasks hugetlb_cgroup is charged and the hugetlb_cgroup is placed is resv_map->reservation_counter. On hugetlb_vm_op_close, we uncharge resv_map->reservation_counter. [akpm@linux-foundation.org: forward declare struct resv_map] Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Link: http://lkml.kernel.org/r/20200211213128.73302-3-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:21 +03:00
static void
resv_map_set_hugetlb_cgroup_uncharge_info(struct resv_map *resv_map,
struct hugetlb_cgroup *h_cg,
struct hstate *h)
{
#ifdef CONFIG_CGROUP_HUGETLB
if (!h_cg || !h) {
resv_map->reservation_counter = NULL;
resv_map->pages_per_hpage = 0;
resv_map->css = NULL;
} else {
resv_map->reservation_counter =
&h_cg->rsvd_hugepage[hstate_index(h)];
resv_map->pages_per_hpage = pages_per_huge_page(h);
resv_map->css = &h_cg->css;
}
#endif
}
struct resv_map *resv_map_alloc(void)
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
{
struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
struct file_region *rg = kmalloc(sizeof(*rg), GFP_KERNEL);
if (!resv_map || !rg) {
kfree(resv_map);
kfree(rg);
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
return NULL;
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
}
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
kref_init(&resv_map->refs);
spin_lock_init(&resv_map->lock);
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
INIT_LIST_HEAD(&resv_map->regions);
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
resv_map->adds_in_progress = 0;
hugetlb_cgroup: add reservation accounting for private mappings Normally the pointer to the cgroup to uncharge hangs off the struct page, and gets queried when it's time to free the page. With hugetlb_cgroup reservations, this is not possible. Because it's possible for a page to be reserved by one task and actually faulted in by another task. The best place to put the hugetlb_cgroup pointer to uncharge for reservations is in the resv_map. But, because the resv_map has different semantics for private and shared mappings, the code patch to charge/uncharge shared and private mappings is different. This patch implements charging and uncharging for private mappings. For private mappings, the counter to uncharge is in resv_map->reservation_counter. On initializing the resv_map this is set to NULL. On reservation of a region in private mapping, the tasks hugetlb_cgroup is charged and the hugetlb_cgroup is placed is resv_map->reservation_counter. On hugetlb_vm_op_close, we uncharge resv_map->reservation_counter. [akpm@linux-foundation.org: forward declare struct resv_map] Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Link: http://lkml.kernel.org/r/20200211213128.73302-3-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:21 +03:00
/*
* Initialize these to 0. On shared mappings, 0's here indicate these
* fields don't do cgroup accounting. On private mappings, these will be
* re-initialized to the proper values, to indicate that hugetlb cgroup
* reservations are to be un-charged from here.
*/
resv_map_set_hugetlb_cgroup_uncharge_info(resv_map, NULL, NULL);
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
INIT_LIST_HEAD(&resv_map->region_cache);
list_add(&rg->link, &resv_map->region_cache);
resv_map->region_cache_count = 1;
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
return resv_map;
}
void resv_map_release(struct kref *ref)
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
{
struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
struct list_head *head = &resv_map->region_cache;
struct file_region *rg, *trg;
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
/* Clear out any active regions before we release the map. */
region_del(resv_map, 0, LONG_MAX);
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
/* ... and any entries left in the cache */
list_for_each_entry_safe(rg, trg, head, link) {
list_del(&rg->link);
kfree(rg);
}
VM_BUG_ON(resv_map->adds_in_progress);
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
kfree(resv_map);
}
static inline struct resv_map *inode_resv_map(struct inode *inode)
{
/*
* At inode evict time, i_mapping may not point to the original
* address space within the inode. This original address space
* contains the pointer to the resv_map. So, always use the
* address space embedded within the inode.
* The VERY common case is inode->mapping == &inode->i_data but,
* this may not be true for device special inodes.
*/
return (struct resv_map *)(&inode->i_data)->private_data;
}
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
{
VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
if (vma->vm_flags & VM_MAYSHARE) {
struct address_space *mapping = vma->vm_file->f_mapping;
struct inode *inode = mapping->host;
return inode_resv_map(inode);
} else {
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
return (struct resv_map *)(get_vma_private_data(vma) &
~HPAGE_RESV_MASK);
}
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
}
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
{
VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
set_vma_private_data(vma, (get_vma_private_data(vma) &
HPAGE_RESV_MASK) | (unsigned long)map);
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
}
static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
{
VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
set_vma_private_data(vma, get_vma_private_data(vma) | flags);
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
}
static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
{
VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
return (get_vma_private_data(vma) & flag) != 0;
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
}
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
/* Reset counters to 0 and clear all HPAGE_RESV_* flags */
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
{
VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
mm: account for MAP_SHARED mappings using VM_MAYSHARE and not VM_SHARED in hugetlbfs Addresses http://bugzilla.kernel.org/show_bug.cgi?id=13302 hugetlbfs reserves huge pages but does not fault them at mmap() time to ensure that future faults succeed. The reservation behaviour differs depending on whether the mapping was mapped MAP_SHARED or MAP_PRIVATE. For MAP_SHARED mappings, hugepages are reserved when mmap() is first called and are tracked based on information associated with the inode. Other processes mapping MAP_SHARED use the same reservation. MAP_PRIVATE track the reservations based on the VMA created as part of the mmap() operation. Each process mapping MAP_PRIVATE must make its own reservation. hugetlbfs currently checks if a VMA is MAP_SHARED with the VM_SHARED flag and not VM_MAYSHARE. For file-backed mappings, such as hugetlbfs, VM_SHARED is set only if the mapping is MAP_SHARED and the file was opened read-write. If a shared memory mapping was mapped shared-read-write for populating of data and mapped shared-read-only by other processes, then hugetlbfs would account for the mapping as if it was MAP_PRIVATE. This causes processes to fail to map the file MAP_SHARED even though it should succeed as the reservation is there. This patch alters mm/hugetlb.c and replaces VM_SHARED with VM_MAYSHARE when the intent of the code was to check whether the VMA was mapped MAP_SHARED or MAP_PRIVATE. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Ingo Molnar <mingo@elte.hu> Cc: <stable@kernel.org> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: <starlight@binnacle.cx> Cc: Eric B Munson <ebmunson@us.ibm.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-05-29 01:34:40 +04:00
if (!(vma->vm_flags & VM_MAYSHARE))
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
vma->vm_private_data = (void *)0;
}
/*
* Reset and decrement one ref on hugepage private reservation.
* Called with mm->mmap_sem writer semaphore held.
* This function should be only used by move_vma() and operate on
* same sized vma. It should never come here with last ref on the
* reservation.
*/
void clear_vma_resv_huge_pages(struct vm_area_struct *vma)
{
/*
* Clear the old hugetlb private page reservation.
* It has already been transferred to new_vma.
*
* During a mremap() operation of a hugetlb vma we call move_vma()
* which copies vma into new_vma and unmaps vma. After the copy
* operation both new_vma and vma share a reference to the resv_map
* struct, and at that point vma is about to be unmapped. We don't
* want to return the reservation to the pool at unmap of vma because
* the reservation still lives on in new_vma, so simply decrement the
* ref here and remove the resv_map reference from this vma.
*/
struct resv_map *reservations = vma_resv_map(vma);
if (reservations && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
resv_map_put_hugetlb_cgroup_uncharge_info(reservations);
kref_put(&reservations->refs, resv_map_release);
}
reset_vma_resv_huge_pages(vma);
}
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
/* Returns true if the VMA has associated reserve pages */
static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
{
mm, hugetlb: decrement reserve count if VM_NORESERVE alloc page cache If a vma with VM_NORESERVE allocate a new page for page cache, we should check whether this area is reserved or not. If this address is already reserved by other process(in case of chg == 0), we should decrement reserve count, because this allocated page will go into page cache and currently, there is no way to know that this page comes from reserved pool or not when releasing inode. This may introduce over-counting problem to reserved count. With following example code, you can easily reproduce this situation. Assume 2MB, nr_hugepages = 100 size = 20 * MB; flag = MAP_SHARED; p = mmap(NULL, size, PROT_READ|PROT_WRITE, flag, fd, 0); if (p == MAP_FAILED) { fprintf(stderr, "mmap() failed: %s\n", strerror(errno)); return -1; } flag = MAP_SHARED | MAP_NORESERVE; q = mmap(NULL, size, PROT_READ|PROT_WRITE, flag, fd, 0); if (q == MAP_FAILED) { fprintf(stderr, "mmap() failed: %s\n", strerror(errno)); } q[0] = 'c'; After finish the program, run 'cat /proc/meminfo'. You can see below result. HugePages_Free: 100 HugePages_Rsvd: 1 To fix this, we should check our mapping type and tracked region. If our mapping is VM_NORESERVE, VM_MAYSHARE and chg is 0, this imply that current allocated page will go into page cache which is already reserved region when mapping is created. In this case, we should decrease reserve count. As implementing above, this patch solve the problem. [akpm@linux-foundation.org: fix spelling in comment] Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:21:18 +04:00
if (vma->vm_flags & VM_NORESERVE) {
/*
* This address is already reserved by other process(chg == 0),
* so, we should decrement reserved count. Without decrementing,
* reserve count remains after releasing inode, because this
* allocated page will go into page cache and is regarded as
* coming from reserved pool in releasing step. Currently, we
* don't have any other solution to deal with this situation
* properly, so add work-around here.
*/
if (vma->vm_flags & VM_MAYSHARE && chg == 0)
return true;
mm, hugetlb: decrement reserve count if VM_NORESERVE alloc page cache If a vma with VM_NORESERVE allocate a new page for page cache, we should check whether this area is reserved or not. If this address is already reserved by other process(in case of chg == 0), we should decrement reserve count, because this allocated page will go into page cache and currently, there is no way to know that this page comes from reserved pool or not when releasing inode. This may introduce over-counting problem to reserved count. With following example code, you can easily reproduce this situation. Assume 2MB, nr_hugepages = 100 size = 20 * MB; flag = MAP_SHARED; p = mmap(NULL, size, PROT_READ|PROT_WRITE, flag, fd, 0); if (p == MAP_FAILED) { fprintf(stderr, "mmap() failed: %s\n", strerror(errno)); return -1; } flag = MAP_SHARED | MAP_NORESERVE; q = mmap(NULL, size, PROT_READ|PROT_WRITE, flag, fd, 0); if (q == MAP_FAILED) { fprintf(stderr, "mmap() failed: %s\n", strerror(errno)); } q[0] = 'c'; After finish the program, run 'cat /proc/meminfo'. You can see below result. HugePages_Free: 100 HugePages_Rsvd: 1 To fix this, we should check our mapping type and tracked region. If our mapping is VM_NORESERVE, VM_MAYSHARE and chg is 0, this imply that current allocated page will go into page cache which is already reserved region when mapping is created. In this case, we should decrease reserve count. As implementing above, this patch solve the problem. [akpm@linux-foundation.org: fix spelling in comment] Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:21:18 +04:00
else
return false;
mm, hugetlb: decrement reserve count if VM_NORESERVE alloc page cache If a vma with VM_NORESERVE allocate a new page for page cache, we should check whether this area is reserved or not. If this address is already reserved by other process(in case of chg == 0), we should decrement reserve count, because this allocated page will go into page cache and currently, there is no way to know that this page comes from reserved pool or not when releasing inode. This may introduce over-counting problem to reserved count. With following example code, you can easily reproduce this situation. Assume 2MB, nr_hugepages = 100 size = 20 * MB; flag = MAP_SHARED; p = mmap(NULL, size, PROT_READ|PROT_WRITE, flag, fd, 0); if (p == MAP_FAILED) { fprintf(stderr, "mmap() failed: %s\n", strerror(errno)); return -1; } flag = MAP_SHARED | MAP_NORESERVE; q = mmap(NULL, size, PROT_READ|PROT_WRITE, flag, fd, 0); if (q == MAP_FAILED) { fprintf(stderr, "mmap() failed: %s\n", strerror(errno)); } q[0] = 'c'; After finish the program, run 'cat /proc/meminfo'. You can see below result. HugePages_Free: 100 HugePages_Rsvd: 1 To fix this, we should check our mapping type and tracked region. If our mapping is VM_NORESERVE, VM_MAYSHARE and chg is 0, this imply that current allocated page will go into page cache which is already reserved region when mapping is created. In this case, we should decrease reserve count. As implementing above, this patch solve the problem. [akpm@linux-foundation.org: fix spelling in comment] Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:21:18 +04:00
}
/* Shared mappings always use reserves */
if (vma->vm_flags & VM_MAYSHARE) {
/*
* We know VM_NORESERVE is not set. Therefore, there SHOULD
* be a region map for all pages. The only situation where
* there is no region map is if a hole was punched via
* fallocate. In this case, there really are no reserves to
* use. This situation is indicated if chg != 0.
*/
if (chg)
return false;
else
return true;
}
/*
* Only the process that called mmap() has reserves for
* private mappings.
*/
mm/hugetlb: fix huge page reserve accounting for private mappings When creating a private mapping of a hugetlbfs file, it is possible to unmap pages via ftruncate or fallocate hole punch. If subsequent faults repopulate these mappings, the reserve counts will go negative. This is because the code currently assumes all faults to private mappings will consume reserves. The problem can be recreated as follows: - mmap(MAP_PRIVATE) a file in hugetlbfs filesystem - write fault in pages in the mapping - fallocate(FALLOC_FL_PUNCH_HOLE) some pages in the mapping - write fault in pages in the hole This will result in negative huge page reserve counts and negative subpool usage counts for the hugetlbfs. Note that this can also be recreated with ftruncate, but fallocate is more straight forward. This patch modifies the routines vma_needs_reserves and vma_has_reserves to examine the reserve map associated with private mappings similar to that for shared mappings. However, the reserve map semantics for private and shared mappings are very different. This results in subtly different code that is explained in the comments. Link: http://lkml.kernel.org/r/1464720957-15698-1-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-09 01:33:42 +03:00
if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
/*
* Like the shared case above, a hole punch or truncate
* could have been performed on the private mapping.
* Examine the value of chg to determine if reserves
* actually exist or were previously consumed.
* Very Subtle - The value of chg comes from a previous
* call to vma_needs_reserves(). The reserve map for
* private mappings has different (opposite) semantics
* than that of shared mappings. vma_needs_reserves()
* has already taken this difference in semantics into
* account. Therefore, the meaning of chg is the same
* as in the shared case above. Code could easily be
* combined, but keeping it separate draws attention to
* subtle differences.
*/
if (chg)
return false;
else
return true;
}
return false;
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
}
static void enqueue_huge_page(struct hstate *h, struct page *page)
{
int nid = page_to_nid(page);
lockdep_assert_held(&hugetlb_lock);
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
VM_BUG_ON_PAGE(page_count(page), page);
list_move(&page->lru, &h->hugepage_freelists[nid]);
h->free_huge_pages++;
h->free_huge_pages_node[nid]++;
SetHPageFreed(page);
}
static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid)
{
struct page *page;
mm cma: rename PF_MEMALLOC_NOCMA to PF_MEMALLOC_PIN PF_MEMALLOC_NOCMA is used ot guarantee that the allocator will not return pages that might belong to CMA region. This is currently used for long term gup to make sure that such pins are not going to be done on any CMA pages. When PF_MEMALLOC_NOCMA has been introduced we haven't realized that it is focusing on CMA pages too much and that there is larger class of pages that need the same treatment. MOVABLE zone cannot contain any long term pins as well so it makes sense to reuse and redefine this flag for that usecase as well. Rename the flag to PF_MEMALLOC_PIN which defines an allocation context which can only get pages suitable for long-term pins. Also rename: memalloc_nocma_save()/memalloc_nocma_restore to memalloc_pin_save()/memalloc_pin_restore() and make the new functions common. [rppt@linux.ibm.com: fix renaming of PF_MEMALLOC_NOCMA to PF_MEMALLOC_PIN] Link: https://lkml.kernel.org/r/20210331163816.11517-1-rppt@kernel.org Link: https://lkml.kernel.org/r/20210215161349.246722-6-pasha.tatashin@soleen.com Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: James Morris <jmorris@namei.org> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sashal@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Tyler Hicks <tyhicks@linux.microsoft.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:38:53 +03:00
bool pin = !!(current->flags & PF_MEMALLOC_PIN);
mm/hugetlb: make hugetlb migration callback CMA aware new_non_cma_page() in gup.c requires to allocate the new page that is not on the CMA area. new_non_cma_page() implements it by using allocation scope APIs. However, there is a work-around for hugetlb. Normal hugetlb page allocation API for migration is alloc_huge_page_nodemask(). It consists of two steps. First is dequeing from the pool. Second is, if there is no available page on the queue, allocating by using the page allocator. new_non_cma_page() can't use this API since first step (deque) isn't aware of scope API to exclude CMA area. So, new_non_cma_page() exports hugetlb internal function for the second step, alloc_migrate_huge_page(), to global scope and uses it directly. This is suboptimal since hugetlb pages on the queue cannot be utilized. This patch tries to fix this situation by making the deque function on hugetlb CMA aware. In the deque function, CMA memory is skipped if PF_MEMALLOC_NOCMA flag is found. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Roman Gushchin <guro@fb.com> Link: http://lkml.kernel.org/r/1596180906-8442-2-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 04:37:38 +03:00
lockdep_assert_held(&hugetlb_lock);
mm/hugetlb: make hugetlb migration callback CMA aware new_non_cma_page() in gup.c requires to allocate the new page that is not on the CMA area. new_non_cma_page() implements it by using allocation scope APIs. However, there is a work-around for hugetlb. Normal hugetlb page allocation API for migration is alloc_huge_page_nodemask(). It consists of two steps. First is dequeing from the pool. Second is, if there is no available page on the queue, allocating by using the page allocator. new_non_cma_page() can't use this API since first step (deque) isn't aware of scope API to exclude CMA area. So, new_non_cma_page() exports hugetlb internal function for the second step, alloc_migrate_huge_page(), to global scope and uses it directly. This is suboptimal since hugetlb pages on the queue cannot be utilized. This patch tries to fix this situation by making the deque function on hugetlb CMA aware. In the deque function, CMA memory is skipped if PF_MEMALLOC_NOCMA flag is found. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Roman Gushchin <guro@fb.com> Link: http://lkml.kernel.org/r/1596180906-8442-2-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 04:37:38 +03:00
list_for_each_entry(page, &h->hugepage_freelists[nid], lru) {
2021-05-05 04:39:00 +03:00
if (pin && !is_pinnable_page(page))
mm/hugetlb: make hugetlb migration callback CMA aware new_non_cma_page() in gup.c requires to allocate the new page that is not on the CMA area. new_non_cma_page() implements it by using allocation scope APIs. However, there is a work-around for hugetlb. Normal hugetlb page allocation API for migration is alloc_huge_page_nodemask(). It consists of two steps. First is dequeing from the pool. Second is, if there is no available page on the queue, allocating by using the page allocator. new_non_cma_page() can't use this API since first step (deque) isn't aware of scope API to exclude CMA area. So, new_non_cma_page() exports hugetlb internal function for the second step, alloc_migrate_huge_page(), to global scope and uses it directly. This is suboptimal since hugetlb pages on the queue cannot be utilized. This patch tries to fix this situation by making the deque function on hugetlb CMA aware. In the deque function, CMA memory is skipped if PF_MEMALLOC_NOCMA flag is found. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Roman Gushchin <guro@fb.com> Link: http://lkml.kernel.org/r/1596180906-8442-2-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 04:37:38 +03:00
continue;
if (PageHWPoison(page))
continue;
list_move(&page->lru, &h->hugepage_activelist);
set_page_refcounted(page);
ClearHPageFreed(page);
h->free_huge_pages--;
h->free_huge_pages_node[nid]--;
return page;
mm/hugetlb: make hugetlb migration callback CMA aware new_non_cma_page() in gup.c requires to allocate the new page that is not on the CMA area. new_non_cma_page() implements it by using allocation scope APIs. However, there is a work-around for hugetlb. Normal hugetlb page allocation API for migration is alloc_huge_page_nodemask(). It consists of two steps. First is dequeing from the pool. Second is, if there is no available page on the queue, allocating by using the page allocator. new_non_cma_page() can't use this API since first step (deque) isn't aware of scope API to exclude CMA area. So, new_non_cma_page() exports hugetlb internal function for the second step, alloc_migrate_huge_page(), to global scope and uses it directly. This is suboptimal since hugetlb pages on the queue cannot be utilized. This patch tries to fix this situation by making the deque function on hugetlb CMA aware. In the deque function, CMA memory is skipped if PF_MEMALLOC_NOCMA flag is found. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Roman Gushchin <guro@fb.com> Link: http://lkml.kernel.org/r/1596180906-8442-2-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 04:37:38 +03:00
}
return NULL;
}
static struct page *dequeue_huge_page_nodemask(struct hstate *h, gfp_t gfp_mask, int nid,
nodemask_t *nmask)
{
unsigned int cpuset_mems_cookie;
struct zonelist *zonelist;
struct zone *zone;
struct zoneref *z;
mm: replace all open encodings for NUMA_NO_NODE Patch series "Replace all open encodings for NUMA_NO_NODE", v3. All these places for replacement were found by running the following grep patterns on the entire kernel code. Please let me know if this might have missed some instances. This might also have replaced some false positives. I will appreciate suggestions, inputs and review. 1. git grep "nid == -1" 2. git grep "node == -1" 3. git grep "nid = -1" 4. git grep "node = -1" This patch (of 2): At present there are multiple places where invalid node number is encoded as -1. Even though implicitly understood it is always better to have macros in there. Replace these open encodings for an invalid node number with the global macro NUMA_NO_NODE. This helps remove NUMA related assumptions like 'invalid node' from various places redirecting them to a common definition. Link: http://lkml.kernel.org/r/1545127933-10711-2-git-send-email-anshuman.khandual@arm.com Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> [ixgbe] Acked-by: Jens Axboe <axboe@kernel.dk> [mtip32xx] Acked-by: Vinod Koul <vkoul@kernel.org> [dmaengine.c] Acked-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc] Acked-by: Doug Ledford <dledford@redhat.com> [drivers/infiniband] Cc: Joseph Qi <jiangqi903@gmail.com> Cc: Hans Verkuil <hverkuil@xs4all.nl> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-06 02:42:58 +03:00
int node = NUMA_NO_NODE;
zonelist = node_zonelist(nid, gfp_mask);
retry_cpuset:
cpuset_mems_cookie = read_mems_allowed_begin();
for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(gfp_mask), nmask) {
struct page *page;
if (!cpuset_zone_allowed(zone, gfp_mask))
continue;
/*
* no need to ask again on the same node. Pool is node rather than
* zone aware
*/
if (zone_to_nid(zone) == node)
continue;
node = zone_to_nid(zone);
page = dequeue_huge_page_node_exact(h, node);
if (page)
return page;
}
if (unlikely(read_mems_allowed_retry(cpuset_mems_cookie)))
goto retry_cpuset;
return NULL;
}
static struct page *dequeue_huge_page_vma(struct hstate *h,
struct vm_area_struct *vma,
mm, hugetlb: decrement reserve count if VM_NORESERVE alloc page cache If a vma with VM_NORESERVE allocate a new page for page cache, we should check whether this area is reserved or not. If this address is already reserved by other process(in case of chg == 0), we should decrement reserve count, because this allocated page will go into page cache and currently, there is no way to know that this page comes from reserved pool or not when releasing inode. This may introduce over-counting problem to reserved count. With following example code, you can easily reproduce this situation. Assume 2MB, nr_hugepages = 100 size = 20 * MB; flag = MAP_SHARED; p = mmap(NULL, size, PROT_READ|PROT_WRITE, flag, fd, 0); if (p == MAP_FAILED) { fprintf(stderr, "mmap() failed: %s\n", strerror(errno)); return -1; } flag = MAP_SHARED | MAP_NORESERVE; q = mmap(NULL, size, PROT_READ|PROT_WRITE, flag, fd, 0); if (q == MAP_FAILED) { fprintf(stderr, "mmap() failed: %s\n", strerror(errno)); } q[0] = 'c'; After finish the program, run 'cat /proc/meminfo'. You can see below result. HugePages_Free: 100 HugePages_Rsvd: 1 To fix this, we should check our mapping type and tracked region. If our mapping is VM_NORESERVE, VM_MAYSHARE and chg is 0, this imply that current allocated page will go into page cache which is already reserved region when mapping is created. In this case, we should decrease reserve count. As implementing above, this patch solve the problem. [akpm@linux-foundation.org: fix spelling in comment] Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:21:18 +04:00
unsigned long address, int avoid_reserve,
long chg)
{
mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY Implement the missing huge page allocation functionality while obeying the preferred node semantics. This is similar to the implementation for general page allocation, as it uses a fallback mechanism to try multiple preferred nodes first, and then all other nodes. To avoid adding too many "#ifdef CONFIG_NUMA" check, add a helper function in mempolicy.h to check whether a mempolicy is MPOL_PREFERRED_MANY. [akpm@linux-foundation.org: fix compiling issue when merging with other hugetlb patch] [Thanks to 0day bot for catching the !CONFIG_NUMA compiling issue] [mhocko@suse.com: suggest to remove the #ifdef CONFIG_NUMA check] [ben.widawsky@intel.com: add helpers to avoid ifdefs] Link: https://lore.kernel.org/r/20200630212517.308045-12-ben.widawsky@intel.com Link: https://lkml.kernel.org/r/1627970362-61305-4-git-send-email-feng.tang@intel.com Link: https://lkml.kernel.org/r/20210809024430.GA46432@shbuild999.sh.intel.com [nathan@kernel.org: initialize page to NULL in alloc_buddy_huge_page_with_mpol()] Link: https://lkml.kernel.org/r/20210810200632.3812797-1-nathan@kernel.org Link: https://lore.kernel.org/r/20200630212517.308045-12-ben.widawsky@intel.com Link: https://lkml.kernel.org/r/1627970362-61305-4-git-send-email-feng.tang@intel.com Link: https://lkml.kernel.org/r/20210809024430.GA46432@shbuild999.sh.intel.com Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> Signed-off-by: Feng Tang <feng.tang@intel.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Co-developed-by: Feng Tang <feng.tang@intel.com> Suggested-by: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 01:00:13 +03:00
struct page *page = NULL;
Fix NUMA Memory Policy Reference Counting This patch proposes fixes to the reference counting of memory policy in the page allocation paths and in show_numa_map(). Extracted from my "Memory Policy Cleanups and Enhancements" series as stand-alone. Shared policy lookup [shmem] has always added a reference to the policy, but this was never unrefed after page allocation or after formatting the numa map data. Default system policy should not require additional ref counting, nor should the current task's task policy. However, show_numa_map() calls get_vma_policy() to examine what may be [likely is] another task's policy. The latter case needs protection against freeing of the policy. This patch adds a reference count to a mempolicy returned by get_vma_policy() when the policy is a vma policy or another task's mempolicy. Again, shared policy is already reference counted on lookup. A matching "unref" [__mpol_free()] is performed in alloc_page_vma() for shared and vma policies, and in show_numa_map() for shared and another task's mempolicy. We can call __mpol_free() directly, saving an admittedly inexpensive inline NULL test, because we know we have a non-NULL policy. Handling policy ref counts for hugepages is a bit trickier. huge_zonelist() returns a zone list that might come from a shared or vma 'BIND policy. In this case, we should hold the reference until after the huge page allocation in dequeue_hugepage(). The patch modifies huge_zonelist() to return a pointer to the mempolicy if it needs to be unref'd after allocation. Kernel Build [16cpu, 32GB, ia64] - average of 10 runs: w/o patch w/ refcount patch Avg Std Devn Avg Std Devn Real: 100.59 0.38 100.63 0.43 User: 1209.60 0.37 1209.91 0.31 System: 81.52 0.42 81.64 0.34 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Andi Kleen <ak@suse.de> Cc: Christoph Lameter <clameter@sgi.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-09-19 09:46:47 +04:00
struct mempolicy *mpol;
gfp_t gfp_mask;
nodemask_t *nodemask;
int nid;
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
/*
* A child process with MAP_PRIVATE mappings created by their parent
* have no page reserves. This check ensures that reservations are
* not "stolen". The child may still get SIGKILLed
*/
mm, hugetlb: decrement reserve count if VM_NORESERVE alloc page cache If a vma with VM_NORESERVE allocate a new page for page cache, we should check whether this area is reserved or not. If this address is already reserved by other process(in case of chg == 0), we should decrement reserve count, because this allocated page will go into page cache and currently, there is no way to know that this page comes from reserved pool or not when releasing inode. This may introduce over-counting problem to reserved count. With following example code, you can easily reproduce this situation. Assume 2MB, nr_hugepages = 100 size = 20 * MB; flag = MAP_SHARED; p = mmap(NULL, size, PROT_READ|PROT_WRITE, flag, fd, 0); if (p == MAP_FAILED) { fprintf(stderr, "mmap() failed: %s\n", strerror(errno)); return -1; } flag = MAP_SHARED | MAP_NORESERVE; q = mmap(NULL, size, PROT_READ|PROT_WRITE, flag, fd, 0); if (q == MAP_FAILED) { fprintf(stderr, "mmap() failed: %s\n", strerror(errno)); } q[0] = 'c'; After finish the program, run 'cat /proc/meminfo'. You can see below result. HugePages_Free: 100 HugePages_Rsvd: 1 To fix this, we should check our mapping type and tracked region. If our mapping is VM_NORESERVE, VM_MAYSHARE and chg is 0, this imply that current allocated page will go into page cache which is already reserved region when mapping is created. In this case, we should decrease reserve count. As implementing above, this patch solve the problem. [akpm@linux-foundation.org: fix spelling in comment] Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:21:18 +04:00
if (!vma_has_reserves(vma, chg) &&
h->free_huge_pages - h->resv_huge_pages == 0)
cpuset,mm: fix no node to alloc memory when changing cpuset's mems Before applying this patch, cpuset updates task->mems_allowed and mempolicy by setting all new bits in the nodemask first, and clearing all old unallowed bits later. But in the way, the allocator may find that there is no node to alloc memory. The reason is that cpuset rebinds the task's mempolicy, it cleans the nodes which the allocater can alloc pages on, for example: (mpol: mempolicy) task1 task1's mpol task2 alloc page 1 alloc on node0? NO 1 1 change mems from 1 to 0 1 rebind task1's mpol 0-1 set new bits 0 clear disallowed bits alloc on node1? NO 0 ... can't alloc page goto oom This patch fixes this problem by expanding the nodes range first(set newly allowed bits) and shrink it lazily(clear newly disallowed bits). So we use a variable to tell the write-side task that read-side task is reading nodemask, and the write-side task clears newly disallowed nodes after read-side task ends the current memory allocation. [akpm@linux-foundation.org: fix spello] Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Paul Menage <menage@google.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Ravikiran Thirumalai <kiran@scalex86.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-05-25 01:32:08 +04:00
goto err;
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
/* If reserves cannot be used, ensure enough pages are in the pool */
if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
goto err;
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
gfp_mask = htlb_alloc_mask(h);
nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY Implement the missing huge page allocation functionality while obeying the preferred node semantics. This is similar to the implementation for general page allocation, as it uses a fallback mechanism to try multiple preferred nodes first, and then all other nodes. To avoid adding too many "#ifdef CONFIG_NUMA" check, add a helper function in mempolicy.h to check whether a mempolicy is MPOL_PREFERRED_MANY. [akpm@linux-foundation.org: fix compiling issue when merging with other hugetlb patch] [Thanks to 0day bot for catching the !CONFIG_NUMA compiling issue] [mhocko@suse.com: suggest to remove the #ifdef CONFIG_NUMA check] [ben.widawsky@intel.com: add helpers to avoid ifdefs] Link: https://lore.kernel.org/r/20200630212517.308045-12-ben.widawsky@intel.com Link: https://lkml.kernel.org/r/1627970362-61305-4-git-send-email-feng.tang@intel.com Link: https://lkml.kernel.org/r/20210809024430.GA46432@shbuild999.sh.intel.com [nathan@kernel.org: initialize page to NULL in alloc_buddy_huge_page_with_mpol()] Link: https://lkml.kernel.org/r/20210810200632.3812797-1-nathan@kernel.org Link: https://lore.kernel.org/r/20200630212517.308045-12-ben.widawsky@intel.com Link: https://lkml.kernel.org/r/1627970362-61305-4-git-send-email-feng.tang@intel.com Link: https://lkml.kernel.org/r/20210809024430.GA46432@shbuild999.sh.intel.com Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> Signed-off-by: Feng Tang <feng.tang@intel.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Co-developed-by: Feng Tang <feng.tang@intel.com> Suggested-by: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 01:00:13 +03:00
if (mpol_is_preferred_many(mpol)) {
page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask);
/* Fallback to all nodes if page==NULL */
nodemask = NULL;
}
if (!page)
page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask);
if (page && !avoid_reserve && vma_has_reserves(vma, chg)) {
hugetlb: use page.private for hugetlb specific page flags Patch series "create hugetlb flags to consolidate state", v3. While discussing a series of hugetlb fixes in [1], it became evident that the hugetlb specific page state information is stored in a somewhat haphazard manner. Code dealing with state information would be easier to read, understand and maintain if this information was stored in a consistent manner. This series uses page.private of the hugetlb head page for storing a set of hugetlb specific page flags. Routines are priovided for test, set and clear of the flags. [1] https://lore.kernel.org/r/20210106084739.63318-1-songmuchun@bytedance.com This patch (of 4): As hugetlbfs evolved, state information about hugetlb pages was added. One 'convenient' way of doing this was to use available fields in tail pages. Over time, it has become difficult to know the meaning or contents of fields simply by looking at a small bit of code. Sometimes, the naming is just confusing. For example: The PagePrivate flag indicates a huge page reservation was consumed and needs to be restored if an error is encountered and the page is freed before it is instantiated. The page.private field contains the pointer to a subpool if the page is associated with one. In an effort to make the code more readable, use page.private to contain hugetlb specific page flags. These flags will have test, set and clear functions similar to those used for 'normal' page flags. More importantly, an enum of flag values will be created with names that actually reflect their purpose. In this patch, - Create infrastructure for hugetlb specific page flag functions - Move subpool pointer to page[1].private to make way for flags Create routines with meaningful names to modify subpool field - Use new HPageRestoreReserve flag instead of PagePrivate Conversion of other state information will happen in subsequent patches. Link: https://lkml.kernel.org/r/20210122195231.324857-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210122195231.324857-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:51 +03:00
SetHPageRestoreReserve(page);
h->resv_huge_pages--;
}
cpuset: mm: reduce large amounts of memory barrier related damage v3 Commit c0ff7453bb5c ("cpuset,mm: fix no node to alloc memory when changing cpuset's mems") wins a super prize for the largest number of memory barriers entered into fast paths for one commit. [get|put]_mems_allowed is incredibly heavy with pairs of full memory barriers inserted into a number of hot paths. This was detected while investigating at large page allocator slowdown introduced some time after 2.6.32. The largest portion of this overhead was shown by oprofile to be at an mfence introduced by this commit into the page allocator hot path. For extra style points, the commit introduced the use of yield() in an implementation of what looks like a spinning mutex. This patch replaces the full memory barriers on both read and write sides with a sequence counter with just read barriers on the fast path side. This is much cheaper on some architectures, including x86. The main bulk of the patch is the retry logic if the nodemask changes in a manner that can cause a false failure. While updating the nodemask, a check is made to see if a false failure is a risk. If it is, the sequence number gets bumped and parallel allocators will briefly stall while the nodemask update takes place. In a page fault test microbenchmark, oprofile samples from __alloc_pages_nodemask went from 4.53% of all samples to 1.15%. The actual results were 3.3.0-rc3 3.3.0-rc3 rc3-vanilla nobarrier-v2r1 Clients 1 UserTime 0.07 ( 0.00%) 0.08 (-14.19%) Clients 2 UserTime 0.07 ( 0.00%) 0.07 ( 2.72%) Clients 4 UserTime 0.08 ( 0.00%) 0.07 ( 3.29%) Clients 1 SysTime 0.70 ( 0.00%) 0.65 ( 6.65%) Clients 2 SysTime 0.85 ( 0.00%) 0.82 ( 3.65%) Clients 4 SysTime 1.41 ( 0.00%) 1.41 ( 0.32%) Clients 1 WallTime 0.77 ( 0.00%) 0.74 ( 4.19%) Clients 2 WallTime 0.47 ( 0.00%) 0.45 ( 3.73%) Clients 4 WallTime 0.38 ( 0.00%) 0.37 ( 1.58%) Clients 1 Flt/sec/cpu 497620.28 ( 0.00%) 520294.53 ( 4.56%) Clients 2 Flt/sec/cpu 414639.05 ( 0.00%) 429882.01 ( 3.68%) Clients 4 Flt/sec/cpu 257959.16 ( 0.00%) 258761.48 ( 0.31%) Clients 1 Flt/sec 495161.39 ( 0.00%) 517292.87 ( 4.47%) Clients 2 Flt/sec 820325.95 ( 0.00%) 850289.77 ( 3.65%) Clients 4 Flt/sec 1020068.93 ( 0.00%) 1022674.06 ( 0.26%) MMTests Statistics: duration Sys Time Running Test (seconds) 135.68 132.17 User+Sys Time Running Test (seconds) 164.2 160.13 Total Elapsed Time (seconds) 123.46 120.87 The overall improvement is small but the System CPU time is much improved and roughly in correlation to what oprofile reported (these performance figures are without profiling so skew is expected). The actual number of page faults is noticeably improved. For benchmarks like kernel builds, the overall benefit is marginal but the system CPU time is slightly reduced. To test the actual bug the commit fixed I opened two terminals. The first ran within a cpuset and continually ran a small program that faulted 100M of anonymous data. In a second window, the nodemask of the cpuset was continually randomised in a loop. Without the commit, the program would fail every so often (usually within 10 seconds) and obviously with the commit everything worked fine. With this patch applied, it also worked fine so the fix should be functionally equivalent. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Miao Xie <miaox@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:11 +04:00
mempolicy: rework mempolicy Reference Counting [yet again] After further discussion with Christoph Lameter, it has become clear that my earlier attempts to clean up the mempolicy reference counting were a bit of overkill in some areas, resulting in superflous ref/unref in what are usually fast paths. In other areas, further inspection reveals that I botched the unref for interleave policies. A separate patch, suitable for upstream/stable trees, fixes up the known errors in the previous attempt to fix reference counting. This patch reworks the memory policy referencing counting and, one hopes, simplifies the code. Maybe I'll get it right this time. See the update to the numa_memory_policy.txt document for a discussion of memory policy reference counting that motivates this patch. Summary: Lookup of mempolicy, based on (vma, address) need only add a reference for shared policy, and we need only unref the policy when finished for shared policies. So, this patch backs out all of the unneeded extra reference counting added by my previous attempt. It then unrefs only shared policies when we're finished with them, using the mpol_cond_put() [conditional put] helper function introduced by this patch. Note that shmem_swapin() calls read_swap_cache_async() with a dummy vma containing just the policy. read_swap_cache_async() can call alloc_page_vma() multiple times, so we can't let alloc_page_vma() unref the shared policy in this case. To avoid this, we make a copy of any non-null shared policy and remove the MPOL_F_SHARED flag from the copy. This copy occurs before reading a page [or multiple pages] from swap, so the overhead should not be an issue here. I introduced a new static inline function "mpol_cond_copy()" to copy the shared policy to an on-stack policy and remove the flags that would require a conditional free. The current implementation of mpol_cond_copy() assumes that the struct mempolicy contains no pointers to dynamically allocated structures that must be duplicated or reference counted during copy. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-28 13:13:16 +04:00
mpol_cond_put(mpol);
return page;
cpuset: mm: reduce large amounts of memory barrier related damage v3 Commit c0ff7453bb5c ("cpuset,mm: fix no node to alloc memory when changing cpuset's mems") wins a super prize for the largest number of memory barriers entered into fast paths for one commit. [get|put]_mems_allowed is incredibly heavy with pairs of full memory barriers inserted into a number of hot paths. This was detected while investigating at large page allocator slowdown introduced some time after 2.6.32. The largest portion of this overhead was shown by oprofile to be at an mfence introduced by this commit into the page allocator hot path. For extra style points, the commit introduced the use of yield() in an implementation of what looks like a spinning mutex. This patch replaces the full memory barriers on both read and write sides with a sequence counter with just read barriers on the fast path side. This is much cheaper on some architectures, including x86. The main bulk of the patch is the retry logic if the nodemask changes in a manner that can cause a false failure. While updating the nodemask, a check is made to see if a false failure is a risk. If it is, the sequence number gets bumped and parallel allocators will briefly stall while the nodemask update takes place. In a page fault test microbenchmark, oprofile samples from __alloc_pages_nodemask went from 4.53% of all samples to 1.15%. The actual results were 3.3.0-rc3 3.3.0-rc3 rc3-vanilla nobarrier-v2r1 Clients 1 UserTime 0.07 ( 0.00%) 0.08 (-14.19%) Clients 2 UserTime 0.07 ( 0.00%) 0.07 ( 2.72%) Clients 4 UserTime 0.08 ( 0.00%) 0.07 ( 3.29%) Clients 1 SysTime 0.70 ( 0.00%) 0.65 ( 6.65%) Clients 2 SysTime 0.85 ( 0.00%) 0.82 ( 3.65%) Clients 4 SysTime 1.41 ( 0.00%) 1.41 ( 0.32%) Clients 1 WallTime 0.77 ( 0.00%) 0.74 ( 4.19%) Clients 2 WallTime 0.47 ( 0.00%) 0.45 ( 3.73%) Clients 4 WallTime 0.38 ( 0.00%) 0.37 ( 1.58%) Clients 1 Flt/sec/cpu 497620.28 ( 0.00%) 520294.53 ( 4.56%) Clients 2 Flt/sec/cpu 414639.05 ( 0.00%) 429882.01 ( 3.68%) Clients 4 Flt/sec/cpu 257959.16 ( 0.00%) 258761.48 ( 0.31%) Clients 1 Flt/sec 495161.39 ( 0.00%) 517292.87 ( 4.47%) Clients 2 Flt/sec 820325.95 ( 0.00%) 850289.77 ( 3.65%) Clients 4 Flt/sec 1020068.93 ( 0.00%) 1022674.06 ( 0.26%) MMTests Statistics: duration Sys Time Running Test (seconds) 135.68 132.17 User+Sys Time Running Test (seconds) 164.2 160.13 Total Elapsed Time (seconds) 123.46 120.87 The overall improvement is small but the System CPU time is much improved and roughly in correlation to what oprofile reported (these performance figures are without profiling so skew is expected). The actual number of page faults is noticeably improved. For benchmarks like kernel builds, the overall benefit is marginal but the system CPU time is slightly reduced. To test the actual bug the commit fixed I opened two terminals. The first ran within a cpuset and continually ran a small program that faulted 100M of anonymous data. In a second window, the nodemask of the cpuset was continually randomised in a loop. Without the commit, the program would fail every so often (usually within 10 seconds) and obviously with the commit everything worked fine. With this patch applied, it also worked fine so the fix should be functionally equivalent. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Miao Xie <miaox@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:11 +04:00
err:
return NULL;
}
/*
* common helper functions for hstate_next_node_to_{alloc|free}.
* We may have allocated or freed a huge page based on a different
* nodes_allowed previously, so h->next_node_to_{alloc|free} might
* be outside of *nodes_allowed. Ensure that we use an allowed
* node for alloc or free.
*/
static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
{
nid = next_node_in(nid, *nodes_allowed);
VM_BUG_ON(nid >= MAX_NUMNODES);
return nid;
}
static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
{
if (!node_isset(nid, *nodes_allowed))
nid = next_node_allowed(nid, nodes_allowed);
return nid;
}
/*
* returns the previously saved node ["this node"] from which to
* allocate a persistent huge page for the pool and advance the
* next node from which to allocate, handling wrap at end of node
* mask.
*/
static int hstate_next_node_to_alloc(struct hstate *h,
nodemask_t *nodes_allowed)
{
int nid;
VM_BUG_ON(!nodes_allowed);
nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
return nid;
}
/*
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
* helper for remove_pool_huge_page() - return the previously saved
* node ["this node"] from which to free a huge page. Advance the
* next node id whether or not we find a free huge page to free so
* that the next attempt to free addresses the next node.
*/
static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
{
int nid;
VM_BUG_ON(!nodes_allowed);
nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
return nid;
}
#define for_each_node_mask_to_alloc(hs, nr_nodes, node, mask) \
for (nr_nodes = nodes_weight(*mask); \
nr_nodes > 0 && \
((node = hstate_next_node_to_alloc(hs, mask)) || 1); \
nr_nodes--)
#define for_each_node_mask_to_free(hs, nr_nodes, node, mask) \
for (nr_nodes = nodes_weight(*mask); \
nr_nodes > 0 && \
((node = hstate_next_node_to_free(hs, mask)) || 1); \
nr_nodes--)
/* used to demote non-gigantic_huge pages as well */
hugetlb: add demote bool to gigantic page routines The routines remove_hugetlb_page and destroy_compound_gigantic_page will remove a gigantic page and make the set of base pages ready to be returned to a lower level allocator. In the process of doing this, they make all base pages reference counted. The routine prep_compound_gigantic_page creates a gigantic page from a set of base pages. It assumes that all these base pages are reference counted. During demotion, a gigantic page will be split into huge pages of a smaller size. This logically involves use of the routines, remove_hugetlb_page, and destroy_compound_gigantic_page followed by prep_compound*_page for each smaller huge page. When pages are reference counted (ref count >= 0), additional speculative ref counts could be taken as described in previous commits [1] and [2]. This could result in errors while demoting a huge page. Quite a bit of code would need to be created to handle all possible issues. Instead of dealing with the possibility of speculative ref counts, avoid the possibility by keeping ref counts at zero during the demote process. Add a boolean 'demote' to the routines remove_hugetlb_page, destroy_compound_gigantic_page and prep_compound_gigantic_page. If the boolean is set, the remove and destroy routines will not reference count pages and the prep routine will not expect reference counted pages. '*_for_demote' wrappers of the routines will be added in a subsequent patch where this functionality is used. [1] https://lore.kernel.org/linux-mm/20210622021423.154662-3-mike.kravetz@oracle.com/ [2] https://lore.kernel.org/linux-mm/20210809184832.18342-3-mike.kravetz@oracle.com/ Link: https://lkml.kernel.org/r/20211007181918.136982-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:30 +03:00
static void __destroy_compound_gigantic_page(struct page *page,
unsigned int order, bool demote)
hugetlb: add support for gigantic page allocation at runtime HugeTLB is limited to allocating hugepages whose size are less than MAX_ORDER order. This is so because HugeTLB allocates hugepages via the buddy allocator. Gigantic pages (that is, pages whose size is greater than MAX_ORDER order) have to be allocated at boottime. However, boottime allocation has at least two serious problems. First, it doesn't support NUMA and second, gigantic pages allocated at boottime can't be freed. This commit solves both issues by adding support for allocating gigantic pages during runtime. It works just like regular sized hugepages, meaning that the interface in sysfs is the same, it supports NUMA, and gigantic pages can be freed. For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And to free them all: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages The one problem with gigantic page allocation at runtime is that it can't be serviced by the buddy allocator. To overcome that problem, this commit scans all zones from a node looking for a large enough contiguous region. When one is found, it's allocated by using CMA, that is, we call alloc_contig_range() to do the actual allocation. For example, on x86_64 we scan all zones looking for a 1GB contiguous region. When one is found, it's allocated by alloc_contig_range(). One expected issue with that approach is that such gigantic contiguous regions tend to vanish as runtime goes by. The best way to avoid this for now is to make gigantic page allocations very early during system boot, say from a init script. Other possible optimization include using compaction, which is supported by CMA but is not explicitly used by this commit. It's also important to note the following: 1. Gigantic pages allocated at boottime by the hugepages= command-line option can be freed at runtime just fine 2. This commit adds support for gigantic pages only to x86_64. The reason is that I don't have access to nor experience with other archs. The code is arch indepedent though, so it should be simple to add support to different archs 3. I didn't add support for hugepage overcommit, that is allocating a gigantic page on demand when /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't think it's reasonable to do the hard and long work required for allocating a gigantic page at fault time. But it should be simple to add this if wanted [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-05 03:07:13 +04:00
{
int i;
int nr_pages = 1 << order;
struct page *p = page + 1;
mm/hugetlb: clear compound_mapcount when freeing gigantic pages While working on s390 support for gigantic hugepages I ran into the following "Bad page state" warning when freeing gigantic pages: BUG: Bad page state in process bash pfn:580001 page:000003d116000040 count:0 mapcount:0 mapping:ffffffff00000000 index:0x0 flags: 0x7fffc0000000000() page dumped because: non-NULL mapping This is because page->compound_mapcount, which is part of a union with page->mapping, is initialized with -1 in prep_compound_gigantic_page(), and not cleared again during destroy_compound_gigantic_page(). Fix this by clearing the compound_mapcount in destroy_compound_gigantic_page() before clearing compound_head. Interestingly enough, the warning will not show up on x86_64, although this should not be architecture specific. Apparently there is an endianness issue, combined with the fact that the union contains both a 64 bit ->mapping pointer and a 32 bit atomic_t ->compound_mapcount as members. The resulting bogus page->mapping on x86_64 therefore contains 00000000ffffffff instead of ffffffff00000000 on s390, which will falsely trigger the PageAnon() check in free_pages_prepare() because page->mapping & PAGE_MAPPING_ANON is true on little-endian architectures like x86_64 in this case (the page is not compound anymore, ->compound_head was already cleared before). As a result, page->mapping will be cleared before doing the checks in free_pages_check(). Not sure if the bogus "PageAnon() returning true" on x86_64 for the first tail page of a gigantic page (at this stage) has other theoretical implications, but they would also be fixed with this patch. Link: http://lkml.kernel.org/r/1466612719-5642-1-git-send-email-gerald.schaefer@de.ibm.com Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-25 00:50:04 +03:00
atomic_set(compound_mapcount_ptr(page), 0);
atomic_set(compound_pincount_ptr(page), 0);
mm/gup: page->hpage_pinned_refcount: exact pin counts for huge pages For huge pages (and in fact, any compound page), the GUP_PIN_COUNTING_BIAS scheme tends to overflow too easily, each tail page increments the head page->_refcount by GUP_PIN_COUNTING_BIAS (1024). That limits the number of huge pages that can be pinned. This patch removes that limitation, by using an exact form of pin counting for compound pages of order > 1. The "order > 1" is required because this approach uses the 3rd struct page in the compound page, and order 1 compound pages only have two pages, so that won't work there. A new struct page field, hpage_pinned_refcount, has been added, replacing a padding field in the union (so no new space is used). This enhancement also has a useful side effect: huge pages and compound pages (of order > 1) do not suffer from the "potential false positives" problem that is discussed in the page_dma_pinned() comment block. That is because these compound pages have extra space for tracking things, so they get exact pin counts instead of overloading page->_refcount. Documentation/core-api/pin_user_pages.rst is updated accordingly. Suggested-by: Jan Kara <jack@suse.cz> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200211001536.1027652-8-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:05:33 +03:00
hugetlb: add support for gigantic page allocation at runtime HugeTLB is limited to allocating hugepages whose size are less than MAX_ORDER order. This is so because HugeTLB allocates hugepages via the buddy allocator. Gigantic pages (that is, pages whose size is greater than MAX_ORDER order) have to be allocated at boottime. However, boottime allocation has at least two serious problems. First, it doesn't support NUMA and second, gigantic pages allocated at boottime can't be freed. This commit solves both issues by adding support for allocating gigantic pages during runtime. It works just like regular sized hugepages, meaning that the interface in sysfs is the same, it supports NUMA, and gigantic pages can be freed. For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And to free them all: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages The one problem with gigantic page allocation at runtime is that it can't be serviced by the buddy allocator. To overcome that problem, this commit scans all zones from a node looking for a large enough contiguous region. When one is found, it's allocated by using CMA, that is, we call alloc_contig_range() to do the actual allocation. For example, on x86_64 we scan all zones looking for a 1GB contiguous region. When one is found, it's allocated by alloc_contig_range(). One expected issue with that approach is that such gigantic contiguous regions tend to vanish as runtime goes by. The best way to avoid this for now is to make gigantic page allocations very early during system boot, say from a init script. Other possible optimization include using compaction, which is supported by CMA but is not explicitly used by this commit. It's also important to note the following: 1. Gigantic pages allocated at boottime by the hugepages= command-line option can be freed at runtime just fine 2. This commit adds support for gigantic pages only to x86_64. The reason is that I don't have access to nor experience with other archs. The code is arch indepedent though, so it should be simple to add support to different archs 3. I didn't add support for hugepage overcommit, that is allocating a gigantic page on demand when /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't think it's reasonable to do the hard and long work required for allocating a gigantic page at fault time. But it should be simple to add this if wanted [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-05 03:07:13 +04:00
for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
hugetlb: be sure to free demoted CMA pages to CMA When huge page demotion is fully implemented, gigantic pages can be demoted to a smaller huge page size. For example, on x86 a 1G page can be demoted to 512 2M pages. However, gigantic pages can potentially be allocated from CMA. If a gigantic page which was allocated from CMA is demoted, the corresponding demoted pages needs to be returned to CMA. Use the new interface cma_pages_valid() to determine if a non-gigantic hugetlb page should be freed to CMA. Also, clear mapping field of these pages as expected by cma_release. This also requires a change to CMA region creation for gigantic pages. CMA uses a per-region bit map to track allocations. When setting up the region, you specify how many pages each bit represents. Currently, only gigantic pages are allocated/freed from CMA so the region is set up such that one bit represents a gigantic page size allocation. With demote, a gigantic page (allocation) could be split into smaller size pages. And, these smaller size pages will be freed to CMA. So, since the per-region bit map needs to be set up to represent the smallest allocation/free size, it now needs to be set to the smallest huge page size which can be freed to CMA. Unfortunately, we set up the CMA region for huge pages before we set up huge pages sizes (hstates). So, technically we do not know the smallest huge page size as this can change via command line options and architecture specific code. Therefore, at region setup time we use HUGETLB_PAGE_ORDER as the smallest possible huge page size that can be given back to CMA. It is possible that this value is sub-optimal for some architectures/config options. If needed, this can be addressed in follow on work. Link: https://lkml.kernel.org/r/20211007181918.136982-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:27 +03:00
p->mapping = NULL;
mm: make compound_head() robust Hugh has pointed that compound_head() call can be unsafe in some context. There's one example: CPU0 CPU1 isolate_migratepages_block() page_count() compound_head() !!PageTail() == true put_page() tail->first_page = NULL head = tail->first_page alloc_pages(__GFP_COMP) prep_compound_page() tail->first_page = head __SetPageTail(p); !!PageTail() == true <head == NULL dereferencing> The race is pure theoretical. I don't it's possible to trigger it in practice. But who knows. We can fix the race by changing how encode PageTail() and compound_head() within struct page to be able to update them in one shot. The patch introduces page->compound_head into third double word block in front of compound_dtor and compound_order. Bit 0 encodes PageTail() and the rest bits are pointer to head page if bit zero is set. The patch moves page->pmd_huge_pte out of word, just in case if an architecture defines pgtable_t into something what can have the bit 0 set. hugetlb_cgroup uses page->lru.next in the second tail page to store pointer struct hugetlb_cgroup. The patch switch it to use page->private in the second tail page instead. The space is free since ->first_page is removed from the union. The patch also opens possibility to remove HUGETLB_CGROUP_MIN_ORDER limitation, since there's now space in first tail page to store struct hugetlb_cgroup pointer. But that's out of scope of the patch. That means page->compound_head shares storage space with: - page->lru.next; - page->next; - page->rcu_head.next; That's too long list to be absolutely sure, but looks like nobody uses bit 0 of the word. page->rcu_head.next guaranteed[1] to have bit 0 clean as long as we use call_rcu(), call_rcu_bh(), call_rcu_sched(), or call_srcu(). But future call_rcu_lazy() is not allowed as it makes use of the bit and we can get false positive PageTail(). [1] http://lkml.kernel.org/g/20150827163634.GD4029@linux.vnet.ibm.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-07 03:29:54 +03:00
clear_compound_head(p);
hugetlb: add demote bool to gigantic page routines The routines remove_hugetlb_page and destroy_compound_gigantic_page will remove a gigantic page and make the set of base pages ready to be returned to a lower level allocator. In the process of doing this, they make all base pages reference counted. The routine prep_compound_gigantic_page creates a gigantic page from a set of base pages. It assumes that all these base pages are reference counted. During demotion, a gigantic page will be split into huge pages of a smaller size. This logically involves use of the routines, remove_hugetlb_page, and destroy_compound_gigantic_page followed by prep_compound*_page for each smaller huge page. When pages are reference counted (ref count >= 0), additional speculative ref counts could be taken as described in previous commits [1] and [2]. This could result in errors while demoting a huge page. Quite a bit of code would need to be created to handle all possible issues. Instead of dealing with the possibility of speculative ref counts, avoid the possibility by keeping ref counts at zero during the demote process. Add a boolean 'demote' to the routines remove_hugetlb_page, destroy_compound_gigantic_page and prep_compound_gigantic_page. If the boolean is set, the remove and destroy routines will not reference count pages and the prep routine will not expect reference counted pages. '*_for_demote' wrappers of the routines will be added in a subsequent patch where this functionality is used. [1] https://lore.kernel.org/linux-mm/20210622021423.154662-3-mike.kravetz@oracle.com/ [2] https://lore.kernel.org/linux-mm/20210809184832.18342-3-mike.kravetz@oracle.com/ Link: https://lkml.kernel.org/r/20211007181918.136982-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:30 +03:00
if (!demote)
set_page_refcounted(p);
hugetlb: add support for gigantic page allocation at runtime HugeTLB is limited to allocating hugepages whose size are less than MAX_ORDER order. This is so because HugeTLB allocates hugepages via the buddy allocator. Gigantic pages (that is, pages whose size is greater than MAX_ORDER order) have to be allocated at boottime. However, boottime allocation has at least two serious problems. First, it doesn't support NUMA and second, gigantic pages allocated at boottime can't be freed. This commit solves both issues by adding support for allocating gigantic pages during runtime. It works just like regular sized hugepages, meaning that the interface in sysfs is the same, it supports NUMA, and gigantic pages can be freed. For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And to free them all: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages The one problem with gigantic page allocation at runtime is that it can't be serviced by the buddy allocator. To overcome that problem, this commit scans all zones from a node looking for a large enough contiguous region. When one is found, it's allocated by using CMA, that is, we call alloc_contig_range() to do the actual allocation. For example, on x86_64 we scan all zones looking for a 1GB contiguous region. When one is found, it's allocated by alloc_contig_range(). One expected issue with that approach is that such gigantic contiguous regions tend to vanish as runtime goes by. The best way to avoid this for now is to make gigantic page allocations very early during system boot, say from a init script. Other possible optimization include using compaction, which is supported by CMA but is not explicitly used by this commit. It's also important to note the following: 1. Gigantic pages allocated at boottime by the hugepages= command-line option can be freed at runtime just fine 2. This commit adds support for gigantic pages only to x86_64. The reason is that I don't have access to nor experience with other archs. The code is arch indepedent though, so it should be simple to add support to different archs 3. I didn't add support for hugepage overcommit, that is allocating a gigantic page on demand when /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't think it's reasonable to do the hard and long work required for allocating a gigantic page at fault time. But it should be simple to add this if wanted [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-05 03:07:13 +04:00
}
set_compound_order(page, 0);
#ifdef CONFIG_64BIT
mm/hugetlb: clear compound_nr before freeing gigantic pages Commit 1378a5ee451a ("mm: store compound_nr as well as compound_order") added compound_nr counter to first tail struct page, overlaying with page->mapping. The overlay itself is fine, but while freeing gigantic hugepages via free_contig_range(), a "bad page" check will trigger for non-NULL page->mapping on the first tail page: BUG: Bad page state in process bash pfn:380001 page:00000000c35f0856 refcount:0 mapcount:0 mapping:00000000126b68aa index:0x0 pfn:0x380001 aops:0x0 flags: 0x3ffff00000000000() raw: 3ffff00000000000 0000000000000100 0000000000000122 0000000100000000 raw: 0000000000000000 0000000000000000 ffffffff00000000 0000000000000000 page dumped because: non-NULL mapping Modules linked in: CPU: 6 PID: 616 Comm: bash Not tainted 5.10.0-rc7-next-20201208 #1 Hardware name: IBM 3906 M03 703 (LPAR) Call Trace: show_stack+0x6e/0xe8 dump_stack+0x90/0xc8 bad_page+0xd6/0x130 free_pcppages_bulk+0x26a/0x800 free_unref_page+0x6e/0x90 free_contig_range+0x94/0xe8 update_and_free_page+0x1c4/0x2c8 free_pool_huge_page+0x11e/0x138 set_max_huge_pages+0x228/0x300 nr_hugepages_store_common+0xb8/0x130 kernfs_fop_write+0xd2/0x218 vfs_write+0xb0/0x2b8 ksys_write+0xac/0xe0 system_call+0xe6/0x288 Disabling lock debugging due to kernel taint This is because only the compound_order is cleared in destroy_compound_gigantic_page(), and compound_nr is set to 1U << order == 1 for order 0 in set_compound_order(page, 0). Fix this by explicitly clearing compound_nr for first tail page after calling set_compound_order(page, 0). Link: https://lkml.kernel.org/r/20201208182813.66391-2-gerald.schaefer@linux.ibm.com Fixes: 1378a5ee451a ("mm: store compound_nr as well as compound_order") Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: <stable@vger.kernel.org> [5.9+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-12 00:36:53 +03:00
page[1].compound_nr = 0;
#endif
hugetlb: add support for gigantic page allocation at runtime HugeTLB is limited to allocating hugepages whose size are less than MAX_ORDER order. This is so because HugeTLB allocates hugepages via the buddy allocator. Gigantic pages (that is, pages whose size is greater than MAX_ORDER order) have to be allocated at boottime. However, boottime allocation has at least two serious problems. First, it doesn't support NUMA and second, gigantic pages allocated at boottime can't be freed. This commit solves both issues by adding support for allocating gigantic pages during runtime. It works just like regular sized hugepages, meaning that the interface in sysfs is the same, it supports NUMA, and gigantic pages can be freed. For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And to free them all: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages The one problem with gigantic page allocation at runtime is that it can't be serviced by the buddy allocator. To overcome that problem, this commit scans all zones from a node looking for a large enough contiguous region. When one is found, it's allocated by using CMA, that is, we call alloc_contig_range() to do the actual allocation. For example, on x86_64 we scan all zones looking for a 1GB contiguous region. When one is found, it's allocated by alloc_contig_range(). One expected issue with that approach is that such gigantic contiguous regions tend to vanish as runtime goes by. The best way to avoid this for now is to make gigantic page allocations very early during system boot, say from a init script. Other possible optimization include using compaction, which is supported by CMA but is not explicitly used by this commit. It's also important to note the following: 1. Gigantic pages allocated at boottime by the hugepages= command-line option can be freed at runtime just fine 2. This commit adds support for gigantic pages only to x86_64. The reason is that I don't have access to nor experience with other archs. The code is arch indepedent though, so it should be simple to add support to different archs 3. I didn't add support for hugepage overcommit, that is allocating a gigantic page on demand when /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't think it's reasonable to do the hard and long work required for allocating a gigantic page at fault time. But it should be simple to add this if wanted [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-05 03:07:13 +04:00
__ClearPageHead(page);
}
static void destroy_compound_hugetlb_page_for_demote(struct page *page,
unsigned int order)
{
__destroy_compound_gigantic_page(page, order, true);
}
#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
hugetlb: add demote bool to gigantic page routines The routines remove_hugetlb_page and destroy_compound_gigantic_page will remove a gigantic page and make the set of base pages ready to be returned to a lower level allocator. In the process of doing this, they make all base pages reference counted. The routine prep_compound_gigantic_page creates a gigantic page from a set of base pages. It assumes that all these base pages are reference counted. During demotion, a gigantic page will be split into huge pages of a smaller size. This logically involves use of the routines, remove_hugetlb_page, and destroy_compound_gigantic_page followed by prep_compound*_page for each smaller huge page. When pages are reference counted (ref count >= 0), additional speculative ref counts could be taken as described in previous commits [1] and [2]. This could result in errors while demoting a huge page. Quite a bit of code would need to be created to handle all possible issues. Instead of dealing with the possibility of speculative ref counts, avoid the possibility by keeping ref counts at zero during the demote process. Add a boolean 'demote' to the routines remove_hugetlb_page, destroy_compound_gigantic_page and prep_compound_gigantic_page. If the boolean is set, the remove and destroy routines will not reference count pages and the prep routine will not expect reference counted pages. '*_for_demote' wrappers of the routines will be added in a subsequent patch where this functionality is used. [1] https://lore.kernel.org/linux-mm/20210622021423.154662-3-mike.kravetz@oracle.com/ [2] https://lore.kernel.org/linux-mm/20210809184832.18342-3-mike.kravetz@oracle.com/ Link: https://lkml.kernel.org/r/20211007181918.136982-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:30 +03:00
static void destroy_compound_gigantic_page(struct page *page,
unsigned int order)
{
__destroy_compound_gigantic_page(page, order, false);
}
static void free_gigantic_page(struct page *page, unsigned int order)
hugetlb: add support for gigantic page allocation at runtime HugeTLB is limited to allocating hugepages whose size are less than MAX_ORDER order. This is so because HugeTLB allocates hugepages via the buddy allocator. Gigantic pages (that is, pages whose size is greater than MAX_ORDER order) have to be allocated at boottime. However, boottime allocation has at least two serious problems. First, it doesn't support NUMA and second, gigantic pages allocated at boottime can't be freed. This commit solves both issues by adding support for allocating gigantic pages during runtime. It works just like regular sized hugepages, meaning that the interface in sysfs is the same, it supports NUMA, and gigantic pages can be freed. For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And to free them all: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages The one problem with gigantic page allocation at runtime is that it can't be serviced by the buddy allocator. To overcome that problem, this commit scans all zones from a node looking for a large enough contiguous region. When one is found, it's allocated by using CMA, that is, we call alloc_contig_range() to do the actual allocation. For example, on x86_64 we scan all zones looking for a 1GB contiguous region. When one is found, it's allocated by alloc_contig_range(). One expected issue with that approach is that such gigantic contiguous regions tend to vanish as runtime goes by. The best way to avoid this for now is to make gigantic page allocations very early during system boot, say from a init script. Other possible optimization include using compaction, which is supported by CMA but is not explicitly used by this commit. It's also important to note the following: 1. Gigantic pages allocated at boottime by the hugepages= command-line option can be freed at runtime just fine 2. This commit adds support for gigantic pages only to x86_64. The reason is that I don't have access to nor experience with other archs. The code is arch indepedent though, so it should be simple to add support to different archs 3. I didn't add support for hugepage overcommit, that is allocating a gigantic page on demand when /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't think it's reasonable to do the hard and long work required for allocating a gigantic page at fault time. But it should be simple to add this if wanted [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-05 03:07:13 +04:00
{
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
/*
* If the page isn't allocated using the cma allocator,
* cma_release() returns false.
*/
#ifdef CONFIG_CMA
if (cma_release(hugetlb_cma[page_to_nid(page)], page, 1 << order))
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
return;
#endif
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
hugetlb: add support for gigantic page allocation at runtime HugeTLB is limited to allocating hugepages whose size are less than MAX_ORDER order. This is so because HugeTLB allocates hugepages via the buddy allocator. Gigantic pages (that is, pages whose size is greater than MAX_ORDER order) have to be allocated at boottime. However, boottime allocation has at least two serious problems. First, it doesn't support NUMA and second, gigantic pages allocated at boottime can't be freed. This commit solves both issues by adding support for allocating gigantic pages during runtime. It works just like regular sized hugepages, meaning that the interface in sysfs is the same, it supports NUMA, and gigantic pages can be freed. For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And to free them all: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages The one problem with gigantic page allocation at runtime is that it can't be serviced by the buddy allocator. To overcome that problem, this commit scans all zones from a node looking for a large enough contiguous region. When one is found, it's allocated by using CMA, that is, we call alloc_contig_range() to do the actual allocation. For example, on x86_64 we scan all zones looking for a 1GB contiguous region. When one is found, it's allocated by alloc_contig_range(). One expected issue with that approach is that such gigantic contiguous regions tend to vanish as runtime goes by. The best way to avoid this for now is to make gigantic page allocations very early during system boot, say from a init script. Other possible optimization include using compaction, which is supported by CMA but is not explicitly used by this commit. It's also important to note the following: 1. Gigantic pages allocated at boottime by the hugepages= command-line option can be freed at runtime just fine 2. This commit adds support for gigantic pages only to x86_64. The reason is that I don't have access to nor experience with other archs. The code is arch indepedent though, so it should be simple to add support to different archs 3. I didn't add support for hugepage overcommit, that is allocating a gigantic page on demand when /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't think it's reasonable to do the hard and long work required for allocating a gigantic page at fault time. But it should be simple to add this if wanted [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-05 03:07:13 +04:00
free_contig_range(page_to_pfn(page), 1 << order);
}
#ifdef CONFIG_CONTIG_ALLOC
static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
int nid, nodemask_t *nodemask)
hugetlb: add support for gigantic page allocation at runtime HugeTLB is limited to allocating hugepages whose size are less than MAX_ORDER order. This is so because HugeTLB allocates hugepages via the buddy allocator. Gigantic pages (that is, pages whose size is greater than MAX_ORDER order) have to be allocated at boottime. However, boottime allocation has at least two serious problems. First, it doesn't support NUMA and second, gigantic pages allocated at boottime can't be freed. This commit solves both issues by adding support for allocating gigantic pages during runtime. It works just like regular sized hugepages, meaning that the interface in sysfs is the same, it supports NUMA, and gigantic pages can be freed. For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And to free them all: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages The one problem with gigantic page allocation at runtime is that it can't be serviced by the buddy allocator. To overcome that problem, this commit scans all zones from a node looking for a large enough contiguous region. When one is found, it's allocated by using CMA, that is, we call alloc_contig_range() to do the actual allocation. For example, on x86_64 we scan all zones looking for a 1GB contiguous region. When one is found, it's allocated by alloc_contig_range(). One expected issue with that approach is that such gigantic contiguous regions tend to vanish as runtime goes by. The best way to avoid this for now is to make gigantic page allocations very early during system boot, say from a init script. Other possible optimization include using compaction, which is supported by CMA but is not explicitly used by this commit. It's also important to note the following: 1. Gigantic pages allocated at boottime by the hugepages= command-line option can be freed at runtime just fine 2. This commit adds support for gigantic pages only to x86_64. The reason is that I don't have access to nor experience with other archs. The code is arch indepedent though, so it should be simple to add support to different archs 3. I didn't add support for hugepage overcommit, that is allocating a gigantic page on demand when /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't think it's reasonable to do the hard and long work required for allocating a gigantic page at fault time. But it should be simple to add this if wanted [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-05 03:07:13 +04:00
{
unsigned long nr_pages = pages_per_huge_page(h);
if (nid == NUMA_NO_NODE)
nid = numa_mem_id();
hugetlb: add support for gigantic page allocation at runtime HugeTLB is limited to allocating hugepages whose size are less than MAX_ORDER order. This is so because HugeTLB allocates hugepages via the buddy allocator. Gigantic pages (that is, pages whose size is greater than MAX_ORDER order) have to be allocated at boottime. However, boottime allocation has at least two serious problems. First, it doesn't support NUMA and second, gigantic pages allocated at boottime can't be freed. This commit solves both issues by adding support for allocating gigantic pages during runtime. It works just like regular sized hugepages, meaning that the interface in sysfs is the same, it supports NUMA, and gigantic pages can be freed. For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And to free them all: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages The one problem with gigantic page allocation at runtime is that it can't be serviced by the buddy allocator. To overcome that problem, this commit scans all zones from a node looking for a large enough contiguous region. When one is found, it's allocated by using CMA, that is, we call alloc_contig_range() to do the actual allocation. For example, on x86_64 we scan all zones looking for a 1GB contiguous region. When one is found, it's allocated by alloc_contig_range(). One expected issue with that approach is that such gigantic contiguous regions tend to vanish as runtime goes by. The best way to avoid this for now is to make gigantic page allocations very early during system boot, say from a init script. Other possible optimization include using compaction, which is supported by CMA but is not explicitly used by this commit. It's also important to note the following: 1. Gigantic pages allocated at boottime by the hugepages= command-line option can be freed at runtime just fine 2. This commit adds support for gigantic pages only to x86_64. The reason is that I don't have access to nor experience with other archs. The code is arch indepedent though, so it should be simple to add support to different archs 3. I didn't add support for hugepage overcommit, that is allocating a gigantic page on demand when /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't think it's reasonable to do the hard and long work required for allocating a gigantic page at fault time. But it should be simple to add this if wanted [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-05 03:07:13 +04:00
#ifdef CONFIG_CMA
{
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
struct page *page;
int node;
if (hugetlb_cma[nid]) {
page = cma_alloc(hugetlb_cma[nid], nr_pages,
huge_page_order(h), true);
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
if (page)
return page;
}
if (!(gfp_mask & __GFP_THISNODE)) {
for_each_node_mask(node, *nodemask) {
if (node == nid || !hugetlb_cma[node])
continue;
page = cma_alloc(hugetlb_cma[node], nr_pages,
huge_page_order(h), true);
if (page)
return page;
}
}
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
}
#endif
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
mm/page_alloc: add alloc_contig_pages() HugeTLB helper alloc_gigantic_page() implements fairly generic allocation method where it scans over various zones looking for a large contiguous pfn range before trying to allocate it with alloc_contig_range(). Other than deriving the requested order from 'struct hstate', there is nothing HugeTLB specific in there. This can be made available for general use to allocate contiguous memory which could not have been allocated through the buddy allocator. alloc_gigantic_page() has been split carving out actual allocation method which is then made available via new alloc_contig_pages() helper wrapped under CONFIG_CONTIG_ALLOC. All references to 'gigantic' have been replaced with more generic term 'contig'. Allocated pages here should be freed with free_contig_range() or by calling __free_page() on each allocated page. Link: http://lkml.kernel.org/r/1571300646-32240-1-git-send-email-anshuman.khandual@arm.com Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Acked-by: David Hildenbrand <david@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Pavel Tatashin <pavel.tatashin@microsoft.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-12-01 04:55:06 +03:00
return alloc_contig_pages(nr_pages, gfp_mask, nid, nodemask);
hugetlb: add support for gigantic page allocation at runtime HugeTLB is limited to allocating hugepages whose size are less than MAX_ORDER order. This is so because HugeTLB allocates hugepages via the buddy allocator. Gigantic pages (that is, pages whose size is greater than MAX_ORDER order) have to be allocated at boottime. However, boottime allocation has at least two serious problems. First, it doesn't support NUMA and second, gigantic pages allocated at boottime can't be freed. This commit solves both issues by adding support for allocating gigantic pages during runtime. It works just like regular sized hugepages, meaning that the interface in sysfs is the same, it supports NUMA, and gigantic pages can be freed. For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And to free them all: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages The one problem with gigantic page allocation at runtime is that it can't be serviced by the buddy allocator. To overcome that problem, this commit scans all zones from a node looking for a large enough contiguous region. When one is found, it's allocated by using CMA, that is, we call alloc_contig_range() to do the actual allocation. For example, on x86_64 we scan all zones looking for a 1GB contiguous region. When one is found, it's allocated by alloc_contig_range(). One expected issue with that approach is that such gigantic contiguous regions tend to vanish as runtime goes by. The best way to avoid this for now is to make gigantic page allocations very early during system boot, say from a init script. Other possible optimization include using compaction, which is supported by CMA but is not explicitly used by this commit. It's also important to note the following: 1. Gigantic pages allocated at boottime by the hugepages= command-line option can be freed at runtime just fine 2. This commit adds support for gigantic pages only to x86_64. The reason is that I don't have access to nor experience with other archs. The code is arch indepedent though, so it should be simple to add support to different archs 3. I didn't add support for hugepage overcommit, that is allocating a gigantic page on demand when /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't think it's reasonable to do the hard and long work required for allocating a gigantic page at fault time. But it should be simple to add this if wanted [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-05 03:07:13 +04:00
}
#else /* !CONFIG_CONTIG_ALLOC */
static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
int nid, nodemask_t *nodemask)
{
return NULL;
}
#endif /* CONFIG_CONTIG_ALLOC */
hugetlb: add support for gigantic page allocation at runtime HugeTLB is limited to allocating hugepages whose size are less than MAX_ORDER order. This is so because HugeTLB allocates hugepages via the buddy allocator. Gigantic pages (that is, pages whose size is greater than MAX_ORDER order) have to be allocated at boottime. However, boottime allocation has at least two serious problems. First, it doesn't support NUMA and second, gigantic pages allocated at boottime can't be freed. This commit solves both issues by adding support for allocating gigantic pages during runtime. It works just like regular sized hugepages, meaning that the interface in sysfs is the same, it supports NUMA, and gigantic pages can be freed. For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And to free them all: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages The one problem with gigantic page allocation at runtime is that it can't be serviced by the buddy allocator. To overcome that problem, this commit scans all zones from a node looking for a large enough contiguous region. When one is found, it's allocated by using CMA, that is, we call alloc_contig_range() to do the actual allocation. For example, on x86_64 we scan all zones looking for a 1GB contiguous region. When one is found, it's allocated by alloc_contig_range(). One expected issue with that approach is that such gigantic contiguous regions tend to vanish as runtime goes by. The best way to avoid this for now is to make gigantic page allocations very early during system boot, say from a init script. Other possible optimization include using compaction, which is supported by CMA but is not explicitly used by this commit. It's also important to note the following: 1. Gigantic pages allocated at boottime by the hugepages= command-line option can be freed at runtime just fine 2. This commit adds support for gigantic pages only to x86_64. The reason is that I don't have access to nor experience with other archs. The code is arch indepedent though, so it should be simple to add support to different archs 3. I didn't add support for hugepage overcommit, that is allocating a gigantic page on demand when /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't think it's reasonable to do the hard and long work required for allocating a gigantic page at fault time. But it should be simple to add this if wanted [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-05 03:07:13 +04:00
#else /* !CONFIG_ARCH_HAS_GIGANTIC_PAGE */
static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
int nid, nodemask_t *nodemask)
{
return NULL;
}
static inline void free_gigantic_page(struct page *page, unsigned int order) { }
hugetlb: add support for gigantic page allocation at runtime HugeTLB is limited to allocating hugepages whose size are less than MAX_ORDER order. This is so because HugeTLB allocates hugepages via the buddy allocator. Gigantic pages (that is, pages whose size is greater than MAX_ORDER order) have to be allocated at boottime. However, boottime allocation has at least two serious problems. First, it doesn't support NUMA and second, gigantic pages allocated at boottime can't be freed. This commit solves both issues by adding support for allocating gigantic pages during runtime. It works just like regular sized hugepages, meaning that the interface in sysfs is the same, it supports NUMA, and gigantic pages can be freed. For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And to free them all: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages The one problem with gigantic page allocation at runtime is that it can't be serviced by the buddy allocator. To overcome that problem, this commit scans all zones from a node looking for a large enough contiguous region. When one is found, it's allocated by using CMA, that is, we call alloc_contig_range() to do the actual allocation. For example, on x86_64 we scan all zones looking for a 1GB contiguous region. When one is found, it's allocated by alloc_contig_range(). One expected issue with that approach is that such gigantic contiguous regions tend to vanish as runtime goes by. The best way to avoid this for now is to make gigantic page allocations very early during system boot, say from a init script. Other possible optimization include using compaction, which is supported by CMA but is not explicitly used by this commit. It's also important to note the following: 1. Gigantic pages allocated at boottime by the hugepages= command-line option can be freed at runtime just fine 2. This commit adds support for gigantic pages only to x86_64. The reason is that I don't have access to nor experience with other archs. The code is arch indepedent though, so it should be simple to add support to different archs 3. I didn't add support for hugepage overcommit, that is allocating a gigantic page on demand when /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't think it's reasonable to do the hard and long work required for allocating a gigantic page at fault time. But it should be simple to add this if wanted [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-05 03:07:13 +04:00
static inline void destroy_compound_gigantic_page(struct page *page,
unsigned int order) { }
hugetlb: add support for gigantic page allocation at runtime HugeTLB is limited to allocating hugepages whose size are less than MAX_ORDER order. This is so because HugeTLB allocates hugepages via the buddy allocator. Gigantic pages (that is, pages whose size is greater than MAX_ORDER order) have to be allocated at boottime. However, boottime allocation has at least two serious problems. First, it doesn't support NUMA and second, gigantic pages allocated at boottime can't be freed. This commit solves both issues by adding support for allocating gigantic pages during runtime. It works just like regular sized hugepages, meaning that the interface in sysfs is the same, it supports NUMA, and gigantic pages can be freed. For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And to free them all: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages The one problem with gigantic page allocation at runtime is that it can't be serviced by the buddy allocator. To overcome that problem, this commit scans all zones from a node looking for a large enough contiguous region. When one is found, it's allocated by using CMA, that is, we call alloc_contig_range() to do the actual allocation. For example, on x86_64 we scan all zones looking for a 1GB contiguous region. When one is found, it's allocated by alloc_contig_range(). One expected issue with that approach is that such gigantic contiguous regions tend to vanish as runtime goes by. The best way to avoid this for now is to make gigantic page allocations very early during system boot, say from a init script. Other possible optimization include using compaction, which is supported by CMA but is not explicitly used by this commit. It's also important to note the following: 1. Gigantic pages allocated at boottime by the hugepages= command-line option can be freed at runtime just fine 2. This commit adds support for gigantic pages only to x86_64. The reason is that I don't have access to nor experience with other archs. The code is arch indepedent though, so it should be simple to add support to different archs 3. I didn't add support for hugepage overcommit, that is allocating a gigantic page on demand when /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't think it's reasonable to do the hard and long work required for allocating a gigantic page at fault time. But it should be simple to add this if wanted [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-05 03:07:13 +04:00
#endif
hugetlb: create remove_hugetlb_page() to separate functionality The new remove_hugetlb_page() routine is designed to remove a hugetlb page from hugetlbfs processing. It will remove the page from the active or free list, update global counters and set the compound page destructor to NULL so that PageHuge() will return false for the 'page'. After this call, the 'page' can be treated as a normal compound page or a collection of base size pages. update_and_free_page no longer decrements h->nr_huge_pages{_node} as this is performed in remove_hugetlb_page. The only functionality performed by update_and_free_page is to free the base pages to the lower level allocators. update_and_free_page is typically called after remove_hugetlb_page. remove_hugetlb_page is to be called with the hugetlb_lock held. Creating this routine and separating functionality is in preparation for restructuring code to reduce lock hold times. This commit should not introduce any changes to functionality. Link: https://lkml.kernel.org/r/20210409205254.242291-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:55 +03:00
/*
* Remove hugetlb page from lists, and update dtor so that page appears
hugetlb: add demote bool to gigantic page routines The routines remove_hugetlb_page and destroy_compound_gigantic_page will remove a gigantic page and make the set of base pages ready to be returned to a lower level allocator. In the process of doing this, they make all base pages reference counted. The routine prep_compound_gigantic_page creates a gigantic page from a set of base pages. It assumes that all these base pages are reference counted. During demotion, a gigantic page will be split into huge pages of a smaller size. This logically involves use of the routines, remove_hugetlb_page, and destroy_compound_gigantic_page followed by prep_compound*_page for each smaller huge page. When pages are reference counted (ref count >= 0), additional speculative ref counts could be taken as described in previous commits [1] and [2]. This could result in errors while demoting a huge page. Quite a bit of code would need to be created to handle all possible issues. Instead of dealing with the possibility of speculative ref counts, avoid the possibility by keeping ref counts at zero during the demote process. Add a boolean 'demote' to the routines remove_hugetlb_page, destroy_compound_gigantic_page and prep_compound_gigantic_page. If the boolean is set, the remove and destroy routines will not reference count pages and the prep routine will not expect reference counted pages. '*_for_demote' wrappers of the routines will be added in a subsequent patch where this functionality is used. [1] https://lore.kernel.org/linux-mm/20210622021423.154662-3-mike.kravetz@oracle.com/ [2] https://lore.kernel.org/linux-mm/20210809184832.18342-3-mike.kravetz@oracle.com/ Link: https://lkml.kernel.org/r/20211007181918.136982-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:30 +03:00
* as just a compound page.
*
* A reference is held on the page, except in the case of demote.
hugetlb: create remove_hugetlb_page() to separate functionality The new remove_hugetlb_page() routine is designed to remove a hugetlb page from hugetlbfs processing. It will remove the page from the active or free list, update global counters and set the compound page destructor to NULL so that PageHuge() will return false for the 'page'. After this call, the 'page' can be treated as a normal compound page or a collection of base size pages. update_and_free_page no longer decrements h->nr_huge_pages{_node} as this is performed in remove_hugetlb_page. The only functionality performed by update_and_free_page is to free the base pages to the lower level allocators. update_and_free_page is typically called after remove_hugetlb_page. remove_hugetlb_page is to be called with the hugetlb_lock held. Creating this routine and separating functionality is in preparation for restructuring code to reduce lock hold times. This commit should not introduce any changes to functionality. Link: https://lkml.kernel.org/r/20210409205254.242291-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:55 +03:00
*
* Must be called with hugetlb lock held.
*/
hugetlb: add demote bool to gigantic page routines The routines remove_hugetlb_page and destroy_compound_gigantic_page will remove a gigantic page and make the set of base pages ready to be returned to a lower level allocator. In the process of doing this, they make all base pages reference counted. The routine prep_compound_gigantic_page creates a gigantic page from a set of base pages. It assumes that all these base pages are reference counted. During demotion, a gigantic page will be split into huge pages of a smaller size. This logically involves use of the routines, remove_hugetlb_page, and destroy_compound_gigantic_page followed by prep_compound*_page for each smaller huge page. When pages are reference counted (ref count >= 0), additional speculative ref counts could be taken as described in previous commits [1] and [2]. This could result in errors while demoting a huge page. Quite a bit of code would need to be created to handle all possible issues. Instead of dealing with the possibility of speculative ref counts, avoid the possibility by keeping ref counts at zero during the demote process. Add a boolean 'demote' to the routines remove_hugetlb_page, destroy_compound_gigantic_page and prep_compound_gigantic_page. If the boolean is set, the remove and destroy routines will not reference count pages and the prep routine will not expect reference counted pages. '*_for_demote' wrappers of the routines will be added in a subsequent patch where this functionality is used. [1] https://lore.kernel.org/linux-mm/20210622021423.154662-3-mike.kravetz@oracle.com/ [2] https://lore.kernel.org/linux-mm/20210809184832.18342-3-mike.kravetz@oracle.com/ Link: https://lkml.kernel.org/r/20211007181918.136982-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:30 +03:00
static void __remove_hugetlb_page(struct hstate *h, struct page *page,
bool adjust_surplus,
bool demote)
hugetlb: create remove_hugetlb_page() to separate functionality The new remove_hugetlb_page() routine is designed to remove a hugetlb page from hugetlbfs processing. It will remove the page from the active or free list, update global counters and set the compound page destructor to NULL so that PageHuge() will return false for the 'page'. After this call, the 'page' can be treated as a normal compound page or a collection of base size pages. update_and_free_page no longer decrements h->nr_huge_pages{_node} as this is performed in remove_hugetlb_page. The only functionality performed by update_and_free_page is to free the base pages to the lower level allocators. update_and_free_page is typically called after remove_hugetlb_page. remove_hugetlb_page is to be called with the hugetlb_lock held. Creating this routine and separating functionality is in preparation for restructuring code to reduce lock hold times. This commit should not introduce any changes to functionality. Link: https://lkml.kernel.org/r/20210409205254.242291-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:55 +03:00
{
int nid = page_to_nid(page);
VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
VM_BUG_ON_PAGE(hugetlb_cgroup_from_page_rsvd(page), page);
lockdep_assert_held(&hugetlb_lock);
hugetlb: create remove_hugetlb_page() to separate functionality The new remove_hugetlb_page() routine is designed to remove a hugetlb page from hugetlbfs processing. It will remove the page from the active or free list, update global counters and set the compound page destructor to NULL so that PageHuge() will return false for the 'page'. After this call, the 'page' can be treated as a normal compound page or a collection of base size pages. update_and_free_page no longer decrements h->nr_huge_pages{_node} as this is performed in remove_hugetlb_page. The only functionality performed by update_and_free_page is to free the base pages to the lower level allocators. update_and_free_page is typically called after remove_hugetlb_page. remove_hugetlb_page is to be called with the hugetlb_lock held. Creating this routine and separating functionality is in preparation for restructuring code to reduce lock hold times. This commit should not introduce any changes to functionality. Link: https://lkml.kernel.org/r/20210409205254.242291-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:55 +03:00
if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
return;
list_del(&page->lru);
if (HPageFreed(page)) {
h->free_huge_pages--;
h->free_huge_pages_node[nid]--;
}
if (adjust_surplus) {
h->surplus_huge_pages--;
h->surplus_huge_pages_node[nid]--;
}
hugetlb: before freeing hugetlb page set dtor to appropriate value When removing a hugetlb page from the pool the ref count is set to one (as the free page has no ref count) and compound page destructor is set to NULL_COMPOUND_DTOR. Since a subsequent call to free the hugetlb page will call __free_pages for non-gigantic pages and free_gigantic_page for gigantic pages the destructor is not used. However, consider the following race with code taking a speculative reference on the page: Thread 0 Thread 1 -------- -------- remove_hugetlb_page set_page_refcounted(page); set_compound_page_dtor(page, NULL_COMPOUND_DTOR); get_page_unless_zero(page) __update_and_free_page __free_pages(page, huge_page_order(h)); /* Note that __free_pages() will simply drop the reference to the page. */ put_page(page) __put_compound_page() destroy_compound_page NULL_COMPOUND_DTOR BUG: kernel NULL pointer dereference, address: 0000000000000000 To address this race, set the dtor to the normal compound page dtor for non-gigantic pages. The dtor for gigantic pages does not matter as gigantic pages are changed from a compound page to 'just a group of pages' before freeing. Hence, the destructor is not used. Link: https://lkml.kernel.org/r/20210809184832.18342-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:50 +03:00
/*
* Very subtle
*
* For non-gigantic pages set the destructor to the normal compound
* page dtor. This is needed in case someone takes an additional
* temporary ref to the page, and freeing is delayed until they drop
* their reference.
*
* For gigantic pages set the destructor to the null dtor. This
* destructor will never be called. Before freeing the gigantic
* page destroy_compound_gigantic_page will turn the compound page
* into a simple group of pages. After this the destructor does not
* apply.
*
* This handles the case where more than one ref is held when and
* after update_and_free_page is called.
hugetlb: add demote bool to gigantic page routines The routines remove_hugetlb_page and destroy_compound_gigantic_page will remove a gigantic page and make the set of base pages ready to be returned to a lower level allocator. In the process of doing this, they make all base pages reference counted. The routine prep_compound_gigantic_page creates a gigantic page from a set of base pages. It assumes that all these base pages are reference counted. During demotion, a gigantic page will be split into huge pages of a smaller size. This logically involves use of the routines, remove_hugetlb_page, and destroy_compound_gigantic_page followed by prep_compound*_page for each smaller huge page. When pages are reference counted (ref count >= 0), additional speculative ref counts could be taken as described in previous commits [1] and [2]. This could result in errors while demoting a huge page. Quite a bit of code would need to be created to handle all possible issues. Instead of dealing with the possibility of speculative ref counts, avoid the possibility by keeping ref counts at zero during the demote process. Add a boolean 'demote' to the routines remove_hugetlb_page, destroy_compound_gigantic_page and prep_compound_gigantic_page. If the boolean is set, the remove and destroy routines will not reference count pages and the prep routine will not expect reference counted pages. '*_for_demote' wrappers of the routines will be added in a subsequent patch where this functionality is used. [1] https://lore.kernel.org/linux-mm/20210622021423.154662-3-mike.kravetz@oracle.com/ [2] https://lore.kernel.org/linux-mm/20210809184832.18342-3-mike.kravetz@oracle.com/ Link: https://lkml.kernel.org/r/20211007181918.136982-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:30 +03:00
*
* In the case of demote we do not ref count the page as it will soon
* be turned into a page of smaller size.
hugetlb: before freeing hugetlb page set dtor to appropriate value When removing a hugetlb page from the pool the ref count is set to one (as the free page has no ref count) and compound page destructor is set to NULL_COMPOUND_DTOR. Since a subsequent call to free the hugetlb page will call __free_pages for non-gigantic pages and free_gigantic_page for gigantic pages the destructor is not used. However, consider the following race with code taking a speculative reference on the page: Thread 0 Thread 1 -------- -------- remove_hugetlb_page set_page_refcounted(page); set_compound_page_dtor(page, NULL_COMPOUND_DTOR); get_page_unless_zero(page) __update_and_free_page __free_pages(page, huge_page_order(h)); /* Note that __free_pages() will simply drop the reference to the page. */ put_page(page) __put_compound_page() destroy_compound_page NULL_COMPOUND_DTOR BUG: kernel NULL pointer dereference, address: 0000000000000000 To address this race, set the dtor to the normal compound page dtor for non-gigantic pages. The dtor for gigantic pages does not matter as gigantic pages are changed from a compound page to 'just a group of pages' before freeing. Hence, the destructor is not used. Link: https://lkml.kernel.org/r/20210809184832.18342-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:50 +03:00
*/
hugetlb: add demote bool to gigantic page routines The routines remove_hugetlb_page and destroy_compound_gigantic_page will remove a gigantic page and make the set of base pages ready to be returned to a lower level allocator. In the process of doing this, they make all base pages reference counted. The routine prep_compound_gigantic_page creates a gigantic page from a set of base pages. It assumes that all these base pages are reference counted. During demotion, a gigantic page will be split into huge pages of a smaller size. This logically involves use of the routines, remove_hugetlb_page, and destroy_compound_gigantic_page followed by prep_compound*_page for each smaller huge page. When pages are reference counted (ref count >= 0), additional speculative ref counts could be taken as described in previous commits [1] and [2]. This could result in errors while demoting a huge page. Quite a bit of code would need to be created to handle all possible issues. Instead of dealing with the possibility of speculative ref counts, avoid the possibility by keeping ref counts at zero during the demote process. Add a boolean 'demote' to the routines remove_hugetlb_page, destroy_compound_gigantic_page and prep_compound_gigantic_page. If the boolean is set, the remove and destroy routines will not reference count pages and the prep routine will not expect reference counted pages. '*_for_demote' wrappers of the routines will be added in a subsequent patch where this functionality is used. [1] https://lore.kernel.org/linux-mm/20210622021423.154662-3-mike.kravetz@oracle.com/ [2] https://lore.kernel.org/linux-mm/20210809184832.18342-3-mike.kravetz@oracle.com/ Link: https://lkml.kernel.org/r/20211007181918.136982-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:30 +03:00
if (!demote)
set_page_refcounted(page);
hugetlb: before freeing hugetlb page set dtor to appropriate value When removing a hugetlb page from the pool the ref count is set to one (as the free page has no ref count) and compound page destructor is set to NULL_COMPOUND_DTOR. Since a subsequent call to free the hugetlb page will call __free_pages for non-gigantic pages and free_gigantic_page for gigantic pages the destructor is not used. However, consider the following race with code taking a speculative reference on the page: Thread 0 Thread 1 -------- -------- remove_hugetlb_page set_page_refcounted(page); set_compound_page_dtor(page, NULL_COMPOUND_DTOR); get_page_unless_zero(page) __update_and_free_page __free_pages(page, huge_page_order(h)); /* Note that __free_pages() will simply drop the reference to the page. */ put_page(page) __put_compound_page() destroy_compound_page NULL_COMPOUND_DTOR BUG: kernel NULL pointer dereference, address: 0000000000000000 To address this race, set the dtor to the normal compound page dtor for non-gigantic pages. The dtor for gigantic pages does not matter as gigantic pages are changed from a compound page to 'just a group of pages' before freeing. Hence, the destructor is not used. Link: https://lkml.kernel.org/r/20210809184832.18342-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:50 +03:00
if (hstate_is_gigantic(h))
set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
else
set_compound_page_dtor(page, COMPOUND_PAGE_DTOR);
hugetlb: create remove_hugetlb_page() to separate functionality The new remove_hugetlb_page() routine is designed to remove a hugetlb page from hugetlbfs processing. It will remove the page from the active or free list, update global counters and set the compound page destructor to NULL so that PageHuge() will return false for the 'page'. After this call, the 'page' can be treated as a normal compound page or a collection of base size pages. update_and_free_page no longer decrements h->nr_huge_pages{_node} as this is performed in remove_hugetlb_page. The only functionality performed by update_and_free_page is to free the base pages to the lower level allocators. update_and_free_page is typically called after remove_hugetlb_page. remove_hugetlb_page is to be called with the hugetlb_lock held. Creating this routine and separating functionality is in preparation for restructuring code to reduce lock hold times. This commit should not introduce any changes to functionality. Link: https://lkml.kernel.org/r/20210409205254.242291-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:55 +03:00
h->nr_huge_pages--;
h->nr_huge_pages_node[nid]--;
}
hugetlb: add demote bool to gigantic page routines The routines remove_hugetlb_page and destroy_compound_gigantic_page will remove a gigantic page and make the set of base pages ready to be returned to a lower level allocator. In the process of doing this, they make all base pages reference counted. The routine prep_compound_gigantic_page creates a gigantic page from a set of base pages. It assumes that all these base pages are reference counted. During demotion, a gigantic page will be split into huge pages of a smaller size. This logically involves use of the routines, remove_hugetlb_page, and destroy_compound_gigantic_page followed by prep_compound*_page for each smaller huge page. When pages are reference counted (ref count >= 0), additional speculative ref counts could be taken as described in previous commits [1] and [2]. This could result in errors while demoting a huge page. Quite a bit of code would need to be created to handle all possible issues. Instead of dealing with the possibility of speculative ref counts, avoid the possibility by keeping ref counts at zero during the demote process. Add a boolean 'demote' to the routines remove_hugetlb_page, destroy_compound_gigantic_page and prep_compound_gigantic_page. If the boolean is set, the remove and destroy routines will not reference count pages and the prep routine will not expect reference counted pages. '*_for_demote' wrappers of the routines will be added in a subsequent patch where this functionality is used. [1] https://lore.kernel.org/linux-mm/20210622021423.154662-3-mike.kravetz@oracle.com/ [2] https://lore.kernel.org/linux-mm/20210809184832.18342-3-mike.kravetz@oracle.com/ Link: https://lkml.kernel.org/r/20211007181918.136982-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:30 +03:00
static void remove_hugetlb_page(struct hstate *h, struct page *page,
bool adjust_surplus)
{
__remove_hugetlb_page(h, page, adjust_surplus, false);
}
static void remove_hugetlb_page_for_demote(struct hstate *h, struct page *page,
bool adjust_surplus)
{
__remove_hugetlb_page(h, page, adjust_surplus, true);
}
mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page When we free a HugeTLB page to the buddy allocator, we need to allocate the vmemmap pages associated with it. However, we may not be able to allocate the vmemmap pages when the system is under memory pressure. In this case, we just refuse to free the HugeTLB page. This changes behavior in some corner cases as listed below: 1) Failing to free a huge page triggered by the user (decrease nr_pages). User needs to try again later. 2) Failing to free a surplus huge page when freed by the application. Try again later when freeing a huge page next time. 3) Failing to dissolve a free huge page on ZONE_MOVABLE via offline_pages(). This can happen when we have plenty of ZONE_MOVABLE memory, but not enough kernel memory to allocate vmemmmap pages. We may even be able to migrate huge page contents, but will not be able to dissolve the source huge page. This will prevent an offline operation and is unfortunate as memory offlining is expected to succeed on movable zones. Users that depend on memory hotplug to succeed for movable zones should carefully consider whether the memory savings gained from this feature are worth the risk of possibly not being able to offline memory in certain situations. 4) Failing to dissolve a huge page on CMA/ZONE_MOVABLE via alloc_contig_range() - once we have that handling in place. Mainly affects CMA and virtio-mem. Similar to 3). virito-mem will handle migration errors gracefully. CMA might be able to fallback on other free areas within the CMA region. Vmemmap pages are allocated from the page freeing context. In order for those allocations to be not disruptive (e.g. trigger oom killer) __GFP_NORETRY is used. hugetlb_lock is dropped for the allocation because a non sleeping allocation would be too fragile and it could fail too easily under memory pressure. GFP_ATOMIC or other modes to access memory reserves is not used because we want to prevent consuming reserves under heavy hugetlb freeing. [mike.kravetz@oracle.com: fix dissolve_free_huge_page use of tail/head page] Link: https://lkml.kernel.org/r/20210527231225.226987-1-mike.kravetz@oracle.com [willy@infradead.org: fix alloc_vmemmap_page_list documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-6-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-7-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:21 +03:00
static void add_hugetlb_page(struct hstate *h, struct page *page,
bool adjust_surplus)
{
int zeroed;
int nid = page_to_nid(page);
VM_BUG_ON_PAGE(!HPageVmemmapOptimized(page), page);
lockdep_assert_held(&hugetlb_lock);
INIT_LIST_HEAD(&page->lru);
h->nr_huge_pages++;
h->nr_huge_pages_node[nid]++;
if (adjust_surplus) {
h->surplus_huge_pages++;
h->surplus_huge_pages_node[nid]++;
}
set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
set_page_private(page, 0);
SetHPageVmemmapOptimized(page);
/*
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
* This page is about to be managed by the hugetlb allocator and
* should have no users. Drop our reference, and check for others
* just in case.
mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page When we free a HugeTLB page to the buddy allocator, we need to allocate the vmemmap pages associated with it. However, we may not be able to allocate the vmemmap pages when the system is under memory pressure. In this case, we just refuse to free the HugeTLB page. This changes behavior in some corner cases as listed below: 1) Failing to free a huge page triggered by the user (decrease nr_pages). User needs to try again later. 2) Failing to free a surplus huge page when freed by the application. Try again later when freeing a huge page next time. 3) Failing to dissolve a free huge page on ZONE_MOVABLE via offline_pages(). This can happen when we have plenty of ZONE_MOVABLE memory, but not enough kernel memory to allocate vmemmmap pages. We may even be able to migrate huge page contents, but will not be able to dissolve the source huge page. This will prevent an offline operation and is unfortunate as memory offlining is expected to succeed on movable zones. Users that depend on memory hotplug to succeed for movable zones should carefully consider whether the memory savings gained from this feature are worth the risk of possibly not being able to offline memory in certain situations. 4) Failing to dissolve a huge page on CMA/ZONE_MOVABLE via alloc_contig_range() - once we have that handling in place. Mainly affects CMA and virtio-mem. Similar to 3). virito-mem will handle migration errors gracefully. CMA might be able to fallback on other free areas within the CMA region. Vmemmap pages are allocated from the page freeing context. In order for those allocations to be not disruptive (e.g. trigger oom killer) __GFP_NORETRY is used. hugetlb_lock is dropped for the allocation because a non sleeping allocation would be too fragile and it could fail too easily under memory pressure. GFP_ATOMIC or other modes to access memory reserves is not used because we want to prevent consuming reserves under heavy hugetlb freeing. [mike.kravetz@oracle.com: fix dissolve_free_huge_page use of tail/head page] Link: https://lkml.kernel.org/r/20210527231225.226987-1-mike.kravetz@oracle.com [willy@infradead.org: fix alloc_vmemmap_page_list documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-6-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-7-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:21 +03:00
*/
zeroed = put_page_testzero(page);
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
if (!zeroed)
/*
* It is VERY unlikely soneone else has taken a ref on
* the page. In this case, we simply return as the
* hugetlb destructor (free_huge_page) will be called
* when this other ref is dropped.
*/
return;
mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page When we free a HugeTLB page to the buddy allocator, we need to allocate the vmemmap pages associated with it. However, we may not be able to allocate the vmemmap pages when the system is under memory pressure. In this case, we just refuse to free the HugeTLB page. This changes behavior in some corner cases as listed below: 1) Failing to free a huge page triggered by the user (decrease nr_pages). User needs to try again later. 2) Failing to free a surplus huge page when freed by the application. Try again later when freeing a huge page next time. 3) Failing to dissolve a free huge page on ZONE_MOVABLE via offline_pages(). This can happen when we have plenty of ZONE_MOVABLE memory, but not enough kernel memory to allocate vmemmmap pages. We may even be able to migrate huge page contents, but will not be able to dissolve the source huge page. This will prevent an offline operation and is unfortunate as memory offlining is expected to succeed on movable zones. Users that depend on memory hotplug to succeed for movable zones should carefully consider whether the memory savings gained from this feature are worth the risk of possibly not being able to offline memory in certain situations. 4) Failing to dissolve a huge page on CMA/ZONE_MOVABLE via alloc_contig_range() - once we have that handling in place. Mainly affects CMA and virtio-mem. Similar to 3). virito-mem will handle migration errors gracefully. CMA might be able to fallback on other free areas within the CMA region. Vmemmap pages are allocated from the page freeing context. In order for those allocations to be not disruptive (e.g. trigger oom killer) __GFP_NORETRY is used. hugetlb_lock is dropped for the allocation because a non sleeping allocation would be too fragile and it could fail too easily under memory pressure. GFP_ATOMIC or other modes to access memory reserves is not used because we want to prevent consuming reserves under heavy hugetlb freeing. [mike.kravetz@oracle.com: fix dissolve_free_huge_page use of tail/head page] Link: https://lkml.kernel.org/r/20210527231225.226987-1-mike.kravetz@oracle.com [willy@infradead.org: fix alloc_vmemmap_page_list documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-6-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-7-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:21 +03:00
arch_clear_hugepage_flags(page);
enqueue_huge_page(h, page);
}
mm: hugetlb: defer freeing of HugeTLB pages In the subsequent patch, we should allocate the vmemmap pages when freeing a HugeTLB page. But update_and_free_page() can be called under any context, so we cannot use GFP_KERNEL to allocate vmemmap pages. However, we can defer the actual freeing in a kworker to prevent from using GFP_ATOMIC to allocate the vmemmap pages. The __update_and_free_page() is where the call to allocate vmemmmap pages will be inserted. Link: https://lkml.kernel.org/r/20210510030027.56044-6-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:17 +03:00
static void __update_and_free_page(struct hstate *h, struct page *page)
hugetlb: Move update_and_free_page Dynamic huge page pool resizing. In most real-world scenarios, configuring the size of the hugetlb pool correctly is a difficult task. If too few pages are allocated to the pool, applications using MAP_SHARED may fail to mmap() a hugepage region and applications using MAP_PRIVATE may receive SIGBUS. Isolating too much memory in the hugetlb pool means it is not available for other uses, especially those programs not using huge pages. The obvious answer is to let the hugetlb pool grow and shrink in response to the runtime demand for huge pages. The work Mel Gorman has been doing to establish a memory zone for movable memory allocations makes dynamically resizing the hugetlb pool reliable within the limits of that zone. This patch series implements dynamic pool resizing for private and shared mappings while being careful to maintain existing semantics. Please reply with your comments and feedback; even just to say whether it would be a useful feature to you. Thanks. How it works ============ Upon depletion of the hugetlb pool, rather than reporting an error immediately, first try and allocate the needed huge pages directly from the buddy allocator. Care must be taken to avoid unbounded growth of the hugetlb pool, so the hugetlb filesystem quota is used to limit overall pool size. The real work begins when we decide there is a shortage of huge pages. What happens next depends on whether the pages are for a private or shared mapping. Private mappings are straightforward. At fault time, if alloc_huge_page() fails, we allocate a page from the buddy allocator and increment the source node's surplus_huge_pages counter. When free_huge_page() is called for a page on a node with a surplus, the page is freed directly to the buddy allocator instead of the hugetlb pool. Because shared mappings require all of the pages to be reserved up front, some additional work must be done at mmap() to support them. We determine the reservation shortage and allocate the required number of pages all at once. These pages are then added to the hugetlb pool and marked reserved. Where that is not possible the mmap() will fail. As with private mappings, the appropriate surplus counters are updated. Since reserved huge pages won't necessarily be used by the process, we can't be sure that free_huge_page() will always be called to return surplus pages to the buddy allocator. To prevent the huge page pool from bloating, we must free unused surplus pages when their reservation has ended. Controlling it ============== With the entire patch series applied, pool resizing is off by default so unless specific action is taken, the semantics are unchanged. To take advantage of the flexibility afforded by this patch series one must tolerate a change in semantics. To control hugetlb pool growth, the following techniques can be employed: * A sysctl tunable to enable/disable the feature entirely * The size= mount option for hugetlbfs filesystems to limit pool size Performance =========== When contiguous memory is readily available, it is expected that the cost of dynamicly resizing the pool will be small. This series has been performance tested with 'stream' to measure this cost. Stream (http://www.cs.virginia.edu/stream/) was linked with libhugetlbfs to enable remapping of the text and data/bss segments into huge pages. Stream with small array ----------------------- Baseline: nr_hugepages = 0, No libhugetlbfs segment remapping Preallocated: nr_hugepages = 5, Text and data/bss remapping Dynamic: nr_hugepages = 0, Text and data/bss remapping Rate (MB/s) Function Baseline Preallocated Dynamic Copy: 4695.6266 5942.8371 5982.2287 Scale: 4451.5776 5017.1419 5658.7843 Add: 5815.8849 7927.7827 8119.3552 Triad: 5949.4144 8527.6492 8110.6903 Stream with large array ----------------------- Baseline: nr_hugepages = 0, No libhugetlbfs segment remapping Preallocated: nr_hugepages = 67, Text and data/bss remapping Dynamic: nr_hugepages = 0, Text and data/bss remapping Rate (MB/s) Function Baseline Preallocated Dynamic Copy: 2227.8281 2544.2732 2546.4947 Scale: 2136.3208 2430.7294 2421.2074 Add: 2773.1449 4004.0021 3999.4331 Triad: 2748.4502 3777.0109 3773.4970 * All numbers are averages taken from 10 consecutive runs with a maximum standard deviation of 1.3 percent noted. This patch: Simply move update_and_free_page() so that it can be reused later in this patch series. The implementation is not changed. Signed-off-by: Adam Litke <agl@us.ibm.com> Acked-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Dave McCracken <dave.mccracken@oracle.com> Acked-by: William Irwin <bill.irwin@oracle.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Ken Chen <kenchen@google.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16 12:26:16 +04:00
{
int i;
hugetlb: fix update_and_free_page contig page struct assumption page structs are not guaranteed to be contiguous for gigantic pages. The routine update_and_free_page can encounter a gigantic page, yet it assumes page structs are contiguous when setting page flags in subpages. If update_and_free_page encounters non-contiguous page structs, we can see “BUG: Bad page state in process …” errors. Non-contiguous page structs are generally not an issue. However, they can exist with a specific kernel configuration and hotplug operations. For example: Configure the kernel with CONFIG_SPARSEMEM and !CONFIG_SPARSEMEM_VMEMMAP. Then, hotplug add memory for the area where the gigantic page will be allocated. Zi Yan outlined steps to reproduce here [1]. [1] https://lore.kernel.org/linux-mm/16F7C58B-4D79-41C5-9B64-A1A1628F4AF2@nvidia.com/ Link: https://lkml.kernel.org/r/20210217184926.33567-1-mike.kravetz@oracle.com Fixes: 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") Signed-off-by: Zi Yan <ziy@nvidia.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:07:50 +03:00
struct page *subpage = page;
if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
hugetlb: add support for gigantic page allocation at runtime HugeTLB is limited to allocating hugepages whose size are less than MAX_ORDER order. This is so because HugeTLB allocates hugepages via the buddy allocator. Gigantic pages (that is, pages whose size is greater than MAX_ORDER order) have to be allocated at boottime. However, boottime allocation has at least two serious problems. First, it doesn't support NUMA and second, gigantic pages allocated at boottime can't be freed. This commit solves both issues by adding support for allocating gigantic pages during runtime. It works just like regular sized hugepages, meaning that the interface in sysfs is the same, it supports NUMA, and gigantic pages can be freed. For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And to free them all: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages The one problem with gigantic page allocation at runtime is that it can't be serviced by the buddy allocator. To overcome that problem, this commit scans all zones from a node looking for a large enough contiguous region. When one is found, it's allocated by using CMA, that is, we call alloc_contig_range() to do the actual allocation. For example, on x86_64 we scan all zones looking for a 1GB contiguous region. When one is found, it's allocated by alloc_contig_range(). One expected issue with that approach is that such gigantic contiguous regions tend to vanish as runtime goes by. The best way to avoid this for now is to make gigantic page allocations very early during system boot, say from a init script. Other possible optimization include using compaction, which is supported by CMA but is not explicitly used by this commit. It's also important to note the following: 1. Gigantic pages allocated at boottime by the hugepages= command-line option can be freed at runtime just fine 2. This commit adds support for gigantic pages only to x86_64. The reason is that I don't have access to nor experience with other archs. The code is arch indepedent though, so it should be simple to add support to different archs 3. I didn't add support for hugepage overcommit, that is allocating a gigantic page on demand when /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't think it's reasonable to do the hard and long work required for allocating a gigantic page at fault time. But it should be simple to add this if wanted [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-05 03:07:13 +04:00
return;
if (hugetlb_vmemmap_alloc(h, page)) {
mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page When we free a HugeTLB page to the buddy allocator, we need to allocate the vmemmap pages associated with it. However, we may not be able to allocate the vmemmap pages when the system is under memory pressure. In this case, we just refuse to free the HugeTLB page. This changes behavior in some corner cases as listed below: 1) Failing to free a huge page triggered by the user (decrease nr_pages). User needs to try again later. 2) Failing to free a surplus huge page when freed by the application. Try again later when freeing a huge page next time. 3) Failing to dissolve a free huge page on ZONE_MOVABLE via offline_pages(). This can happen when we have plenty of ZONE_MOVABLE memory, but not enough kernel memory to allocate vmemmmap pages. We may even be able to migrate huge page contents, but will not be able to dissolve the source huge page. This will prevent an offline operation and is unfortunate as memory offlining is expected to succeed on movable zones. Users that depend on memory hotplug to succeed for movable zones should carefully consider whether the memory savings gained from this feature are worth the risk of possibly not being able to offline memory in certain situations. 4) Failing to dissolve a huge page on CMA/ZONE_MOVABLE via alloc_contig_range() - once we have that handling in place. Mainly affects CMA and virtio-mem. Similar to 3). virito-mem will handle migration errors gracefully. CMA might be able to fallback on other free areas within the CMA region. Vmemmap pages are allocated from the page freeing context. In order for those allocations to be not disruptive (e.g. trigger oom killer) __GFP_NORETRY is used. hugetlb_lock is dropped for the allocation because a non sleeping allocation would be too fragile and it could fail too easily under memory pressure. GFP_ATOMIC or other modes to access memory reserves is not used because we want to prevent consuming reserves under heavy hugetlb freeing. [mike.kravetz@oracle.com: fix dissolve_free_huge_page use of tail/head page] Link: https://lkml.kernel.org/r/20210527231225.226987-1-mike.kravetz@oracle.com [willy@infradead.org: fix alloc_vmemmap_page_list documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-6-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-7-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:21 +03:00
spin_lock_irq(&hugetlb_lock);
/*
* If we cannot allocate vmemmap pages, just refuse to free the
* page and put the page back on the hugetlb free list and treat
* as a surplus page.
*/
add_hugetlb_page(h, page, true);
spin_unlock_irq(&hugetlb_lock);
return;
}
hugetlb: fix update_and_free_page contig page struct assumption page structs are not guaranteed to be contiguous for gigantic pages. The routine update_and_free_page can encounter a gigantic page, yet it assumes page structs are contiguous when setting page flags in subpages. If update_and_free_page encounters non-contiguous page structs, we can see “BUG: Bad page state in process …” errors. Non-contiguous page structs are generally not an issue. However, they can exist with a specific kernel configuration and hotplug operations. For example: Configure the kernel with CONFIG_SPARSEMEM and !CONFIG_SPARSEMEM_VMEMMAP. Then, hotplug add memory for the area where the gigantic page will be allocated. Zi Yan outlined steps to reproduce here [1]. [1] https://lore.kernel.org/linux-mm/16F7C58B-4D79-41C5-9B64-A1A1628F4AF2@nvidia.com/ Link: https://lkml.kernel.org/r/20210217184926.33567-1-mike.kravetz@oracle.com Fixes: 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") Signed-off-by: Zi Yan <ziy@nvidia.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:07:50 +03:00
for (i = 0; i < pages_per_huge_page(h);
i++, subpage = mem_map_next(subpage, page, i)) {
subpage->flags &= ~(1 << PG_locked | 1 << PG_error |
1 << PG_referenced | 1 << PG_dirty |
1 << PG_active | 1 << PG_private |
1 << PG_writeback);
hugetlb: Move update_and_free_page Dynamic huge page pool resizing. In most real-world scenarios, configuring the size of the hugetlb pool correctly is a difficult task. If too few pages are allocated to the pool, applications using MAP_SHARED may fail to mmap() a hugepage region and applications using MAP_PRIVATE may receive SIGBUS. Isolating too much memory in the hugetlb pool means it is not available for other uses, especially those programs not using huge pages. The obvious answer is to let the hugetlb pool grow and shrink in response to the runtime demand for huge pages. The work Mel Gorman has been doing to establish a memory zone for movable memory allocations makes dynamically resizing the hugetlb pool reliable within the limits of that zone. This patch series implements dynamic pool resizing for private and shared mappings while being careful to maintain existing semantics. Please reply with your comments and feedback; even just to say whether it would be a useful feature to you. Thanks. How it works ============ Upon depletion of the hugetlb pool, rather than reporting an error immediately, first try and allocate the needed huge pages directly from the buddy allocator. Care must be taken to avoid unbounded growth of the hugetlb pool, so the hugetlb filesystem quota is used to limit overall pool size. The real work begins when we decide there is a shortage of huge pages. What happens next depends on whether the pages are for a private or shared mapping. Private mappings are straightforward. At fault time, if alloc_huge_page() fails, we allocate a page from the buddy allocator and increment the source node's surplus_huge_pages counter. When free_huge_page() is called for a page on a node with a surplus, the page is freed directly to the buddy allocator instead of the hugetlb pool. Because shared mappings require all of the pages to be reserved up front, some additional work must be done at mmap() to support them. We determine the reservation shortage and allocate the required number of pages all at once. These pages are then added to the hugetlb pool and marked reserved. Where that is not possible the mmap() will fail. As with private mappings, the appropriate surplus counters are updated. Since reserved huge pages won't necessarily be used by the process, we can't be sure that free_huge_page() will always be called to return surplus pages to the buddy allocator. To prevent the huge page pool from bloating, we must free unused surplus pages when their reservation has ended. Controlling it ============== With the entire patch series applied, pool resizing is off by default so unless specific action is taken, the semantics are unchanged. To take advantage of the flexibility afforded by this patch series one must tolerate a change in semantics. To control hugetlb pool growth, the following techniques can be employed: * A sysctl tunable to enable/disable the feature entirely * The size= mount option for hugetlbfs filesystems to limit pool size Performance =========== When contiguous memory is readily available, it is expected that the cost of dynamicly resizing the pool will be small. This series has been performance tested with 'stream' to measure this cost. Stream (http://www.cs.virginia.edu/stream/) was linked with libhugetlbfs to enable remapping of the text and data/bss segments into huge pages. Stream with small array ----------------------- Baseline: nr_hugepages = 0, No libhugetlbfs segment remapping Preallocated: nr_hugepages = 5, Text and data/bss remapping Dynamic: nr_hugepages = 0, Text and data/bss remapping Rate (MB/s) Function Baseline Preallocated Dynamic Copy: 4695.6266 5942.8371 5982.2287 Scale: 4451.5776 5017.1419 5658.7843 Add: 5815.8849 7927.7827 8119.3552 Triad: 5949.4144 8527.6492 8110.6903 Stream with large array ----------------------- Baseline: nr_hugepages = 0, No libhugetlbfs segment remapping Preallocated: nr_hugepages = 67, Text and data/bss remapping Dynamic: nr_hugepages = 0, Text and data/bss remapping Rate (MB/s) Function Baseline Preallocated Dynamic Copy: 2227.8281 2544.2732 2546.4947 Scale: 2136.3208 2430.7294 2421.2074 Add: 2773.1449 4004.0021 3999.4331 Triad: 2748.4502 3777.0109 3773.4970 * All numbers are averages taken from 10 consecutive runs with a maximum standard deviation of 1.3 percent noted. This patch: Simply move update_and_free_page() so that it can be reused later in this patch series. The implementation is not changed. Signed-off-by: Adam Litke <agl@us.ibm.com> Acked-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Dave McCracken <dave.mccracken@oracle.com> Acked-by: William Irwin <bill.irwin@oracle.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Ken Chen <kenchen@google.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16 12:26:16 +04:00
}
hugetlb: be sure to free demoted CMA pages to CMA When huge page demotion is fully implemented, gigantic pages can be demoted to a smaller huge page size. For example, on x86 a 1G page can be demoted to 512 2M pages. However, gigantic pages can potentially be allocated from CMA. If a gigantic page which was allocated from CMA is demoted, the corresponding demoted pages needs to be returned to CMA. Use the new interface cma_pages_valid() to determine if a non-gigantic hugetlb page should be freed to CMA. Also, clear mapping field of these pages as expected by cma_release. This also requires a change to CMA region creation for gigantic pages. CMA uses a per-region bit map to track allocations. When setting up the region, you specify how many pages each bit represents. Currently, only gigantic pages are allocated/freed from CMA so the region is set up such that one bit represents a gigantic page size allocation. With demote, a gigantic page (allocation) could be split into smaller size pages. And, these smaller size pages will be freed to CMA. So, since the per-region bit map needs to be set up to represent the smallest allocation/free size, it now needs to be set to the smallest huge page size which can be freed to CMA. Unfortunately, we set up the CMA region for huge pages before we set up huge pages sizes (hstates). So, technically we do not know the smallest huge page size as this can change via command line options and architecture specific code. Therefore, at region setup time we use HUGETLB_PAGE_ORDER as the smallest possible huge page size that can be given back to CMA. It is possible that this value is sub-optimal for some architectures/config options. If needed, this can be addressed in follow on work. Link: https://lkml.kernel.org/r/20211007181918.136982-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:27 +03:00
/*
* Non-gigantic pages demoted from CMA allocated gigantic pages
* need to be given back to CMA in free_gigantic_page.
*/
if (hstate_is_gigantic(h) ||
hugetlb_cma_page(page, huge_page_order(h))) {
hugetlb: add support for gigantic page allocation at runtime HugeTLB is limited to allocating hugepages whose size are less than MAX_ORDER order. This is so because HugeTLB allocates hugepages via the buddy allocator. Gigantic pages (that is, pages whose size is greater than MAX_ORDER order) have to be allocated at boottime. However, boottime allocation has at least two serious problems. First, it doesn't support NUMA and second, gigantic pages allocated at boottime can't be freed. This commit solves both issues by adding support for allocating gigantic pages during runtime. It works just like regular sized hugepages, meaning that the interface in sysfs is the same, it supports NUMA, and gigantic pages can be freed. For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And to free them all: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages The one problem with gigantic page allocation at runtime is that it can't be serviced by the buddy allocator. To overcome that problem, this commit scans all zones from a node looking for a large enough contiguous region. When one is found, it's allocated by using CMA, that is, we call alloc_contig_range() to do the actual allocation. For example, on x86_64 we scan all zones looking for a 1GB contiguous region. When one is found, it's allocated by alloc_contig_range(). One expected issue with that approach is that such gigantic contiguous regions tend to vanish as runtime goes by. The best way to avoid this for now is to make gigantic page allocations very early during system boot, say from a init script. Other possible optimization include using compaction, which is supported by CMA but is not explicitly used by this commit. It's also important to note the following: 1. Gigantic pages allocated at boottime by the hugepages= command-line option can be freed at runtime just fine 2. This commit adds support for gigantic pages only to x86_64. The reason is that I don't have access to nor experience with other archs. The code is arch indepedent though, so it should be simple to add support to different archs 3. I didn't add support for hugepage overcommit, that is allocating a gigantic page on demand when /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't think it's reasonable to do the hard and long work required for allocating a gigantic page at fault time. But it should be simple to add this if wanted [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-05 03:07:13 +04:00
destroy_compound_gigantic_page(page, huge_page_order(h));
free_gigantic_page(page, huge_page_order(h));
} else {
__free_pages(page, huge_page_order(h));
}
hugetlb: Move update_and_free_page Dynamic huge page pool resizing. In most real-world scenarios, configuring the size of the hugetlb pool correctly is a difficult task. If too few pages are allocated to the pool, applications using MAP_SHARED may fail to mmap() a hugepage region and applications using MAP_PRIVATE may receive SIGBUS. Isolating too much memory in the hugetlb pool means it is not available for other uses, especially those programs not using huge pages. The obvious answer is to let the hugetlb pool grow and shrink in response to the runtime demand for huge pages. The work Mel Gorman has been doing to establish a memory zone for movable memory allocations makes dynamically resizing the hugetlb pool reliable within the limits of that zone. This patch series implements dynamic pool resizing for private and shared mappings while being careful to maintain existing semantics. Please reply with your comments and feedback; even just to say whether it would be a useful feature to you. Thanks. How it works ============ Upon depletion of the hugetlb pool, rather than reporting an error immediately, first try and allocate the needed huge pages directly from the buddy allocator. Care must be taken to avoid unbounded growth of the hugetlb pool, so the hugetlb filesystem quota is used to limit overall pool size. The real work begins when we decide there is a shortage of huge pages. What happens next depends on whether the pages are for a private or shared mapping. Private mappings are straightforward. At fault time, if alloc_huge_page() fails, we allocate a page from the buddy allocator and increment the source node's surplus_huge_pages counter. When free_huge_page() is called for a page on a node with a surplus, the page is freed directly to the buddy allocator instead of the hugetlb pool. Because shared mappings require all of the pages to be reserved up front, some additional work must be done at mmap() to support them. We determine the reservation shortage and allocate the required number of pages all at once. These pages are then added to the hugetlb pool and marked reserved. Where that is not possible the mmap() will fail. As with private mappings, the appropriate surplus counters are updated. Since reserved huge pages won't necessarily be used by the process, we can't be sure that free_huge_page() will always be called to return surplus pages to the buddy allocator. To prevent the huge page pool from bloating, we must free unused surplus pages when their reservation has ended. Controlling it ============== With the entire patch series applied, pool resizing is off by default so unless specific action is taken, the semantics are unchanged. To take advantage of the flexibility afforded by this patch series one must tolerate a change in semantics. To control hugetlb pool growth, the following techniques can be employed: * A sysctl tunable to enable/disable the feature entirely * The size= mount option for hugetlbfs filesystems to limit pool size Performance =========== When contiguous memory is readily available, it is expected that the cost of dynamicly resizing the pool will be small. This series has been performance tested with 'stream' to measure this cost. Stream (http://www.cs.virginia.edu/stream/) was linked with libhugetlbfs to enable remapping of the text and data/bss segments into huge pages. Stream with small array ----------------------- Baseline: nr_hugepages = 0, No libhugetlbfs segment remapping Preallocated: nr_hugepages = 5, Text and data/bss remapping Dynamic: nr_hugepages = 0, Text and data/bss remapping Rate (MB/s) Function Baseline Preallocated Dynamic Copy: 4695.6266 5942.8371 5982.2287 Scale: 4451.5776 5017.1419 5658.7843 Add: 5815.8849 7927.7827 8119.3552 Triad: 5949.4144 8527.6492 8110.6903 Stream with large array ----------------------- Baseline: nr_hugepages = 0, No libhugetlbfs segment remapping Preallocated: nr_hugepages = 67, Text and data/bss remapping Dynamic: nr_hugepages = 0, Text and data/bss remapping Rate (MB/s) Function Baseline Preallocated Dynamic Copy: 2227.8281 2544.2732 2546.4947 Scale: 2136.3208 2430.7294 2421.2074 Add: 2773.1449 4004.0021 3999.4331 Triad: 2748.4502 3777.0109 3773.4970 * All numbers are averages taken from 10 consecutive runs with a maximum standard deviation of 1.3 percent noted. This patch: Simply move update_and_free_page() so that it can be reused later in this patch series. The implementation is not changed. Signed-off-by: Adam Litke <agl@us.ibm.com> Acked-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Dave McCracken <dave.mccracken@oracle.com> Acked-by: William Irwin <bill.irwin@oracle.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Ken Chen <kenchen@google.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16 12:26:16 +04:00
}
mm: hugetlb: defer freeing of HugeTLB pages In the subsequent patch, we should allocate the vmemmap pages when freeing a HugeTLB page. But update_and_free_page() can be called under any context, so we cannot use GFP_KERNEL to allocate vmemmap pages. However, we can defer the actual freeing in a kworker to prevent from using GFP_ATOMIC to allocate the vmemmap pages. The __update_and_free_page() is where the call to allocate vmemmmap pages will be inserted. Link: https://lkml.kernel.org/r/20210510030027.56044-6-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:17 +03:00
/*
* As update_and_free_page() can be called under any context, so we cannot
* use GFP_KERNEL to allocate vmemmap pages. However, we can defer the
* actual freeing in a workqueue to prevent from using GFP_ATOMIC to allocate
* the vmemmap pages.
*
* free_hpage_workfn() locklessly retrieves the linked list of pages to be
* freed and frees them one-by-one. As the page->mapping pointer is going
* to be cleared in free_hpage_workfn() anyway, it is reused as the llist_node
* structure of a lockless linked list of huge pages to be freed.
*/
static LLIST_HEAD(hpage_freelist);
static void free_hpage_workfn(struct work_struct *work)
{
struct llist_node *node;
node = llist_del_all(&hpage_freelist);
while (node) {
struct page *page;
struct hstate *h;
page = container_of((struct address_space **)node,
struct page, mapping);
node = node->next;
page->mapping = NULL;
/*
* The VM_BUG_ON_PAGE(!PageHuge(page), page) in page_hstate()
* is going to trigger because a previous call to
* remove_hugetlb_page() will set_compound_page_dtor(page,
* NULL_COMPOUND_DTOR), so do not use page_hstate() directly.
*/
h = size_to_hstate(page_size(page));
__update_and_free_page(h, page);
cond_resched();
}
}
static DECLARE_WORK(free_hpage_work, free_hpage_workfn);
static inline void flush_free_hpage_work(struct hstate *h)
{
if (hugetlb_optimize_vmemmap_pages(h))
mm: hugetlb: defer freeing of HugeTLB pages In the subsequent patch, we should allocate the vmemmap pages when freeing a HugeTLB page. But update_and_free_page() can be called under any context, so we cannot use GFP_KERNEL to allocate vmemmap pages. However, we can defer the actual freeing in a kworker to prevent from using GFP_ATOMIC to allocate the vmemmap pages. The __update_and_free_page() is where the call to allocate vmemmmap pages will be inserted. Link: https://lkml.kernel.org/r/20210510030027.56044-6-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:17 +03:00
flush_work(&free_hpage_work);
}
static void update_and_free_page(struct hstate *h, struct page *page,
bool atomic)
{
mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page When we free a HugeTLB page to the buddy allocator, we need to allocate the vmemmap pages associated with it. However, we may not be able to allocate the vmemmap pages when the system is under memory pressure. In this case, we just refuse to free the HugeTLB page. This changes behavior in some corner cases as listed below: 1) Failing to free a huge page triggered by the user (decrease nr_pages). User needs to try again later. 2) Failing to free a surplus huge page when freed by the application. Try again later when freeing a huge page next time. 3) Failing to dissolve a free huge page on ZONE_MOVABLE via offline_pages(). This can happen when we have plenty of ZONE_MOVABLE memory, but not enough kernel memory to allocate vmemmmap pages. We may even be able to migrate huge page contents, but will not be able to dissolve the source huge page. This will prevent an offline operation and is unfortunate as memory offlining is expected to succeed on movable zones. Users that depend on memory hotplug to succeed for movable zones should carefully consider whether the memory savings gained from this feature are worth the risk of possibly not being able to offline memory in certain situations. 4) Failing to dissolve a huge page on CMA/ZONE_MOVABLE via alloc_contig_range() - once we have that handling in place. Mainly affects CMA and virtio-mem. Similar to 3). virito-mem will handle migration errors gracefully. CMA might be able to fallback on other free areas within the CMA region. Vmemmap pages are allocated from the page freeing context. In order for those allocations to be not disruptive (e.g. trigger oom killer) __GFP_NORETRY is used. hugetlb_lock is dropped for the allocation because a non sleeping allocation would be too fragile and it could fail too easily under memory pressure. GFP_ATOMIC or other modes to access memory reserves is not used because we want to prevent consuming reserves under heavy hugetlb freeing. [mike.kravetz@oracle.com: fix dissolve_free_huge_page use of tail/head page] Link: https://lkml.kernel.org/r/20210527231225.226987-1-mike.kravetz@oracle.com [willy@infradead.org: fix alloc_vmemmap_page_list documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-6-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-7-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:21 +03:00
if (!HPageVmemmapOptimized(page) || !atomic) {
mm: hugetlb: defer freeing of HugeTLB pages In the subsequent patch, we should allocate the vmemmap pages when freeing a HugeTLB page. But update_and_free_page() can be called under any context, so we cannot use GFP_KERNEL to allocate vmemmap pages. However, we can defer the actual freeing in a kworker to prevent from using GFP_ATOMIC to allocate the vmemmap pages. The __update_and_free_page() is where the call to allocate vmemmmap pages will be inserted. Link: https://lkml.kernel.org/r/20210510030027.56044-6-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:17 +03:00
__update_and_free_page(h, page);
return;
}
/*
* Defer freeing to avoid using GFP_ATOMIC to allocate vmemmap pages.
*
* Only call schedule_work() if hpage_freelist is previously
* empty. Otherwise, schedule_work() had been called but the workfn
* hasn't retrieved the list yet.
*/
if (llist_add((struct llist_node *)&page->mapping, &hpage_freelist))
schedule_work(&free_hpage_work);
}
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
static void update_and_free_pages_bulk(struct hstate *h, struct list_head *list)
{
struct page *page, *t_page;
list_for_each_entry_safe(page, t_page, list, lru) {
mm: hugetlb: defer freeing of HugeTLB pages In the subsequent patch, we should allocate the vmemmap pages when freeing a HugeTLB page. But update_and_free_page() can be called under any context, so we cannot use GFP_KERNEL to allocate vmemmap pages. However, we can defer the actual freeing in a kworker to prevent from using GFP_ATOMIC to allocate the vmemmap pages. The __update_and_free_page() is where the call to allocate vmemmmap pages will be inserted. Link: https://lkml.kernel.org/r/20210510030027.56044-6-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:17 +03:00
update_and_free_page(h, page, false);
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
cond_resched();
}
}
struct hstate *size_to_hstate(unsigned long size)
{
struct hstate *h;
for_each_hstate(h) {
if (huge_page_size(h) == size)
return h;
}
return NULL;
}
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
void free_huge_page(struct page *page)
{
/*
* Can't pass hstate in here because it is called from the
* compound page destructor.
*/
struct hstate *h = page_hstate(page);
int nid = page_to_nid(page);
hugetlb: use page.private for hugetlb specific page flags Patch series "create hugetlb flags to consolidate state", v3. While discussing a series of hugetlb fixes in [1], it became evident that the hugetlb specific page state information is stored in a somewhat haphazard manner. Code dealing with state information would be easier to read, understand and maintain if this information was stored in a consistent manner. This series uses page.private of the hugetlb head page for storing a set of hugetlb specific page flags. Routines are priovided for test, set and clear of the flags. [1] https://lore.kernel.org/r/20210106084739.63318-1-songmuchun@bytedance.com This patch (of 4): As hugetlbfs evolved, state information about hugetlb pages was added. One 'convenient' way of doing this was to use available fields in tail pages. Over time, it has become difficult to know the meaning or contents of fields simply by looking at a small bit of code. Sometimes, the naming is just confusing. For example: The PagePrivate flag indicates a huge page reservation was consumed and needs to be restored if an error is encountered and the page is freed before it is instantiated. The page.private field contains the pointer to a subpool if the page is associated with one. In an effort to make the code more readable, use page.private to contain hugetlb specific page flags. These flags will have test, set and clear functions similar to those used for 'normal' page flags. More importantly, an enum of flag values will be created with names that actually reflect their purpose. In this patch, - Create infrastructure for hugetlb specific page flag functions - Move subpool pointer to page[1].private to make way for flags Create routines with meaningful names to modify subpool field - Use new HPageRestoreReserve flag instead of PagePrivate Conversion of other state information will happen in subsequent patches. Link: https://lkml.kernel.org/r/20210122195231.324857-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210122195231.324857-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:51 +03:00
struct hugepage_subpool *spool = hugetlb_page_subpool(page);
bool restore_reserve;
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
unsigned long flags;
VM_BUG_ON_PAGE(page_count(page), page);
VM_BUG_ON_PAGE(page_mapcount(page), page);
hugetlb: use page.private for hugetlb specific page flags Patch series "create hugetlb flags to consolidate state", v3. While discussing a series of hugetlb fixes in [1], it became evident that the hugetlb specific page state information is stored in a somewhat haphazard manner. Code dealing with state information would be easier to read, understand and maintain if this information was stored in a consistent manner. This series uses page.private of the hugetlb head page for storing a set of hugetlb specific page flags. Routines are priovided for test, set and clear of the flags. [1] https://lore.kernel.org/r/20210106084739.63318-1-songmuchun@bytedance.com This patch (of 4): As hugetlbfs evolved, state information about hugetlb pages was added. One 'convenient' way of doing this was to use available fields in tail pages. Over time, it has become difficult to know the meaning or contents of fields simply by looking at a small bit of code. Sometimes, the naming is just confusing. For example: The PagePrivate flag indicates a huge page reservation was consumed and needs to be restored if an error is encountered and the page is freed before it is instantiated. The page.private field contains the pointer to a subpool if the page is associated with one. In an effort to make the code more readable, use page.private to contain hugetlb specific page flags. These flags will have test, set and clear functions similar to those used for 'normal' page flags. More importantly, an enum of flag values will be created with names that actually reflect their purpose. In this patch, - Create infrastructure for hugetlb specific page flag functions - Move subpool pointer to page[1].private to make way for flags Create routines with meaningful names to modify subpool field - Use new HPageRestoreReserve flag instead of PagePrivate Conversion of other state information will happen in subsequent patches. Link: https://lkml.kernel.org/r/20210122195231.324857-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210122195231.324857-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:51 +03:00
hugetlb_set_page_subpool(page, NULL);
mm/page-flags: reuse PG_mappedtodisk as PG_anon_exclusive for PageAnon() pages The basic question we would like to have a reliable and efficient answer to is: is this anonymous page exclusive to a single process or might it be shared? We need that information for ordinary/single pages, hugetlb pages, and possibly each subpage of a THP. Introduce a way to mark an anonymous page as exclusive, with the ultimate goal of teaching our COW logic to not do "wrong COWs", whereby GUP pins lose consistency with the pages mapped into the page table, resulting in reported memory corruptions. Most pageflags already have semantics for anonymous pages, however, PG_mappedtodisk should never apply to pages in the swapcache, so let's reuse that flag. As PG_has_hwpoisoned also uses that flag on the second tail page of a compound page, convert it to PG_error instead, which is marked as PF_NO_TAIL, so never used for tail pages. Use custom page flag modification functions such that we can do additional sanity checks. The semantics we'll put into some kernel doc in the future are: " PG_anon_exclusive is *usually* only expressive in combination with a page table entry. Depending on the page table entry type it might store the following information: Is what's mapped via this page table entry exclusive to the single process and can be mapped writable without further checks? If not, it might be shared and we might have to COW. For now, we only expect PTE-mapped THPs to make use of PG_anon_exclusive in subpages. For other anonymous compound folios (i.e., hugetlb), only the head page is logically mapped and holds this information. For example, an exclusive, PMD-mapped THP only has PG_anon_exclusive set on the head page. When replacing the PMD by a page table full of PTEs, PG_anon_exclusive, if set on the head page, will be set on all tail pages accordingly. Note that converting from a PTE-mapping to a PMD mapping using the same compound page is currently not possible and consequently doesn't require care. If GUP wants to take a reliable pin (FOLL_PIN) on an anonymous page, it should only pin if the relevant PG_anon_exclusive is set. In that case, the pin will be fully reliable and stay consistent with the pages mapped into the page table, as the bit cannot get cleared (e.g., by fork(), KSM) while the page is pinned. For anonymous pages that are mapped R/W, PG_anon_exclusive can be assumed to always be set because such pages cannot possibly be shared. The page table lock protecting the page table entry is the primary synchronization mechanism for PG_anon_exclusive; GUP-fast that does not take the PT lock needs special care when trying to clear the flag. Page table entry types and PG_anon_exclusive: * Present: PG_anon_exclusive applies. * Swap: the information is lost. PG_anon_exclusive was cleared. * Migration: the entry holds this information instead. PG_anon_exclusive was cleared. * Device private: PG_anon_exclusive applies. * Device exclusive: PG_anon_exclusive applies. * HW Poison: PG_anon_exclusive is stale and not changed. If the page may be pinned (FOLL_PIN), clearing PG_anon_exclusive is not allowed and the flag will stick around until the page is freed and folio->mapping is cleared. " We won't be clearing PG_anon_exclusive on destructive unmapping (i.e., zapping) of page table entries, page freeing code will handle that when also invalidate page->mapping to not indicate PageAnon() anymore. Letting information about exclusivity stick around will be an important property when adding sanity checks to unpinning code. Note that we properly clear the flag in free_pages_prepare() via PAGE_FLAGS_CHECK_AT_PREP for each individual subpage of a compound page, so there is no need to manually clear the flag. Link: https://lkml.kernel.org/r/20220428083441.37290-12-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:44 +03:00
if (PageAnon(page))
__ClearPageAnonExclusive(page);
page->mapping = NULL;
hugetlb: use page.private for hugetlb specific page flags Patch series "create hugetlb flags to consolidate state", v3. While discussing a series of hugetlb fixes in [1], it became evident that the hugetlb specific page state information is stored in a somewhat haphazard manner. Code dealing with state information would be easier to read, understand and maintain if this information was stored in a consistent manner. This series uses page.private of the hugetlb head page for storing a set of hugetlb specific page flags. Routines are priovided for test, set and clear of the flags. [1] https://lore.kernel.org/r/20210106084739.63318-1-songmuchun@bytedance.com This patch (of 4): As hugetlbfs evolved, state information about hugetlb pages was added. One 'convenient' way of doing this was to use available fields in tail pages. Over time, it has become difficult to know the meaning or contents of fields simply by looking at a small bit of code. Sometimes, the naming is just confusing. For example: The PagePrivate flag indicates a huge page reservation was consumed and needs to be restored if an error is encountered and the page is freed before it is instantiated. The page.private field contains the pointer to a subpool if the page is associated with one. In an effort to make the code more readable, use page.private to contain hugetlb specific page flags. These flags will have test, set and clear functions similar to those used for 'normal' page flags. More importantly, an enum of flag values will be created with names that actually reflect their purpose. In this patch, - Create infrastructure for hugetlb specific page flag functions - Move subpool pointer to page[1].private to make way for flags Create routines with meaningful names to modify subpool field - Use new HPageRestoreReserve flag instead of PagePrivate Conversion of other state information will happen in subsequent patches. Link: https://lkml.kernel.org/r/20210122195231.324857-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210122195231.324857-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:51 +03:00
restore_reserve = HPageRestoreReserve(page);
ClearHPageRestoreReserve(page);
/*
hugetlb: use page.private for hugetlb specific page flags Patch series "create hugetlb flags to consolidate state", v3. While discussing a series of hugetlb fixes in [1], it became evident that the hugetlb specific page state information is stored in a somewhat haphazard manner. Code dealing with state information would be easier to read, understand and maintain if this information was stored in a consistent manner. This series uses page.private of the hugetlb head page for storing a set of hugetlb specific page flags. Routines are priovided for test, set and clear of the flags. [1] https://lore.kernel.org/r/20210106084739.63318-1-songmuchun@bytedance.com This patch (of 4): As hugetlbfs evolved, state information about hugetlb pages was added. One 'convenient' way of doing this was to use available fields in tail pages. Over time, it has become difficult to know the meaning or contents of fields simply by looking at a small bit of code. Sometimes, the naming is just confusing. For example: The PagePrivate flag indicates a huge page reservation was consumed and needs to be restored if an error is encountered and the page is freed before it is instantiated. The page.private field contains the pointer to a subpool if the page is associated with one. In an effort to make the code more readable, use page.private to contain hugetlb specific page flags. These flags will have test, set and clear functions similar to those used for 'normal' page flags. More importantly, an enum of flag values will be created with names that actually reflect their purpose. In this patch, - Create infrastructure for hugetlb specific page flag functions - Move subpool pointer to page[1].private to make way for flags Create routines with meaningful names to modify subpool field - Use new HPageRestoreReserve flag instead of PagePrivate Conversion of other state information will happen in subsequent patches. Link: https://lkml.kernel.org/r/20210122195231.324857-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210122195231.324857-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:51 +03:00
* If HPageRestoreReserve was set on page, page allocation consumed a
hugetlbfs: on restore reserve error path retain subpool reservation When a huge page is allocated, PagePrivate() is set if the allocation consumed a reservation. When freeing a huge page, PagePrivate is checked. If set, it indicates the reservation should be restored. PagePrivate being set at free huge page time mostly happens on error paths. When huge page reservations are created, a check is made to determine if the mapping is associated with an explicitly mounted filesystem. If so, pages are also reserved within the filesystem. The default action when freeing a huge page is to decrement the usage count in any associated explicitly mounted filesystem. However, if the reservation is to be restored the reservation/use count within the filesystem should not be decrementd. Otherwise, a subsequent page allocation and free for the same mapping location will cause the file filesystem usage to go 'negative'. Filesystem Size Used Avail Use% Mounted on nodev 4.0G -4.0M 4.1G - /opt/hugepool To fix, when freeing a huge page do not adjust filesystem usage if PagePrivate() is set to indicate the reservation should be restored. I did not cc stable as the problem has been around since reserves were added to hugetlbfs and nobody has noticed. Link: http://lkml.kernel.org/r/20190328234704.27083-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 03:19:38 +03:00
* reservation. If the page was associated with a subpool, there
* would have been a page reserved in the subpool before allocation
* via hugepage_subpool_get_pages(). Since we are 'restoring' the
* reservation, do not call hugepage_subpool_put_pages() as this will
hugetlbfs: on restore reserve error path retain subpool reservation When a huge page is allocated, PagePrivate() is set if the allocation consumed a reservation. When freeing a huge page, PagePrivate is checked. If set, it indicates the reservation should be restored. PagePrivate being set at free huge page time mostly happens on error paths. When huge page reservations are created, a check is made to determine if the mapping is associated with an explicitly mounted filesystem. If so, pages are also reserved within the filesystem. The default action when freeing a huge page is to decrement the usage count in any associated explicitly mounted filesystem. However, if the reservation is to be restored the reservation/use count within the filesystem should not be decrementd. Otherwise, a subsequent page allocation and free for the same mapping location will cause the file filesystem usage to go 'negative'. Filesystem Size Used Avail Use% Mounted on nodev 4.0G -4.0M 4.1G - /opt/hugepool To fix, when freeing a huge page do not adjust filesystem usage if PagePrivate() is set to indicate the reservation should be restored. I did not cc stable as the problem has been around since reserves were added to hugetlbfs and nobody has noticed. Link: http://lkml.kernel.org/r/20190328234704.27083-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 03:19:38 +03:00
* remove the reserved page from the subpool.
*/
hugetlbfs: on restore reserve error path retain subpool reservation When a huge page is allocated, PagePrivate() is set if the allocation consumed a reservation. When freeing a huge page, PagePrivate is checked. If set, it indicates the reservation should be restored. PagePrivate being set at free huge page time mostly happens on error paths. When huge page reservations are created, a check is made to determine if the mapping is associated with an explicitly mounted filesystem. If so, pages are also reserved within the filesystem. The default action when freeing a huge page is to decrement the usage count in any associated explicitly mounted filesystem. However, if the reservation is to be restored the reservation/use count within the filesystem should not be decrementd. Otherwise, a subsequent page allocation and free for the same mapping location will cause the file filesystem usage to go 'negative'. Filesystem Size Used Avail Use% Mounted on nodev 4.0G -4.0M 4.1G - /opt/hugepool To fix, when freeing a huge page do not adjust filesystem usage if PagePrivate() is set to indicate the reservation should be restored. I did not cc stable as the problem has been around since reserves were added to hugetlbfs and nobody has noticed. Link: http://lkml.kernel.org/r/20190328234704.27083-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 03:19:38 +03:00
if (!restore_reserve) {
/*
* A return code of zero implies that the subpool will be
* under its minimum size if the reservation is not restored
* after page is free. Therefore, force restore_reserve
* operation.
*/
if (hugepage_subpool_put_pages(spool, 1) == 0)
restore_reserve = true;
}
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irqsave(&hugetlb_lock, flags);
hugetlb: convert page_huge_active() HPageMigratable flag Use the new hugetlb page specific flag HPageMigratable to replace the page_huge_active interfaces. By it's name, page_huge_active implied that a huge page was on the active list. However, that is not really what code checking the flag wanted to know. It really wanted to determine if the huge page could be migrated. This happens when the page is actually added to the page cache and/or task page table. This is the reasoning behind the name change. The VM_BUG_ON_PAGE() calls in the *_huge_active() interfaces are not really necessary as we KNOW the page is a hugetlb page. Therefore, they are removed. The routine page_huge_active checked for PageHeadHuge before testing the active bit. This is unnecessary in the case where we hold a reference or lock and know it is a hugetlb head page. page_huge_active is also called without holding a reference or lock (scan_movable_pages), and can race with code freeing the page. The extra check in page_huge_active shortened the race window, but did not prevent the race. Offline code calling scan_movable_pages already deals with these races, so removing the check is acceptable. Add comment to racy code. [songmuchun@bytedance.com: remove set_page_huge_active() declaration from include/linux/hugetlb.h] Link: https://lkml.kernel.org/r/CAMZfGtUda+KoAZscU0718TN61cSFwp4zy=y2oZ=+6Z2TAZZwng@mail.gmail.com Link: https://lkml.kernel.org/r/20210122195231.324857-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:56 +03:00
ClearHPageMigratable(page);
hugetlb_cgroup_uncharge_page(hstate_index(h),
pages_per_huge_page(h), page);
hugetlb_cgroup_uncharge_page_rsvd(hstate_index(h),
pages_per_huge_page(h), page);
if (restore_reserve)
h->resv_huge_pages++;
if (HPageTemporary(page)) {
hugetlb: create remove_hugetlb_page() to separate functionality The new remove_hugetlb_page() routine is designed to remove a hugetlb page from hugetlbfs processing. It will remove the page from the active or free list, update global counters and set the compound page destructor to NULL so that PageHuge() will return false for the 'page'. After this call, the 'page' can be treated as a normal compound page or a collection of base size pages. update_and_free_page no longer decrements h->nr_huge_pages{_node} as this is performed in remove_hugetlb_page. The only functionality performed by update_and_free_page is to free the base pages to the lower level allocators. update_and_free_page is typically called after remove_hugetlb_page. remove_hugetlb_page is to be called with the hugetlb_lock held. Creating this routine and separating functionality is in preparation for restructuring code to reduce lock hold times. This commit should not introduce any changes to functionality. Link: https://lkml.kernel.org/r/20210409205254.242291-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:55 +03:00
remove_hugetlb_page(h, page, false);
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irqrestore(&hugetlb_lock, flags);
mm: hugetlb: defer freeing of HugeTLB pages In the subsequent patch, we should allocate the vmemmap pages when freeing a HugeTLB page. But update_and_free_page() can be called under any context, so we cannot use GFP_KERNEL to allocate vmemmap pages. However, we can defer the actual freeing in a kworker to prevent from using GFP_ATOMIC to allocate the vmemmap pages. The __update_and_free_page() is where the call to allocate vmemmmap pages will be inserted. Link: https://lkml.kernel.org/r/20210510030027.56044-6-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:17 +03:00
update_and_free_page(h, page, true);
mm, hugetlb: do not rely on overcommit limit during migration hugepage migration relies on __alloc_buddy_huge_page to get a new page. This has 2 main disadvantages. 1) it doesn't allow to migrate any huge page if the pool is used completely which is not an exceptional case as the pool is static and unused memory is just wasted. 2) it leads to a weird semantic when migration between two numa nodes might increase the pool size of the destination NUMA node while the page is in use. The issue is caused by per NUMA node surplus pages tracking (see free_huge_page). Address both issues by changing the way how we allocate and account pages allocated for migration. Those should temporal by definition. So we mark them that way (we will abuse page flags in the 3rd page) and update free_huge_page to free such pages to the page allocator. Page migration path then just transfers the temporal status from the new page to the old one which will be freed on the last reference. The global surplus count will never change during this path but we still have to be careful when migrating a per-node suprlus page. This is now handled in move_hugetlb_state which is called from the migration path and it copies the hugetlb specific page state and fixes up the accounting when needed Rename __alloc_buddy_huge_page to __alloc_surplus_huge_page to better reflect its purpose. The new allocation routine for the migration path is __alloc_migrate_huge_page. The user visible effect of this patch is that migrated pages are really temporal and they travel between NUMA nodes as per the migration request: Before migration /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 After /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 with the previous implementation, both nodes would have nr_hugepages:1 until the page is freed. Link: http://lkml.kernel.org/r/20180103093213.26329-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:48 +03:00
} else if (h->surplus_huge_pages_node[nid]) {
/* remove the page from active list */
hugetlb: create remove_hugetlb_page() to separate functionality The new remove_hugetlb_page() routine is designed to remove a hugetlb page from hugetlbfs processing. It will remove the page from the active or free list, update global counters and set the compound page destructor to NULL so that PageHuge() will return false for the 'page'. After this call, the 'page' can be treated as a normal compound page or a collection of base size pages. update_and_free_page no longer decrements h->nr_huge_pages{_node} as this is performed in remove_hugetlb_page. The only functionality performed by update_and_free_page is to free the base pages to the lower level allocators. update_and_free_page is typically called after remove_hugetlb_page. remove_hugetlb_page is to be called with the hugetlb_lock held. Creating this routine and separating functionality is in preparation for restructuring code to reduce lock hold times. This commit should not introduce any changes to functionality. Link: https://lkml.kernel.org/r/20210409205254.242291-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:55 +03:00
remove_hugetlb_page(h, page, true);
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irqrestore(&hugetlb_lock, flags);
mm: hugetlb: defer freeing of HugeTLB pages In the subsequent patch, we should allocate the vmemmap pages when freeing a HugeTLB page. But update_and_free_page() can be called under any context, so we cannot use GFP_KERNEL to allocate vmemmap pages. However, we can defer the actual freeing in a kworker to prevent from using GFP_ATOMIC to allocate the vmemmap pages. The __update_and_free_page() is where the call to allocate vmemmmap pages will be inserted. Link: https://lkml.kernel.org/r/20210510030027.56044-6-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:17 +03:00
update_and_free_page(h, page, true);
} else {
arch_clear_hugepage_flags(page);
enqueue_huge_page(h, page);
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irqrestore(&hugetlb_lock, flags);
mm/hugetlb: defer freeing of huge pages if in non-task context The following lockdep splat was observed when a certain hugetlbfs test was run: ================================ WARNING: inconsistent lock state 4.18.0-159.el8.x86_64+debug #1 Tainted: G W --------- - - -------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. swapper/30/0 [HC0[0]:SC1[1]:HE1:SE0] takes: ffffffff9acdc038 (hugetlb_lock){+.?.}, at: free_huge_page+0x36f/0xaa0 {SOFTIRQ-ON-W} state was registered at: lock_acquire+0x14f/0x3b0 _raw_spin_lock+0x30/0x70 __nr_hugepages_store_common+0x11b/0xb30 hugetlb_sysctl_handler_common+0x209/0x2d0 proc_sys_call_handler+0x37f/0x450 vfs_write+0x157/0x460 ksys_write+0xb8/0x170 do_syscall_64+0xa5/0x4d0 entry_SYSCALL_64_after_hwframe+0x6a/0xdf irq event stamp: 691296 hardirqs last enabled at (691296): [<ffffffff99bb034b>] _raw_spin_unlock_irqrestore+0x4b/0x60 hardirqs last disabled at (691295): [<ffffffff99bb0ad2>] _raw_spin_lock_irqsave+0x22/0x81 softirqs last enabled at (691284): [<ffffffff97ff0c63>] irq_enter+0xc3/0xe0 softirqs last disabled at (691285): [<ffffffff97ff0ebe>] irq_exit+0x23e/0x2b0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(hugetlb_lock); <Interrupt> lock(hugetlb_lock); *** DEADLOCK *** : Call Trace: <IRQ> __lock_acquire+0x146b/0x48c0 lock_acquire+0x14f/0x3b0 _raw_spin_lock+0x30/0x70 free_huge_page+0x36f/0xaa0 bio_check_pages_dirty+0x2fc/0x5c0 clone_endio+0x17f/0x670 [dm_mod] blk_update_request+0x276/0xe50 scsi_end_request+0x7b/0x6a0 scsi_io_completion+0x1c6/0x1570 blk_done_softirq+0x22e/0x350 __do_softirq+0x23d/0xad8 irq_exit+0x23e/0x2b0 do_IRQ+0x11a/0x200 common_interrupt+0xf/0xf </IRQ> Both the hugetbl_lock and the subpool lock can be acquired in free_huge_page(). One way to solve the problem is to make both locks irq-safe. However, Mike Kravetz had learned that the hugetlb_lock is held for a linear scan of ALL hugetlb pages during a cgroup reparentling operation. So it is just too long to have irq disabled unless we can break hugetbl_lock down into finer-grained locks with shorter lock hold times. Another alternative is to defer the freeing to a workqueue job. This patch implements the deferred freeing by adding a free_hpage_workfn() work function to do the actual freeing. The free_huge_page() call in a non-task context saves the page to be freed in the hpage_freelist linked list in a lockless manner using the llist APIs. The generic workqueue is used to process the work, but a dedicated workqueue can be used instead if it is desirable to have the huge page freed ASAP. Thanks to Kirill Tkhai <ktkhai@virtuozzo.com> for suggesting the use of llist APIs which simplfy the code. Link: http://lkml.kernel.org/r/20191217170331.30893-1-longman@redhat.com Signed-off-by: Waiman Long <longman@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-01-05 00:00:15 +03:00
}
}
/*
* Must be called with the hugetlb lock held
*/
static void __prep_account_new_huge_page(struct hstate *h, int nid)
{
lockdep_assert_held(&hugetlb_lock);
h->nr_huge_pages++;
h->nr_huge_pages_node[nid]++;
}
mm: hugetlb: free the vmemmap pages associated with each HugeTLB page Every HugeTLB has more than one struct page structure. We __know__ that we only use the first 4 (__NR_USED_SUBPAGE) struct page structures to store metadata associated with each HugeTLB. There are a lot of struct page structures associated with each HugeTLB page. For tail pages, the value of compound_head is the same. So we can reuse first page of tail page structures. We map the virtual addresses of the remaining pages of tail page structures to the first tail page struct, and then free these page frames. Therefore, we need to reserve two pages as vmemmap areas. When we allocate a HugeTLB page from the buddy, we can free some vmemmap pages associated with each HugeTLB page. It is more appropriate to do it in the prep_new_huge_page(). The free_vmemmap_pages_per_hpage(), which indicates how many vmemmap pages associated with a HugeTLB page can be freed, returns zero for now, which means the feature is disabled. We will enable it once all the infrastructure is there. [willy@infradead.org: fix documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-5-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-5-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Oscar Salvador <osalvador@suse.de> Tested-by: Chen Huang <chenhuang5@huawei.com> Tested-by: Bodeddula Balasubramaniam <bodeddub@amazon.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:13 +03:00
static void __prep_new_huge_page(struct hstate *h, struct page *page)
{
hugetlb_vmemmap_free(h, page);
INIT_LIST_HEAD(&page->lru);
set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
hugetlb: fix uninitialized subpool pointer Gerald Schaefer reported a panic on s390 in hugepage_subpool_put_pages() with linux-next 5.12.0-20210222. Call trace: hugepage_subpool_put_pages.part.0+0x2c/0x138 __free_huge_page+0xce/0x310 alloc_pool_huge_page+0x102/0x120 set_max_huge_pages+0x13e/0x350 hugetlb_sysctl_handler_common+0xd8/0x110 hugetlb_sysctl_handler+0x48/0x58 proc_sys_call_handler+0x138/0x238 new_sync_write+0x10e/0x198 vfs_write.part.0+0x12c/0x238 ksys_write+0x68/0xf8 do_syscall+0x82/0xd0 __do_syscall+0xb4/0xc8 system_call+0x72/0x98 This is a result of the change which moved the hugetlb page subpool pointer from page->private to page[1]->private. When new pages are allocated from the buddy allocator, the private field of the head page will be cleared, but the private field of subpages is not modified. Therefore, old values may remain. Fix by initializing hugetlb page subpool pointer in prep_new_huge_page(). Link: https://lkml.kernel.org/r/20210223215544.313871-1-mike.kravetz@oracle.com Fixes: f1280272ae4d ("hugetlb: use page.private for hugetlb specific page flags") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:09:11 +03:00
hugetlb_set_page_subpool(page, NULL);
set_hugetlb_cgroup(page, NULL);
set_hugetlb_cgroup_rsvd(page, NULL);
}
static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
{
mm: hugetlb: free the vmemmap pages associated with each HugeTLB page Every HugeTLB has more than one struct page structure. We __know__ that we only use the first 4 (__NR_USED_SUBPAGE) struct page structures to store metadata associated with each HugeTLB. There are a lot of struct page structures associated with each HugeTLB page. For tail pages, the value of compound_head is the same. So we can reuse first page of tail page structures. We map the virtual addresses of the remaining pages of tail page structures to the first tail page struct, and then free these page frames. Therefore, we need to reserve two pages as vmemmap areas. When we allocate a HugeTLB page from the buddy, we can free some vmemmap pages associated with each HugeTLB page. It is more appropriate to do it in the prep_new_huge_page(). The free_vmemmap_pages_per_hpage(), which indicates how many vmemmap pages associated with a HugeTLB page can be freed, returns zero for now, which means the feature is disabled. We will enable it once all the infrastructure is there. [willy@infradead.org: fix documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-5-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-5-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Oscar Salvador <osalvador@suse.de> Tested-by: Chen Huang <chenhuang5@huawei.com> Tested-by: Bodeddula Balasubramaniam <bodeddub@amazon.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:13 +03:00
__prep_new_huge_page(h, page);
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
__prep_account_new_huge_page(h, nid);
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
}
hugetlb: add demote bool to gigantic page routines The routines remove_hugetlb_page and destroy_compound_gigantic_page will remove a gigantic page and make the set of base pages ready to be returned to a lower level allocator. In the process of doing this, they make all base pages reference counted. The routine prep_compound_gigantic_page creates a gigantic page from a set of base pages. It assumes that all these base pages are reference counted. During demotion, a gigantic page will be split into huge pages of a smaller size. This logically involves use of the routines, remove_hugetlb_page, and destroy_compound_gigantic_page followed by prep_compound*_page for each smaller huge page. When pages are reference counted (ref count >= 0), additional speculative ref counts could be taken as described in previous commits [1] and [2]. This could result in errors while demoting a huge page. Quite a bit of code would need to be created to handle all possible issues. Instead of dealing with the possibility of speculative ref counts, avoid the possibility by keeping ref counts at zero during the demote process. Add a boolean 'demote' to the routines remove_hugetlb_page, destroy_compound_gigantic_page and prep_compound_gigantic_page. If the boolean is set, the remove and destroy routines will not reference count pages and the prep routine will not expect reference counted pages. '*_for_demote' wrappers of the routines will be added in a subsequent patch where this functionality is used. [1] https://lore.kernel.org/linux-mm/20210622021423.154662-3-mike.kravetz@oracle.com/ [2] https://lore.kernel.org/linux-mm/20210809184832.18342-3-mike.kravetz@oracle.com/ Link: https://lkml.kernel.org/r/20211007181918.136982-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:30 +03:00
static bool __prep_compound_gigantic_page(struct page *page, unsigned int order,
bool demote)
mm: introduce PageHuge() for testing huge/gigantic pages A series of patches to enhance the /proc/pagemap interface and to add a userspace executable which can be used to present the pagemap data. Export 10 more flags to end users (and more for kernel developers): 11. KPF_MMAP (pseudo flag) memory mapped page 12. KPF_ANON (pseudo flag) memory mapped page (anonymous) 13. KPF_SWAPCACHE page is in swap cache 14. KPF_SWAPBACKED page is swap/RAM backed 15. KPF_COMPOUND_HEAD (*) 16. KPF_COMPOUND_TAIL (*) 17. KPF_HUGE hugeTLB pages 18. KPF_UNEVICTABLE page is in the unevictable LRU list 19. KPF_HWPOISON hardware detected corruption 20. KPF_NOPAGE (pseudo flag) no page frame at the address (*) For compound pages, exporting _both_ head/tail info enables users to tell where a compound page starts/ends, and its order. a simple demo of the page-types tool # ./page-types -h page-types [options] -r|--raw Raw mode, for kernel developers -a|--addr addr-spec Walk a range of pages -b|--bits bits-spec Walk pages with specified bits -l|--list Show page details in ranges -L|--list-each Show page details one by one -N|--no-summary Don't show summay info -h|--help Show this usage message addr-spec: N one page at offset N (unit: pages) N+M pages range from N to N+M-1 N,M pages range from N to M-1 N, pages range from N to end ,M pages range from 0 to M bits-spec: bit1,bit2 (flags & (bit1|bit2)) != 0 bit1,bit2=bit1 (flags & (bit1|bit2)) == bit1 bit1,~bit2 (flags & (bit1|bit2)) == bit1 =bit1,bit2 flags == (bit1|bit2) bit-names: locked error referenced uptodate dirty lru active slab writeback reclaim buddy mmap anonymous swapcache swapbacked compound_head compound_tail huge unevictable hwpoison nopage reserved(r) mlocked(r) mappedtodisk(r) private(r) private_2(r) owner_private(r) arch(r) uncached(r) readahead(o) slob_free(o) slub_frozen(o) slub_debug(o) (r) raw mode bits (o) overloaded bits # ./page-types flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 487369 1903 _________________________________ 0x0000000000000014 5 0 __R_D____________________________ referenced,dirty 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000000000024 34 0 __R__l___________________________ referenced,lru 0x0000000000000028 3838 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 48 0 ___U_l_______________________I___ uptodate,lru,readahead 0x000000000000002c 6478 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x0000000000000040 8344 32 ______A__________________________ active 0x0000000000000060 1 0 _____lA__________________________ lru,active 0x0000000000000068 348 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x000000000000006c 988 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 503 1 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 30 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types -r flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 468002 1828 _________________________________ 0x0000000100000000 19102 74 _____________________r___________ reserved 0x0000000000008000 41 0 _______________H_________________ compound_head 0x0000000000010000 188 0 ________________T________________ compound_tail 0x0000000000008014 1 0 __R_D__________H_________________ referenced,dirty,compound_head 0x0000000000010014 4 0 __R_D___________T________________ referenced,dirty,compound_tail 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000800000024 34 0 __R__l__________________P________ referenced,lru,private 0x0000000000000028 3794 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 46 0 ___U_l_______________________I___ uptodate,lru,readahead 0x0000000400000028 44 0 ___U_l_________________d_________ uptodate,lru,mappedtodisk 0x0001000400000028 2 0 ___U_l_________________d_____I___ uptodate,lru,mappedtodisk,readahead 0x000000000000002c 6434 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x000000040000002c 14 0 __RU_l_________________d_________ referenced,uptodate,lru,mappedtodisk 0x000000080000002c 30 0 __RU_l__________________P________ referenced,uptodate,lru,private 0x0000000800000040 8124 31 ______A_________________P________ active,private 0x0000000000000040 219 0 ______A__________________________ active 0x0000000800000060 1 0 _____lA_________________P________ lru,active,private 0x0000000000000068 322 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x0000000400000068 13 0 ___U_lA________________d_________ uptodate,lru,active,mappedtodisk 0x0000000800000068 12 0 ___U_lA_________________P________ uptodate,lru,active,private 0x000000000000006c 977 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x000000040000006c 5 0 __RU_lA________________d_________ referenced,uptodate,lru,active,mappedtodisk 0x000000080000006c 3 0 __RU_lA_________________P________ referenced,uptodate,lru,active,private 0x0000000c0000006c 3 0 __RU_lA________________dP________ referenced,uptodate,lru,active,mappedtodisk,private 0x0000000c00000068 1 0 ___U_lA________________dP________ uptodate,lru,active,mappedtodisk,private 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 538 2 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005008 2 0 ___U________a_b__________________ uptodate,anonymous,swapbacked 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x000000000000580c 1 0 __RU_______Ma_b__________________ referenced,uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 29 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types --raw --list --no-summary --bits reserved offset count flags 0 15 _____________________r___________ 31 4 _____________________r___________ 159 97 _____________________r___________ 4096 2067 _____________________r___________ 6752 2390 _____________________r___________ 9355 3 _____________________r___________ 9728 14526 _____________________r___________ This patch: Introduce PageHuge(), which identifies huge/gigantic pages by their dedicated compound destructor functions. Also move prep_compound_gigantic_page() to hugetlb.c and make __free_pages_ok() non-static. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-17 02:32:22 +04:00
{
hugetlb: address ref count racing in prep_compound_gigantic_page In [1], Jann Horn points out a possible race between prep_compound_gigantic_page and __page_cache_add_speculative. The root cause of the possible race is prep_compound_gigantic_page uncondittionally setting the ref count of pages to zero. It does this because prep_compound_gigantic_page is handed a 'group' of pages from an allocator and needs to convert that group of pages to a compound page. The ref count of each page in this 'group' is one as set by the allocator. However, the ref count of compound page tail pages must be zero. The potential race comes about when ref counted pages are returned from the allocator. When this happens, other mm code could also take a reference on the page. __page_cache_add_speculative is one such example. Therefore, prep_compound_gigantic_page can not just set the ref count of pages to zero as it does today. Doing so would lose the reference taken by any other code. This would lead to BUGs in code checking ref counts and could possibly even lead to memory corruption. There are two possible ways to address this issue. 1) Make all allocators of gigantic groups of pages be able to return a properly constructed compound page. 2) Make prep_compound_gigantic_page be more careful when constructing a compound page. This patch takes approach 2. In prep_compound_gigantic_page, use cmpxchg to only set ref count to zero if it is one. If the cmpxchg fails, call synchronize_rcu() in the hope that the extra ref count will be driopped during a rcu grace period. This is not a performance critical code path and the wait should be accceptable. If the ref count is still inflated after the grace period, then undo any modifications made and return an error. Currently prep_compound_gigantic_page is type void and does not return errors. Modify the two callers to check for and handle error returns. On error, the caller must free the 'group' of pages as they can not be used to form a gigantic page. After freeing pages, the runtime caller (alloc_fresh_huge_page) will retry the allocation once. Boot time allocations can not be retried. The routine prep_compound_page also unconditionally sets the ref count of compound page tail pages to zero. However, in this case the buddy allocator is constructing a compound page from freshly allocated pages. The ref count on those freshly allocated pages is already zero, so the set_page_count(p, 0) is unnecessary and could lead to confusion. Just remove it. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210622021423.154662-3-mike.kravetz@oracle.com Fixes: 58a84aa92723 ("thp: set compound tail page _count to zero") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jann Horn <jannh@google.com> Cc: Youquan Song <youquan.song@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:34 +03:00
int i, j;
mm: introduce PageHuge() for testing huge/gigantic pages A series of patches to enhance the /proc/pagemap interface and to add a userspace executable which can be used to present the pagemap data. Export 10 more flags to end users (and more for kernel developers): 11. KPF_MMAP (pseudo flag) memory mapped page 12. KPF_ANON (pseudo flag) memory mapped page (anonymous) 13. KPF_SWAPCACHE page is in swap cache 14. KPF_SWAPBACKED page is swap/RAM backed 15. KPF_COMPOUND_HEAD (*) 16. KPF_COMPOUND_TAIL (*) 17. KPF_HUGE hugeTLB pages 18. KPF_UNEVICTABLE page is in the unevictable LRU list 19. KPF_HWPOISON hardware detected corruption 20. KPF_NOPAGE (pseudo flag) no page frame at the address (*) For compound pages, exporting _both_ head/tail info enables users to tell where a compound page starts/ends, and its order. a simple demo of the page-types tool # ./page-types -h page-types [options] -r|--raw Raw mode, for kernel developers -a|--addr addr-spec Walk a range of pages -b|--bits bits-spec Walk pages with specified bits -l|--list Show page details in ranges -L|--list-each Show page details one by one -N|--no-summary Don't show summay info -h|--help Show this usage message addr-spec: N one page at offset N (unit: pages) N+M pages range from N to N+M-1 N,M pages range from N to M-1 N, pages range from N to end ,M pages range from 0 to M bits-spec: bit1,bit2 (flags & (bit1|bit2)) != 0 bit1,bit2=bit1 (flags & (bit1|bit2)) == bit1 bit1,~bit2 (flags & (bit1|bit2)) == bit1 =bit1,bit2 flags == (bit1|bit2) bit-names: locked error referenced uptodate dirty lru active slab writeback reclaim buddy mmap anonymous swapcache swapbacked compound_head compound_tail huge unevictable hwpoison nopage reserved(r) mlocked(r) mappedtodisk(r) private(r) private_2(r) owner_private(r) arch(r) uncached(r) readahead(o) slob_free(o) slub_frozen(o) slub_debug(o) (r) raw mode bits (o) overloaded bits # ./page-types flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 487369 1903 _________________________________ 0x0000000000000014 5 0 __R_D____________________________ referenced,dirty 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000000000024 34 0 __R__l___________________________ referenced,lru 0x0000000000000028 3838 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 48 0 ___U_l_______________________I___ uptodate,lru,readahead 0x000000000000002c 6478 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x0000000000000040 8344 32 ______A__________________________ active 0x0000000000000060 1 0 _____lA__________________________ lru,active 0x0000000000000068 348 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x000000000000006c 988 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 503 1 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 30 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types -r flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 468002 1828 _________________________________ 0x0000000100000000 19102 74 _____________________r___________ reserved 0x0000000000008000 41 0 _______________H_________________ compound_head 0x0000000000010000 188 0 ________________T________________ compound_tail 0x0000000000008014 1 0 __R_D__________H_________________ referenced,dirty,compound_head 0x0000000000010014 4 0 __R_D___________T________________ referenced,dirty,compound_tail 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000800000024 34 0 __R__l__________________P________ referenced,lru,private 0x0000000000000028 3794 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 46 0 ___U_l_______________________I___ uptodate,lru,readahead 0x0000000400000028 44 0 ___U_l_________________d_________ uptodate,lru,mappedtodisk 0x0001000400000028 2 0 ___U_l_________________d_____I___ uptodate,lru,mappedtodisk,readahead 0x000000000000002c 6434 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x000000040000002c 14 0 __RU_l_________________d_________ referenced,uptodate,lru,mappedtodisk 0x000000080000002c 30 0 __RU_l__________________P________ referenced,uptodate,lru,private 0x0000000800000040 8124 31 ______A_________________P________ active,private 0x0000000000000040 219 0 ______A__________________________ active 0x0000000800000060 1 0 _____lA_________________P________ lru,active,private 0x0000000000000068 322 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x0000000400000068 13 0 ___U_lA________________d_________ uptodate,lru,active,mappedtodisk 0x0000000800000068 12 0 ___U_lA_________________P________ uptodate,lru,active,private 0x000000000000006c 977 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x000000040000006c 5 0 __RU_lA________________d_________ referenced,uptodate,lru,active,mappedtodisk 0x000000080000006c 3 0 __RU_lA_________________P________ referenced,uptodate,lru,active,private 0x0000000c0000006c 3 0 __RU_lA________________dP________ referenced,uptodate,lru,active,mappedtodisk,private 0x0000000c00000068 1 0 ___U_lA________________dP________ uptodate,lru,active,mappedtodisk,private 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 538 2 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005008 2 0 ___U________a_b__________________ uptodate,anonymous,swapbacked 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x000000000000580c 1 0 __RU_______Ma_b__________________ referenced,uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 29 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types --raw --list --no-summary --bits reserved offset count flags 0 15 _____________________r___________ 31 4 _____________________r___________ 159 97 _____________________r___________ 4096 2067 _____________________r___________ 6752 2390 _____________________r___________ 9355 3 _____________________r___________ 9728 14526 _____________________r___________ This patch: Introduce PageHuge(), which identifies huge/gigantic pages by their dedicated compound destructor functions. Also move prep_compound_gigantic_page() to hugetlb.c and make __free_pages_ok() non-static. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-17 02:32:22 +04:00
int nr_pages = 1 << order;
struct page *p = page + 1;
/* we rely on prep_new_huge_page to set the destructor */
set_compound_order(page, order);
mm: hugetlb: initialize PG_reserved for tail pages of gigantic compound pages Commit 11feeb498086 ("kvm: optimize away THP checks in kvm_is_mmio_pfn()") introduced a memory leak when KVM is run on gigantic compound pages. That commit depends on the assumption that PG_reserved is identical for all head and tail pages of a compound page. So that if get_user_pages returns a tail page, we don't need to check the head page in order to know if we deal with a reserved page that requires different refcounting. The assumption that PG_reserved is the same for head and tail pages is certainly correct for THP and regular hugepages, but gigantic hugepages allocated through bootmem don't clear the PG_reserved on the tail pages (the clearing of PG_reserved is done later only if the gigantic hugepage is freed). This patch corrects the gigantic compound page initialization so that we can retain the optimization in 11feeb498086. The cacheline was already modified in order to set PG_tail so this won't affect the boot time of large memory systems. [akpm@linux-foundation.org: tweak comment layout and grammar] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: andy123 <ajs124.ajs124@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Acked-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-10-17 00:46:56 +04:00
__ClearPageReserved(page);
__SetPageHead(page);
mm: introduce PageHuge() for testing huge/gigantic pages A series of patches to enhance the /proc/pagemap interface and to add a userspace executable which can be used to present the pagemap data. Export 10 more flags to end users (and more for kernel developers): 11. KPF_MMAP (pseudo flag) memory mapped page 12. KPF_ANON (pseudo flag) memory mapped page (anonymous) 13. KPF_SWAPCACHE page is in swap cache 14. KPF_SWAPBACKED page is swap/RAM backed 15. KPF_COMPOUND_HEAD (*) 16. KPF_COMPOUND_TAIL (*) 17. KPF_HUGE hugeTLB pages 18. KPF_UNEVICTABLE page is in the unevictable LRU list 19. KPF_HWPOISON hardware detected corruption 20. KPF_NOPAGE (pseudo flag) no page frame at the address (*) For compound pages, exporting _both_ head/tail info enables users to tell where a compound page starts/ends, and its order. a simple demo of the page-types tool # ./page-types -h page-types [options] -r|--raw Raw mode, for kernel developers -a|--addr addr-spec Walk a range of pages -b|--bits bits-spec Walk pages with specified bits -l|--list Show page details in ranges -L|--list-each Show page details one by one -N|--no-summary Don't show summay info -h|--help Show this usage message addr-spec: N one page at offset N (unit: pages) N+M pages range from N to N+M-1 N,M pages range from N to M-1 N, pages range from N to end ,M pages range from 0 to M bits-spec: bit1,bit2 (flags & (bit1|bit2)) != 0 bit1,bit2=bit1 (flags & (bit1|bit2)) == bit1 bit1,~bit2 (flags & (bit1|bit2)) == bit1 =bit1,bit2 flags == (bit1|bit2) bit-names: locked error referenced uptodate dirty lru active slab writeback reclaim buddy mmap anonymous swapcache swapbacked compound_head compound_tail huge unevictable hwpoison nopage reserved(r) mlocked(r) mappedtodisk(r) private(r) private_2(r) owner_private(r) arch(r) uncached(r) readahead(o) slob_free(o) slub_frozen(o) slub_debug(o) (r) raw mode bits (o) overloaded bits # ./page-types flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 487369 1903 _________________________________ 0x0000000000000014 5 0 __R_D____________________________ referenced,dirty 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000000000024 34 0 __R__l___________________________ referenced,lru 0x0000000000000028 3838 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 48 0 ___U_l_______________________I___ uptodate,lru,readahead 0x000000000000002c 6478 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x0000000000000040 8344 32 ______A__________________________ active 0x0000000000000060 1 0 _____lA__________________________ lru,active 0x0000000000000068 348 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x000000000000006c 988 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 503 1 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 30 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types -r flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 468002 1828 _________________________________ 0x0000000100000000 19102 74 _____________________r___________ reserved 0x0000000000008000 41 0 _______________H_________________ compound_head 0x0000000000010000 188 0 ________________T________________ compound_tail 0x0000000000008014 1 0 __R_D__________H_________________ referenced,dirty,compound_head 0x0000000000010014 4 0 __R_D___________T________________ referenced,dirty,compound_tail 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000800000024 34 0 __R__l__________________P________ referenced,lru,private 0x0000000000000028 3794 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 46 0 ___U_l_______________________I___ uptodate,lru,readahead 0x0000000400000028 44 0 ___U_l_________________d_________ uptodate,lru,mappedtodisk 0x0001000400000028 2 0 ___U_l_________________d_____I___ uptodate,lru,mappedtodisk,readahead 0x000000000000002c 6434 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x000000040000002c 14 0 __RU_l_________________d_________ referenced,uptodate,lru,mappedtodisk 0x000000080000002c 30 0 __RU_l__________________P________ referenced,uptodate,lru,private 0x0000000800000040 8124 31 ______A_________________P________ active,private 0x0000000000000040 219 0 ______A__________________________ active 0x0000000800000060 1 0 _____lA_________________P________ lru,active,private 0x0000000000000068 322 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x0000000400000068 13 0 ___U_lA________________d_________ uptodate,lru,active,mappedtodisk 0x0000000800000068 12 0 ___U_lA_________________P________ uptodate,lru,active,private 0x000000000000006c 977 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x000000040000006c 5 0 __RU_lA________________d_________ referenced,uptodate,lru,active,mappedtodisk 0x000000080000006c 3 0 __RU_lA_________________P________ referenced,uptodate,lru,active,private 0x0000000c0000006c 3 0 __RU_lA________________dP________ referenced,uptodate,lru,active,mappedtodisk,private 0x0000000c00000068 1 0 ___U_lA________________dP________ uptodate,lru,active,mappedtodisk,private 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 538 2 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005008 2 0 ___U________a_b__________________ uptodate,anonymous,swapbacked 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x000000000000580c 1 0 __RU_______Ma_b__________________ referenced,uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 29 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types --raw --list --no-summary --bits reserved offset count flags 0 15 _____________________r___________ 31 4 _____________________r___________ 159 97 _____________________r___________ 4096 2067 _____________________r___________ 6752 2390 _____________________r___________ 9355 3 _____________________r___________ 9728 14526 _____________________r___________ This patch: Introduce PageHuge(), which identifies huge/gigantic pages by their dedicated compound destructor functions. Also move prep_compound_gigantic_page() to hugetlb.c and make __free_pages_ok() non-static. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-17 02:32:22 +04:00
for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
mm: hugetlb: initialize PG_reserved for tail pages of gigantic compound pages Commit 11feeb498086 ("kvm: optimize away THP checks in kvm_is_mmio_pfn()") introduced a memory leak when KVM is run on gigantic compound pages. That commit depends on the assumption that PG_reserved is identical for all head and tail pages of a compound page. So that if get_user_pages returns a tail page, we don't need to check the head page in order to know if we deal with a reserved page that requires different refcounting. The assumption that PG_reserved is the same for head and tail pages is certainly correct for THP and regular hugepages, but gigantic hugepages allocated through bootmem don't clear the PG_reserved on the tail pages (the clearing of PG_reserved is done later only if the gigantic hugepage is freed). This patch corrects the gigantic compound page initialization so that we can retain the optimization in 11feeb498086. The cacheline was already modified in order to set PG_tail so this won't affect the boot time of large memory systems. [akpm@linux-foundation.org: tweak comment layout and grammar] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: andy123 <ajs124.ajs124@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Acked-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-10-17 00:46:56 +04:00
/*
* For gigantic hugepages allocated through bootmem at
* boot, it's safer to be consistent with the not-gigantic
* hugepages and clear the PG_reserved bit from all tail pages
* too. Otherwise drivers using get_user_pages() to access tail
mm: hugetlb: initialize PG_reserved for tail pages of gigantic compound pages Commit 11feeb498086 ("kvm: optimize away THP checks in kvm_is_mmio_pfn()") introduced a memory leak when KVM is run on gigantic compound pages. That commit depends on the assumption that PG_reserved is identical for all head and tail pages of a compound page. So that if get_user_pages returns a tail page, we don't need to check the head page in order to know if we deal with a reserved page that requires different refcounting. The assumption that PG_reserved is the same for head and tail pages is certainly correct for THP and regular hugepages, but gigantic hugepages allocated through bootmem don't clear the PG_reserved on the tail pages (the clearing of PG_reserved is done later only if the gigantic hugepage is freed). This patch corrects the gigantic compound page initialization so that we can retain the optimization in 11feeb498086. The cacheline was already modified in order to set PG_tail so this won't affect the boot time of large memory systems. [akpm@linux-foundation.org: tweak comment layout and grammar] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: andy123 <ajs124.ajs124@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Acked-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-10-17 00:46:56 +04:00
* pages may get the reference counting wrong if they see
* PG_reserved set on a tail page (despite the head page not
* having PG_reserved set). Enforcing this consistency between
* head and tail pages allows drivers to optimize away a check
* on the head page when they need know if put_page() is needed
* after get_user_pages().
*/
__ClearPageReserved(p);
hugetlb: address ref count racing in prep_compound_gigantic_page In [1], Jann Horn points out a possible race between prep_compound_gigantic_page and __page_cache_add_speculative. The root cause of the possible race is prep_compound_gigantic_page uncondittionally setting the ref count of pages to zero. It does this because prep_compound_gigantic_page is handed a 'group' of pages from an allocator and needs to convert that group of pages to a compound page. The ref count of each page in this 'group' is one as set by the allocator. However, the ref count of compound page tail pages must be zero. The potential race comes about when ref counted pages are returned from the allocator. When this happens, other mm code could also take a reference on the page. __page_cache_add_speculative is one such example. Therefore, prep_compound_gigantic_page can not just set the ref count of pages to zero as it does today. Doing so would lose the reference taken by any other code. This would lead to BUGs in code checking ref counts and could possibly even lead to memory corruption. There are two possible ways to address this issue. 1) Make all allocators of gigantic groups of pages be able to return a properly constructed compound page. 2) Make prep_compound_gigantic_page be more careful when constructing a compound page. This patch takes approach 2. In prep_compound_gigantic_page, use cmpxchg to only set ref count to zero if it is one. If the cmpxchg fails, call synchronize_rcu() in the hope that the extra ref count will be driopped during a rcu grace period. This is not a performance critical code path and the wait should be accceptable. If the ref count is still inflated after the grace period, then undo any modifications made and return an error. Currently prep_compound_gigantic_page is type void and does not return errors. Modify the two callers to check for and handle error returns. On error, the caller must free the 'group' of pages as they can not be used to form a gigantic page. After freeing pages, the runtime caller (alloc_fresh_huge_page) will retry the allocation once. Boot time allocations can not be retried. The routine prep_compound_page also unconditionally sets the ref count of compound page tail pages to zero. However, in this case the buddy allocator is constructing a compound page from freshly allocated pages. The ref count on those freshly allocated pages is already zero, so the set_page_count(p, 0) is unnecessary and could lead to confusion. Just remove it. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210622021423.154662-3-mike.kravetz@oracle.com Fixes: 58a84aa92723 ("thp: set compound tail page _count to zero") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jann Horn <jannh@google.com> Cc: Youquan Song <youquan.song@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:34 +03:00
/*
* Subtle and very unlikely
*
* Gigantic 'page allocators' such as memblock or cma will
* return a set of pages with each page ref counted. We need
* to turn this set of pages into a compound page with tail
* page ref counts set to zero. Code such as speculative page
* cache adding could take a ref on a 'to be' tail page.
* We need to respect any increased ref count, and only set
* the ref count to zero if count is currently 1. If count
* is not 1, we return an error. An error return indicates
* the set of pages can not be converted to a gigantic page.
* The caller who allocated the pages should then discard the
* pages using the appropriate free interface.
hugetlb: add demote bool to gigantic page routines The routines remove_hugetlb_page and destroy_compound_gigantic_page will remove a gigantic page and make the set of base pages ready to be returned to a lower level allocator. In the process of doing this, they make all base pages reference counted. The routine prep_compound_gigantic_page creates a gigantic page from a set of base pages. It assumes that all these base pages are reference counted. During demotion, a gigantic page will be split into huge pages of a smaller size. This logically involves use of the routines, remove_hugetlb_page, and destroy_compound_gigantic_page followed by prep_compound*_page for each smaller huge page. When pages are reference counted (ref count >= 0), additional speculative ref counts could be taken as described in previous commits [1] and [2]. This could result in errors while demoting a huge page. Quite a bit of code would need to be created to handle all possible issues. Instead of dealing with the possibility of speculative ref counts, avoid the possibility by keeping ref counts at zero during the demote process. Add a boolean 'demote' to the routines remove_hugetlb_page, destroy_compound_gigantic_page and prep_compound_gigantic_page. If the boolean is set, the remove and destroy routines will not reference count pages and the prep routine will not expect reference counted pages. '*_for_demote' wrappers of the routines will be added in a subsequent patch where this functionality is used. [1] https://lore.kernel.org/linux-mm/20210622021423.154662-3-mike.kravetz@oracle.com/ [2] https://lore.kernel.org/linux-mm/20210809184832.18342-3-mike.kravetz@oracle.com/ Link: https://lkml.kernel.org/r/20211007181918.136982-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:30 +03:00
*
* In the case of demote, the ref count will be zero.
hugetlb: address ref count racing in prep_compound_gigantic_page In [1], Jann Horn points out a possible race between prep_compound_gigantic_page and __page_cache_add_speculative. The root cause of the possible race is prep_compound_gigantic_page uncondittionally setting the ref count of pages to zero. It does this because prep_compound_gigantic_page is handed a 'group' of pages from an allocator and needs to convert that group of pages to a compound page. The ref count of each page in this 'group' is one as set by the allocator. However, the ref count of compound page tail pages must be zero. The potential race comes about when ref counted pages are returned from the allocator. When this happens, other mm code could also take a reference on the page. __page_cache_add_speculative is one such example. Therefore, prep_compound_gigantic_page can not just set the ref count of pages to zero as it does today. Doing so would lose the reference taken by any other code. This would lead to BUGs in code checking ref counts and could possibly even lead to memory corruption. There are two possible ways to address this issue. 1) Make all allocators of gigantic groups of pages be able to return a properly constructed compound page. 2) Make prep_compound_gigantic_page be more careful when constructing a compound page. This patch takes approach 2. In prep_compound_gigantic_page, use cmpxchg to only set ref count to zero if it is one. If the cmpxchg fails, call synchronize_rcu() in the hope that the extra ref count will be driopped during a rcu grace period. This is not a performance critical code path and the wait should be accceptable. If the ref count is still inflated after the grace period, then undo any modifications made and return an error. Currently prep_compound_gigantic_page is type void and does not return errors. Modify the two callers to check for and handle error returns. On error, the caller must free the 'group' of pages as they can not be used to form a gigantic page. After freeing pages, the runtime caller (alloc_fresh_huge_page) will retry the allocation once. Boot time allocations can not be retried. The routine prep_compound_page also unconditionally sets the ref count of compound page tail pages to zero. However, in this case the buddy allocator is constructing a compound page from freshly allocated pages. The ref count on those freshly allocated pages is already zero, so the set_page_count(p, 0) is unnecessary and could lead to confusion. Just remove it. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210622021423.154662-3-mike.kravetz@oracle.com Fixes: 58a84aa92723 ("thp: set compound tail page _count to zero") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jann Horn <jannh@google.com> Cc: Youquan Song <youquan.song@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:34 +03:00
*/
hugetlb: add demote bool to gigantic page routines The routines remove_hugetlb_page and destroy_compound_gigantic_page will remove a gigantic page and make the set of base pages ready to be returned to a lower level allocator. In the process of doing this, they make all base pages reference counted. The routine prep_compound_gigantic_page creates a gigantic page from a set of base pages. It assumes that all these base pages are reference counted. During demotion, a gigantic page will be split into huge pages of a smaller size. This logically involves use of the routines, remove_hugetlb_page, and destroy_compound_gigantic_page followed by prep_compound*_page for each smaller huge page. When pages are reference counted (ref count >= 0), additional speculative ref counts could be taken as described in previous commits [1] and [2]. This could result in errors while demoting a huge page. Quite a bit of code would need to be created to handle all possible issues. Instead of dealing with the possibility of speculative ref counts, avoid the possibility by keeping ref counts at zero during the demote process. Add a boolean 'demote' to the routines remove_hugetlb_page, destroy_compound_gigantic_page and prep_compound_gigantic_page. If the boolean is set, the remove and destroy routines will not reference count pages and the prep routine will not expect reference counted pages. '*_for_demote' wrappers of the routines will be added in a subsequent patch where this functionality is used. [1] https://lore.kernel.org/linux-mm/20210622021423.154662-3-mike.kravetz@oracle.com/ [2] https://lore.kernel.org/linux-mm/20210809184832.18342-3-mike.kravetz@oracle.com/ Link: https://lkml.kernel.org/r/20211007181918.136982-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:30 +03:00
if (!demote) {
if (!page_ref_freeze(p, 1)) {
pr_warn("HugeTLB page can not be used due to unexpected inflated ref count\n");
goto out_error;
}
} else {
VM_BUG_ON_PAGE(page_count(p), p);
hugetlb: address ref count racing in prep_compound_gigantic_page In [1], Jann Horn points out a possible race between prep_compound_gigantic_page and __page_cache_add_speculative. The root cause of the possible race is prep_compound_gigantic_page uncondittionally setting the ref count of pages to zero. It does this because prep_compound_gigantic_page is handed a 'group' of pages from an allocator and needs to convert that group of pages to a compound page. The ref count of each page in this 'group' is one as set by the allocator. However, the ref count of compound page tail pages must be zero. The potential race comes about when ref counted pages are returned from the allocator. When this happens, other mm code could also take a reference on the page. __page_cache_add_speculative is one such example. Therefore, prep_compound_gigantic_page can not just set the ref count of pages to zero as it does today. Doing so would lose the reference taken by any other code. This would lead to BUGs in code checking ref counts and could possibly even lead to memory corruption. There are two possible ways to address this issue. 1) Make all allocators of gigantic groups of pages be able to return a properly constructed compound page. 2) Make prep_compound_gigantic_page be more careful when constructing a compound page. This patch takes approach 2. In prep_compound_gigantic_page, use cmpxchg to only set ref count to zero if it is one. If the cmpxchg fails, call synchronize_rcu() in the hope that the extra ref count will be driopped during a rcu grace period. This is not a performance critical code path and the wait should be accceptable. If the ref count is still inflated after the grace period, then undo any modifications made and return an error. Currently prep_compound_gigantic_page is type void and does not return errors. Modify the two callers to check for and handle error returns. On error, the caller must free the 'group' of pages as they can not be used to form a gigantic page. After freeing pages, the runtime caller (alloc_fresh_huge_page) will retry the allocation once. Boot time allocations can not be retried. The routine prep_compound_page also unconditionally sets the ref count of compound page tail pages to zero. However, in this case the buddy allocator is constructing a compound page from freshly allocated pages. The ref count on those freshly allocated pages is already zero, so the set_page_count(p, 0) is unnecessary and could lead to confusion. Just remove it. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210622021423.154662-3-mike.kravetz@oracle.com Fixes: 58a84aa92723 ("thp: set compound tail page _count to zero") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jann Horn <jannh@google.com> Cc: Youquan Song <youquan.song@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:34 +03:00
}
mm: make compound_head() robust Hugh has pointed that compound_head() call can be unsafe in some context. There's one example: CPU0 CPU1 isolate_migratepages_block() page_count() compound_head() !!PageTail() == true put_page() tail->first_page = NULL head = tail->first_page alloc_pages(__GFP_COMP) prep_compound_page() tail->first_page = head __SetPageTail(p); !!PageTail() == true <head == NULL dereferencing> The race is pure theoretical. I don't it's possible to trigger it in practice. But who knows. We can fix the race by changing how encode PageTail() and compound_head() within struct page to be able to update them in one shot. The patch introduces page->compound_head into third double word block in front of compound_dtor and compound_order. Bit 0 encodes PageTail() and the rest bits are pointer to head page if bit zero is set. The patch moves page->pmd_huge_pte out of word, just in case if an architecture defines pgtable_t into something what can have the bit 0 set. hugetlb_cgroup uses page->lru.next in the second tail page to store pointer struct hugetlb_cgroup. The patch switch it to use page->private in the second tail page instead. The space is free since ->first_page is removed from the union. The patch also opens possibility to remove HUGETLB_CGROUP_MIN_ORDER limitation, since there's now space in first tail page to store struct hugetlb_cgroup pointer. But that's out of scope of the patch. That means page->compound_head shares storage space with: - page->lru.next; - page->next; - page->rcu_head.next; That's too long list to be absolutely sure, but looks like nobody uses bit 0 of the word. page->rcu_head.next guaranteed[1] to have bit 0 clean as long as we use call_rcu(), call_rcu_bh(), call_rcu_sched(), or call_srcu(). But future call_rcu_lazy() is not allowed as it makes use of the bit and we can get false positive PageTail(). [1] http://lkml.kernel.org/g/20150827163634.GD4029@linux.vnet.ibm.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-07 03:29:54 +03:00
set_compound_head(p, page);
mm: introduce PageHuge() for testing huge/gigantic pages A series of patches to enhance the /proc/pagemap interface and to add a userspace executable which can be used to present the pagemap data. Export 10 more flags to end users (and more for kernel developers): 11. KPF_MMAP (pseudo flag) memory mapped page 12. KPF_ANON (pseudo flag) memory mapped page (anonymous) 13. KPF_SWAPCACHE page is in swap cache 14. KPF_SWAPBACKED page is swap/RAM backed 15. KPF_COMPOUND_HEAD (*) 16. KPF_COMPOUND_TAIL (*) 17. KPF_HUGE hugeTLB pages 18. KPF_UNEVICTABLE page is in the unevictable LRU list 19. KPF_HWPOISON hardware detected corruption 20. KPF_NOPAGE (pseudo flag) no page frame at the address (*) For compound pages, exporting _both_ head/tail info enables users to tell where a compound page starts/ends, and its order. a simple demo of the page-types tool # ./page-types -h page-types [options] -r|--raw Raw mode, for kernel developers -a|--addr addr-spec Walk a range of pages -b|--bits bits-spec Walk pages with specified bits -l|--list Show page details in ranges -L|--list-each Show page details one by one -N|--no-summary Don't show summay info -h|--help Show this usage message addr-spec: N one page at offset N (unit: pages) N+M pages range from N to N+M-1 N,M pages range from N to M-1 N, pages range from N to end ,M pages range from 0 to M bits-spec: bit1,bit2 (flags & (bit1|bit2)) != 0 bit1,bit2=bit1 (flags & (bit1|bit2)) == bit1 bit1,~bit2 (flags & (bit1|bit2)) == bit1 =bit1,bit2 flags == (bit1|bit2) bit-names: locked error referenced uptodate dirty lru active slab writeback reclaim buddy mmap anonymous swapcache swapbacked compound_head compound_tail huge unevictable hwpoison nopage reserved(r) mlocked(r) mappedtodisk(r) private(r) private_2(r) owner_private(r) arch(r) uncached(r) readahead(o) slob_free(o) slub_frozen(o) slub_debug(o) (r) raw mode bits (o) overloaded bits # ./page-types flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 487369 1903 _________________________________ 0x0000000000000014 5 0 __R_D____________________________ referenced,dirty 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000000000024 34 0 __R__l___________________________ referenced,lru 0x0000000000000028 3838 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 48 0 ___U_l_______________________I___ uptodate,lru,readahead 0x000000000000002c 6478 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x0000000000000040 8344 32 ______A__________________________ active 0x0000000000000060 1 0 _____lA__________________________ lru,active 0x0000000000000068 348 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x000000000000006c 988 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 503 1 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 30 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types -r flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 468002 1828 _________________________________ 0x0000000100000000 19102 74 _____________________r___________ reserved 0x0000000000008000 41 0 _______________H_________________ compound_head 0x0000000000010000 188 0 ________________T________________ compound_tail 0x0000000000008014 1 0 __R_D__________H_________________ referenced,dirty,compound_head 0x0000000000010014 4 0 __R_D___________T________________ referenced,dirty,compound_tail 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000800000024 34 0 __R__l__________________P________ referenced,lru,private 0x0000000000000028 3794 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 46 0 ___U_l_______________________I___ uptodate,lru,readahead 0x0000000400000028 44 0 ___U_l_________________d_________ uptodate,lru,mappedtodisk 0x0001000400000028 2 0 ___U_l_________________d_____I___ uptodate,lru,mappedtodisk,readahead 0x000000000000002c 6434 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x000000040000002c 14 0 __RU_l_________________d_________ referenced,uptodate,lru,mappedtodisk 0x000000080000002c 30 0 __RU_l__________________P________ referenced,uptodate,lru,private 0x0000000800000040 8124 31 ______A_________________P________ active,private 0x0000000000000040 219 0 ______A__________________________ active 0x0000000800000060 1 0 _____lA_________________P________ lru,active,private 0x0000000000000068 322 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x0000000400000068 13 0 ___U_lA________________d_________ uptodate,lru,active,mappedtodisk 0x0000000800000068 12 0 ___U_lA_________________P________ uptodate,lru,active,private 0x000000000000006c 977 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x000000040000006c 5 0 __RU_lA________________d_________ referenced,uptodate,lru,active,mappedtodisk 0x000000080000006c 3 0 __RU_lA_________________P________ referenced,uptodate,lru,active,private 0x0000000c0000006c 3 0 __RU_lA________________dP________ referenced,uptodate,lru,active,mappedtodisk,private 0x0000000c00000068 1 0 ___U_lA________________dP________ uptodate,lru,active,mappedtodisk,private 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 538 2 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005008 2 0 ___U________a_b__________________ uptodate,anonymous,swapbacked 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x000000000000580c 1 0 __RU_______Ma_b__________________ referenced,uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 29 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types --raw --list --no-summary --bits reserved offset count flags 0 15 _____________________r___________ 31 4 _____________________r___________ 159 97 _____________________r___________ 4096 2067 _____________________r___________ 6752 2390 _____________________r___________ 9355 3 _____________________r___________ 9728 14526 _____________________r___________ This patch: Introduce PageHuge(), which identifies huge/gigantic pages by their dedicated compound destructor functions. Also move prep_compound_gigantic_page() to hugetlb.c and make __free_pages_ok() non-static. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-17 02:32:22 +04:00
}
atomic_set(compound_mapcount_ptr(page), -1);
atomic_set(compound_pincount_ptr(page), 0);
hugetlb: address ref count racing in prep_compound_gigantic_page In [1], Jann Horn points out a possible race between prep_compound_gigantic_page and __page_cache_add_speculative. The root cause of the possible race is prep_compound_gigantic_page uncondittionally setting the ref count of pages to zero. It does this because prep_compound_gigantic_page is handed a 'group' of pages from an allocator and needs to convert that group of pages to a compound page. The ref count of each page in this 'group' is one as set by the allocator. However, the ref count of compound page tail pages must be zero. The potential race comes about when ref counted pages are returned from the allocator. When this happens, other mm code could also take a reference on the page. __page_cache_add_speculative is one such example. Therefore, prep_compound_gigantic_page can not just set the ref count of pages to zero as it does today. Doing so would lose the reference taken by any other code. This would lead to BUGs in code checking ref counts and could possibly even lead to memory corruption. There are two possible ways to address this issue. 1) Make all allocators of gigantic groups of pages be able to return a properly constructed compound page. 2) Make prep_compound_gigantic_page be more careful when constructing a compound page. This patch takes approach 2. In prep_compound_gigantic_page, use cmpxchg to only set ref count to zero if it is one. If the cmpxchg fails, call synchronize_rcu() in the hope that the extra ref count will be driopped during a rcu grace period. This is not a performance critical code path and the wait should be accceptable. If the ref count is still inflated after the grace period, then undo any modifications made and return an error. Currently prep_compound_gigantic_page is type void and does not return errors. Modify the two callers to check for and handle error returns. On error, the caller must free the 'group' of pages as they can not be used to form a gigantic page. After freeing pages, the runtime caller (alloc_fresh_huge_page) will retry the allocation once. Boot time allocations can not be retried. The routine prep_compound_page also unconditionally sets the ref count of compound page tail pages to zero. However, in this case the buddy allocator is constructing a compound page from freshly allocated pages. The ref count on those freshly allocated pages is already zero, so the set_page_count(p, 0) is unnecessary and could lead to confusion. Just remove it. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210622021423.154662-3-mike.kravetz@oracle.com Fixes: 58a84aa92723 ("thp: set compound tail page _count to zero") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jann Horn <jannh@google.com> Cc: Youquan Song <youquan.song@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:34 +03:00
return true;
out_error:
/* undo tail page modifications made above */
p = page + 1;
for (j = 1; j < i; j++, p = mem_map_next(p, page, j)) {
clear_compound_head(p);
set_page_refcounted(p);
}
/* need to clear PG_reserved on remaining tail pages */
for (; j < nr_pages; j++, p = mem_map_next(p, page, j))
__ClearPageReserved(p);
set_compound_order(page, 0);
#ifdef CONFIG_64BIT
hugetlb: address ref count racing in prep_compound_gigantic_page In [1], Jann Horn points out a possible race between prep_compound_gigantic_page and __page_cache_add_speculative. The root cause of the possible race is prep_compound_gigantic_page uncondittionally setting the ref count of pages to zero. It does this because prep_compound_gigantic_page is handed a 'group' of pages from an allocator and needs to convert that group of pages to a compound page. The ref count of each page in this 'group' is one as set by the allocator. However, the ref count of compound page tail pages must be zero. The potential race comes about when ref counted pages are returned from the allocator. When this happens, other mm code could also take a reference on the page. __page_cache_add_speculative is one such example. Therefore, prep_compound_gigantic_page can not just set the ref count of pages to zero as it does today. Doing so would lose the reference taken by any other code. This would lead to BUGs in code checking ref counts and could possibly even lead to memory corruption. There are two possible ways to address this issue. 1) Make all allocators of gigantic groups of pages be able to return a properly constructed compound page. 2) Make prep_compound_gigantic_page be more careful when constructing a compound page. This patch takes approach 2. In prep_compound_gigantic_page, use cmpxchg to only set ref count to zero if it is one. If the cmpxchg fails, call synchronize_rcu() in the hope that the extra ref count will be driopped during a rcu grace period. This is not a performance critical code path and the wait should be accceptable. If the ref count is still inflated after the grace period, then undo any modifications made and return an error. Currently prep_compound_gigantic_page is type void and does not return errors. Modify the two callers to check for and handle error returns. On error, the caller must free the 'group' of pages as they can not be used to form a gigantic page. After freeing pages, the runtime caller (alloc_fresh_huge_page) will retry the allocation once. Boot time allocations can not be retried. The routine prep_compound_page also unconditionally sets the ref count of compound page tail pages to zero. However, in this case the buddy allocator is constructing a compound page from freshly allocated pages. The ref count on those freshly allocated pages is already zero, so the set_page_count(p, 0) is unnecessary and could lead to confusion. Just remove it. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210622021423.154662-3-mike.kravetz@oracle.com Fixes: 58a84aa92723 ("thp: set compound tail page _count to zero") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jann Horn <jannh@google.com> Cc: Youquan Song <youquan.song@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:34 +03:00
page[1].compound_nr = 0;
#endif
hugetlb: address ref count racing in prep_compound_gigantic_page In [1], Jann Horn points out a possible race between prep_compound_gigantic_page and __page_cache_add_speculative. The root cause of the possible race is prep_compound_gigantic_page uncondittionally setting the ref count of pages to zero. It does this because prep_compound_gigantic_page is handed a 'group' of pages from an allocator and needs to convert that group of pages to a compound page. The ref count of each page in this 'group' is one as set by the allocator. However, the ref count of compound page tail pages must be zero. The potential race comes about when ref counted pages are returned from the allocator. When this happens, other mm code could also take a reference on the page. __page_cache_add_speculative is one such example. Therefore, prep_compound_gigantic_page can not just set the ref count of pages to zero as it does today. Doing so would lose the reference taken by any other code. This would lead to BUGs in code checking ref counts and could possibly even lead to memory corruption. There are two possible ways to address this issue. 1) Make all allocators of gigantic groups of pages be able to return a properly constructed compound page. 2) Make prep_compound_gigantic_page be more careful when constructing a compound page. This patch takes approach 2. In prep_compound_gigantic_page, use cmpxchg to only set ref count to zero if it is one. If the cmpxchg fails, call synchronize_rcu() in the hope that the extra ref count will be driopped during a rcu grace period. This is not a performance critical code path and the wait should be accceptable. If the ref count is still inflated after the grace period, then undo any modifications made and return an error. Currently prep_compound_gigantic_page is type void and does not return errors. Modify the two callers to check for and handle error returns. On error, the caller must free the 'group' of pages as they can not be used to form a gigantic page. After freeing pages, the runtime caller (alloc_fresh_huge_page) will retry the allocation once. Boot time allocations can not be retried. The routine prep_compound_page also unconditionally sets the ref count of compound page tail pages to zero. However, in this case the buddy allocator is constructing a compound page from freshly allocated pages. The ref count on those freshly allocated pages is already zero, so the set_page_count(p, 0) is unnecessary and could lead to confusion. Just remove it. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210622021423.154662-3-mike.kravetz@oracle.com Fixes: 58a84aa92723 ("thp: set compound tail page _count to zero") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jann Horn <jannh@google.com> Cc: Youquan Song <youquan.song@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:34 +03:00
__ClearPageHead(page);
return false;
mm: introduce PageHuge() for testing huge/gigantic pages A series of patches to enhance the /proc/pagemap interface and to add a userspace executable which can be used to present the pagemap data. Export 10 more flags to end users (and more for kernel developers): 11. KPF_MMAP (pseudo flag) memory mapped page 12. KPF_ANON (pseudo flag) memory mapped page (anonymous) 13. KPF_SWAPCACHE page is in swap cache 14. KPF_SWAPBACKED page is swap/RAM backed 15. KPF_COMPOUND_HEAD (*) 16. KPF_COMPOUND_TAIL (*) 17. KPF_HUGE hugeTLB pages 18. KPF_UNEVICTABLE page is in the unevictable LRU list 19. KPF_HWPOISON hardware detected corruption 20. KPF_NOPAGE (pseudo flag) no page frame at the address (*) For compound pages, exporting _both_ head/tail info enables users to tell where a compound page starts/ends, and its order. a simple demo of the page-types tool # ./page-types -h page-types [options] -r|--raw Raw mode, for kernel developers -a|--addr addr-spec Walk a range of pages -b|--bits bits-spec Walk pages with specified bits -l|--list Show page details in ranges -L|--list-each Show page details one by one -N|--no-summary Don't show summay info -h|--help Show this usage message addr-spec: N one page at offset N (unit: pages) N+M pages range from N to N+M-1 N,M pages range from N to M-1 N, pages range from N to end ,M pages range from 0 to M bits-spec: bit1,bit2 (flags & (bit1|bit2)) != 0 bit1,bit2=bit1 (flags & (bit1|bit2)) == bit1 bit1,~bit2 (flags & (bit1|bit2)) == bit1 =bit1,bit2 flags == (bit1|bit2) bit-names: locked error referenced uptodate dirty lru active slab writeback reclaim buddy mmap anonymous swapcache swapbacked compound_head compound_tail huge unevictable hwpoison nopage reserved(r) mlocked(r) mappedtodisk(r) private(r) private_2(r) owner_private(r) arch(r) uncached(r) readahead(o) slob_free(o) slub_frozen(o) slub_debug(o) (r) raw mode bits (o) overloaded bits # ./page-types flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 487369 1903 _________________________________ 0x0000000000000014 5 0 __R_D____________________________ referenced,dirty 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000000000024 34 0 __R__l___________________________ referenced,lru 0x0000000000000028 3838 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 48 0 ___U_l_______________________I___ uptodate,lru,readahead 0x000000000000002c 6478 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x0000000000000040 8344 32 ______A__________________________ active 0x0000000000000060 1 0 _____lA__________________________ lru,active 0x0000000000000068 348 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x000000000000006c 988 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 503 1 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 30 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types -r flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 468002 1828 _________________________________ 0x0000000100000000 19102 74 _____________________r___________ reserved 0x0000000000008000 41 0 _______________H_________________ compound_head 0x0000000000010000 188 0 ________________T________________ compound_tail 0x0000000000008014 1 0 __R_D__________H_________________ referenced,dirty,compound_head 0x0000000000010014 4 0 __R_D___________T________________ referenced,dirty,compound_tail 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000800000024 34 0 __R__l__________________P________ referenced,lru,private 0x0000000000000028 3794 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 46 0 ___U_l_______________________I___ uptodate,lru,readahead 0x0000000400000028 44 0 ___U_l_________________d_________ uptodate,lru,mappedtodisk 0x0001000400000028 2 0 ___U_l_________________d_____I___ uptodate,lru,mappedtodisk,readahead 0x000000000000002c 6434 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x000000040000002c 14 0 __RU_l_________________d_________ referenced,uptodate,lru,mappedtodisk 0x000000080000002c 30 0 __RU_l__________________P________ referenced,uptodate,lru,private 0x0000000800000040 8124 31 ______A_________________P________ active,private 0x0000000000000040 219 0 ______A__________________________ active 0x0000000800000060 1 0 _____lA_________________P________ lru,active,private 0x0000000000000068 322 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x0000000400000068 13 0 ___U_lA________________d_________ uptodate,lru,active,mappedtodisk 0x0000000800000068 12 0 ___U_lA_________________P________ uptodate,lru,active,private 0x000000000000006c 977 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x000000040000006c 5 0 __RU_lA________________d_________ referenced,uptodate,lru,active,mappedtodisk 0x000000080000006c 3 0 __RU_lA_________________P________ referenced,uptodate,lru,active,private 0x0000000c0000006c 3 0 __RU_lA________________dP________ referenced,uptodate,lru,active,mappedtodisk,private 0x0000000c00000068 1 0 ___U_lA________________dP________ uptodate,lru,active,mappedtodisk,private 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 538 2 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005008 2 0 ___U________a_b__________________ uptodate,anonymous,swapbacked 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x000000000000580c 1 0 __RU_______Ma_b__________________ referenced,uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 29 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types --raw --list --no-summary --bits reserved offset count flags 0 15 _____________________r___________ 31 4 _____________________r___________ 159 97 _____________________r___________ 4096 2067 _____________________r___________ 6752 2390 _____________________r___________ 9355 3 _____________________r___________ 9728 14526 _____________________r___________ This patch: Introduce PageHuge(), which identifies huge/gigantic pages by their dedicated compound destructor functions. Also move prep_compound_gigantic_page() to hugetlb.c and make __free_pages_ok() non-static. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-17 02:32:22 +04:00
}
hugetlb: add demote bool to gigantic page routines The routines remove_hugetlb_page and destroy_compound_gigantic_page will remove a gigantic page and make the set of base pages ready to be returned to a lower level allocator. In the process of doing this, they make all base pages reference counted. The routine prep_compound_gigantic_page creates a gigantic page from a set of base pages. It assumes that all these base pages are reference counted. During demotion, a gigantic page will be split into huge pages of a smaller size. This logically involves use of the routines, remove_hugetlb_page, and destroy_compound_gigantic_page followed by prep_compound*_page for each smaller huge page. When pages are reference counted (ref count >= 0), additional speculative ref counts could be taken as described in previous commits [1] and [2]. This could result in errors while demoting a huge page. Quite a bit of code would need to be created to handle all possible issues. Instead of dealing with the possibility of speculative ref counts, avoid the possibility by keeping ref counts at zero during the demote process. Add a boolean 'demote' to the routines remove_hugetlb_page, destroy_compound_gigantic_page and prep_compound_gigantic_page. If the boolean is set, the remove and destroy routines will not reference count pages and the prep routine will not expect reference counted pages. '*_for_demote' wrappers of the routines will be added in a subsequent patch where this functionality is used. [1] https://lore.kernel.org/linux-mm/20210622021423.154662-3-mike.kravetz@oracle.com/ [2] https://lore.kernel.org/linux-mm/20210809184832.18342-3-mike.kravetz@oracle.com/ Link: https://lkml.kernel.org/r/20211007181918.136982-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:30 +03:00
static bool prep_compound_gigantic_page(struct page *page, unsigned int order)
{
return __prep_compound_gigantic_page(page, order, false);
}
static bool prep_compound_gigantic_page_for_demote(struct page *page,
unsigned int order)
{
return __prep_compound_gigantic_page(page, order, true);
}
/*
* PageHuge() only returns true for hugetlbfs pages, but not for normal or
* transparent huge pages. See the PageTransHuge() documentation for more
* details.
*/
mm: introduce PageHuge() for testing huge/gigantic pages A series of patches to enhance the /proc/pagemap interface and to add a userspace executable which can be used to present the pagemap data. Export 10 more flags to end users (and more for kernel developers): 11. KPF_MMAP (pseudo flag) memory mapped page 12. KPF_ANON (pseudo flag) memory mapped page (anonymous) 13. KPF_SWAPCACHE page is in swap cache 14. KPF_SWAPBACKED page is swap/RAM backed 15. KPF_COMPOUND_HEAD (*) 16. KPF_COMPOUND_TAIL (*) 17. KPF_HUGE hugeTLB pages 18. KPF_UNEVICTABLE page is in the unevictable LRU list 19. KPF_HWPOISON hardware detected corruption 20. KPF_NOPAGE (pseudo flag) no page frame at the address (*) For compound pages, exporting _both_ head/tail info enables users to tell where a compound page starts/ends, and its order. a simple demo of the page-types tool # ./page-types -h page-types [options] -r|--raw Raw mode, for kernel developers -a|--addr addr-spec Walk a range of pages -b|--bits bits-spec Walk pages with specified bits -l|--list Show page details in ranges -L|--list-each Show page details one by one -N|--no-summary Don't show summay info -h|--help Show this usage message addr-spec: N one page at offset N (unit: pages) N+M pages range from N to N+M-1 N,M pages range from N to M-1 N, pages range from N to end ,M pages range from 0 to M bits-spec: bit1,bit2 (flags & (bit1|bit2)) != 0 bit1,bit2=bit1 (flags & (bit1|bit2)) == bit1 bit1,~bit2 (flags & (bit1|bit2)) == bit1 =bit1,bit2 flags == (bit1|bit2) bit-names: locked error referenced uptodate dirty lru active slab writeback reclaim buddy mmap anonymous swapcache swapbacked compound_head compound_tail huge unevictable hwpoison nopage reserved(r) mlocked(r) mappedtodisk(r) private(r) private_2(r) owner_private(r) arch(r) uncached(r) readahead(o) slob_free(o) slub_frozen(o) slub_debug(o) (r) raw mode bits (o) overloaded bits # ./page-types flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 487369 1903 _________________________________ 0x0000000000000014 5 0 __R_D____________________________ referenced,dirty 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000000000024 34 0 __R__l___________________________ referenced,lru 0x0000000000000028 3838 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 48 0 ___U_l_______________________I___ uptodate,lru,readahead 0x000000000000002c 6478 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x0000000000000040 8344 32 ______A__________________________ active 0x0000000000000060 1 0 _____lA__________________________ lru,active 0x0000000000000068 348 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x000000000000006c 988 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 503 1 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 30 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types -r flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 468002 1828 _________________________________ 0x0000000100000000 19102 74 _____________________r___________ reserved 0x0000000000008000 41 0 _______________H_________________ compound_head 0x0000000000010000 188 0 ________________T________________ compound_tail 0x0000000000008014 1 0 __R_D__________H_________________ referenced,dirty,compound_head 0x0000000000010014 4 0 __R_D___________T________________ referenced,dirty,compound_tail 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000800000024 34 0 __R__l__________________P________ referenced,lru,private 0x0000000000000028 3794 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 46 0 ___U_l_______________________I___ uptodate,lru,readahead 0x0000000400000028 44 0 ___U_l_________________d_________ uptodate,lru,mappedtodisk 0x0001000400000028 2 0 ___U_l_________________d_____I___ uptodate,lru,mappedtodisk,readahead 0x000000000000002c 6434 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x000000040000002c 14 0 __RU_l_________________d_________ referenced,uptodate,lru,mappedtodisk 0x000000080000002c 30 0 __RU_l__________________P________ referenced,uptodate,lru,private 0x0000000800000040 8124 31 ______A_________________P________ active,private 0x0000000000000040 219 0 ______A__________________________ active 0x0000000800000060 1 0 _____lA_________________P________ lru,active,private 0x0000000000000068 322 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x0000000400000068 13 0 ___U_lA________________d_________ uptodate,lru,active,mappedtodisk 0x0000000800000068 12 0 ___U_lA_________________P________ uptodate,lru,active,private 0x000000000000006c 977 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x000000040000006c 5 0 __RU_lA________________d_________ referenced,uptodate,lru,active,mappedtodisk 0x000000080000006c 3 0 __RU_lA_________________P________ referenced,uptodate,lru,active,private 0x0000000c0000006c 3 0 __RU_lA________________dP________ referenced,uptodate,lru,active,mappedtodisk,private 0x0000000c00000068 1 0 ___U_lA________________dP________ uptodate,lru,active,mappedtodisk,private 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 538 2 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005008 2 0 ___U________a_b__________________ uptodate,anonymous,swapbacked 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x000000000000580c 1 0 __RU_______Ma_b__________________ referenced,uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 29 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types --raw --list --no-summary --bits reserved offset count flags 0 15 _____________________r___________ 31 4 _____________________r___________ 159 97 _____________________r___________ 4096 2067 _____________________r___________ 6752 2390 _____________________r___________ 9355 3 _____________________r___________ 9728 14526 _____________________r___________ This patch: Introduce PageHuge(), which identifies huge/gigantic pages by their dedicated compound destructor functions. Also move prep_compound_gigantic_page() to hugetlb.c and make __free_pages_ok() non-static. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-17 02:32:22 +04:00
int PageHuge(struct page *page)
{
if (!PageCompound(page))
return 0;
page = compound_head(page);
return page[1].compound_dtor == HUGETLB_PAGE_DTOR;
mm: introduce PageHuge() for testing huge/gigantic pages A series of patches to enhance the /proc/pagemap interface and to add a userspace executable which can be used to present the pagemap data. Export 10 more flags to end users (and more for kernel developers): 11. KPF_MMAP (pseudo flag) memory mapped page 12. KPF_ANON (pseudo flag) memory mapped page (anonymous) 13. KPF_SWAPCACHE page is in swap cache 14. KPF_SWAPBACKED page is swap/RAM backed 15. KPF_COMPOUND_HEAD (*) 16. KPF_COMPOUND_TAIL (*) 17. KPF_HUGE hugeTLB pages 18. KPF_UNEVICTABLE page is in the unevictable LRU list 19. KPF_HWPOISON hardware detected corruption 20. KPF_NOPAGE (pseudo flag) no page frame at the address (*) For compound pages, exporting _both_ head/tail info enables users to tell where a compound page starts/ends, and its order. a simple demo of the page-types tool # ./page-types -h page-types [options] -r|--raw Raw mode, for kernel developers -a|--addr addr-spec Walk a range of pages -b|--bits bits-spec Walk pages with specified bits -l|--list Show page details in ranges -L|--list-each Show page details one by one -N|--no-summary Don't show summay info -h|--help Show this usage message addr-spec: N one page at offset N (unit: pages) N+M pages range from N to N+M-1 N,M pages range from N to M-1 N, pages range from N to end ,M pages range from 0 to M bits-spec: bit1,bit2 (flags & (bit1|bit2)) != 0 bit1,bit2=bit1 (flags & (bit1|bit2)) == bit1 bit1,~bit2 (flags & (bit1|bit2)) == bit1 =bit1,bit2 flags == (bit1|bit2) bit-names: locked error referenced uptodate dirty lru active slab writeback reclaim buddy mmap anonymous swapcache swapbacked compound_head compound_tail huge unevictable hwpoison nopage reserved(r) mlocked(r) mappedtodisk(r) private(r) private_2(r) owner_private(r) arch(r) uncached(r) readahead(o) slob_free(o) slub_frozen(o) slub_debug(o) (r) raw mode bits (o) overloaded bits # ./page-types flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 487369 1903 _________________________________ 0x0000000000000014 5 0 __R_D____________________________ referenced,dirty 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000000000024 34 0 __R__l___________________________ referenced,lru 0x0000000000000028 3838 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 48 0 ___U_l_______________________I___ uptodate,lru,readahead 0x000000000000002c 6478 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x0000000000000040 8344 32 ______A__________________________ active 0x0000000000000060 1 0 _____lA__________________________ lru,active 0x0000000000000068 348 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x000000000000006c 988 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 503 1 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 30 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types -r flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 468002 1828 _________________________________ 0x0000000100000000 19102 74 _____________________r___________ reserved 0x0000000000008000 41 0 _______________H_________________ compound_head 0x0000000000010000 188 0 ________________T________________ compound_tail 0x0000000000008014 1 0 __R_D__________H_________________ referenced,dirty,compound_head 0x0000000000010014 4 0 __R_D___________T________________ referenced,dirty,compound_tail 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000800000024 34 0 __R__l__________________P________ referenced,lru,private 0x0000000000000028 3794 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 46 0 ___U_l_______________________I___ uptodate,lru,readahead 0x0000000400000028 44 0 ___U_l_________________d_________ uptodate,lru,mappedtodisk 0x0001000400000028 2 0 ___U_l_________________d_____I___ uptodate,lru,mappedtodisk,readahead 0x000000000000002c 6434 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x000000040000002c 14 0 __RU_l_________________d_________ referenced,uptodate,lru,mappedtodisk 0x000000080000002c 30 0 __RU_l__________________P________ referenced,uptodate,lru,private 0x0000000800000040 8124 31 ______A_________________P________ active,private 0x0000000000000040 219 0 ______A__________________________ active 0x0000000800000060 1 0 _____lA_________________P________ lru,active,private 0x0000000000000068 322 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x0000000400000068 13 0 ___U_lA________________d_________ uptodate,lru,active,mappedtodisk 0x0000000800000068 12 0 ___U_lA_________________P________ uptodate,lru,active,private 0x000000000000006c 977 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x000000040000006c 5 0 __RU_lA________________d_________ referenced,uptodate,lru,active,mappedtodisk 0x000000080000006c 3 0 __RU_lA_________________P________ referenced,uptodate,lru,active,private 0x0000000c0000006c 3 0 __RU_lA________________dP________ referenced,uptodate,lru,active,mappedtodisk,private 0x0000000c00000068 1 0 ___U_lA________________dP________ uptodate,lru,active,mappedtodisk,private 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 538 2 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005008 2 0 ___U________a_b__________________ uptodate,anonymous,swapbacked 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x000000000000580c 1 0 __RU_______Ma_b__________________ referenced,uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 29 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types --raw --list --no-summary --bits reserved offset count flags 0 15 _____________________r___________ 31 4 _____________________r___________ 159 97 _____________________r___________ 4096 2067 _____________________r___________ 6752 2390 _____________________r___________ 9355 3 _____________________r___________ 9728 14526 _____________________r___________ This patch: Introduce PageHuge(), which identifies huge/gigantic pages by their dedicated compound destructor functions. Also move prep_compound_gigantic_page() to hugetlb.c and make __free_pages_ok() non-static. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-17 02:32:22 +04:00
}
EXPORT_SYMBOL_GPL(PageHuge);
mm: hugetlbfs: fix hugetlbfs optimization Commit 7cb2ef56e6a8 ("mm: fix aio performance regression for database caused by THP") can cause dereference of a dangling pointer if split_huge_page runs during PageHuge() if there are updates to the tail_page->private field. Also it is repeating compound_head twice for hugetlbfs and it is running compound_head+compound_trans_head for THP when a single one is needed in both cases. The new code within the PageSlab() check doesn't need to verify that the THP page size is never bigger than the smallest hugetlbfs page size, to avoid memory corruption. A longstanding theoretical race condition was found while fixing the above (see the change right after the skip_unlock label, that is relevant for the compound_lock path too). By re-establishing the _mapcount tail refcounting for all compound pages, this also fixes the below problem: echo 0 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages BUG: Bad page state in process bash pfn:59a01 page:ffffea000139b038 count:0 mapcount:10 mapping: (null) index:0x0 page flags: 0x1c00000000008000(tail) Modules linked in: CPU: 6 PID: 2018 Comm: bash Not tainted 3.12.0+ #25 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 Call Trace: dump_stack+0x55/0x76 bad_page+0xd5/0x130 free_pages_prepare+0x213/0x280 __free_pages+0x36/0x80 update_and_free_page+0xc1/0xd0 free_pool_huge_page+0xc2/0xe0 set_max_huge_pages.part.58+0x14c/0x220 nr_hugepages_store_common.isra.60+0xd0/0xf0 nr_hugepages_store+0x13/0x20 kobj_attr_store+0xf/0x20 sysfs_write_file+0x189/0x1e0 vfs_write+0xc5/0x1f0 SyS_write+0x55/0xb0 system_call_fastpath+0x16/0x1b Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Tested-by: Khalid Aziz <khalid.aziz@oracle.com> Cc: Pravin Shelar <pshelar@nicira.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Ben Hutchings <bhutchings@solarflare.com> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-22 02:32:02 +04:00
/*
* PageHeadHuge() only returns true for hugetlbfs head page, but not for
* normal or transparent huge pages.
*/
int PageHeadHuge(struct page *page_head)
{
if (!PageHead(page_head))
return 0;
return page_head[1].compound_dtor == HUGETLB_PAGE_DTOR;
mm: hugetlbfs: fix hugetlbfs optimization Commit 7cb2ef56e6a8 ("mm: fix aio performance regression for database caused by THP") can cause dereference of a dangling pointer if split_huge_page runs during PageHuge() if there are updates to the tail_page->private field. Also it is repeating compound_head twice for hugetlbfs and it is running compound_head+compound_trans_head for THP when a single one is needed in both cases. The new code within the PageSlab() check doesn't need to verify that the THP page size is never bigger than the smallest hugetlbfs page size, to avoid memory corruption. A longstanding theoretical race condition was found while fixing the above (see the change right after the skip_unlock label, that is relevant for the compound_lock path too). By re-establishing the _mapcount tail refcounting for all compound pages, this also fixes the below problem: echo 0 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages BUG: Bad page state in process bash pfn:59a01 page:ffffea000139b038 count:0 mapcount:10 mapping: (null) index:0x0 page flags: 0x1c00000000008000(tail) Modules linked in: CPU: 6 PID: 2018 Comm: bash Not tainted 3.12.0+ #25 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 Call Trace: dump_stack+0x55/0x76 bad_page+0xd5/0x130 free_pages_prepare+0x213/0x280 __free_pages+0x36/0x80 update_and_free_page+0xc1/0xd0 free_pool_huge_page+0xc2/0xe0 set_max_huge_pages.part.58+0x14c/0x220 nr_hugepages_store_common.isra.60+0xd0/0xf0 nr_hugepages_store+0x13/0x20 kobj_attr_store+0xf/0x20 sysfs_write_file+0x189/0x1e0 vfs_write+0xc5/0x1f0 SyS_write+0x55/0xb0 system_call_fastpath+0x16/0x1b Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Tested-by: Khalid Aziz <khalid.aziz@oracle.com> Cc: Pravin Shelar <pshelar@nicira.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Ben Hutchings <bhutchings@solarflare.com> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-22 02:32:02 +04:00
}
EXPORT_SYMBOL_GPL(PageHeadHuge);
mm: hugetlbfs: fix hugetlbfs optimization Commit 7cb2ef56e6a8 ("mm: fix aio performance regression for database caused by THP") can cause dereference of a dangling pointer if split_huge_page runs during PageHuge() if there are updates to the tail_page->private field. Also it is repeating compound_head twice for hugetlbfs and it is running compound_head+compound_trans_head for THP when a single one is needed in both cases. The new code within the PageSlab() check doesn't need to verify that the THP page size is never bigger than the smallest hugetlbfs page size, to avoid memory corruption. A longstanding theoretical race condition was found while fixing the above (see the change right after the skip_unlock label, that is relevant for the compound_lock path too). By re-establishing the _mapcount tail refcounting for all compound pages, this also fixes the below problem: echo 0 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages BUG: Bad page state in process bash pfn:59a01 page:ffffea000139b038 count:0 mapcount:10 mapping: (null) index:0x0 page flags: 0x1c00000000008000(tail) Modules linked in: CPU: 6 PID: 2018 Comm: bash Not tainted 3.12.0+ #25 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 Call Trace: dump_stack+0x55/0x76 bad_page+0xd5/0x130 free_pages_prepare+0x213/0x280 __free_pages+0x36/0x80 update_and_free_page+0xc1/0xd0 free_pool_huge_page+0xc2/0xe0 set_max_huge_pages.part.58+0x14c/0x220 nr_hugepages_store_common.isra.60+0xd0/0xf0 nr_hugepages_store+0x13/0x20 kobj_attr_store+0xf/0x20 sysfs_write_file+0x189/0x1e0 vfs_write+0xc5/0x1f0 SyS_write+0x55/0xb0 system_call_fastpath+0x16/0x1b Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Tested-by: Khalid Aziz <khalid.aziz@oracle.com> Cc: Pravin Shelar <pshelar@nicira.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Ben Hutchings <bhutchings@solarflare.com> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-22 02:32:02 +04:00
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
/*
* Find and lock address space (mapping) in write mode.
*
hugetlbfs: fix anon huge page migration race Qian Cai reported the following BUG in [1] LTP: starting move_pages12 BUG: unable to handle page fault for address: ffffffffffffffe0 ... RIP: 0010:anon_vma_interval_tree_iter_first+0xa2/0x170 avc_start_pgoff at mm/interval_tree.c:63 Call Trace: rmap_walk_anon+0x141/0xa30 rmap_walk_anon at mm/rmap.c:1864 try_to_unmap+0x209/0x2d0 try_to_unmap at mm/rmap.c:1763 migrate_pages+0x1005/0x1fb0 move_pages_and_store_status.isra.47+0xd7/0x1a0 __x64_sys_move_pages+0xa5c/0x1100 do_syscall_64+0x5f/0x310 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Hugh Dickins diagnosed this as a migration bug caused by code introduced to use i_mmap_rwsem for pmd sharing synchronization. Specifically, the routine unmap_and_move_huge_page() is always passing the TTU_RMAP_LOCKED flag to try_to_unmap() while holding i_mmap_rwsem. This is wrong for anon pages as the anon_vma_lock should be held in this case. Further analysis suggested that i_mmap_rwsem was not required to he held at all when calling try_to_unmap for anon pages as an anon page could never be part of a shared pmd mapping. Discussion also revealed that the hack in hugetlb_page_mapping_lock_write to drop page lock and acquire i_mmap_rwsem is wrong. There is no way to keep mapping valid while dropping page lock. This patch does the following: - Do not take i_mmap_rwsem and set TTU_RMAP_LOCKED for anon pages when calling try_to_unmap. - Remove the hacky code in hugetlb_page_mapping_lock_write. The routine will now simply do a 'trylock' while still holding the page lock. If the trylock fails, it will return NULL. This could impact the callers: - migration calling code will receive -EAGAIN and retry up to the hard coded limit (10). - memory error code will treat the page as BUSY. This will force killing (SIGKILL) instead of SIGBUS any mapping tasks. Do note that this change in behavior only happens when there is a race. None of the standard kernel testing suites actually hit this race, but it is possible. [1] https://lore.kernel.org/lkml/20200708012044.GC992@lca.pw/ [2] https://lore.kernel.org/linux-mm/alpine.LSU.2.11.2010071833100.2214@eggly.anvils/ Fixes: c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") Reported-by: Qian Cai <cai@lca.pw> Suggested-by: Hugh Dickins <hughd@google.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/20201105195058.78401-1-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-11-14 09:52:16 +03:00
* Upon entry, the page is locked which means that page_mapping() is
* stable. Due to locking order, we can only trylock_write. If we can
* not get the lock, simply return NULL to caller.
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
*/
struct address_space *hugetlb_page_mapping_lock_write(struct page *hpage)
{
hugetlbfs: fix anon huge page migration race Qian Cai reported the following BUG in [1] LTP: starting move_pages12 BUG: unable to handle page fault for address: ffffffffffffffe0 ... RIP: 0010:anon_vma_interval_tree_iter_first+0xa2/0x170 avc_start_pgoff at mm/interval_tree.c:63 Call Trace: rmap_walk_anon+0x141/0xa30 rmap_walk_anon at mm/rmap.c:1864 try_to_unmap+0x209/0x2d0 try_to_unmap at mm/rmap.c:1763 migrate_pages+0x1005/0x1fb0 move_pages_and_store_status.isra.47+0xd7/0x1a0 __x64_sys_move_pages+0xa5c/0x1100 do_syscall_64+0x5f/0x310 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Hugh Dickins diagnosed this as a migration bug caused by code introduced to use i_mmap_rwsem for pmd sharing synchronization. Specifically, the routine unmap_and_move_huge_page() is always passing the TTU_RMAP_LOCKED flag to try_to_unmap() while holding i_mmap_rwsem. This is wrong for anon pages as the anon_vma_lock should be held in this case. Further analysis suggested that i_mmap_rwsem was not required to he held at all when calling try_to_unmap for anon pages as an anon page could never be part of a shared pmd mapping. Discussion also revealed that the hack in hugetlb_page_mapping_lock_write to drop page lock and acquire i_mmap_rwsem is wrong. There is no way to keep mapping valid while dropping page lock. This patch does the following: - Do not take i_mmap_rwsem and set TTU_RMAP_LOCKED for anon pages when calling try_to_unmap. - Remove the hacky code in hugetlb_page_mapping_lock_write. The routine will now simply do a 'trylock' while still holding the page lock. If the trylock fails, it will return NULL. This could impact the callers: - migration calling code will receive -EAGAIN and retry up to the hard coded limit (10). - memory error code will treat the page as BUSY. This will force killing (SIGKILL) instead of SIGBUS any mapping tasks. Do note that this change in behavior only happens when there is a race. None of the standard kernel testing suites actually hit this race, but it is possible. [1] https://lore.kernel.org/lkml/20200708012044.GC992@lca.pw/ [2] https://lore.kernel.org/linux-mm/alpine.LSU.2.11.2010071833100.2214@eggly.anvils/ Fixes: c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") Reported-by: Qian Cai <cai@lca.pw> Suggested-by: Hugh Dickins <hughd@google.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/20201105195058.78401-1-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-11-14 09:52:16 +03:00
struct address_space *mapping = page_mapping(hpage);
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
if (!mapping)
return mapping;
if (i_mmap_trylock_write(mapping))
return mapping;
hugetlbfs: fix anon huge page migration race Qian Cai reported the following BUG in [1] LTP: starting move_pages12 BUG: unable to handle page fault for address: ffffffffffffffe0 ... RIP: 0010:anon_vma_interval_tree_iter_first+0xa2/0x170 avc_start_pgoff at mm/interval_tree.c:63 Call Trace: rmap_walk_anon+0x141/0xa30 rmap_walk_anon at mm/rmap.c:1864 try_to_unmap+0x209/0x2d0 try_to_unmap at mm/rmap.c:1763 migrate_pages+0x1005/0x1fb0 move_pages_and_store_status.isra.47+0xd7/0x1a0 __x64_sys_move_pages+0xa5c/0x1100 do_syscall_64+0x5f/0x310 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Hugh Dickins diagnosed this as a migration bug caused by code introduced to use i_mmap_rwsem for pmd sharing synchronization. Specifically, the routine unmap_and_move_huge_page() is always passing the TTU_RMAP_LOCKED flag to try_to_unmap() while holding i_mmap_rwsem. This is wrong for anon pages as the anon_vma_lock should be held in this case. Further analysis suggested that i_mmap_rwsem was not required to he held at all when calling try_to_unmap for anon pages as an anon page could never be part of a shared pmd mapping. Discussion also revealed that the hack in hugetlb_page_mapping_lock_write to drop page lock and acquire i_mmap_rwsem is wrong. There is no way to keep mapping valid while dropping page lock. This patch does the following: - Do not take i_mmap_rwsem and set TTU_RMAP_LOCKED for anon pages when calling try_to_unmap. - Remove the hacky code in hugetlb_page_mapping_lock_write. The routine will now simply do a 'trylock' while still holding the page lock. If the trylock fails, it will return NULL. This could impact the callers: - migration calling code will receive -EAGAIN and retry up to the hard coded limit (10). - memory error code will treat the page as BUSY. This will force killing (SIGKILL) instead of SIGBUS any mapping tasks. Do note that this change in behavior only happens when there is a race. None of the standard kernel testing suites actually hit this race, but it is possible. [1] https://lore.kernel.org/lkml/20200708012044.GC992@lca.pw/ [2] https://lore.kernel.org/linux-mm/alpine.LSU.2.11.2010071833100.2214@eggly.anvils/ Fixes: c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") Reported-by: Qian Cai <cai@lca.pw> Suggested-by: Hugh Dickins <hughd@google.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/20201105195058.78401-1-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-11-14 09:52:16 +03:00
return NULL;
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
}
mm, futex: fix shared futex pgoff on shmem huge page If more than one futex is placed on a shmem huge page, it can happen that waking the second wakes the first instead, and leaves the second waiting: the key's shared.pgoff is wrong. When 3.11 commit 13d60f4b6ab5 ("futex: Take hugepages into account when generating futex_key"), the only shared huge pages came from hugetlbfs, and the code added to deal with its exceptional page->index was put into hugetlb source. Then that was missed when 4.8 added shmem huge pages. page_to_pgoff() is what others use for this nowadays: except that, as currently written, it gives the right answer on hugetlbfs head, but nonsense on hugetlbfs tails. Fix that by calling hugetlbfs-specific hugetlb_basepage_index() on PageHuge tails as well as on head. Yes, it's unconventional to declare hugetlb_basepage_index() there in pagemap.h, rather than in hugetlb.h; but I do not expect anything but page_to_pgoff() ever to need it. [akpm@linux-foundation.org: give hugetlb_basepage_index() prototype the correct scope] Link: https://lkml.kernel.org/r/b17d946b-d09-326e-b42a-52884c36df32@google.com Fixes: 800d8c63b2e9 ("shmem: add huge pages support") Reported-by: Neel Natu <neelnatu@google.com> Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Zhang Yi <wetpzy@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Darren Hart <dvhart@infradead.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-25 04:39:52 +03:00
pgoff_t hugetlb_basepage_index(struct page *page)
futex: Take hugepages into account when generating futex_key The futex_keys of process shared futexes are generated from the page offset, the mapping host and the mapping index of the futex user space address. This should result in an unique identifier for each futex. Though this is not true when futexes are located in different subpages of an hugepage. The reason is, that the mapping index for all those futexes evaluates to the index of the base page of the hugetlbfs mapping. So a futex at offset 0 of the hugepage mapping and another one at offset PAGE_SIZE of the same hugepage mapping have identical futex_keys. This happens because the futex code blindly uses page->index. Steps to reproduce the bug: 1. Map a file from hugetlbfs. Initialize pthread_mutex1 at offset 0 and pthread_mutex2 at offset PAGE_SIZE of the hugetlbfs mapping. The mutexes must be initialized as PTHREAD_PROCESS_SHARED because PTHREAD_PROCESS_PRIVATE mutexes are not affected by this issue as their keys solely depend on the user space address. 2. Lock mutex1 and mutex2 3. Create thread1 and in the thread function lock mutex1, which results in thread1 blocking on the locked mutex1. 4. Create thread2 and in the thread function lock mutex2, which results in thread2 blocking on the locked mutex2. 5. Unlock mutex2. Despite the fact that mutex2 got unlocked, thread2 still blocks on mutex2 because the futex_key points to mutex1. To solve this issue we need to take the normal page index of the page which contains the futex into account, if the futex is in an hugetlbfs mapping. In other words, we calculate the normal page mapping index of the subpage in the hugetlbfs mapping. Mappings which are not based on hugetlbfs are not affected and still use page->index. Thanks to Mel Gorman who provided a patch for adding proper evaluation functions to the hugetlbfs code to avoid exposing hugetlbfs specific details to the futex code. [ tglx: Massaged changelog ] Signed-off-by: Zhang Yi <zhang.yi20@zte.com.cn> Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn> Tested-by: Ma Chenggong <ma.chenggong@zte.com.cn> Reviewed-by: 'Mel Gorman' <mgorman@suse.de> Acked-by: 'Darren Hart' <dvhart@linux.intel.com> Cc: 'Peter Zijlstra' <peterz@infradead.org> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/000101ce71a6%24a83c5880%24f8b50980%24@com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-06-25 17:19:31 +04:00
{
struct page *page_head = compound_head(page);
pgoff_t index = page_index(page_head);
unsigned long compound_idx;
if (compound_order(page_head) >= MAX_ORDER)
compound_idx = page_to_pfn(page) - page_to_pfn(page_head);
else
compound_idx = page - page_head;
return (index << compound_order(page_head)) + compound_idx;
}
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
static struct page *alloc_buddy_huge_page(struct hstate *h,
gfp_t gfp_mask, int nid, nodemask_t *nmask,
nodemask_t *node_alloc_noretry)
{
mm, hugetlb: unify core page allocation accounting and initialization Patch series "mm, hugetlb: allocation API and migration improvements" Motivation: this is a follow up for [3] for the allocation API and [4] for the hugetlb migration. It wasn't really easy to split those into two separate patch series as they share some code. My primary motivation to touch this code is to make the gigantic pages migration working. The giga pages allocation code is just too fragile and hacked into the hugetlb code now. This series tries to move giga pages closer to the first class citizen. We are not there yet but having 5 patches is quite a lot already and it will already make the code much easier to follow. I will come with other changes on top after this sees some review. The first two patches should be trivial to review. The third patch changes the way how we migrate huge pages. Newly allocated pages are a subject of the overcommit check and they participate surplus accounting which is quite unfortunate as the changelog explains. This patch doesn't change anything wrt. giga pages. Patch #4 removes the surplus accounting hack from __alloc_surplus_huge_page. I hope I didn't miss anything there and a deeper review is really due there. Patch #5 finally unifies allocation paths and giga pages shouldn't be any special anymore. There is also some renaming going on as well. This patch (of 6): hugetlb allocator has two entry points to the page allocator - alloc_fresh_huge_page_node - __hugetlb_alloc_buddy_huge_page The two differ very subtly in two aspects. The first one doesn't care about HTLB_BUDDY_* stats and it doesn't initialize the huge page. prep_new_huge_page is not used because it not only initializes hugetlb specific stuff but because it also put_page and releases the page to the hugetlb pool which is not what is required in some contexts. This makes things more complicated than necessary. Simplify things by a) removing the page allocator entry point duplicity and only keep __hugetlb_alloc_buddy_huge_page and b) make prep_new_huge_page more reusable by removing the put_page which moves the page to the allocator pool. All current callers are updated to call put_page explicitly. Later patches will add new callers which won't need it. This patch shouldn't introduce any functional change. Link: http://lkml.kernel.org/r/20180103093213.26329-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:41 +03:00
int order = huge_page_order(h);
struct page *page;
bool alloc_try_hard = true;
/*
* By default we always try hard to allocate the page with
* __GFP_RETRY_MAYFAIL flag. However, if we are allocating pages in
* a loop (to adjust global huge page counts) and previous allocation
* failed, do not continue to try hard on the same node. Use the
* node_alloc_noretry bitmap to manage this state information.
*/
if (node_alloc_noretry && node_isset(nid, *node_alloc_noretry))
alloc_try_hard = false;
gfp_mask |= __GFP_COMP|__GFP_NOWARN;
if (alloc_try_hard)
gfp_mask |= __GFP_RETRY_MAYFAIL;
mm, hugetlb: unify core page allocation accounting and initialization Patch series "mm, hugetlb: allocation API and migration improvements" Motivation: this is a follow up for [3] for the allocation API and [4] for the hugetlb migration. It wasn't really easy to split those into two separate patch series as they share some code. My primary motivation to touch this code is to make the gigantic pages migration working. The giga pages allocation code is just too fragile and hacked into the hugetlb code now. This series tries to move giga pages closer to the first class citizen. We are not there yet but having 5 patches is quite a lot already and it will already make the code much easier to follow. I will come with other changes on top after this sees some review. The first two patches should be trivial to review. The third patch changes the way how we migrate huge pages. Newly allocated pages are a subject of the overcommit check and they participate surplus accounting which is quite unfortunate as the changelog explains. This patch doesn't change anything wrt. giga pages. Patch #4 removes the surplus accounting hack from __alloc_surplus_huge_page. I hope I didn't miss anything there and a deeper review is really due there. Patch #5 finally unifies allocation paths and giga pages shouldn't be any special anymore. There is also some renaming going on as well. This patch (of 6): hugetlb allocator has two entry points to the page allocator - alloc_fresh_huge_page_node - __hugetlb_alloc_buddy_huge_page The two differ very subtly in two aspects. The first one doesn't care about HTLB_BUDDY_* stats and it doesn't initialize the huge page. prep_new_huge_page is not used because it not only initializes hugetlb specific stuff but because it also put_page and releases the page to the hugetlb pool which is not what is required in some contexts. This makes things more complicated than necessary. Simplify things by a) removing the page allocator entry point duplicity and only keep __hugetlb_alloc_buddy_huge_page and b) make prep_new_huge_page more reusable by removing the put_page which moves the page to the allocator pool. All current callers are updated to call put_page explicitly. Later patches will add new callers which won't need it. This patch shouldn't introduce any functional change. Link: http://lkml.kernel.org/r/20180103093213.26329-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:41 +03:00
if (nid == NUMA_NO_NODE)
nid = numa_mem_id();
page = __alloc_pages(gfp_mask, order, nid, nmask);
mm, hugetlb: unify core page allocation accounting and initialization Patch series "mm, hugetlb: allocation API and migration improvements" Motivation: this is a follow up for [3] for the allocation API and [4] for the hugetlb migration. It wasn't really easy to split those into two separate patch series as they share some code. My primary motivation to touch this code is to make the gigantic pages migration working. The giga pages allocation code is just too fragile and hacked into the hugetlb code now. This series tries to move giga pages closer to the first class citizen. We are not there yet but having 5 patches is quite a lot already and it will already make the code much easier to follow. I will come with other changes on top after this sees some review. The first two patches should be trivial to review. The third patch changes the way how we migrate huge pages. Newly allocated pages are a subject of the overcommit check and they participate surplus accounting which is quite unfortunate as the changelog explains. This patch doesn't change anything wrt. giga pages. Patch #4 removes the surplus accounting hack from __alloc_surplus_huge_page. I hope I didn't miss anything there and a deeper review is really due there. Patch #5 finally unifies allocation paths and giga pages shouldn't be any special anymore. There is also some renaming going on as well. This patch (of 6): hugetlb allocator has two entry points to the page allocator - alloc_fresh_huge_page_node - __hugetlb_alloc_buddy_huge_page The two differ very subtly in two aspects. The first one doesn't care about HTLB_BUDDY_* stats and it doesn't initialize the huge page. prep_new_huge_page is not used because it not only initializes hugetlb specific stuff but because it also put_page and releases the page to the hugetlb pool which is not what is required in some contexts. This makes things more complicated than necessary. Simplify things by a) removing the page allocator entry point duplicity and only keep __hugetlb_alloc_buddy_huge_page and b) make prep_new_huge_page more reusable by removing the put_page which moves the page to the allocator pool. All current callers are updated to call put_page explicitly. Later patches will add new callers which won't need it. This patch shouldn't introduce any functional change. Link: http://lkml.kernel.org/r/20180103093213.26329-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:41 +03:00
if (page)
__count_vm_event(HTLB_BUDDY_PGALLOC);
else
__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
hugetlb: fix hugepage allocation with memoryless nodes Anton found a problem with the hugetlb pool allocation when some nodes have no memory (http://marc.info/?l=linux-mm&m=118133042025995&w=2). Lee worked on versions that tried to fix it, but none were accepted. Christoph has created a set of patches which allow for GFP_THISNODE allocations to fail if the node has no memory. Currently, alloc_fresh_huge_page() returns NULL when it is not able to allocate a huge page on the current node, as specified by its custom interleave variable. The callers of this function, though, assume that a failure in alloc_fresh_huge_page() indicates no hugepages can be allocated on the system period. This might not be the case, for instance, if we have an uneven NUMA system, and we happen to try to allocate a hugepage on a node with less memory and fail, while there is still plenty of free memory on the other nodes. To correct this, make alloc_fresh_huge_page() search through all online nodes before deciding no hugepages can be allocated. Add a helper function for actually allocating the hugepage. Use a new global nid iterator to control which nid to allocate on. Note: we expect particular semantics for __GFP_THISNODE, which are now enforced even for memoryless nodes. That is, there is should be no fallback to other nodes. Therefore, we rely on the nid passed into alloc_pages_node() to be the nid the page comes from. If this is incorrect, accounting will break. Tested on x86 !NUMA, x86 NUMA, x86_64 NUMA and ppc64 NUMA (with 2 memoryless nodes). Before on the ppc64 box: Trying to clear the hugetlb pool Done. 0 free Trying to resize the pool to 100 Node 0 HugePages_Free: 25 Node 1 HugePages_Free: 75 Node 2 HugePages_Free: 0 Node 3 HugePages_Free: 0 Done. Initially 100 free Trying to resize the pool to 200 Node 0 HugePages_Free: 50 Node 1 HugePages_Free: 150 Node 2 HugePages_Free: 0 Node 3 HugePages_Free: 0 Done. 200 free After: Trying to clear the hugetlb pool Done. 0 free Trying to resize the pool to 100 Node 0 HugePages_Free: 50 Node 1 HugePages_Free: 50 Node 2 HugePages_Free: 0 Node 3 HugePages_Free: 0 Done. Initially 100 free Trying to resize the pool to 200 Node 0 HugePages_Free: 100 Node 1 HugePages_Free: 100 Node 2 HugePages_Free: 0 Node 3 HugePages_Free: 0 Done. 200 free Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Acked-by: Christoph Lameter <clameter@sgi.com> Cc: Adam Litke <agl@us.ibm.com> Cc: David Gibson <hermes@gibson.dropbear.id.au> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Ken Chen <kenchen@google.com> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16 12:26:24 +04:00
/*
* If we did not specify __GFP_RETRY_MAYFAIL, but still got a page this
* indicates an overall state change. Clear bit so that we resume
* normal 'try hard' allocations.
*/
if (node_alloc_noretry && page && !alloc_try_hard)
node_clear(nid, *node_alloc_noretry);
/*
* If we tried hard to get a page but failed, set bit so that
* subsequent attempts will not try as hard until there is an
* overall state change.
*/
if (node_alloc_noretry && !page && alloc_try_hard)
node_set(nid, *node_alloc_noretry);
hugetlb: fix hugepage allocation with memoryless nodes Anton found a problem with the hugetlb pool allocation when some nodes have no memory (http://marc.info/?l=linux-mm&m=118133042025995&w=2). Lee worked on versions that tried to fix it, but none were accepted. Christoph has created a set of patches which allow for GFP_THISNODE allocations to fail if the node has no memory. Currently, alloc_fresh_huge_page() returns NULL when it is not able to allocate a huge page on the current node, as specified by its custom interleave variable. The callers of this function, though, assume that a failure in alloc_fresh_huge_page() indicates no hugepages can be allocated on the system period. This might not be the case, for instance, if we have an uneven NUMA system, and we happen to try to allocate a hugepage on a node with less memory and fail, while there is still plenty of free memory on the other nodes. To correct this, make alloc_fresh_huge_page() search through all online nodes before deciding no hugepages can be allocated. Add a helper function for actually allocating the hugepage. Use a new global nid iterator to control which nid to allocate on. Note: we expect particular semantics for __GFP_THISNODE, which are now enforced even for memoryless nodes. That is, there is should be no fallback to other nodes. Therefore, we rely on the nid passed into alloc_pages_node() to be the nid the page comes from. If this is incorrect, accounting will break. Tested on x86 !NUMA, x86 NUMA, x86_64 NUMA and ppc64 NUMA (with 2 memoryless nodes). Before on the ppc64 box: Trying to clear the hugetlb pool Done. 0 free Trying to resize the pool to 100 Node 0 HugePages_Free: 25 Node 1 HugePages_Free: 75 Node 2 HugePages_Free: 0 Node 3 HugePages_Free: 0 Done. Initially 100 free Trying to resize the pool to 200 Node 0 HugePages_Free: 50 Node 1 HugePages_Free: 150 Node 2 HugePages_Free: 0 Node 3 HugePages_Free: 0 Done. 200 free After: Trying to clear the hugetlb pool Done. 0 free Trying to resize the pool to 100 Node 0 HugePages_Free: 50 Node 1 HugePages_Free: 50 Node 2 HugePages_Free: 0 Node 3 HugePages_Free: 0 Done. Initially 100 free Trying to resize the pool to 200 Node 0 HugePages_Free: 100 Node 1 HugePages_Free: 100 Node 2 HugePages_Free: 0 Node 3 HugePages_Free: 0 Done. 200 free Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Acked-by: Christoph Lameter <clameter@sgi.com> Cc: Adam Litke <agl@us.ibm.com> Cc: David Gibson <hermes@gibson.dropbear.id.au> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Ken Chen <kenchen@google.com> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16 12:26:24 +04:00
return page;
}
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
/*
* Common helper to allocate a fresh hugetlb page. All specific allocators
* should use this function to get new hugetlb pages
*/
static struct page *alloc_fresh_huge_page(struct hstate *h,
gfp_t gfp_mask, int nid, nodemask_t *nmask,
nodemask_t *node_alloc_noretry)
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
{
struct page *page;
hugetlb: address ref count racing in prep_compound_gigantic_page In [1], Jann Horn points out a possible race between prep_compound_gigantic_page and __page_cache_add_speculative. The root cause of the possible race is prep_compound_gigantic_page uncondittionally setting the ref count of pages to zero. It does this because prep_compound_gigantic_page is handed a 'group' of pages from an allocator and needs to convert that group of pages to a compound page. The ref count of each page in this 'group' is one as set by the allocator. However, the ref count of compound page tail pages must be zero. The potential race comes about when ref counted pages are returned from the allocator. When this happens, other mm code could also take a reference on the page. __page_cache_add_speculative is one such example. Therefore, prep_compound_gigantic_page can not just set the ref count of pages to zero as it does today. Doing so would lose the reference taken by any other code. This would lead to BUGs in code checking ref counts and could possibly even lead to memory corruption. There are two possible ways to address this issue. 1) Make all allocators of gigantic groups of pages be able to return a properly constructed compound page. 2) Make prep_compound_gigantic_page be more careful when constructing a compound page. This patch takes approach 2. In prep_compound_gigantic_page, use cmpxchg to only set ref count to zero if it is one. If the cmpxchg fails, call synchronize_rcu() in the hope that the extra ref count will be driopped during a rcu grace period. This is not a performance critical code path and the wait should be accceptable. If the ref count is still inflated after the grace period, then undo any modifications made and return an error. Currently prep_compound_gigantic_page is type void and does not return errors. Modify the two callers to check for and handle error returns. On error, the caller must free the 'group' of pages as they can not be used to form a gigantic page. After freeing pages, the runtime caller (alloc_fresh_huge_page) will retry the allocation once. Boot time allocations can not be retried. The routine prep_compound_page also unconditionally sets the ref count of compound page tail pages to zero. However, in this case the buddy allocator is constructing a compound page from freshly allocated pages. The ref count on those freshly allocated pages is already zero, so the set_page_count(p, 0) is unnecessary and could lead to confusion. Just remove it. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210622021423.154662-3-mike.kravetz@oracle.com Fixes: 58a84aa92723 ("thp: set compound tail page _count to zero") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jann Horn <jannh@google.com> Cc: Youquan Song <youquan.song@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:34 +03:00
bool retry = false;
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
hugetlb: address ref count racing in prep_compound_gigantic_page In [1], Jann Horn points out a possible race between prep_compound_gigantic_page and __page_cache_add_speculative. The root cause of the possible race is prep_compound_gigantic_page uncondittionally setting the ref count of pages to zero. It does this because prep_compound_gigantic_page is handed a 'group' of pages from an allocator and needs to convert that group of pages to a compound page. The ref count of each page in this 'group' is one as set by the allocator. However, the ref count of compound page tail pages must be zero. The potential race comes about when ref counted pages are returned from the allocator. When this happens, other mm code could also take a reference on the page. __page_cache_add_speculative is one such example. Therefore, prep_compound_gigantic_page can not just set the ref count of pages to zero as it does today. Doing so would lose the reference taken by any other code. This would lead to BUGs in code checking ref counts and could possibly even lead to memory corruption. There are two possible ways to address this issue. 1) Make all allocators of gigantic groups of pages be able to return a properly constructed compound page. 2) Make prep_compound_gigantic_page be more careful when constructing a compound page. This patch takes approach 2. In prep_compound_gigantic_page, use cmpxchg to only set ref count to zero if it is one. If the cmpxchg fails, call synchronize_rcu() in the hope that the extra ref count will be driopped during a rcu grace period. This is not a performance critical code path and the wait should be accceptable. If the ref count is still inflated after the grace period, then undo any modifications made and return an error. Currently prep_compound_gigantic_page is type void and does not return errors. Modify the two callers to check for and handle error returns. On error, the caller must free the 'group' of pages as they can not be used to form a gigantic page. After freeing pages, the runtime caller (alloc_fresh_huge_page) will retry the allocation once. Boot time allocations can not be retried. The routine prep_compound_page also unconditionally sets the ref count of compound page tail pages to zero. However, in this case the buddy allocator is constructing a compound page from freshly allocated pages. The ref count on those freshly allocated pages is already zero, so the set_page_count(p, 0) is unnecessary and could lead to confusion. Just remove it. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210622021423.154662-3-mike.kravetz@oracle.com Fixes: 58a84aa92723 ("thp: set compound tail page _count to zero") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jann Horn <jannh@google.com> Cc: Youquan Song <youquan.song@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:34 +03:00
retry:
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
if (hstate_is_gigantic(h))
page = alloc_gigantic_page(h, gfp_mask, nid, nmask);
else
page = alloc_buddy_huge_page(h, gfp_mask,
nid, nmask, node_alloc_noretry);
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
if (!page)
return NULL;
hugetlb: address ref count racing in prep_compound_gigantic_page In [1], Jann Horn points out a possible race between prep_compound_gigantic_page and __page_cache_add_speculative. The root cause of the possible race is prep_compound_gigantic_page uncondittionally setting the ref count of pages to zero. It does this because prep_compound_gigantic_page is handed a 'group' of pages from an allocator and needs to convert that group of pages to a compound page. The ref count of each page in this 'group' is one as set by the allocator. However, the ref count of compound page tail pages must be zero. The potential race comes about when ref counted pages are returned from the allocator. When this happens, other mm code could also take a reference on the page. __page_cache_add_speculative is one such example. Therefore, prep_compound_gigantic_page can not just set the ref count of pages to zero as it does today. Doing so would lose the reference taken by any other code. This would lead to BUGs in code checking ref counts and could possibly even lead to memory corruption. There are two possible ways to address this issue. 1) Make all allocators of gigantic groups of pages be able to return a properly constructed compound page. 2) Make prep_compound_gigantic_page be more careful when constructing a compound page. This patch takes approach 2. In prep_compound_gigantic_page, use cmpxchg to only set ref count to zero if it is one. If the cmpxchg fails, call synchronize_rcu() in the hope that the extra ref count will be driopped during a rcu grace period. This is not a performance critical code path and the wait should be accceptable. If the ref count is still inflated after the grace period, then undo any modifications made and return an error. Currently prep_compound_gigantic_page is type void and does not return errors. Modify the two callers to check for and handle error returns. On error, the caller must free the 'group' of pages as they can not be used to form a gigantic page. After freeing pages, the runtime caller (alloc_fresh_huge_page) will retry the allocation once. Boot time allocations can not be retried. The routine prep_compound_page also unconditionally sets the ref count of compound page tail pages to zero. However, in this case the buddy allocator is constructing a compound page from freshly allocated pages. The ref count on those freshly allocated pages is already zero, so the set_page_count(p, 0) is unnecessary and could lead to confusion. Just remove it. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210622021423.154662-3-mike.kravetz@oracle.com Fixes: 58a84aa92723 ("thp: set compound tail page _count to zero") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jann Horn <jannh@google.com> Cc: Youquan Song <youquan.song@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:34 +03:00
if (hstate_is_gigantic(h)) {
if (!prep_compound_gigantic_page(page, huge_page_order(h))) {
/*
* Rare failure to convert pages to compound page.
* Free pages and try again - ONCE!
*/
free_gigantic_page(page, huge_page_order(h));
if (!retry) {
retry = true;
goto retry;
}
return NULL;
}
}
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
prep_new_huge_page(h, page, page_to_nid(page));
return page;
}
mm, hugetlb: unify core page allocation accounting and initialization Patch series "mm, hugetlb: allocation API and migration improvements" Motivation: this is a follow up for [3] for the allocation API and [4] for the hugetlb migration. It wasn't really easy to split those into two separate patch series as they share some code. My primary motivation to touch this code is to make the gigantic pages migration working. The giga pages allocation code is just too fragile and hacked into the hugetlb code now. This series tries to move giga pages closer to the first class citizen. We are not there yet but having 5 patches is quite a lot already and it will already make the code much easier to follow. I will come with other changes on top after this sees some review. The first two patches should be trivial to review. The third patch changes the way how we migrate huge pages. Newly allocated pages are a subject of the overcommit check and they participate surplus accounting which is quite unfortunate as the changelog explains. This patch doesn't change anything wrt. giga pages. Patch #4 removes the surplus accounting hack from __alloc_surplus_huge_page. I hope I didn't miss anything there and a deeper review is really due there. Patch #5 finally unifies allocation paths and giga pages shouldn't be any special anymore. There is also some renaming going on as well. This patch (of 6): hugetlb allocator has two entry points to the page allocator - alloc_fresh_huge_page_node - __hugetlb_alloc_buddy_huge_page The two differ very subtly in two aspects. The first one doesn't care about HTLB_BUDDY_* stats and it doesn't initialize the huge page. prep_new_huge_page is not used because it not only initializes hugetlb specific stuff but because it also put_page and releases the page to the hugetlb pool which is not what is required in some contexts. This makes things more complicated than necessary. Simplify things by a) removing the page allocator entry point duplicity and only keep __hugetlb_alloc_buddy_huge_page and b) make prep_new_huge_page more reusable by removing the put_page which moves the page to the allocator pool. All current callers are updated to call put_page explicitly. Later patches will add new callers which won't need it. This patch shouldn't introduce any functional change. Link: http://lkml.kernel.org/r/20180103093213.26329-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:41 +03:00
/*
* Allocates a fresh page to the hugetlb allocator pool in the node interleaved
* manner.
*/
static int alloc_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
nodemask_t *node_alloc_noretry)
{
struct page *page;
int nr_nodes, node;
mm, hugetlb: unify core page allocation accounting and initialization Patch series "mm, hugetlb: allocation API and migration improvements" Motivation: this is a follow up for [3] for the allocation API and [4] for the hugetlb migration. It wasn't really easy to split those into two separate patch series as they share some code. My primary motivation to touch this code is to make the gigantic pages migration working. The giga pages allocation code is just too fragile and hacked into the hugetlb code now. This series tries to move giga pages closer to the first class citizen. We are not there yet but having 5 patches is quite a lot already and it will already make the code much easier to follow. I will come with other changes on top after this sees some review. The first two patches should be trivial to review. The third patch changes the way how we migrate huge pages. Newly allocated pages are a subject of the overcommit check and they participate surplus accounting which is quite unfortunate as the changelog explains. This patch doesn't change anything wrt. giga pages. Patch #4 removes the surplus accounting hack from __alloc_surplus_huge_page. I hope I didn't miss anything there and a deeper review is really due there. Patch #5 finally unifies allocation paths and giga pages shouldn't be any special anymore. There is also some renaming going on as well. This patch (of 6): hugetlb allocator has two entry points to the page allocator - alloc_fresh_huge_page_node - __hugetlb_alloc_buddy_huge_page The two differ very subtly in two aspects. The first one doesn't care about HTLB_BUDDY_* stats and it doesn't initialize the huge page. prep_new_huge_page is not used because it not only initializes hugetlb specific stuff but because it also put_page and releases the page to the hugetlb pool which is not what is required in some contexts. This makes things more complicated than necessary. Simplify things by a) removing the page allocator entry point duplicity and only keep __hugetlb_alloc_buddy_huge_page and b) make prep_new_huge_page more reusable by removing the put_page which moves the page to the allocator pool. All current callers are updated to call put_page explicitly. Later patches will add new callers which won't need it. This patch shouldn't introduce any functional change. Link: http://lkml.kernel.org/r/20180103093213.26329-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:41 +03:00
gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
page = alloc_fresh_huge_page(h, gfp_mask, node, nodes_allowed,
node_alloc_noretry);
mm, hugetlb: unify core page allocation accounting and initialization Patch series "mm, hugetlb: allocation API and migration improvements" Motivation: this is a follow up for [3] for the allocation API and [4] for the hugetlb migration. It wasn't really easy to split those into two separate patch series as they share some code. My primary motivation to touch this code is to make the gigantic pages migration working. The giga pages allocation code is just too fragile and hacked into the hugetlb code now. This series tries to move giga pages closer to the first class citizen. We are not there yet but having 5 patches is quite a lot already and it will already make the code much easier to follow. I will come with other changes on top after this sees some review. The first two patches should be trivial to review. The third patch changes the way how we migrate huge pages. Newly allocated pages are a subject of the overcommit check and they participate surplus accounting which is quite unfortunate as the changelog explains. This patch doesn't change anything wrt. giga pages. Patch #4 removes the surplus accounting hack from __alloc_surplus_huge_page. I hope I didn't miss anything there and a deeper review is really due there. Patch #5 finally unifies allocation paths and giga pages shouldn't be any special anymore. There is also some renaming going on as well. This patch (of 6): hugetlb allocator has two entry points to the page allocator - alloc_fresh_huge_page_node - __hugetlb_alloc_buddy_huge_page The two differ very subtly in two aspects. The first one doesn't care about HTLB_BUDDY_* stats and it doesn't initialize the huge page. prep_new_huge_page is not used because it not only initializes hugetlb specific stuff but because it also put_page and releases the page to the hugetlb pool which is not what is required in some contexts. This makes things more complicated than necessary. Simplify things by a) removing the page allocator entry point duplicity and only keep __hugetlb_alloc_buddy_huge_page and b) make prep_new_huge_page more reusable by removing the put_page which moves the page to the allocator pool. All current callers are updated to call put_page explicitly. Later patches will add new callers which won't need it. This patch shouldn't introduce any functional change. Link: http://lkml.kernel.org/r/20180103093213.26329-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:41 +03:00
if (page)
break;
}
mm, hugetlb: unify core page allocation accounting and initialization Patch series "mm, hugetlb: allocation API and migration improvements" Motivation: this is a follow up for [3] for the allocation API and [4] for the hugetlb migration. It wasn't really easy to split those into two separate patch series as they share some code. My primary motivation to touch this code is to make the gigantic pages migration working. The giga pages allocation code is just too fragile and hacked into the hugetlb code now. This series tries to move giga pages closer to the first class citizen. We are not there yet but having 5 patches is quite a lot already and it will already make the code much easier to follow. I will come with other changes on top after this sees some review. The first two patches should be trivial to review. The third patch changes the way how we migrate huge pages. Newly allocated pages are a subject of the overcommit check and they participate surplus accounting which is quite unfortunate as the changelog explains. This patch doesn't change anything wrt. giga pages. Patch #4 removes the surplus accounting hack from __alloc_surplus_huge_page. I hope I didn't miss anything there and a deeper review is really due there. Patch #5 finally unifies allocation paths and giga pages shouldn't be any special anymore. There is also some renaming going on as well. This patch (of 6): hugetlb allocator has two entry points to the page allocator - alloc_fresh_huge_page_node - __hugetlb_alloc_buddy_huge_page The two differ very subtly in two aspects. The first one doesn't care about HTLB_BUDDY_* stats and it doesn't initialize the huge page. prep_new_huge_page is not used because it not only initializes hugetlb specific stuff but because it also put_page and releases the page to the hugetlb pool which is not what is required in some contexts. This makes things more complicated than necessary. Simplify things by a) removing the page allocator entry point duplicity and only keep __hugetlb_alloc_buddy_huge_page and b) make prep_new_huge_page more reusable by removing the put_page which moves the page to the allocator pool. All current callers are updated to call put_page explicitly. Later patches will add new callers which won't need it. This patch shouldn't introduce any functional change. Link: http://lkml.kernel.org/r/20180103093213.26329-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:41 +03:00
if (!page)
return 0;
mm, hugetlb: unify core page allocation accounting and initialization Patch series "mm, hugetlb: allocation API and migration improvements" Motivation: this is a follow up for [3] for the allocation API and [4] for the hugetlb migration. It wasn't really easy to split those into two separate patch series as they share some code. My primary motivation to touch this code is to make the gigantic pages migration working. The giga pages allocation code is just too fragile and hacked into the hugetlb code now. This series tries to move giga pages closer to the first class citizen. We are not there yet but having 5 patches is quite a lot already and it will already make the code much easier to follow. I will come with other changes on top after this sees some review. The first two patches should be trivial to review. The third patch changes the way how we migrate huge pages. Newly allocated pages are a subject of the overcommit check and they participate surplus accounting which is quite unfortunate as the changelog explains. This patch doesn't change anything wrt. giga pages. Patch #4 removes the surplus accounting hack from __alloc_surplus_huge_page. I hope I didn't miss anything there and a deeper review is really due there. Patch #5 finally unifies allocation paths and giga pages shouldn't be any special anymore. There is also some renaming going on as well. This patch (of 6): hugetlb allocator has two entry points to the page allocator - alloc_fresh_huge_page_node - __hugetlb_alloc_buddy_huge_page The two differ very subtly in two aspects. The first one doesn't care about HTLB_BUDDY_* stats and it doesn't initialize the huge page. prep_new_huge_page is not used because it not only initializes hugetlb specific stuff but because it also put_page and releases the page to the hugetlb pool which is not what is required in some contexts. This makes things more complicated than necessary. Simplify things by a) removing the page allocator entry point duplicity and only keep __hugetlb_alloc_buddy_huge_page and b) make prep_new_huge_page more reusable by removing the put_page which moves the page to the allocator pool. All current callers are updated to call put_page explicitly. Later patches will add new callers which won't need it. This patch shouldn't introduce any functional change. Link: http://lkml.kernel.org/r/20180103093213.26329-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:41 +03:00
put_page(page); /* free it into the hugepage allocator */
return 1;
}
/*
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
* Remove huge page from pool from next node to free. Attempt to keep
* persistent huge pages more or less balanced over allowed nodes.
* This routine only 'removes' the hugetlb page. The caller must make
* an additional call to free the page to low level allocators.
* Called with hugetlb_lock locked.
*/
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
static struct page *remove_pool_huge_page(struct hstate *h,
nodemask_t *nodes_allowed,
bool acct_surplus)
{
int nr_nodes, node;
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
struct page *page = NULL;
lockdep_assert_held(&hugetlb_lock);
for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
/*
* If we're returning unused surplus pages, only examine
* nodes with surplus pages.
*/
if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
!list_empty(&h->hugepage_freelists[node])) {
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
page = list_entry(h->hugepage_freelists[node].next,
struct page, lru);
hugetlb: create remove_hugetlb_page() to separate functionality The new remove_hugetlb_page() routine is designed to remove a hugetlb page from hugetlbfs processing. It will remove the page from the active or free list, update global counters and set the compound page destructor to NULL so that PageHuge() will return false for the 'page'. After this call, the 'page' can be treated as a normal compound page or a collection of base size pages. update_and_free_page no longer decrements h->nr_huge_pages{_node} as this is performed in remove_hugetlb_page. The only functionality performed by update_and_free_page is to free the base pages to the lower level allocators. update_and_free_page is typically called after remove_hugetlb_page. remove_hugetlb_page is to be called with the hugetlb_lock held. Creating this routine and separating functionality is in preparation for restructuring code to reduce lock hold times. This commit should not introduce any changes to functionality. Link: https://lkml.kernel.org/r/20210409205254.242291-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:55 +03:00
remove_hugetlb_page(h, page, acct_surplus);
break;
}
}
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
return page;
}
mm: memory-hotplug: enable memory hotplug to handle hugepage Until now we can't offline memory blocks which contain hugepages because a hugepage is considered as an unmovable page. But now with this patch series, a hugepage has become movable, so by using hugepage migration we can offline such memory blocks. What's different from other users of hugepage migration is that we need to decompose all the hugepages inside the target memory block into free buddy pages after hugepage migration, because otherwise free hugepages remaining in the memory block intervene the memory offlining. For this reason we introduce new functions dissolve_free_huge_page() and dissolve_free_huge_pages(). Other than that, what this patch does is straightforwardly to add hugepage migration code, that is, adding hugepage code to the functions which scan over pfn and collect hugepages to be migrated, and adding a hugepage allocation function to alloc_migrate_target(). As for larger hugepages (1GB for x86_64), it's not easy to do hotremove over them because it's larger than memory block. So we now simply leave it to fail as it is. [yongjun_wei@trendmicro.com.cn: remove duplicated include] Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:22:09 +04:00
/*
* Dissolve a given free hugepage into free buddy pages. This function does
mm: hugetlb: soft-offline: dissolve_free_huge_page() return zero on !PageHuge madvise(MADV_SOFT_OFFLINE) often returns -EBUSY when calling soft offline for hugepages with overcommitting enabled. That was caused by the suboptimal code in current soft-offline code. See the following part: ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL, MIGRATE_SYNC, MR_MEMORY_FAILURE); if (ret) { ... } else { /* * We set PG_hwpoison only when the migration source hugepage * was successfully dissolved, because otherwise hwpoisoned * hugepage remains on free hugepage list, then userspace will * find it as SIGBUS by allocation failure. That's not expected * in soft-offlining. */ ret = dissolve_free_huge_page(page); if (!ret) { if (set_hwpoison_free_buddy_page(page)) num_poisoned_pages_inc(); } } return ret; Here dissolve_free_huge_page() returns -EBUSY if the migration source page was freed into buddy in migrate_pages(), but even in that case we actually has a chance that set_hwpoison_free_buddy_page() succeeds. So that means current code gives up offlining too early now. dissolve_free_huge_page() checks that a given hugepage is suitable for dissolving, where we should return success for !PageHuge() case because the given hugepage is considered as already dissolved. This change also affects other callers of dissolve_free_huge_page(), which are cleaned up together. [n-horiguchi@ah.jp.nec.com: v3] Link: http://lkml.kernel.org/r/1560761476-4651-3-git-send-email-n-horiguchi@ah.jp.nec.comLink: http://lkml.kernel.org/r/1560154686-18497-3-git-send-email-n-horiguchi@ah.jp.nec.com Fixes: 6bc9b56433b76 ("mm: fix race on soft-offlining") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Chen, Jerry T <jerry.t.chen@intel.com> Tested-by: Chen, Jerry T <jerry.t.chen@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Xishi Qiu <xishi.qiuxishi@alibaba-inc.com> Cc: "Chen, Jerry T" <jerry.t.chen@intel.com> Cc: "Zhuo, Qiuxu" <qiuxu.zhuo@intel.com> Cc: <stable@vger.kernel.org> [4.19+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-06-28 22:06:56 +03:00
* nothing for in-use hugepages and non-hugepages.
* This function returns values like below:
*
mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page When we free a HugeTLB page to the buddy allocator, we need to allocate the vmemmap pages associated with it. However, we may not be able to allocate the vmemmap pages when the system is under memory pressure. In this case, we just refuse to free the HugeTLB page. This changes behavior in some corner cases as listed below: 1) Failing to free a huge page triggered by the user (decrease nr_pages). User needs to try again later. 2) Failing to free a surplus huge page when freed by the application. Try again later when freeing a huge page next time. 3) Failing to dissolve a free huge page on ZONE_MOVABLE via offline_pages(). This can happen when we have plenty of ZONE_MOVABLE memory, but not enough kernel memory to allocate vmemmmap pages. We may even be able to migrate huge page contents, but will not be able to dissolve the source huge page. This will prevent an offline operation and is unfortunate as memory offlining is expected to succeed on movable zones. Users that depend on memory hotplug to succeed for movable zones should carefully consider whether the memory savings gained from this feature are worth the risk of possibly not being able to offline memory in certain situations. 4) Failing to dissolve a huge page on CMA/ZONE_MOVABLE via alloc_contig_range() - once we have that handling in place. Mainly affects CMA and virtio-mem. Similar to 3). virito-mem will handle migration errors gracefully. CMA might be able to fallback on other free areas within the CMA region. Vmemmap pages are allocated from the page freeing context. In order for those allocations to be not disruptive (e.g. trigger oom killer) __GFP_NORETRY is used. hugetlb_lock is dropped for the allocation because a non sleeping allocation would be too fragile and it could fail too easily under memory pressure. GFP_ATOMIC or other modes to access memory reserves is not used because we want to prevent consuming reserves under heavy hugetlb freeing. [mike.kravetz@oracle.com: fix dissolve_free_huge_page use of tail/head page] Link: https://lkml.kernel.org/r/20210527231225.226987-1-mike.kravetz@oracle.com [willy@infradead.org: fix alloc_vmemmap_page_list documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-6-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-7-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:21 +03:00
* -ENOMEM: failed to allocate vmemmap pages to free the freed hugepages
* when the system is under memory pressure and the feature of
* freeing unused vmemmap pages associated with each hugetlb page
* is enabled.
* -EBUSY: failed to dissolved free hugepages or the hugepage is in-use
* (allocated or reserved.)
* 0: successfully dissolved free hugepages or the page is not a
* hugepage (considered as already dissolved)
mm: memory-hotplug: enable memory hotplug to handle hugepage Until now we can't offline memory blocks which contain hugepages because a hugepage is considered as an unmovable page. But now with this patch series, a hugepage has become movable, so by using hugepage migration we can offline such memory blocks. What's different from other users of hugepage migration is that we need to decompose all the hugepages inside the target memory block into free buddy pages after hugepage migration, because otherwise free hugepages remaining in the memory block intervene the memory offlining. For this reason we introduce new functions dissolve_free_huge_page() and dissolve_free_huge_pages(). Other than that, what this patch does is straightforwardly to add hugepage migration code, that is, adding hugepage code to the functions which scan over pfn and collect hugepages to be migrated, and adding a hugepage allocation function to alloc_migrate_target(). As for larger hugepages (1GB for x86_64), it's not easy to do hotremove over them because it's larger than memory block. So we now simply leave it to fail as it is. [yongjun_wei@trendmicro.com.cn: remove duplicated include] Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:22:09 +04:00
*/
int dissolve_free_huge_page(struct page *page)
mm: memory-hotplug: enable memory hotplug to handle hugepage Until now we can't offline memory blocks which contain hugepages because a hugepage is considered as an unmovable page. But now with this patch series, a hugepage has become movable, so by using hugepage migration we can offline such memory blocks. What's different from other users of hugepage migration is that we need to decompose all the hugepages inside the target memory block into free buddy pages after hugepage migration, because otherwise free hugepages remaining in the memory block intervene the memory offlining. For this reason we introduce new functions dissolve_free_huge_page() and dissolve_free_huge_pages(). Other than that, what this patch does is straightforwardly to add hugepage migration code, that is, adding hugepage code to the functions which scan over pfn and collect hugepages to be migrated, and adding a hugepage allocation function to alloc_migrate_target(). As for larger hugepages (1GB for x86_64), it's not easy to do hotremove over them because it's larger than memory block. So we now simply leave it to fail as it is. [yongjun_wei@trendmicro.com.cn: remove duplicated include] Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:22:09 +04:00
{
mm: fix race on soft-offlining free huge pages Patch series "mm: soft-offline: fix race against page allocation". Xishi recently reported the issue about race on reusing the target pages of soft offlining. Discussion and analysis showed that we need make sure that setting PG_hwpoison should be done in the right place under zone->lock for soft offline. 1/2 handles free hugepage's case, and 2/2 hanldes free buddy page's case. This patch (of 2): There's a race condition between soft offline and hugetlb_fault which causes unexpected process killing and/or hugetlb allocation failure. The process killing is caused by the following flow: CPU 0 CPU 1 CPU 2 soft offline get_any_page // find the hugetlb is free mmap a hugetlb file page fault ... hugetlb_fault hugetlb_no_page alloc_huge_page // succeed soft_offline_free_page // set hwpoison flag mmap the hugetlb file page fault ... hugetlb_fault hugetlb_no_page find_lock_page return VM_FAULT_HWPOISON mm_fault_error do_sigbus // kill the process The hugetlb allocation failure comes from the following flow: CPU 0 CPU 1 mmap a hugetlb file // reserve all free page but don't fault-in soft offline get_any_page // find the hugetlb is free soft_offline_free_page // set hwpoison flag dissolve_free_huge_page // fail because all free hugepages are reserved page fault ... hugetlb_fault hugetlb_no_page alloc_huge_page ... dequeue_huge_page_node_exact // ignore hwpoisoned hugepage // and finally fail due to no-mem The root cause of this is that current soft-offline code is written based on an assumption that PageHWPoison flag should be set at first to avoid accessing the corrupted data. This makes sense for memory_failure() or hard offline, but does not for soft offline because soft offline is about corrected (not uncorrected) error and is safe from data lost. This patch changes soft offline semantics where it sets PageHWPoison flag only after containment of the error page completes successfully. Link: http://lkml.kernel.org/r/1531452366-11661-2-git-send-email-n-horiguchi@ah.jp.nec.com Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Xishi Qiu <xishi.qiuxishi@alibaba-inc.com> Suggested-by: Xishi Qiu <xishi.qiuxishi@alibaba-inc.com> Tested-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: <zy.zhengyi@alibaba-inc.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-24 03:00:38 +03:00
int rc = -EBUSY;
retry:
mm: hugetlb: soft-offline: dissolve_free_huge_page() return zero on !PageHuge madvise(MADV_SOFT_OFFLINE) often returns -EBUSY when calling soft offline for hugepages with overcommitting enabled. That was caused by the suboptimal code in current soft-offline code. See the following part: ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL, MIGRATE_SYNC, MR_MEMORY_FAILURE); if (ret) { ... } else { /* * We set PG_hwpoison only when the migration source hugepage * was successfully dissolved, because otherwise hwpoisoned * hugepage remains on free hugepage list, then userspace will * find it as SIGBUS by allocation failure. That's not expected * in soft-offlining. */ ret = dissolve_free_huge_page(page); if (!ret) { if (set_hwpoison_free_buddy_page(page)) num_poisoned_pages_inc(); } } return ret; Here dissolve_free_huge_page() returns -EBUSY if the migration source page was freed into buddy in migrate_pages(), but even in that case we actually has a chance that set_hwpoison_free_buddy_page() succeeds. So that means current code gives up offlining too early now. dissolve_free_huge_page() checks that a given hugepage is suitable for dissolving, where we should return success for !PageHuge() case because the given hugepage is considered as already dissolved. This change also affects other callers of dissolve_free_huge_page(), which are cleaned up together. [n-horiguchi@ah.jp.nec.com: v3] Link: http://lkml.kernel.org/r/1560761476-4651-3-git-send-email-n-horiguchi@ah.jp.nec.comLink: http://lkml.kernel.org/r/1560154686-18497-3-git-send-email-n-horiguchi@ah.jp.nec.com Fixes: 6bc9b56433b76 ("mm: fix race on soft-offlining") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Chen, Jerry T <jerry.t.chen@intel.com> Tested-by: Chen, Jerry T <jerry.t.chen@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Xishi Qiu <xishi.qiuxishi@alibaba-inc.com> Cc: "Chen, Jerry T" <jerry.t.chen@intel.com> Cc: "Zhuo, Qiuxu" <qiuxu.zhuo@intel.com> Cc: <stable@vger.kernel.org> [4.19+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-06-28 22:06:56 +03:00
/* Not to disrupt normal path by vainly holding hugetlb_lock */
if (!PageHuge(page))
return 0;
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
mm: hugetlb: soft-offline: dissolve_free_huge_page() return zero on !PageHuge madvise(MADV_SOFT_OFFLINE) often returns -EBUSY when calling soft offline for hugepages with overcommitting enabled. That was caused by the suboptimal code in current soft-offline code. See the following part: ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL, MIGRATE_SYNC, MR_MEMORY_FAILURE); if (ret) { ... } else { /* * We set PG_hwpoison only when the migration source hugepage * was successfully dissolved, because otherwise hwpoisoned * hugepage remains on free hugepage list, then userspace will * find it as SIGBUS by allocation failure. That's not expected * in soft-offlining. */ ret = dissolve_free_huge_page(page); if (!ret) { if (set_hwpoison_free_buddy_page(page)) num_poisoned_pages_inc(); } } return ret; Here dissolve_free_huge_page() returns -EBUSY if the migration source page was freed into buddy in migrate_pages(), but even in that case we actually has a chance that set_hwpoison_free_buddy_page() succeeds. So that means current code gives up offlining too early now. dissolve_free_huge_page() checks that a given hugepage is suitable for dissolving, where we should return success for !PageHuge() case because the given hugepage is considered as already dissolved. This change also affects other callers of dissolve_free_huge_page(), which are cleaned up together. [n-horiguchi@ah.jp.nec.com: v3] Link: http://lkml.kernel.org/r/1560761476-4651-3-git-send-email-n-horiguchi@ah.jp.nec.comLink: http://lkml.kernel.org/r/1560154686-18497-3-git-send-email-n-horiguchi@ah.jp.nec.com Fixes: 6bc9b56433b76 ("mm: fix race on soft-offlining") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Chen, Jerry T <jerry.t.chen@intel.com> Tested-by: Chen, Jerry T <jerry.t.chen@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Xishi Qiu <xishi.qiuxishi@alibaba-inc.com> Cc: "Chen, Jerry T" <jerry.t.chen@intel.com> Cc: "Zhuo, Qiuxu" <qiuxu.zhuo@intel.com> Cc: <stable@vger.kernel.org> [4.19+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-06-28 22:06:56 +03:00
if (!PageHuge(page)) {
rc = 0;
goto out;
}
if (!page_count(page)) {
mm/hugetlb: fix memory offline with hugepage size > memory block size Patch series "mm/hugetlb: memory offline issues with hugepages", v4. This addresses several issues with hugepages and memory offline. While the first patch fixes a panic, and is therefore rather important, the last patch is just a performance optimization. The second patch fixes a theoretical issue with reserved hugepages, while still leaving some ugly usability issue, see description. This patch (of 3): dissolve_free_huge_pages() will either run into the VM_BUG_ON() or a list corruption and addressing exception when trying to set a memory block offline that is part (but not the first part) of a "gigantic" hugetlb page with a size > memory block size. When no other smaller hugetlb page sizes are present, the VM_BUG_ON() will trigger directly. In the other case we will run into an addressing exception later, because dissolve_free_huge_page() will not work on the head page of the compound hugetlb page which will result in a NULL hstate from page_hstate(). To fix this, first remove the VM_BUG_ON() because it is wrong, and then use the compound head page in dissolve_free_huge_page(). This means that an unused pre-allocated gigantic page that has any part of itself inside the memory block that is going offline will be dissolved completely. Losing an unused gigantic hugepage is preferable to failing the memory offline, for example in the situation where a (possibly faulty) memory DIMM needs to go offline. Fixes: c8721bbb ("mm: memory-hotplug: enable memory hotplug to handle hugepage") Link: http://lkml.kernel.org/r/20160926172811.94033-2-gerald.schaefer@de.ibm.com Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Rui Teng <rui.teng@linux.vnet.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-08 03:01:07 +03:00
struct page *head = compound_head(page);
struct hstate *h = page_hstate(head);
mm: fix race on soft-offlining free huge pages Patch series "mm: soft-offline: fix race against page allocation". Xishi recently reported the issue about race on reusing the target pages of soft offlining. Discussion and analysis showed that we need make sure that setting PG_hwpoison should be done in the right place under zone->lock for soft offline. 1/2 handles free hugepage's case, and 2/2 hanldes free buddy page's case. This patch (of 2): There's a race condition between soft offline and hugetlb_fault which causes unexpected process killing and/or hugetlb allocation failure. The process killing is caused by the following flow: CPU 0 CPU 1 CPU 2 soft offline get_any_page // find the hugetlb is free mmap a hugetlb file page fault ... hugetlb_fault hugetlb_no_page alloc_huge_page // succeed soft_offline_free_page // set hwpoison flag mmap the hugetlb file page fault ... hugetlb_fault hugetlb_no_page find_lock_page return VM_FAULT_HWPOISON mm_fault_error do_sigbus // kill the process The hugetlb allocation failure comes from the following flow: CPU 0 CPU 1 mmap a hugetlb file // reserve all free page but don't fault-in soft offline get_any_page // find the hugetlb is free soft_offline_free_page // set hwpoison flag dissolve_free_huge_page // fail because all free hugepages are reserved page fault ... hugetlb_fault hugetlb_no_page alloc_huge_page ... dequeue_huge_page_node_exact // ignore hwpoisoned hugepage // and finally fail due to no-mem The root cause of this is that current soft-offline code is written based on an assumption that PageHWPoison flag should be set at first to avoid accessing the corrupted data. This makes sense for memory_failure() or hard offline, but does not for soft offline because soft offline is about corrected (not uncorrected) error and is safe from data lost. This patch changes soft offline semantics where it sets PageHWPoison flag only after containment of the error page completes successfully. Link: http://lkml.kernel.org/r/1531452366-11661-2-git-send-email-n-horiguchi@ah.jp.nec.com Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Xishi Qiu <xishi.qiuxishi@alibaba-inc.com> Suggested-by: Xishi Qiu <xishi.qiuxishi@alibaba-inc.com> Tested-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: <zy.zhengyi@alibaba-inc.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-24 03:00:38 +03:00
if (h->free_huge_pages - h->resv_huge_pages == 0)
goto out;
/*
* We should make sure that the page is already on the free list
* when it is dissolved.
*/
if (unlikely(!HPageFreed(head))) {
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
cond_resched();
/*
* Theoretically, we should return -EBUSY when we
* encounter this race. In fact, we have a chance
* to successfully dissolve the page if we do a
* retry. Because the race window is quite small.
* If we seize this opportunity, it is an optimization
* for increasing the success rate of dissolving page.
*/
goto retry;
}
remove_hugetlb_page(h, head, false);
h->max_huge_pages--;
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page When we free a HugeTLB page to the buddy allocator, we need to allocate the vmemmap pages associated with it. However, we may not be able to allocate the vmemmap pages when the system is under memory pressure. In this case, we just refuse to free the HugeTLB page. This changes behavior in some corner cases as listed below: 1) Failing to free a huge page triggered by the user (decrease nr_pages). User needs to try again later. 2) Failing to free a surplus huge page when freed by the application. Try again later when freeing a huge page next time. 3) Failing to dissolve a free huge page on ZONE_MOVABLE via offline_pages(). This can happen when we have plenty of ZONE_MOVABLE memory, but not enough kernel memory to allocate vmemmmap pages. We may even be able to migrate huge page contents, but will not be able to dissolve the source huge page. This will prevent an offline operation and is unfortunate as memory offlining is expected to succeed on movable zones. Users that depend on memory hotplug to succeed for movable zones should carefully consider whether the memory savings gained from this feature are worth the risk of possibly not being able to offline memory in certain situations. 4) Failing to dissolve a huge page on CMA/ZONE_MOVABLE via alloc_contig_range() - once we have that handling in place. Mainly affects CMA and virtio-mem. Similar to 3). virito-mem will handle migration errors gracefully. CMA might be able to fallback on other free areas within the CMA region. Vmemmap pages are allocated from the page freeing context. In order for those allocations to be not disruptive (e.g. trigger oom killer) __GFP_NORETRY is used. hugetlb_lock is dropped for the allocation because a non sleeping allocation would be too fragile and it could fail too easily under memory pressure. GFP_ATOMIC or other modes to access memory reserves is not used because we want to prevent consuming reserves under heavy hugetlb freeing. [mike.kravetz@oracle.com: fix dissolve_free_huge_page use of tail/head page] Link: https://lkml.kernel.org/r/20210527231225.226987-1-mike.kravetz@oracle.com [willy@infradead.org: fix alloc_vmemmap_page_list documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-6-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-7-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:21 +03:00
/*
* Normally update_and_free_page will allocate required vmemmmap
* before freeing the page. update_and_free_page will fail to
* free the page if it can not allocate required vmemmap. We
* need to adjust max_huge_pages if the page is not freed.
* Attempt to allocate vmemmmap here so that we can take
* appropriate action on failure.
*/
rc = hugetlb_vmemmap_alloc(h, head);
mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page When we free a HugeTLB page to the buddy allocator, we need to allocate the vmemmap pages associated with it. However, we may not be able to allocate the vmemmap pages when the system is under memory pressure. In this case, we just refuse to free the HugeTLB page. This changes behavior in some corner cases as listed below: 1) Failing to free a huge page triggered by the user (decrease nr_pages). User needs to try again later. 2) Failing to free a surplus huge page when freed by the application. Try again later when freeing a huge page next time. 3) Failing to dissolve a free huge page on ZONE_MOVABLE via offline_pages(). This can happen when we have plenty of ZONE_MOVABLE memory, but not enough kernel memory to allocate vmemmmap pages. We may even be able to migrate huge page contents, but will not be able to dissolve the source huge page. This will prevent an offline operation and is unfortunate as memory offlining is expected to succeed on movable zones. Users that depend on memory hotplug to succeed for movable zones should carefully consider whether the memory savings gained from this feature are worth the risk of possibly not being able to offline memory in certain situations. 4) Failing to dissolve a huge page on CMA/ZONE_MOVABLE via alloc_contig_range() - once we have that handling in place. Mainly affects CMA and virtio-mem. Similar to 3). virito-mem will handle migration errors gracefully. CMA might be able to fallback on other free areas within the CMA region. Vmemmap pages are allocated from the page freeing context. In order for those allocations to be not disruptive (e.g. trigger oom killer) __GFP_NORETRY is used. hugetlb_lock is dropped for the allocation because a non sleeping allocation would be too fragile and it could fail too easily under memory pressure. GFP_ATOMIC or other modes to access memory reserves is not used because we want to prevent consuming reserves under heavy hugetlb freeing. [mike.kravetz@oracle.com: fix dissolve_free_huge_page use of tail/head page] Link: https://lkml.kernel.org/r/20210527231225.226987-1-mike.kravetz@oracle.com [willy@infradead.org: fix alloc_vmemmap_page_list documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-6-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-7-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:21 +03:00
if (!rc) {
/*
* Move PageHWPoison flag from head page to the raw
* error page, which makes any subpages rather than
* the error page reusable.
*/
if (PageHWPoison(head) && page != head) {
SetPageHWPoison(page);
ClearPageHWPoison(head);
}
update_and_free_page(h, head, false);
} else {
spin_lock_irq(&hugetlb_lock);
add_hugetlb_page(h, head, false);
h->max_huge_pages++;
spin_unlock_irq(&hugetlb_lock);
}
return rc;
mm: memory-hotplug: enable memory hotplug to handle hugepage Until now we can't offline memory blocks which contain hugepages because a hugepage is considered as an unmovable page. But now with this patch series, a hugepage has become movable, so by using hugepage migration we can offline such memory blocks. What's different from other users of hugepage migration is that we need to decompose all the hugepages inside the target memory block into free buddy pages after hugepage migration, because otherwise free hugepages remaining in the memory block intervene the memory offlining. For this reason we introduce new functions dissolve_free_huge_page() and dissolve_free_huge_pages(). Other than that, what this patch does is straightforwardly to add hugepage migration code, that is, adding hugepage code to the functions which scan over pfn and collect hugepages to be migrated, and adding a hugepage allocation function to alloc_migrate_target(). As for larger hugepages (1GB for x86_64), it's not easy to do hotremove over them because it's larger than memory block. So we now simply leave it to fail as it is. [yongjun_wei@trendmicro.com.cn: remove duplicated include] Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:22:09 +04:00
}
out:
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
return rc;
mm: memory-hotplug: enable memory hotplug to handle hugepage Until now we can't offline memory blocks which contain hugepages because a hugepage is considered as an unmovable page. But now with this patch series, a hugepage has become movable, so by using hugepage migration we can offline such memory blocks. What's different from other users of hugepage migration is that we need to decompose all the hugepages inside the target memory block into free buddy pages after hugepage migration, because otherwise free hugepages remaining in the memory block intervene the memory offlining. For this reason we introduce new functions dissolve_free_huge_page() and dissolve_free_huge_pages(). Other than that, what this patch does is straightforwardly to add hugepage migration code, that is, adding hugepage code to the functions which scan over pfn and collect hugepages to be migrated, and adding a hugepage allocation function to alloc_migrate_target(). As for larger hugepages (1GB for x86_64), it's not easy to do hotremove over them because it's larger than memory block. So we now simply leave it to fail as it is. [yongjun_wei@trendmicro.com.cn: remove duplicated include] Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:22:09 +04:00
}
/*
* Dissolve free hugepages in a given pfn range. Used by memory hotplug to
* make specified memory blocks removable from the system.
mm/hugetlb: fix memory offline with hugepage size > memory block size Patch series "mm/hugetlb: memory offline issues with hugepages", v4. This addresses several issues with hugepages and memory offline. While the first patch fixes a panic, and is therefore rather important, the last patch is just a performance optimization. The second patch fixes a theoretical issue with reserved hugepages, while still leaving some ugly usability issue, see description. This patch (of 3): dissolve_free_huge_pages() will either run into the VM_BUG_ON() or a list corruption and addressing exception when trying to set a memory block offline that is part (but not the first part) of a "gigantic" hugetlb page with a size > memory block size. When no other smaller hugetlb page sizes are present, the VM_BUG_ON() will trigger directly. In the other case we will run into an addressing exception later, because dissolve_free_huge_page() will not work on the head page of the compound hugetlb page which will result in a NULL hstate from page_hstate(). To fix this, first remove the VM_BUG_ON() because it is wrong, and then use the compound head page in dissolve_free_huge_page(). This means that an unused pre-allocated gigantic page that has any part of itself inside the memory block that is going offline will be dissolved completely. Losing an unused gigantic hugepage is preferable to failing the memory offline, for example in the situation where a (possibly faulty) memory DIMM needs to go offline. Fixes: c8721bbb ("mm: memory-hotplug: enable memory hotplug to handle hugepage") Link: http://lkml.kernel.org/r/20160926172811.94033-2-gerald.schaefer@de.ibm.com Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Rui Teng <rui.teng@linux.vnet.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-08 03:01:07 +03:00
* Note that this will dissolve a free gigantic hugepage completely, if any
* part of it lies within the given range.
* Also note that if dissolve_free_huge_page() returns with an error, all
* free hugepages that were dissolved before that error are lost.
mm: memory-hotplug: enable memory hotplug to handle hugepage Until now we can't offline memory blocks which contain hugepages because a hugepage is considered as an unmovable page. But now with this patch series, a hugepage has become movable, so by using hugepage migration we can offline such memory blocks. What's different from other users of hugepage migration is that we need to decompose all the hugepages inside the target memory block into free buddy pages after hugepage migration, because otherwise free hugepages remaining in the memory block intervene the memory offlining. For this reason we introduce new functions dissolve_free_huge_page() and dissolve_free_huge_pages(). Other than that, what this patch does is straightforwardly to add hugepage migration code, that is, adding hugepage code to the functions which scan over pfn and collect hugepages to be migrated, and adding a hugepage allocation function to alloc_migrate_target(). As for larger hugepages (1GB for x86_64), it's not easy to do hotremove over them because it's larger than memory block. So we now simply leave it to fail as it is. [yongjun_wei@trendmicro.com.cn: remove duplicated include] Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:22:09 +04:00
*/
int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
mm: memory-hotplug: enable memory hotplug to handle hugepage Until now we can't offline memory blocks which contain hugepages because a hugepage is considered as an unmovable page. But now with this patch series, a hugepage has become movable, so by using hugepage migration we can offline such memory blocks. What's different from other users of hugepage migration is that we need to decompose all the hugepages inside the target memory block into free buddy pages after hugepage migration, because otherwise free hugepages remaining in the memory block intervene the memory offlining. For this reason we introduce new functions dissolve_free_huge_page() and dissolve_free_huge_pages(). Other than that, what this patch does is straightforwardly to add hugepage migration code, that is, adding hugepage code to the functions which scan over pfn and collect hugepages to be migrated, and adding a hugepage allocation function to alloc_migrate_target(). As for larger hugepages (1GB for x86_64), it's not easy to do hotremove over them because it's larger than memory block. So we now simply leave it to fail as it is. [yongjun_wei@trendmicro.com.cn: remove duplicated include] Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:22:09 +04:00
{
unsigned long pfn;
struct page *page;
int rc = 0;
mm: memory-hotplug: enable memory hotplug to handle hugepage Until now we can't offline memory blocks which contain hugepages because a hugepage is considered as an unmovable page. But now with this patch series, a hugepage has become movable, so by using hugepage migration we can offline such memory blocks. What's different from other users of hugepage migration is that we need to decompose all the hugepages inside the target memory block into free buddy pages after hugepage migration, because otherwise free hugepages remaining in the memory block intervene the memory offlining. For this reason we introduce new functions dissolve_free_huge_page() and dissolve_free_huge_pages(). Other than that, what this patch does is straightforwardly to add hugepage migration code, that is, adding hugepage code to the functions which scan over pfn and collect hugepages to be migrated, and adding a hugepage allocation function to alloc_migrate_target(). As for larger hugepages (1GB for x86_64), it's not easy to do hotremove over them because it's larger than memory block. So we now simply leave it to fail as it is. [yongjun_wei@trendmicro.com.cn: remove duplicated include] Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:22:09 +04:00
if (!hugepages_supported())
return rc;
for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order) {
page = pfn_to_page(pfn);
mm: hugetlb: soft-offline: dissolve_free_huge_page() return zero on !PageHuge madvise(MADV_SOFT_OFFLINE) often returns -EBUSY when calling soft offline for hugepages with overcommitting enabled. That was caused by the suboptimal code in current soft-offline code. See the following part: ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL, MIGRATE_SYNC, MR_MEMORY_FAILURE); if (ret) { ... } else { /* * We set PG_hwpoison only when the migration source hugepage * was successfully dissolved, because otherwise hwpoisoned * hugepage remains on free hugepage list, then userspace will * find it as SIGBUS by allocation failure. That's not expected * in soft-offlining. */ ret = dissolve_free_huge_page(page); if (!ret) { if (set_hwpoison_free_buddy_page(page)) num_poisoned_pages_inc(); } } return ret; Here dissolve_free_huge_page() returns -EBUSY if the migration source page was freed into buddy in migrate_pages(), but even in that case we actually has a chance that set_hwpoison_free_buddy_page() succeeds. So that means current code gives up offlining too early now. dissolve_free_huge_page() checks that a given hugepage is suitable for dissolving, where we should return success for !PageHuge() case because the given hugepage is considered as already dissolved. This change also affects other callers of dissolve_free_huge_page(), which are cleaned up together. [n-horiguchi@ah.jp.nec.com: v3] Link: http://lkml.kernel.org/r/1560761476-4651-3-git-send-email-n-horiguchi@ah.jp.nec.comLink: http://lkml.kernel.org/r/1560154686-18497-3-git-send-email-n-horiguchi@ah.jp.nec.com Fixes: 6bc9b56433b76 ("mm: fix race on soft-offlining") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Chen, Jerry T <jerry.t.chen@intel.com> Tested-by: Chen, Jerry T <jerry.t.chen@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Xishi Qiu <xishi.qiuxishi@alibaba-inc.com> Cc: "Chen, Jerry T" <jerry.t.chen@intel.com> Cc: "Zhuo, Qiuxu" <qiuxu.zhuo@intel.com> Cc: <stable@vger.kernel.org> [4.19+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-06-28 22:06:56 +03:00
rc = dissolve_free_huge_page(page);
if (rc)
break;
}
return rc;
mm: memory-hotplug: enable memory hotplug to handle hugepage Until now we can't offline memory blocks which contain hugepages because a hugepage is considered as an unmovable page. But now with this patch series, a hugepage has become movable, so by using hugepage migration we can offline such memory blocks. What's different from other users of hugepage migration is that we need to decompose all the hugepages inside the target memory block into free buddy pages after hugepage migration, because otherwise free hugepages remaining in the memory block intervene the memory offlining. For this reason we introduce new functions dissolve_free_huge_page() and dissolve_free_huge_pages(). Other than that, what this patch does is straightforwardly to add hugepage migration code, that is, adding hugepage code to the functions which scan over pfn and collect hugepages to be migrated, and adding a hugepage allocation function to alloc_migrate_target(). As for larger hugepages (1GB for x86_64), it's not easy to do hotremove over them because it's larger than memory block. So we now simply leave it to fail as it is. [yongjun_wei@trendmicro.com.cn: remove duplicated include] Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:22:09 +04:00
}
mm, hugetlb: do not rely on overcommit limit during migration hugepage migration relies on __alloc_buddy_huge_page to get a new page. This has 2 main disadvantages. 1) it doesn't allow to migrate any huge page if the pool is used completely which is not an exceptional case as the pool is static and unused memory is just wasted. 2) it leads to a weird semantic when migration between two numa nodes might increase the pool size of the destination NUMA node while the page is in use. The issue is caused by per NUMA node surplus pages tracking (see free_huge_page). Address both issues by changing the way how we allocate and account pages allocated for migration. Those should temporal by definition. So we mark them that way (we will abuse page flags in the 3rd page) and update free_huge_page to free such pages to the page allocator. Page migration path then just transfers the temporal status from the new page to the old one which will be freed on the last reference. The global surplus count will never change during this path but we still have to be careful when migrating a per-node suprlus page. This is now handled in move_hugetlb_state which is called from the migration path and it copies the hugetlb specific page state and fixes up the accounting when needed Rename __alloc_buddy_huge_page to __alloc_surplus_huge_page to better reflect its purpose. The new allocation routine for the migration path is __alloc_migrate_huge_page. The user visible effect of this patch is that migrated pages are really temporal and they travel between NUMA nodes as per the migration request: Before migration /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 After /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 with the previous implementation, both nodes would have nr_hugepages:1 until the page is freed. Link: http://lkml.kernel.org/r/20180103093213.26329-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:48 +03:00
/*
* Allocates a fresh surplus page from the page allocator.
*/
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
static struct page *alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask,
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
int nid, nodemask_t *nmask, bool zero_ref)
{
mm, hugetlb: get rid of surplus page accounting tricks alloc_surplus_huge_page increases the pool size and the number of surplus pages opportunistically to prevent from races with the pool size change. See commit d1c3fb1f8f29 ("hugetlb: introduce nr_overcommit_hugepages sysctl") for more details. The resulting code is unnecessarily hairy, cause code duplication and doesn't allow to share the allocation paths. Moreover pool size changes tend to be very seldom so optimizing for them is not really reasonable. Simplify the code and allow to allocate a fresh surplus page as long as we are under the overcommit limit and then recheck the condition after the allocation and drop the new page if the situation has changed. This should provide a reasonable guarantee that an abrupt allocation requests will not go way off the limit. If we consider races with the pool shrinking and enlarging then we should be reasonably safe as well. In the first case we are off by one in the worst case and the second case should work OK because the page is not yet visible. We can waste CPU cycles for the allocation but that should be acceptable for a relatively rare condition. Link: http://lkml.kernel.org/r/20180103093213.26329-5-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:52 +03:00
struct page *page = NULL;
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
bool retry = false;
if (hstate_is_gigantic(h))
return NULL;
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
mm, hugetlb: get rid of surplus page accounting tricks alloc_surplus_huge_page increases the pool size and the number of surplus pages opportunistically to prevent from races with the pool size change. See commit d1c3fb1f8f29 ("hugetlb: introduce nr_overcommit_hugepages sysctl") for more details. The resulting code is unnecessarily hairy, cause code duplication and doesn't allow to share the allocation paths. Moreover pool size changes tend to be very seldom so optimizing for them is not really reasonable. Simplify the code and allow to allocate a fresh surplus page as long as we are under the overcommit limit and then recheck the condition after the allocation and drop the new page if the situation has changed. This should provide a reasonable guarantee that an abrupt allocation requests will not go way off the limit. If we consider races with the pool shrinking and enlarging then we should be reasonably safe as well. In the first case we are off by one in the worst case and the second case should work OK because the page is not yet visible. We can waste CPU cycles for the allocation but that should be acceptable for a relatively rare condition. Link: http://lkml.kernel.org/r/20180103093213.26329-5-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:52 +03:00
if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages)
goto out_unlock;
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
hugetlb: introduce nr_overcommit_hugepages sysctl hugetlb: introduce nr_overcommit_hugepages sysctl While examining the code to support /proc/sys/vm/hugetlb_dynamic_pool, I became convinced that having a boolean sysctl was insufficient: 1) To support per-node control of hugepages, I have previously submitted patches to add a sysfs attribute related to nr_hugepages. However, with a boolean global value and per-mount quota enforcement constraining the dynamic pool, adding corresponding control of the dynamic pool on a per-node basis seems inconsistent to me. 2) Administration of the hugetlb dynamic pool with multiple hugetlbfs mount points is, arguably, more arduous than it needs to be. Each quota would need to be set separately, and the sum would need to be monitored. To ease the administration, and to help make the way for per-node control of the static & dynamic hugepage pool, I added a separate sysctl, nr_overcommit_hugepages. This value serves as a high watermark for the overall hugepage pool, while nr_hugepages serves as a low watermark. The boolean sysctl can then be removed, as the condition nr_overcommit_hugepages > 0 indicates the same administrative setting as hugetlb_dynamic_pool == 1 Quotas still serve as local enforcement of the size of the pool on a per-mount basis. A few caveats: 1) There is a race whereby the global surplus huge page counter is incremented before a hugepage has allocated. Another process could then try grow the pool, and fail to convert a surplus huge page to a normal huge page and instead allocate a fresh huge page. I believe this is benign, as no memory is leaked (the actual pages are still tracked correctly) and the counters won't go out of sync. 2) Shrinking the static pool while a surplus is in effect will allow the number of surplus huge pages to exceed the overcommit value. As long as this condition holds, however, no more surplus huge pages will be allowed on the system until one of the two sysctls are increased sufficiently, or the surplus huge pages go out of use and are freed. Successfully tested on x86_64 with the current libhugetlbfs snapshot, modified to use the new sysctl. Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Acked-by: Adam Litke <agl@us.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-12-18 03:20:12 +03:00
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
retry:
page = alloc_fresh_huge_page(h, gfp_mask, nid, nmask, NULL);
mm, hugetlb: get rid of surplus page accounting tricks alloc_surplus_huge_page increases the pool size and the number of surplus pages opportunistically to prevent from races with the pool size change. See commit d1c3fb1f8f29 ("hugetlb: introduce nr_overcommit_hugepages sysctl") for more details. The resulting code is unnecessarily hairy, cause code duplication and doesn't allow to share the allocation paths. Moreover pool size changes tend to be very seldom so optimizing for them is not really reasonable. Simplify the code and allow to allocate a fresh surplus page as long as we are under the overcommit limit and then recheck the condition after the allocation and drop the new page if the situation has changed. This should provide a reasonable guarantee that an abrupt allocation requests will not go way off the limit. If we consider races with the pool shrinking and enlarging then we should be reasonably safe as well. In the first case we are off by one in the worst case and the second case should work OK because the page is not yet visible. We can waste CPU cycles for the allocation but that should be acceptable for a relatively rare condition. Link: http://lkml.kernel.org/r/20180103093213.26329-5-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:52 +03:00
if (!page)
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
return NULL;
hugetlb: introduce nr_overcommit_hugepages sysctl hugetlb: introduce nr_overcommit_hugepages sysctl While examining the code to support /proc/sys/vm/hugetlb_dynamic_pool, I became convinced that having a boolean sysctl was insufficient: 1) To support per-node control of hugepages, I have previously submitted patches to add a sysfs attribute related to nr_hugepages. However, with a boolean global value and per-mount quota enforcement constraining the dynamic pool, adding corresponding control of the dynamic pool on a per-node basis seems inconsistent to me. 2) Administration of the hugetlb dynamic pool with multiple hugetlbfs mount points is, arguably, more arduous than it needs to be. Each quota would need to be set separately, and the sum would need to be monitored. To ease the administration, and to help make the way for per-node control of the static & dynamic hugepage pool, I added a separate sysctl, nr_overcommit_hugepages. This value serves as a high watermark for the overall hugepage pool, while nr_hugepages serves as a low watermark. The boolean sysctl can then be removed, as the condition nr_overcommit_hugepages > 0 indicates the same administrative setting as hugetlb_dynamic_pool == 1 Quotas still serve as local enforcement of the size of the pool on a per-mount basis. A few caveats: 1) There is a race whereby the global surplus huge page counter is incremented before a hugepage has allocated. Another process could then try grow the pool, and fail to convert a surplus huge page to a normal huge page and instead allocate a fresh huge page. I believe this is benign, as no memory is leaked (the actual pages are still tracked correctly) and the counters won't go out of sync. 2) Shrinking the static pool while a surplus is in effect will allow the number of surplus huge pages to exceed the overcommit value. As long as this condition holds, however, no more surplus huge pages will be allowed on the system until one of the two sysctls are increased sufficiently, or the surplus huge pages go out of use and are freed. Successfully tested on x86_64 with the current libhugetlbfs snapshot, modified to use the new sysctl. Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Acked-by: Adam Litke <agl@us.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-12-18 03:20:12 +03:00
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
mm, hugetlb: get rid of surplus page accounting tricks alloc_surplus_huge_page increases the pool size and the number of surplus pages opportunistically to prevent from races with the pool size change. See commit d1c3fb1f8f29 ("hugetlb: introduce nr_overcommit_hugepages sysctl") for more details. The resulting code is unnecessarily hairy, cause code duplication and doesn't allow to share the allocation paths. Moreover pool size changes tend to be very seldom so optimizing for them is not really reasonable. Simplify the code and allow to allocate a fresh surplus page as long as we are under the overcommit limit and then recheck the condition after the allocation and drop the new page if the situation has changed. This should provide a reasonable guarantee that an abrupt allocation requests will not go way off the limit. If we consider races with the pool shrinking and enlarging then we should be reasonably safe as well. In the first case we are off by one in the worst case and the second case should work OK because the page is not yet visible. We can waste CPU cycles for the allocation but that should be acceptable for a relatively rare condition. Link: http://lkml.kernel.org/r/20180103093213.26329-5-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:52 +03:00
/*
* We could have raced with the pool size change.
* Double check that and simply deallocate the new page
* if we would end up overcommiting the surpluses. Abuse
* temporary page to workaround the nasty free_huge_page
* codeflow
*/
if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
SetHPageTemporary(page);
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
mm, hugetlb: get rid of surplus page accounting tricks alloc_surplus_huge_page increases the pool size and the number of surplus pages opportunistically to prevent from races with the pool size change. See commit d1c3fb1f8f29 ("hugetlb: introduce nr_overcommit_hugepages sysctl") for more details. The resulting code is unnecessarily hairy, cause code duplication and doesn't allow to share the allocation paths. Moreover pool size changes tend to be very seldom so optimizing for them is not really reasonable. Simplify the code and allow to allocate a fresh surplus page as long as we are under the overcommit limit and then recheck the condition after the allocation and drop the new page if the situation has changed. This should provide a reasonable guarantee that an abrupt allocation requests will not go way off the limit. If we consider races with the pool shrinking and enlarging then we should be reasonably safe as well. In the first case we are off by one in the worst case and the second case should work OK because the page is not yet visible. We can waste CPU cycles for the allocation but that should be acceptable for a relatively rare condition. Link: http://lkml.kernel.org/r/20180103093213.26329-5-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:52 +03:00
put_page(page);
mm/hugetlb.c: don't put_page in lock of hugetlb_lock spinlock recursion happened when do LTP test: #!/bin/bash ./runltp -p -f hugetlb & ./runltp -p -f hugetlb & ./runltp -p -f hugetlb & ./runltp -p -f hugetlb & ./runltp -p -f hugetlb & The dtor returned by get_compound_page_dtor in __put_compound_page may be the function of free_huge_page which will lock the hugetlb_lock, so don't put_page in lock of hugetlb_lock. BUG: spinlock recursion on CPU#0, hugemmap05/1079 lock: hugetlb_lock+0x0/0x18, .magic: dead4ead, .owner: hugemmap05/1079, .owner_cpu: 0 Call trace: dump_backtrace+0x0/0x198 show_stack+0x24/0x30 dump_stack+0xa4/0xcc spin_dump+0x84/0xa8 do_raw_spin_lock+0xd0/0x108 _raw_spin_lock+0x20/0x30 free_huge_page+0x9c/0x260 __put_compound_page+0x44/0x50 __put_page+0x2c/0x60 alloc_surplus_huge_page.constprop.19+0xf0/0x140 hugetlb_acct_memory+0x104/0x378 hugetlb_reserve_pages+0xe0/0x250 hugetlbfs_file_mmap+0xc0/0x140 mmap_region+0x3e8/0x5b0 do_mmap+0x280/0x460 vm_mmap_pgoff+0xf4/0x128 ksys_mmap_pgoff+0xb4/0x258 __arm64_sys_mmap+0x34/0x48 el0_svc_common+0x78/0x130 el0_svc_handler+0x38/0x78 el0_svc+0x8/0xc Link: http://lkml.kernel.org/r/b8ade452-2d6b-0372-32c2-703644032b47@huawei.com Fixes: 9980d744a0 ("mm, hugetlb: get rid of surplus page accounting tricks") Signed-off-by: Kai Shen <shenkai8@huawei.com> Signed-off-by: Feilong Lin <linfeilong@huawei.com> Reported-by: Wang Wang <wangwang2@huawei.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 03:15:37 +03:00
return NULL;
}
mm, hugetlb: get rid of surplus page accounting tricks alloc_surplus_huge_page increases the pool size and the number of surplus pages opportunistically to prevent from races with the pool size change. See commit d1c3fb1f8f29 ("hugetlb: introduce nr_overcommit_hugepages sysctl") for more details. The resulting code is unnecessarily hairy, cause code duplication and doesn't allow to share the allocation paths. Moreover pool size changes tend to be very seldom so optimizing for them is not really reasonable. Simplify the code and allow to allocate a fresh surplus page as long as we are under the overcommit limit and then recheck the condition after the allocation and drop the new page if the situation has changed. This should provide a reasonable guarantee that an abrupt allocation requests will not go way off the limit. If we consider races with the pool shrinking and enlarging then we should be reasonably safe as well. In the first case we are off by one in the worst case and the second case should work OK because the page is not yet visible. We can waste CPU cycles for the allocation but that should be acceptable for a relatively rare condition. Link: http://lkml.kernel.org/r/20180103093213.26329-5-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:52 +03:00
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
if (zero_ref) {
/*
* Caller requires a page with zero ref count.
* We will drop ref count here. If someone else is holding
* a ref, the page will be freed when they drop it. Abuse
* temporary page flag to accomplish this.
*/
SetHPageTemporary(page);
if (!put_page_testzero(page)) {
/*
* Unexpected inflated ref count on freshly allocated
* huge. Retry once.
*/
pr_info("HugeTLB unexpected inflated ref count on freshly allocated page\n");
spin_unlock_irq(&hugetlb_lock);
if (retry)
return NULL;
retry = true;
goto retry;
}
ClearHPageTemporary(page);
}
h->surplus_huge_pages++;
h->surplus_huge_pages_node[page_to_nid(page)]++;
mm, hugetlb: get rid of surplus page accounting tricks alloc_surplus_huge_page increases the pool size and the number of surplus pages opportunistically to prevent from races with the pool size change. See commit d1c3fb1f8f29 ("hugetlb: introduce nr_overcommit_hugepages sysctl") for more details. The resulting code is unnecessarily hairy, cause code duplication and doesn't allow to share the allocation paths. Moreover pool size changes tend to be very seldom so optimizing for them is not really reasonable. Simplify the code and allow to allocate a fresh surplus page as long as we are under the overcommit limit and then recheck the condition after the allocation and drop the new page if the situation has changed. This should provide a reasonable guarantee that an abrupt allocation requests will not go way off the limit. If we consider races with the pool shrinking and enlarging then we should be reasonably safe as well. In the first case we are off by one in the worst case and the second case should work OK because the page is not yet visible. We can waste CPU cycles for the allocation but that should be acceptable for a relatively rare condition. Link: http://lkml.kernel.org/r/20180103093213.26329-5-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:52 +03:00
out_unlock:
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
return page;
}
mm/hugetlb: make hugetlb migration callback CMA aware new_non_cma_page() in gup.c requires to allocate the new page that is not on the CMA area. new_non_cma_page() implements it by using allocation scope APIs. However, there is a work-around for hugetlb. Normal hugetlb page allocation API for migration is alloc_huge_page_nodemask(). It consists of two steps. First is dequeing from the pool. Second is, if there is no available page on the queue, allocating by using the page allocator. new_non_cma_page() can't use this API since first step (deque) isn't aware of scope API to exclude CMA area. So, new_non_cma_page() exports hugetlb internal function for the second step, alloc_migrate_huge_page(), to global scope and uses it directly. This is suboptimal since hugetlb pages on the queue cannot be utilized. This patch tries to fix this situation by making the deque function on hugetlb CMA aware. In the deque function, CMA memory is skipped if PF_MEMALLOC_NOCMA flag is found. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Roman Gushchin <guro@fb.com> Link: http://lkml.kernel.org/r/1596180906-8442-2-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 04:37:38 +03:00
static struct page *alloc_migrate_huge_page(struct hstate *h, gfp_t gfp_mask,
int nid, nodemask_t *nmask)
mm, hugetlb: do not rely on overcommit limit during migration hugepage migration relies on __alloc_buddy_huge_page to get a new page. This has 2 main disadvantages. 1) it doesn't allow to migrate any huge page if the pool is used completely which is not an exceptional case as the pool is static and unused memory is just wasted. 2) it leads to a weird semantic when migration between two numa nodes might increase the pool size of the destination NUMA node while the page is in use. The issue is caused by per NUMA node surplus pages tracking (see free_huge_page). Address both issues by changing the way how we allocate and account pages allocated for migration. Those should temporal by definition. So we mark them that way (we will abuse page flags in the 3rd page) and update free_huge_page to free such pages to the page allocator. Page migration path then just transfers the temporal status from the new page to the old one which will be freed on the last reference. The global surplus count will never change during this path but we still have to be careful when migrating a per-node suprlus page. This is now handled in move_hugetlb_state which is called from the migration path and it copies the hugetlb specific page state and fixes up the accounting when needed Rename __alloc_buddy_huge_page to __alloc_surplus_huge_page to better reflect its purpose. The new allocation routine for the migration path is __alloc_migrate_huge_page. The user visible effect of this patch is that migrated pages are really temporal and they travel between NUMA nodes as per the migration request: Before migration /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 After /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 with the previous implementation, both nodes would have nr_hugepages:1 until the page is freed. Link: http://lkml.kernel.org/r/20180103093213.26329-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:48 +03:00
{
struct page *page;
if (hstate_is_gigantic(h))
return NULL;
page = alloc_fresh_huge_page(h, gfp_mask, nid, nmask, NULL);
mm, hugetlb: do not rely on overcommit limit during migration hugepage migration relies on __alloc_buddy_huge_page to get a new page. This has 2 main disadvantages. 1) it doesn't allow to migrate any huge page if the pool is used completely which is not an exceptional case as the pool is static and unused memory is just wasted. 2) it leads to a weird semantic when migration between two numa nodes might increase the pool size of the destination NUMA node while the page is in use. The issue is caused by per NUMA node surplus pages tracking (see free_huge_page). Address both issues by changing the way how we allocate and account pages allocated for migration. Those should temporal by definition. So we mark them that way (we will abuse page flags in the 3rd page) and update free_huge_page to free such pages to the page allocator. Page migration path then just transfers the temporal status from the new page to the old one which will be freed on the last reference. The global surplus count will never change during this path but we still have to be careful when migrating a per-node suprlus page. This is now handled in move_hugetlb_state which is called from the migration path and it copies the hugetlb specific page state and fixes up the accounting when needed Rename __alloc_buddy_huge_page to __alloc_surplus_huge_page to better reflect its purpose. The new allocation routine for the migration path is __alloc_migrate_huge_page. The user visible effect of this patch is that migrated pages are really temporal and they travel between NUMA nodes as per the migration request: Before migration /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 After /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 with the previous implementation, both nodes would have nr_hugepages:1 until the page is freed. Link: http://lkml.kernel.org/r/20180103093213.26329-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:48 +03:00
if (!page)
return NULL;
/*
* We do not account these pages as surplus because they are only
* temporary and will be released properly on the last reference
*/
SetHPageTemporary(page);
mm, hugetlb: do not rely on overcommit limit during migration hugepage migration relies on __alloc_buddy_huge_page to get a new page. This has 2 main disadvantages. 1) it doesn't allow to migrate any huge page if the pool is used completely which is not an exceptional case as the pool is static and unused memory is just wasted. 2) it leads to a weird semantic when migration between two numa nodes might increase the pool size of the destination NUMA node while the page is in use. The issue is caused by per NUMA node surplus pages tracking (see free_huge_page). Address both issues by changing the way how we allocate and account pages allocated for migration. Those should temporal by definition. So we mark them that way (we will abuse page flags in the 3rd page) and update free_huge_page to free such pages to the page allocator. Page migration path then just transfers the temporal status from the new page to the old one which will be freed on the last reference. The global surplus count will never change during this path but we still have to be careful when migrating a per-node suprlus page. This is now handled in move_hugetlb_state which is called from the migration path and it copies the hugetlb specific page state and fixes up the accounting when needed Rename __alloc_buddy_huge_page to __alloc_surplus_huge_page to better reflect its purpose. The new allocation routine for the migration path is __alloc_migrate_huge_page. The user visible effect of this patch is that migrated pages are really temporal and they travel between NUMA nodes as per the migration request: Before migration /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 After /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 with the previous implementation, both nodes would have nr_hugepages:1 until the page is freed. Link: http://lkml.kernel.org/r/20180103093213.26329-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:48 +03:00
return page;
}
mm, hugetlb: use memory policy when available I have a hugetlbfs user which is never explicitly allocating huge pages with 'nr_hugepages'. They only set 'nr_overcommit_hugepages' and then let the pages be allocated from the buddy allocator at fault time. This works, but they noticed that mbind() was not doing them any good and the pages were being allocated without respect for the policy they specified. The code in question is this: > struct page *alloc_huge_page(struct vm_area_struct *vma, ... > page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg); > if (!page) { > page = alloc_buddy_huge_page(h, NUMA_NO_NODE); dequeue_huge_page_vma() is smart and will respect the VMA's memory policy. But, it only grabs _existing_ huge pages from the huge page pool. If the pool is empty, we fall back to alloc_buddy_huge_page() which obviously can't do anything with the VMA's policy because it isn't even passed the VMA. Almost everybody preallocates huge pages. That's probably why nobody has ever noticed this. Looking back at the git history, I don't think this _ever_ worked from when alloc_buddy_huge_page() was introduced in 7893d1d5, 8 years ago. The fix is to pass vma/addr down in to the places where we actually call in to the buddy allocator. It's fairly straightforward plumbing. This has been lightly tested. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06 05:50:17 +03:00
/*
* Use the VMA's mpolicy to allocate a huge page from the buddy.
*/
static
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
struct page *alloc_buddy_huge_page_with_mpol(struct hstate *h,
mm, hugetlb: use memory policy when available I have a hugetlbfs user which is never explicitly allocating huge pages with 'nr_hugepages'. They only set 'nr_overcommit_hugepages' and then let the pages be allocated from the buddy allocator at fault time. This works, but they noticed that mbind() was not doing them any good and the pages were being allocated without respect for the policy they specified. The code in question is this: > struct page *alloc_huge_page(struct vm_area_struct *vma, ... > page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg); > if (!page) { > page = alloc_buddy_huge_page(h, NUMA_NO_NODE); dequeue_huge_page_vma() is smart and will respect the VMA's memory policy. But, it only grabs _existing_ huge pages from the huge page pool. If the pool is empty, we fall back to alloc_buddy_huge_page() which obviously can't do anything with the VMA's policy because it isn't even passed the VMA. Almost everybody preallocates huge pages. That's probably why nobody has ever noticed this. Looking back at the git history, I don't think this _ever_ worked from when alloc_buddy_huge_page() was introduced in 7893d1d5, 8 years ago. The fix is to pass vma/addr down in to the places where we actually call in to the buddy allocator. It's fairly straightforward plumbing. This has been lightly tested. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06 05:50:17 +03:00
struct vm_area_struct *vma, unsigned long addr)
{
mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY Implement the missing huge page allocation functionality while obeying the preferred node semantics. This is similar to the implementation for general page allocation, as it uses a fallback mechanism to try multiple preferred nodes first, and then all other nodes. To avoid adding too many "#ifdef CONFIG_NUMA" check, add a helper function in mempolicy.h to check whether a mempolicy is MPOL_PREFERRED_MANY. [akpm@linux-foundation.org: fix compiling issue when merging with other hugetlb patch] [Thanks to 0day bot for catching the !CONFIG_NUMA compiling issue] [mhocko@suse.com: suggest to remove the #ifdef CONFIG_NUMA check] [ben.widawsky@intel.com: add helpers to avoid ifdefs] Link: https://lore.kernel.org/r/20200630212517.308045-12-ben.widawsky@intel.com Link: https://lkml.kernel.org/r/1627970362-61305-4-git-send-email-feng.tang@intel.com Link: https://lkml.kernel.org/r/20210809024430.GA46432@shbuild999.sh.intel.com [nathan@kernel.org: initialize page to NULL in alloc_buddy_huge_page_with_mpol()] Link: https://lkml.kernel.org/r/20210810200632.3812797-1-nathan@kernel.org Link: https://lore.kernel.org/r/20200630212517.308045-12-ben.widawsky@intel.com Link: https://lkml.kernel.org/r/1627970362-61305-4-git-send-email-feng.tang@intel.com Link: https://lkml.kernel.org/r/20210809024430.GA46432@shbuild999.sh.intel.com Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> Signed-off-by: Feng Tang <feng.tang@intel.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Co-developed-by: Feng Tang <feng.tang@intel.com> Suggested-by: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 01:00:13 +03:00
struct page *page = NULL;
mm, hugetlb: unclutter hugetlb allocation layers Patch series "mm, hugetlb: allow proper node fallback dequeue". While working on a hugetlb migration issue addressed in a separate patchset[1] I have noticed that the hugetlb allocations from the preallocated pool are quite subotimal. [1] //lkml.kernel.org/r/20170608074553.22152-1-mhocko@kernel.org There is no fallback mechanism implemented and no notion of preferred node. I have tried to work around it but Vlastimil was right to push back for a more robust solution. It seems that such a solution is to reuse zonelist approach we use for the page alloctor. This series has 3 patches. The first one tries to make hugetlb allocation layers more clear. The second one implements the zonelist hugetlb pool allocation and introduces a preferred node semantic which is used by the migration callbacks. The last patch is a clean up. This patch (of 3): Hugetlb allocation path for fresh huge pages is unnecessarily complex and it mixes different interfaces between layers. __alloc_buddy_huge_page is the central place to perform a new allocation. It checks for the hugetlb overcommit and then relies on __hugetlb_alloc_buddy_huge_page to invoke the page allocator. This is all good except that __alloc_buddy_huge_page pushes vma and address down the callchain and so __hugetlb_alloc_buddy_huge_page has to deal with two different allocation modes - one for memory policy and other node specific (or to make it more obscure node non-specific) requests. This just screams for a reorganization. This patch pulls out all the vma specific handling up to __alloc_buddy_huge_page_with_mpol where it belongs. __alloc_buddy_huge_page will get nodemask argument and __hugetlb_alloc_buddy_huge_page will become a trivial wrapper over the page allocator. In short: __alloc_buddy_huge_page_with_mpol - memory policy handling __alloc_buddy_huge_page - overcommit handling and accounting __hugetlb_alloc_buddy_huge_page - page allocator layer Also note that __hugetlb_alloc_buddy_huge_page and its cpuset retry loop is not really needed because the page allocator already handles the cpusets update. Finally __hugetlb_alloc_buddy_huge_page had a special case for node specific allocations (when no policy is applied and there is a node given). This has relied on __GFP_THISNODE to not fallback to a different node. alloc_huge_page_node is the only caller which relies on this behavior so move the __GFP_THISNODE there. Not only does this remove quite some code it also should make those layers easier to follow and clear wrt responsibilities. Link: http://lkml.kernel.org/r/20170622193034.28972-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Tested-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-11 01:49:08 +03:00
struct mempolicy *mpol;
gfp_t gfp_mask = htlb_alloc_mask(h);
int nid;
nodemask_t *nodemask;
nid = huge_node(vma, addr, gfp_mask, &mpol, &nodemask);
mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY Implement the missing huge page allocation functionality while obeying the preferred node semantics. This is similar to the implementation for general page allocation, as it uses a fallback mechanism to try multiple preferred nodes first, and then all other nodes. To avoid adding too many "#ifdef CONFIG_NUMA" check, add a helper function in mempolicy.h to check whether a mempolicy is MPOL_PREFERRED_MANY. [akpm@linux-foundation.org: fix compiling issue when merging with other hugetlb patch] [Thanks to 0day bot for catching the !CONFIG_NUMA compiling issue] [mhocko@suse.com: suggest to remove the #ifdef CONFIG_NUMA check] [ben.widawsky@intel.com: add helpers to avoid ifdefs] Link: https://lore.kernel.org/r/20200630212517.308045-12-ben.widawsky@intel.com Link: https://lkml.kernel.org/r/1627970362-61305-4-git-send-email-feng.tang@intel.com Link: https://lkml.kernel.org/r/20210809024430.GA46432@shbuild999.sh.intel.com [nathan@kernel.org: initialize page to NULL in alloc_buddy_huge_page_with_mpol()] Link: https://lkml.kernel.org/r/20210810200632.3812797-1-nathan@kernel.org Link: https://lore.kernel.org/r/20200630212517.308045-12-ben.widawsky@intel.com Link: https://lkml.kernel.org/r/1627970362-61305-4-git-send-email-feng.tang@intel.com Link: https://lkml.kernel.org/r/20210809024430.GA46432@shbuild999.sh.intel.com Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> Signed-off-by: Feng Tang <feng.tang@intel.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Co-developed-by: Feng Tang <feng.tang@intel.com> Suggested-by: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 01:00:13 +03:00
if (mpol_is_preferred_many(mpol)) {
gfp_t gfp = gfp_mask | __GFP_NOWARN;
gfp &= ~(__GFP_DIRECT_RECLAIM | __GFP_NOFAIL);
page = alloc_surplus_huge_page(h, gfp, nid, nodemask, false);
mm, hugetlb: unclutter hugetlb allocation layers Patch series "mm, hugetlb: allow proper node fallback dequeue". While working on a hugetlb migration issue addressed in a separate patchset[1] I have noticed that the hugetlb allocations from the preallocated pool are quite subotimal. [1] //lkml.kernel.org/r/20170608074553.22152-1-mhocko@kernel.org There is no fallback mechanism implemented and no notion of preferred node. I have tried to work around it but Vlastimil was right to push back for a more robust solution. It seems that such a solution is to reuse zonelist approach we use for the page alloctor. This series has 3 patches. The first one tries to make hugetlb allocation layers more clear. The second one implements the zonelist hugetlb pool allocation and introduces a preferred node semantic which is used by the migration callbacks. The last patch is a clean up. This patch (of 3): Hugetlb allocation path for fresh huge pages is unnecessarily complex and it mixes different interfaces between layers. __alloc_buddy_huge_page is the central place to perform a new allocation. It checks for the hugetlb overcommit and then relies on __hugetlb_alloc_buddy_huge_page to invoke the page allocator. This is all good except that __alloc_buddy_huge_page pushes vma and address down the callchain and so __hugetlb_alloc_buddy_huge_page has to deal with two different allocation modes - one for memory policy and other node specific (or to make it more obscure node non-specific) requests. This just screams for a reorganization. This patch pulls out all the vma specific handling up to __alloc_buddy_huge_page_with_mpol where it belongs. __alloc_buddy_huge_page will get nodemask argument and __hugetlb_alloc_buddy_huge_page will become a trivial wrapper over the page allocator. In short: __alloc_buddy_huge_page_with_mpol - memory policy handling __alloc_buddy_huge_page - overcommit handling and accounting __hugetlb_alloc_buddy_huge_page - page allocator layer Also note that __hugetlb_alloc_buddy_huge_page and its cpuset retry loop is not really needed because the page allocator already handles the cpusets update. Finally __hugetlb_alloc_buddy_huge_page had a special case for node specific allocations (when no policy is applied and there is a node given). This has relied on __GFP_THISNODE to not fallback to a different node. alloc_huge_page_node is the only caller which relies on this behavior so move the __GFP_THISNODE there. Not only does this remove quite some code it also should make those layers easier to follow and clear wrt responsibilities. Link: http://lkml.kernel.org/r/20170622193034.28972-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Tested-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-11 01:49:08 +03:00
mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY Implement the missing huge page allocation functionality while obeying the preferred node semantics. This is similar to the implementation for general page allocation, as it uses a fallback mechanism to try multiple preferred nodes first, and then all other nodes. To avoid adding too many "#ifdef CONFIG_NUMA" check, add a helper function in mempolicy.h to check whether a mempolicy is MPOL_PREFERRED_MANY. [akpm@linux-foundation.org: fix compiling issue when merging with other hugetlb patch] [Thanks to 0day bot for catching the !CONFIG_NUMA compiling issue] [mhocko@suse.com: suggest to remove the #ifdef CONFIG_NUMA check] [ben.widawsky@intel.com: add helpers to avoid ifdefs] Link: https://lore.kernel.org/r/20200630212517.308045-12-ben.widawsky@intel.com Link: https://lkml.kernel.org/r/1627970362-61305-4-git-send-email-feng.tang@intel.com Link: https://lkml.kernel.org/r/20210809024430.GA46432@shbuild999.sh.intel.com [nathan@kernel.org: initialize page to NULL in alloc_buddy_huge_page_with_mpol()] Link: https://lkml.kernel.org/r/20210810200632.3812797-1-nathan@kernel.org Link: https://lore.kernel.org/r/20200630212517.308045-12-ben.widawsky@intel.com Link: https://lkml.kernel.org/r/1627970362-61305-4-git-send-email-feng.tang@intel.com Link: https://lkml.kernel.org/r/20210809024430.GA46432@shbuild999.sh.intel.com Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> Signed-off-by: Feng Tang <feng.tang@intel.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Co-developed-by: Feng Tang <feng.tang@intel.com> Suggested-by: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 01:00:13 +03:00
/* Fallback to all nodes if page==NULL */
nodemask = NULL;
}
if (!page)
page = alloc_surplus_huge_page(h, gfp_mask, nid, nodemask, false);
mpol_cond_put(mpol);
mm, hugetlb: unclutter hugetlb allocation layers Patch series "mm, hugetlb: allow proper node fallback dequeue". While working on a hugetlb migration issue addressed in a separate patchset[1] I have noticed that the hugetlb allocations from the preallocated pool are quite subotimal. [1] //lkml.kernel.org/r/20170608074553.22152-1-mhocko@kernel.org There is no fallback mechanism implemented and no notion of preferred node. I have tried to work around it but Vlastimil was right to push back for a more robust solution. It seems that such a solution is to reuse zonelist approach we use for the page alloctor. This series has 3 patches. The first one tries to make hugetlb allocation layers more clear. The second one implements the zonelist hugetlb pool allocation and introduces a preferred node semantic which is used by the migration callbacks. The last patch is a clean up. This patch (of 3): Hugetlb allocation path for fresh huge pages is unnecessarily complex and it mixes different interfaces between layers. __alloc_buddy_huge_page is the central place to perform a new allocation. It checks for the hugetlb overcommit and then relies on __hugetlb_alloc_buddy_huge_page to invoke the page allocator. This is all good except that __alloc_buddy_huge_page pushes vma and address down the callchain and so __hugetlb_alloc_buddy_huge_page has to deal with two different allocation modes - one for memory policy and other node specific (or to make it more obscure node non-specific) requests. This just screams for a reorganization. This patch pulls out all the vma specific handling up to __alloc_buddy_huge_page_with_mpol where it belongs. __alloc_buddy_huge_page will get nodemask argument and __hugetlb_alloc_buddy_huge_page will become a trivial wrapper over the page allocator. In short: __alloc_buddy_huge_page_with_mpol - memory policy handling __alloc_buddy_huge_page - overcommit handling and accounting __hugetlb_alloc_buddy_huge_page - page allocator layer Also note that __hugetlb_alloc_buddy_huge_page and its cpuset retry loop is not really needed because the page allocator already handles the cpusets update. Finally __hugetlb_alloc_buddy_huge_page had a special case for node specific allocations (when no policy is applied and there is a node given). This has relied on __GFP_THISNODE to not fallback to a different node. alloc_huge_page_node is the only caller which relies on this behavior so move the __GFP_THISNODE there. Not only does this remove quite some code it also should make those layers easier to follow and clear wrt responsibilities. Link: http://lkml.kernel.org/r/20170622193034.28972-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Tested-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-11 01:49:08 +03:00
return page;
mm, hugetlb: use memory policy when available I have a hugetlbfs user which is never explicitly allocating huge pages with 'nr_hugepages'. They only set 'nr_overcommit_hugepages' and then let the pages be allocated from the buddy allocator at fault time. This works, but they noticed that mbind() was not doing them any good and the pages were being allocated without respect for the policy they specified. The code in question is this: > struct page *alloc_huge_page(struct vm_area_struct *vma, ... > page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg); > if (!page) { > page = alloc_buddy_huge_page(h, NUMA_NO_NODE); dequeue_huge_page_vma() is smart and will respect the VMA's memory policy. But, it only grabs _existing_ huge pages from the huge page pool. If the pool is empty, we fall back to alloc_buddy_huge_page() which obviously can't do anything with the VMA's policy because it isn't even passed the VMA. Almost everybody preallocates huge pages. That's probably why nobody has ever noticed this. Looking back at the git history, I don't think this _ever_ worked from when alloc_buddy_huge_page() was introduced in 7893d1d5, 8 years ago. The fix is to pass vma/addr down in to the places where we actually call in to the buddy allocator. It's fairly straightforward plumbing. This has been lightly tested. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06 05:50:17 +03:00
}
mm, hugetlb: do not rely on overcommit limit during migration hugepage migration relies on __alloc_buddy_huge_page to get a new page. This has 2 main disadvantages. 1) it doesn't allow to migrate any huge page if the pool is used completely which is not an exceptional case as the pool is static and unused memory is just wasted. 2) it leads to a weird semantic when migration between two numa nodes might increase the pool size of the destination NUMA node while the page is in use. The issue is caused by per NUMA node surplus pages tracking (see free_huge_page). Address both issues by changing the way how we allocate and account pages allocated for migration. Those should temporal by definition. So we mark them that way (we will abuse page flags in the 3rd page) and update free_huge_page to free such pages to the page allocator. Page migration path then just transfers the temporal status from the new page to the old one which will be freed on the last reference. The global surplus count will never change during this path but we still have to be careful when migrating a per-node suprlus page. This is now handled in move_hugetlb_state which is called from the migration path and it copies the hugetlb specific page state and fixes up the accounting when needed Rename __alloc_buddy_huge_page to __alloc_surplus_huge_page to better reflect its purpose. The new allocation routine for the migration path is __alloc_migrate_huge_page. The user visible effect of this patch is that migrated pages are really temporal and they travel between NUMA nodes as per the migration request: Before migration /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 After /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 with the previous implementation, both nodes would have nr_hugepages:1 until the page is freed. Link: http://lkml.kernel.org/r/20180103093213.26329-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:48 +03:00
/* page migration callback function */
struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
nodemask_t *nmask, gfp_t gfp_mask)
hugetlb, memory_hotplug: prefer to use reserved pages for migration new_node_page will try to use the origin's next NUMA node as the migration destination for hugetlb pages. If such a node doesn't have any preallocated pool it falls back to __alloc_buddy_huge_page_no_mpol to allocate a surplus page instead. This is quite subotpimal for any configuration when hugetlb pages are no distributed to all NUMA nodes evenly. Say we have a hotplugable node 4 and spare hugetlb pages are node 0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:10000 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node3/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node4/hugepages/hugepages-2048kB/nr_hugepages:10000 /sys/devices/system/node/node5/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node6/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node7/hugepages/hugepages-2048kB/nr_hugepages:0 Now we consume the whole pool on node 4 and try to offline this node. All the allocated pages should be moved to node0 which has enough preallocated pages to hold them. With the current implementation offlining very likely fails because hugetlb allocations during runtime are much less reliable. Fix this by reusing the nodemask which excludes migration source and try to find a first node which has a page in the preallocated pool first and fall back to __alloc_buddy_huge_page_no_mpol only when the whole pool is consumed. [akpm@linux-foundation.org: remove bogus arg from alloc_huge_page_nodemask() stub] Link: http://lkml.kernel.org/r/20170608074553.22152-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: zhong jiang <zhongjiang@huawei.com> Cc: Joonsoo Kim <js1304@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-11 01:48:44 +03:00
{
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
hugetlb, memory_hotplug: prefer to use reserved pages for migration new_node_page will try to use the origin's next NUMA node as the migration destination for hugetlb pages. If such a node doesn't have any preallocated pool it falls back to __alloc_buddy_huge_page_no_mpol to allocate a surplus page instead. This is quite subotpimal for any configuration when hugetlb pages are no distributed to all NUMA nodes evenly. Say we have a hotplugable node 4 and spare hugetlb pages are node 0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:10000 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node3/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node4/hugepages/hugepages-2048kB/nr_hugepages:10000 /sys/devices/system/node/node5/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node6/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node7/hugepages/hugepages-2048kB/nr_hugepages:0 Now we consume the whole pool on node 4 and try to offline this node. All the allocated pages should be moved to node0 which has enough preallocated pages to hold them. With the current implementation offlining very likely fails because hugetlb allocations during runtime are much less reliable. Fix this by reusing the nodemask which excludes migration source and try to find a first node which has a page in the preallocated pool first and fall back to __alloc_buddy_huge_page_no_mpol only when the whole pool is consumed. [akpm@linux-foundation.org: remove bogus arg from alloc_huge_page_nodemask() stub] Link: http://lkml.kernel.org/r/20170608074553.22152-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: zhong jiang <zhongjiang@huawei.com> Cc: Joonsoo Kim <js1304@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-11 01:48:44 +03:00
if (h->free_huge_pages - h->resv_huge_pages > 0) {
struct page *page;
page = dequeue_huge_page_nodemask(h, gfp_mask, preferred_nid, nmask);
if (page) {
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
return page;
hugetlb, memory_hotplug: prefer to use reserved pages for migration new_node_page will try to use the origin's next NUMA node as the migration destination for hugetlb pages. If such a node doesn't have any preallocated pool it falls back to __alloc_buddy_huge_page_no_mpol to allocate a surplus page instead. This is quite subotpimal for any configuration when hugetlb pages are no distributed to all NUMA nodes evenly. Say we have a hotplugable node 4 and spare hugetlb pages are node 0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:10000 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node3/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node4/hugepages/hugepages-2048kB/nr_hugepages:10000 /sys/devices/system/node/node5/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node6/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node7/hugepages/hugepages-2048kB/nr_hugepages:0 Now we consume the whole pool on node 4 and try to offline this node. All the allocated pages should be moved to node0 which has enough preallocated pages to hold them. With the current implementation offlining very likely fails because hugetlb allocations during runtime are much less reliable. Fix this by reusing the nodemask which excludes migration source and try to find a first node which has a page in the preallocated pool first and fall back to __alloc_buddy_huge_page_no_mpol only when the whole pool is consumed. [akpm@linux-foundation.org: remove bogus arg from alloc_huge_page_nodemask() stub] Link: http://lkml.kernel.org/r/20170608074553.22152-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: zhong jiang <zhongjiang@huawei.com> Cc: Joonsoo Kim <js1304@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-11 01:48:44 +03:00
}
}
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
hugetlb, memory_hotplug: prefer to use reserved pages for migration new_node_page will try to use the origin's next NUMA node as the migration destination for hugetlb pages. If such a node doesn't have any preallocated pool it falls back to __alloc_buddy_huge_page_no_mpol to allocate a surplus page instead. This is quite subotpimal for any configuration when hugetlb pages are no distributed to all NUMA nodes evenly. Say we have a hotplugable node 4 and spare hugetlb pages are node 0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:10000 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node3/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node4/hugepages/hugepages-2048kB/nr_hugepages:10000 /sys/devices/system/node/node5/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node6/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node7/hugepages/hugepages-2048kB/nr_hugepages:0 Now we consume the whole pool on node 4 and try to offline this node. All the allocated pages should be moved to node0 which has enough preallocated pages to hold them. With the current implementation offlining very likely fails because hugetlb allocations during runtime are much less reliable. Fix this by reusing the nodemask which excludes migration source and try to find a first node which has a page in the preallocated pool first and fall back to __alloc_buddy_huge_page_no_mpol only when the whole pool is consumed. [akpm@linux-foundation.org: remove bogus arg from alloc_huge_page_nodemask() stub] Link: http://lkml.kernel.org/r/20170608074553.22152-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: zhong jiang <zhongjiang@huawei.com> Cc: Joonsoo Kim <js1304@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-11 01:48:44 +03:00
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
return alloc_migrate_huge_page(h, gfp_mask, preferred_nid, nmask);
hugetlb, memory_hotplug: prefer to use reserved pages for migration new_node_page will try to use the origin's next NUMA node as the migration destination for hugetlb pages. If such a node doesn't have any preallocated pool it falls back to __alloc_buddy_huge_page_no_mpol to allocate a surplus page instead. This is quite subotpimal for any configuration when hugetlb pages are no distributed to all NUMA nodes evenly. Say we have a hotplugable node 4 and spare hugetlb pages are node 0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:10000 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node3/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node4/hugepages/hugepages-2048kB/nr_hugepages:10000 /sys/devices/system/node/node5/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node6/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node7/hugepages/hugepages-2048kB/nr_hugepages:0 Now we consume the whole pool on node 4 and try to offline this node. All the allocated pages should be moved to node0 which has enough preallocated pages to hold them. With the current implementation offlining very likely fails because hugetlb allocations during runtime are much less reliable. Fix this by reusing the nodemask which excludes migration source and try to find a first node which has a page in the preallocated pool first and fall back to __alloc_buddy_huge_page_no_mpol only when the whole pool is consumed. [akpm@linux-foundation.org: remove bogus arg from alloc_huge_page_nodemask() stub] Link: http://lkml.kernel.org/r/20170608074553.22152-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: zhong jiang <zhongjiang@huawei.com> Cc: Joonsoo Kim <js1304@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-11 01:48:44 +03:00
}
hugetlb, mempolicy: fix the mbind hugetlb migration do_mbind migration code relies on alloc_huge_page_noerr for hugetlb pages. alloc_huge_page_noerr uses alloc_huge_page which is a highlevel allocation function which has to take care of reserves, overcommit or hugetlb cgroup accounting. None of that is really required for the page migration because the new page is only temporal and either will replace the original page or it will be dropped. This is essentially as for other migration call paths and there shouldn't be any reason to handle mbind in a special way. The current implementation is even suboptimal because the migration might fail just because the hugetlb cgroup limit is reached, or the overcommit is saturated. Fix this by making mbind like other hugetlb migration paths. Add a new migration helper alloc_huge_page_vma as a wrapper around alloc_huge_page_nodemask with additional mempolicy handling. alloc_huge_page_noerr has no more users and it can go. Link: http://lkml.kernel.org/r/20180103093213.26329-7-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:21:00 +03:00
/* mempolicy aware migration callback */
struct page *alloc_huge_page_vma(struct hstate *h, struct vm_area_struct *vma,
unsigned long address)
hugetlb, mempolicy: fix the mbind hugetlb migration do_mbind migration code relies on alloc_huge_page_noerr for hugetlb pages. alloc_huge_page_noerr uses alloc_huge_page which is a highlevel allocation function which has to take care of reserves, overcommit or hugetlb cgroup accounting. None of that is really required for the page migration because the new page is only temporal and either will replace the original page or it will be dropped. This is essentially as for other migration call paths and there shouldn't be any reason to handle mbind in a special way. The current implementation is even suboptimal because the migration might fail just because the hugetlb cgroup limit is reached, or the overcommit is saturated. Fix this by making mbind like other hugetlb migration paths. Add a new migration helper alloc_huge_page_vma as a wrapper around alloc_huge_page_nodemask with additional mempolicy handling. alloc_huge_page_noerr has no more users and it can go. Link: http://lkml.kernel.org/r/20180103093213.26329-7-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:21:00 +03:00
{
struct mempolicy *mpol;
nodemask_t *nodemask;
struct page *page;
gfp_t gfp_mask;
int node;
gfp_mask = htlb_alloc_mask(h);
node = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
page = alloc_huge_page_nodemask(h, node, nodemask, gfp_mask);
hugetlb, mempolicy: fix the mbind hugetlb migration do_mbind migration code relies on alloc_huge_page_noerr for hugetlb pages. alloc_huge_page_noerr uses alloc_huge_page which is a highlevel allocation function which has to take care of reserves, overcommit or hugetlb cgroup accounting. None of that is really required for the page migration because the new page is only temporal and either will replace the original page or it will be dropped. This is essentially as for other migration call paths and there shouldn't be any reason to handle mbind in a special way. The current implementation is even suboptimal because the migration might fail just because the hugetlb cgroup limit is reached, or the overcommit is saturated. Fix this by making mbind like other hugetlb migration paths. Add a new migration helper alloc_huge_page_vma as a wrapper around alloc_huge_page_nodemask with additional mempolicy handling. alloc_huge_page_noerr has no more users and it can go. Link: http://lkml.kernel.org/r/20180103093213.26329-7-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:21:00 +03:00
mpol_cond_put(mpol);
return page;
}
/*
* Increase the hugetlb pool such that it can accommodate a reservation
* of size 'delta'.
*/
static int gather_surplus_pages(struct hstate *h, long delta)
__must_hold(&hugetlb_lock)
{
struct list_head surplus_list;
struct page *page, *tmp;
int ret;
long i;
long needed, allocated;
bool alloc_ok = true;
lockdep_assert_held(&hugetlb_lock);
needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
if (needed <= 0) {
h->resv_huge_pages += delta;
return 0;
}
allocated = 0;
INIT_LIST_HEAD(&surplus_list);
ret = -ENOMEM;
retry:
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
for (i = 0; i < needed; i++) {
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
page = alloc_surplus_huge_page(h, htlb_alloc_mask(h),
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
NUMA_NO_NODE, NULL, true);
if (!page) {
alloc_ok = false;
break;
}
list_add(&page->lru, &surplus_list);
cond_resched();
}
allocated += i;
/*
* After retaking hugetlb_lock, we need to recalculate 'needed'
* because either resv_huge_pages or free_huge_pages may have changed.
*/
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
needed = (h->resv_huge_pages + delta) -
(h->free_huge_pages + allocated);
if (needed > 0) {
if (alloc_ok)
goto retry;
/*
* We were not able to allocate enough pages to
* satisfy the entire reservation so we free what
* we've allocated so far.
*/
goto free;
}
/*
* The surplus_list now contains _at_least_ the number of extra pages
* needed to accommodate the reservation. Add the appropriate number
* of pages to the hugetlb pool and free the extras back to the buddy
* allocator. Commit the entire reservation here to prevent another
* process from stealing the pages as they are added to the pool but
* before they are reserved.
*/
needed += allocated;
h->resv_huge_pages += delta;
ret = 0;
/* Free the needed pages to the hugetlb pool */
list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
if ((--needed) < 0)
break;
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
/* Add the page to the hugetlb allocator */
enqueue_huge_page(h, page);
}
free:
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
/*
* Free unnecessary surplus pages to the buddy allocator.
* Pages have no ref count, call free_huge_page directly.
*/
list_for_each_entry_safe(page, tmp, &surplus_list, lru)
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
free_huge_page(page);
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
return ret;
}
/*
mm/hugetlb.c: fix reservation race when freeing surplus pages return_unused_surplus_pages() decrements the global reservation count, and frees any unused surplus pages that were backing the reservation. Commit 7848a4bf51b3 ("mm/hugetlb.c: add cond_resched_lock() in return_unused_surplus_pages()") added a call to cond_resched_lock in the loop freeing the pages. As a result, the hugetlb_lock could be dropped, and someone else could use the pages that will be freed in subsequent iterations of the loop. This could result in inconsistent global hugetlb page state, application api failures (such as mmap) failures or application crashes. When dropping the lock in return_unused_surplus_pages, make sure that the global reservation count (resv_huge_pages) remains sufficiently large to prevent someone else from claiming pages about to be freed. Analyzed by Paul Cassella. Fixes: 7848a4bf51b3 ("mm/hugetlb.c: add cond_resched_lock() in return_unused_surplus_pages()") Link: http://lkml.kernel.org/r/1483991767-6879-1-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Paul Cassella <cassella@cray.com> Suggested-by: Michal Hocko <mhocko@kernel.org> Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: <stable@vger.kernel.org> [3.15+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-01-11 03:58:27 +03:00
* This routine has two main purposes:
* 1) Decrement the reservation count (resv_huge_pages) by the value passed
* in unused_resv_pages. This corresponds to the prior adjustments made
* to the associated reservation map.
* 2) Free any unused surplus pages that may have been allocated to satisfy
* the reservation. As many as unused_resv_pages may be freed.
*/
static void return_unused_surplus_pages(struct hstate *h,
unsigned long unused_resv_pages)
{
unsigned long nr_pages;
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
struct page *page;
LIST_HEAD(page_list);
lockdep_assert_held(&hugetlb_lock);
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
/* Uncommit the reservation */
h->resv_huge_pages -= unused_resv_pages;
/* Cannot return gigantic pages currently */
if (hstate_is_gigantic(h))
mm/hugetlb.c: fix reservation race when freeing surplus pages return_unused_surplus_pages() decrements the global reservation count, and frees any unused surplus pages that were backing the reservation. Commit 7848a4bf51b3 ("mm/hugetlb.c: add cond_resched_lock() in return_unused_surplus_pages()") added a call to cond_resched_lock in the loop freeing the pages. As a result, the hugetlb_lock could be dropped, and someone else could use the pages that will be freed in subsequent iterations of the loop. This could result in inconsistent global hugetlb page state, application api failures (such as mmap) failures or application crashes. When dropping the lock in return_unused_surplus_pages, make sure that the global reservation count (resv_huge_pages) remains sufficiently large to prevent someone else from claiming pages about to be freed. Analyzed by Paul Cassella. Fixes: 7848a4bf51b3 ("mm/hugetlb.c: add cond_resched_lock() in return_unused_surplus_pages()") Link: http://lkml.kernel.org/r/1483991767-6879-1-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Paul Cassella <cassella@cray.com> Suggested-by: Michal Hocko <mhocko@kernel.org> Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: <stable@vger.kernel.org> [3.15+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-01-11 03:58:27 +03:00
goto out;
mm/hugetlb.c: fix reservation race when freeing surplus pages return_unused_surplus_pages() decrements the global reservation count, and frees any unused surplus pages that were backing the reservation. Commit 7848a4bf51b3 ("mm/hugetlb.c: add cond_resched_lock() in return_unused_surplus_pages()") added a call to cond_resched_lock in the loop freeing the pages. As a result, the hugetlb_lock could be dropped, and someone else could use the pages that will be freed in subsequent iterations of the loop. This could result in inconsistent global hugetlb page state, application api failures (such as mmap) failures or application crashes. When dropping the lock in return_unused_surplus_pages, make sure that the global reservation count (resv_huge_pages) remains sufficiently large to prevent someone else from claiming pages about to be freed. Analyzed by Paul Cassella. Fixes: 7848a4bf51b3 ("mm/hugetlb.c: add cond_resched_lock() in return_unused_surplus_pages()") Link: http://lkml.kernel.org/r/1483991767-6879-1-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Paul Cassella <cassella@cray.com> Suggested-by: Michal Hocko <mhocko@kernel.org> Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: <stable@vger.kernel.org> [3.15+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-01-11 03:58:27 +03:00
/*
* Part (or even all) of the reservation could have been backed
* by pre-allocated pages. Only free surplus pages.
*/
nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
/*
* We want to release as many surplus pages as possible, spread
* evenly across all nodes with memory. Iterate across these nodes
* until we can no longer free unreserved surplus pages. This occurs
* when the nodes with surplus pages have no free pages.
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
* remove_pool_huge_page() will balance the freed pages across the
* on-line nodes with memory and will handle the hstate accounting.
*/
while (nr_pages--) {
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
page = remove_pool_huge_page(h, &node_states[N_MEMORY], 1);
if (!page)
mm/hugetlb.c: fix reservation race when freeing surplus pages return_unused_surplus_pages() decrements the global reservation count, and frees any unused surplus pages that were backing the reservation. Commit 7848a4bf51b3 ("mm/hugetlb.c: add cond_resched_lock() in return_unused_surplus_pages()") added a call to cond_resched_lock in the loop freeing the pages. As a result, the hugetlb_lock could be dropped, and someone else could use the pages that will be freed in subsequent iterations of the loop. This could result in inconsistent global hugetlb page state, application api failures (such as mmap) failures or application crashes. When dropping the lock in return_unused_surplus_pages, make sure that the global reservation count (resv_huge_pages) remains sufficiently large to prevent someone else from claiming pages about to be freed. Analyzed by Paul Cassella. Fixes: 7848a4bf51b3 ("mm/hugetlb.c: add cond_resched_lock() in return_unused_surplus_pages()") Link: http://lkml.kernel.org/r/1483991767-6879-1-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Paul Cassella <cassella@cray.com> Suggested-by: Michal Hocko <mhocko@kernel.org> Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: <stable@vger.kernel.org> [3.15+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-01-11 03:58:27 +03:00
goto out;
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
list_add(&page->lru, &page_list);
}
mm/hugetlb.c: fix reservation race when freeing surplus pages return_unused_surplus_pages() decrements the global reservation count, and frees any unused surplus pages that were backing the reservation. Commit 7848a4bf51b3 ("mm/hugetlb.c: add cond_resched_lock() in return_unused_surplus_pages()") added a call to cond_resched_lock in the loop freeing the pages. As a result, the hugetlb_lock could be dropped, and someone else could use the pages that will be freed in subsequent iterations of the loop. This could result in inconsistent global hugetlb page state, application api failures (such as mmap) failures or application crashes. When dropping the lock in return_unused_surplus_pages, make sure that the global reservation count (resv_huge_pages) remains sufficiently large to prevent someone else from claiming pages about to be freed. Analyzed by Paul Cassella. Fixes: 7848a4bf51b3 ("mm/hugetlb.c: add cond_resched_lock() in return_unused_surplus_pages()") Link: http://lkml.kernel.org/r/1483991767-6879-1-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Paul Cassella <cassella@cray.com> Suggested-by: Michal Hocko <mhocko@kernel.org> Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: <stable@vger.kernel.org> [3.15+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-01-11 03:58:27 +03:00
out:
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
update_and_free_pages_bulk(h, &page_list);
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
}
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
/*
* vma_needs_reservation, vma_commit_reservation and vma_end_reservation
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
* are used by the huge page allocation routines to manage reservations.
*
* vma_needs_reservation is called to determine if the huge page at addr
* within the vma has an associated reservation. If a reservation is
* needed, the value 1 is returned. The caller is then responsible for
* managing the global reservation and subpool usage counts. After
* the huge page has been allocated, vma_commit_reservation is called
* to add the page to the reservation map. If the page allocation fails,
* the reservation must be ended instead of committed. vma_end_reservation
* is called in such cases.
*
* In the normal case, vma_commit_reservation returns the same value
* as the preceding vma_needs_reservation call. The only time this
* is not the case is if a reserve map was changed between calls. It
* is the responsibility of the caller to notice the difference and
* take appropriate action.
mm/hugetlb: fix huge page reservation leak in private mapping error paths Error paths in hugetlb_cow() and hugetlb_no_page() may free a newly allocated huge page. If a reservation was associated with the huge page, alloc_huge_page() consumed the reservation while allocating. When the newly allocated page is freed in free_huge_page(), it will increment the global reservation count. However, the reservation entry in the reserve map will remain. This is not an issue for shared mappings as the entry in the reserve map indicates a reservation exists. But, an entry in a private mapping reserve map indicates the reservation was consumed and no longer exists. This results in an inconsistency between the reserve map and the global reservation count. This 'leaks' a reserved huge page. Create a new routine restore_reserve_on_error() to restore the reserve entry in these specific error paths. This routine makes use of a new function vma_add_reservation() which will add a reserve entry for a specific address/page. In general, these error paths were rarely (if ever) taken on most architectures. However, powerpc contained arch specific code that that resulted in an extra fault and execution of these error paths on all private mappings. Fixes: 67961f9db8c4 ("mm/hugetlb: fix huge page reserve accounting for private mappings) Link: http://lkml.kernel.org/r/1476933077-23091-2-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 21:46:32 +03:00
*
* vma_add_reservation is used in error paths where a reservation must
* be restored when a newly allocated huge page must be freed. It is
* to be called after calling vma_needs_reservation to determine if a
* reservation exists.
mm/hugetlb: expand restore_reserve_on_error functionality The routine restore_reserve_on_error is called to restore reservation information when an error occurs after page allocation. The routine alloc_huge_page modifies the mapping reserve map and potentially the reserve count during allocation. If code calling alloc_huge_page encounters an error after allocation and needs to free the page, the reservation information needs to be adjusted. Currently, restore_reserve_on_error only takes action on pages for which the reserve count was adjusted(HPageRestoreReserve flag). There is nothing wrong with these adjustments. However, alloc_huge_page ALWAYS modifies the reserve map during allocation even if the reserve count is not adjusted. This can cause issues as observed during development of this patch [1]. One specific series of operations causing an issue is: - Create a shared hugetlb mapping Reservations for all pages created by default - Fault in a page in the mapping Reservation exists so reservation count is decremented - Punch a hole in the file/mapping at index previously faulted Reservation and any associated pages will be removed - Allocate a page to fill the hole No reservation entry, so reserve count unmodified Reservation entry added to map by alloc_huge_page - Error after allocation and before instantiating the page Reservation entry remains in map - Allocate a page to fill the hole Reservation entry exists, so decrement reservation count This will cause a reservation count underflow as the reservation count was decremented twice for the same index. A user would observe a very large number for HugePages_Rsvd in /proc/meminfo. This would also likely cause subsequent allocations of hugetlb pages to fail as it would 'appear' that all pages are reserved. This sequence of operations is unlikely to happen, however they were easily reproduced and observed using hacked up code as described in [1]. Address the issue by having the routine restore_reserve_on_error take action on pages where HPageRestoreReserve is not set. In this case, we need to remove any reserve map entry created by alloc_huge_page. A new helper routine vma_del_reservation assists with this operation. There are three callers of alloc_huge_page which do not currently call restore_reserve_on error before freeing a page on error paths. Add those missing calls. [1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/ Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com Fixes: 96b96a96ddee ("mm/hugetlb: fix huge page reservation leak in private mapping error paths" Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:29 +03:00
*
* vma_del_reservation is used in error paths where an entry in the reserve
* map was created during huge page allocation and must be removed. It is to
* be called after calling vma_needs_reservation to determine if a reservation
* exists.
*/
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
enum vma_resv_mode {
VMA_NEEDS_RESV,
VMA_COMMIT_RESV,
VMA_END_RESV,
mm/hugetlb: fix huge page reservation leak in private mapping error paths Error paths in hugetlb_cow() and hugetlb_no_page() may free a newly allocated huge page. If a reservation was associated with the huge page, alloc_huge_page() consumed the reservation while allocating. When the newly allocated page is freed in free_huge_page(), it will increment the global reservation count. However, the reservation entry in the reserve map will remain. This is not an issue for shared mappings as the entry in the reserve map indicates a reservation exists. But, an entry in a private mapping reserve map indicates the reservation was consumed and no longer exists. This results in an inconsistency between the reserve map and the global reservation count. This 'leaks' a reserved huge page. Create a new routine restore_reserve_on_error() to restore the reserve entry in these specific error paths. This routine makes use of a new function vma_add_reservation() which will add a reserve entry for a specific address/page. In general, these error paths were rarely (if ever) taken on most architectures. However, powerpc contained arch specific code that that resulted in an extra fault and execution of these error paths on all private mappings. Fixes: 67961f9db8c4 ("mm/hugetlb: fix huge page reserve accounting for private mappings) Link: http://lkml.kernel.org/r/1476933077-23091-2-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 21:46:32 +03:00
VMA_ADD_RESV,
mm/hugetlb: expand restore_reserve_on_error functionality The routine restore_reserve_on_error is called to restore reservation information when an error occurs after page allocation. The routine alloc_huge_page modifies the mapping reserve map and potentially the reserve count during allocation. If code calling alloc_huge_page encounters an error after allocation and needs to free the page, the reservation information needs to be adjusted. Currently, restore_reserve_on_error only takes action on pages for which the reserve count was adjusted(HPageRestoreReserve flag). There is nothing wrong with these adjustments. However, alloc_huge_page ALWAYS modifies the reserve map during allocation even if the reserve count is not adjusted. This can cause issues as observed during development of this patch [1]. One specific series of operations causing an issue is: - Create a shared hugetlb mapping Reservations for all pages created by default - Fault in a page in the mapping Reservation exists so reservation count is decremented - Punch a hole in the file/mapping at index previously faulted Reservation and any associated pages will be removed - Allocate a page to fill the hole No reservation entry, so reserve count unmodified Reservation entry added to map by alloc_huge_page - Error after allocation and before instantiating the page Reservation entry remains in map - Allocate a page to fill the hole Reservation entry exists, so decrement reservation count This will cause a reservation count underflow as the reservation count was decremented twice for the same index. A user would observe a very large number for HugePages_Rsvd in /proc/meminfo. This would also likely cause subsequent allocations of hugetlb pages to fail as it would 'appear' that all pages are reserved. This sequence of operations is unlikely to happen, however they were easily reproduced and observed using hacked up code as described in [1]. Address the issue by having the routine restore_reserve_on_error take action on pages where HPageRestoreReserve is not set. In this case, we need to remove any reserve map entry created by alloc_huge_page. A new helper routine vma_del_reservation assists with this operation. There are three callers of alloc_huge_page which do not currently call restore_reserve_on error before freeing a page on error paths. Add those missing calls. [1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/ Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com Fixes: 96b96a96ddee ("mm/hugetlb: fix huge page reservation leak in private mapping error paths" Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:29 +03:00
VMA_DEL_RESV,
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
};
static long __vma_reservation_common(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr,
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
enum vma_resv_mode mode)
{
struct resv_map *resv;
pgoff_t idx;
long ret;
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
long dummy_out_regions_needed;
resv = vma_resv_map(vma);
if (!resv)
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
return 1;
idx = vma_hugecache_offset(h, vma, addr);
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
switch (mode) {
case VMA_NEEDS_RESV:
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
ret = region_chg(resv, idx, idx + 1, &dummy_out_regions_needed);
/* We assume that vma_reservation_* routines always operate on
* 1 page, and that adding to resv map a 1 page entry can only
* ever require 1 region.
*/
VM_BUG_ON(dummy_out_regions_needed != 1);
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
break;
case VMA_COMMIT_RESV:
ret = region_add(resv, idx, idx + 1, 1, NULL, NULL);
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
/* region_add calls of range 1 should never fail. */
VM_BUG_ON(ret < 0);
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
break;
case VMA_END_RESV:
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
region_abort(resv, idx, idx + 1, 1);
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
ret = 0;
break;
mm/hugetlb: fix huge page reservation leak in private mapping error paths Error paths in hugetlb_cow() and hugetlb_no_page() may free a newly allocated huge page. If a reservation was associated with the huge page, alloc_huge_page() consumed the reservation while allocating. When the newly allocated page is freed in free_huge_page(), it will increment the global reservation count. However, the reservation entry in the reserve map will remain. This is not an issue for shared mappings as the entry in the reserve map indicates a reservation exists. But, an entry in a private mapping reserve map indicates the reservation was consumed and no longer exists. This results in an inconsistency between the reserve map and the global reservation count. This 'leaks' a reserved huge page. Create a new routine restore_reserve_on_error() to restore the reserve entry in these specific error paths. This routine makes use of a new function vma_add_reservation() which will add a reserve entry for a specific address/page. In general, these error paths were rarely (if ever) taken on most architectures. However, powerpc contained arch specific code that that resulted in an extra fault and execution of these error paths on all private mappings. Fixes: 67961f9db8c4 ("mm/hugetlb: fix huge page reserve accounting for private mappings) Link: http://lkml.kernel.org/r/1476933077-23091-2-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 21:46:32 +03:00
case VMA_ADD_RESV:
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
if (vma->vm_flags & VM_MAYSHARE) {
ret = region_add(resv, idx, idx + 1, 1, NULL, NULL);
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
/* region_add calls of range 1 should never fail. */
VM_BUG_ON(ret < 0);
} else {
region_abort(resv, idx, idx + 1, 1);
mm/hugetlb: fix huge page reservation leak in private mapping error paths Error paths in hugetlb_cow() and hugetlb_no_page() may free a newly allocated huge page. If a reservation was associated with the huge page, alloc_huge_page() consumed the reservation while allocating. When the newly allocated page is freed in free_huge_page(), it will increment the global reservation count. However, the reservation entry in the reserve map will remain. This is not an issue for shared mappings as the entry in the reserve map indicates a reservation exists. But, an entry in a private mapping reserve map indicates the reservation was consumed and no longer exists. This results in an inconsistency between the reserve map and the global reservation count. This 'leaks' a reserved huge page. Create a new routine restore_reserve_on_error() to restore the reserve entry in these specific error paths. This routine makes use of a new function vma_add_reservation() which will add a reserve entry for a specific address/page. In general, these error paths were rarely (if ever) taken on most architectures. However, powerpc contained arch specific code that that resulted in an extra fault and execution of these error paths on all private mappings. Fixes: 67961f9db8c4 ("mm/hugetlb: fix huge page reserve accounting for private mappings) Link: http://lkml.kernel.org/r/1476933077-23091-2-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 21:46:32 +03:00
ret = region_del(resv, idx, idx + 1);
}
break;
mm/hugetlb: expand restore_reserve_on_error functionality The routine restore_reserve_on_error is called to restore reservation information when an error occurs after page allocation. The routine alloc_huge_page modifies the mapping reserve map and potentially the reserve count during allocation. If code calling alloc_huge_page encounters an error after allocation and needs to free the page, the reservation information needs to be adjusted. Currently, restore_reserve_on_error only takes action on pages for which the reserve count was adjusted(HPageRestoreReserve flag). There is nothing wrong with these adjustments. However, alloc_huge_page ALWAYS modifies the reserve map during allocation even if the reserve count is not adjusted. This can cause issues as observed during development of this patch [1]. One specific series of operations causing an issue is: - Create a shared hugetlb mapping Reservations for all pages created by default - Fault in a page in the mapping Reservation exists so reservation count is decremented - Punch a hole in the file/mapping at index previously faulted Reservation and any associated pages will be removed - Allocate a page to fill the hole No reservation entry, so reserve count unmodified Reservation entry added to map by alloc_huge_page - Error after allocation and before instantiating the page Reservation entry remains in map - Allocate a page to fill the hole Reservation entry exists, so decrement reservation count This will cause a reservation count underflow as the reservation count was decremented twice for the same index. A user would observe a very large number for HugePages_Rsvd in /proc/meminfo. This would also likely cause subsequent allocations of hugetlb pages to fail as it would 'appear' that all pages are reserved. This sequence of operations is unlikely to happen, however they were easily reproduced and observed using hacked up code as described in [1]. Address the issue by having the routine restore_reserve_on_error take action on pages where HPageRestoreReserve is not set. In this case, we need to remove any reserve map entry created by alloc_huge_page. A new helper routine vma_del_reservation assists with this operation. There are three callers of alloc_huge_page which do not currently call restore_reserve_on error before freeing a page on error paths. Add those missing calls. [1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/ Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com Fixes: 96b96a96ddee ("mm/hugetlb: fix huge page reservation leak in private mapping error paths" Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:29 +03:00
case VMA_DEL_RESV:
if (vma->vm_flags & VM_MAYSHARE) {
region_abort(resv, idx, idx + 1, 1);
ret = region_del(resv, idx, idx + 1);
} else {
ret = region_add(resv, idx, idx + 1, 1, NULL, NULL);
/* region_add calls of range 1 should never fail. */
VM_BUG_ON(ret < 0);
}
break;
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
default:
BUG();
}
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
mm/hugetlb: expand restore_reserve_on_error functionality The routine restore_reserve_on_error is called to restore reservation information when an error occurs after page allocation. The routine alloc_huge_page modifies the mapping reserve map and potentially the reserve count during allocation. If code calling alloc_huge_page encounters an error after allocation and needs to free the page, the reservation information needs to be adjusted. Currently, restore_reserve_on_error only takes action on pages for which the reserve count was adjusted(HPageRestoreReserve flag). There is nothing wrong with these adjustments. However, alloc_huge_page ALWAYS modifies the reserve map during allocation even if the reserve count is not adjusted. This can cause issues as observed during development of this patch [1]. One specific series of operations causing an issue is: - Create a shared hugetlb mapping Reservations for all pages created by default - Fault in a page in the mapping Reservation exists so reservation count is decremented - Punch a hole in the file/mapping at index previously faulted Reservation and any associated pages will be removed - Allocate a page to fill the hole No reservation entry, so reserve count unmodified Reservation entry added to map by alloc_huge_page - Error after allocation and before instantiating the page Reservation entry remains in map - Allocate a page to fill the hole Reservation entry exists, so decrement reservation count This will cause a reservation count underflow as the reservation count was decremented twice for the same index. A user would observe a very large number for HugePages_Rsvd in /proc/meminfo. This would also likely cause subsequent allocations of hugetlb pages to fail as it would 'appear' that all pages are reserved. This sequence of operations is unlikely to happen, however they were easily reproduced and observed using hacked up code as described in [1]. Address the issue by having the routine restore_reserve_on_error take action on pages where HPageRestoreReserve is not set. In this case, we need to remove any reserve map entry created by alloc_huge_page. A new helper routine vma_del_reservation assists with this operation. There are three callers of alloc_huge_page which do not currently call restore_reserve_on error before freeing a page on error paths. Add those missing calls. [1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/ Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com Fixes: 96b96a96ddee ("mm/hugetlb: fix huge page reservation leak in private mapping error paths" Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:29 +03:00
if (vma->vm_flags & VM_MAYSHARE || mode == VMA_DEL_RESV)
return ret;
/*
* We know private mapping must have HPAGE_RESV_OWNER set.
*
* In most cases, reserves always exist for private mappings.
* However, a file associated with mapping could have been
* hole punched or truncated after reserves were consumed.
* As subsequent fault on such a range will not use reserves.
* Subtle - The reserve map for private mappings has the
* opposite meaning than that of shared mappings. If NO
* entry is in the reserve map, it means a reservation exists.
* If an entry exists in the reserve map, it means the
* reservation has already been consumed. As a result, the
* return value of this routine is the opposite of the
* value returned from reserve map manipulation routines above.
*/
if (ret > 0)
return 0;
if (ret == 0)
return 1;
return ret;
}
static long vma_needs_reservation(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr)
{
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
return __vma_reservation_common(h, vma, addr, VMA_NEEDS_RESV);
}
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
static long vma_commit_reservation(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr)
{
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV);
}
static void vma_end_reservation(struct hstate *h,
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
struct vm_area_struct *vma, unsigned long addr)
{
(void)__vma_reservation_common(h, vma, addr, VMA_END_RESV);
}
mm/hugetlb: fix huge page reservation leak in private mapping error paths Error paths in hugetlb_cow() and hugetlb_no_page() may free a newly allocated huge page. If a reservation was associated with the huge page, alloc_huge_page() consumed the reservation while allocating. When the newly allocated page is freed in free_huge_page(), it will increment the global reservation count. However, the reservation entry in the reserve map will remain. This is not an issue for shared mappings as the entry in the reserve map indicates a reservation exists. But, an entry in a private mapping reserve map indicates the reservation was consumed and no longer exists. This results in an inconsistency between the reserve map and the global reservation count. This 'leaks' a reserved huge page. Create a new routine restore_reserve_on_error() to restore the reserve entry in these specific error paths. This routine makes use of a new function vma_add_reservation() which will add a reserve entry for a specific address/page. In general, these error paths were rarely (if ever) taken on most architectures. However, powerpc contained arch specific code that that resulted in an extra fault and execution of these error paths on all private mappings. Fixes: 67961f9db8c4 ("mm/hugetlb: fix huge page reserve accounting for private mappings) Link: http://lkml.kernel.org/r/1476933077-23091-2-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 21:46:32 +03:00
static long vma_add_reservation(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr)
{
return __vma_reservation_common(h, vma, addr, VMA_ADD_RESV);
}
mm/hugetlb: expand restore_reserve_on_error functionality The routine restore_reserve_on_error is called to restore reservation information when an error occurs after page allocation. The routine alloc_huge_page modifies the mapping reserve map and potentially the reserve count during allocation. If code calling alloc_huge_page encounters an error after allocation and needs to free the page, the reservation information needs to be adjusted. Currently, restore_reserve_on_error only takes action on pages for which the reserve count was adjusted(HPageRestoreReserve flag). There is nothing wrong with these adjustments. However, alloc_huge_page ALWAYS modifies the reserve map during allocation even if the reserve count is not adjusted. This can cause issues as observed during development of this patch [1]. One specific series of operations causing an issue is: - Create a shared hugetlb mapping Reservations for all pages created by default - Fault in a page in the mapping Reservation exists so reservation count is decremented - Punch a hole in the file/mapping at index previously faulted Reservation and any associated pages will be removed - Allocate a page to fill the hole No reservation entry, so reserve count unmodified Reservation entry added to map by alloc_huge_page - Error after allocation and before instantiating the page Reservation entry remains in map - Allocate a page to fill the hole Reservation entry exists, so decrement reservation count This will cause a reservation count underflow as the reservation count was decremented twice for the same index. A user would observe a very large number for HugePages_Rsvd in /proc/meminfo. This would also likely cause subsequent allocations of hugetlb pages to fail as it would 'appear' that all pages are reserved. This sequence of operations is unlikely to happen, however they were easily reproduced and observed using hacked up code as described in [1]. Address the issue by having the routine restore_reserve_on_error take action on pages where HPageRestoreReserve is not set. In this case, we need to remove any reserve map entry created by alloc_huge_page. A new helper routine vma_del_reservation assists with this operation. There are three callers of alloc_huge_page which do not currently call restore_reserve_on error before freeing a page on error paths. Add those missing calls. [1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/ Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com Fixes: 96b96a96ddee ("mm/hugetlb: fix huge page reservation leak in private mapping error paths" Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:29 +03:00
static long vma_del_reservation(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr)
{
return __vma_reservation_common(h, vma, addr, VMA_DEL_RESV);
}
mm/hugetlb: fix huge page reservation leak in private mapping error paths Error paths in hugetlb_cow() and hugetlb_no_page() may free a newly allocated huge page. If a reservation was associated with the huge page, alloc_huge_page() consumed the reservation while allocating. When the newly allocated page is freed in free_huge_page(), it will increment the global reservation count. However, the reservation entry in the reserve map will remain. This is not an issue for shared mappings as the entry in the reserve map indicates a reservation exists. But, an entry in a private mapping reserve map indicates the reservation was consumed and no longer exists. This results in an inconsistency between the reserve map and the global reservation count. This 'leaks' a reserved huge page. Create a new routine restore_reserve_on_error() to restore the reserve entry in these specific error paths. This routine makes use of a new function vma_add_reservation() which will add a reserve entry for a specific address/page. In general, these error paths were rarely (if ever) taken on most architectures. However, powerpc contained arch specific code that that resulted in an extra fault and execution of these error paths on all private mappings. Fixes: 67961f9db8c4 ("mm/hugetlb: fix huge page reserve accounting for private mappings) Link: http://lkml.kernel.org/r/1476933077-23091-2-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 21:46:32 +03:00
/*
mm/hugetlb: expand restore_reserve_on_error functionality The routine restore_reserve_on_error is called to restore reservation information when an error occurs after page allocation. The routine alloc_huge_page modifies the mapping reserve map and potentially the reserve count during allocation. If code calling alloc_huge_page encounters an error after allocation and needs to free the page, the reservation information needs to be adjusted. Currently, restore_reserve_on_error only takes action on pages for which the reserve count was adjusted(HPageRestoreReserve flag). There is nothing wrong with these adjustments. However, alloc_huge_page ALWAYS modifies the reserve map during allocation even if the reserve count is not adjusted. This can cause issues as observed during development of this patch [1]. One specific series of operations causing an issue is: - Create a shared hugetlb mapping Reservations for all pages created by default - Fault in a page in the mapping Reservation exists so reservation count is decremented - Punch a hole in the file/mapping at index previously faulted Reservation and any associated pages will be removed - Allocate a page to fill the hole No reservation entry, so reserve count unmodified Reservation entry added to map by alloc_huge_page - Error after allocation and before instantiating the page Reservation entry remains in map - Allocate a page to fill the hole Reservation entry exists, so decrement reservation count This will cause a reservation count underflow as the reservation count was decremented twice for the same index. A user would observe a very large number for HugePages_Rsvd in /proc/meminfo. This would also likely cause subsequent allocations of hugetlb pages to fail as it would 'appear' that all pages are reserved. This sequence of operations is unlikely to happen, however they were easily reproduced and observed using hacked up code as described in [1]. Address the issue by having the routine restore_reserve_on_error take action on pages where HPageRestoreReserve is not set. In this case, we need to remove any reserve map entry created by alloc_huge_page. A new helper routine vma_del_reservation assists with this operation. There are three callers of alloc_huge_page which do not currently call restore_reserve_on error before freeing a page on error paths. Add those missing calls. [1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/ Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com Fixes: 96b96a96ddee ("mm/hugetlb: fix huge page reservation leak in private mapping error paths" Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:29 +03:00
* This routine is called to restore reservation information on error paths.
* It should ONLY be called for pages allocated via alloc_huge_page(), and
* the hugetlb mutex should remain held when calling this routine.
*
* It handles two specific cases:
* 1) A reservation was in place and the page consumed the reservation.
* HPageRestoreReserve is set in the page.
* 2) No reservation was in place for the page, so HPageRestoreReserve is
* not set. However, alloc_huge_page always updates the reserve map.
*
* In case 1, free_huge_page later in the error path will increment the
* global reserve count. But, free_huge_page does not have enough context
* to adjust the reservation map. This case deals primarily with private
* mappings. Adjust the reserve map here to be consistent with global
* reserve count adjustments to be made by free_huge_page. Make sure the
* reserve map indicates there is a reservation present.
*
* In case 2, simply undo reserve map modifications done by alloc_huge_page.
mm/hugetlb: fix huge page reservation leak in private mapping error paths Error paths in hugetlb_cow() and hugetlb_no_page() may free a newly allocated huge page. If a reservation was associated with the huge page, alloc_huge_page() consumed the reservation while allocating. When the newly allocated page is freed in free_huge_page(), it will increment the global reservation count. However, the reservation entry in the reserve map will remain. This is not an issue for shared mappings as the entry in the reserve map indicates a reservation exists. But, an entry in a private mapping reserve map indicates the reservation was consumed and no longer exists. This results in an inconsistency between the reserve map and the global reservation count. This 'leaks' a reserved huge page. Create a new routine restore_reserve_on_error() to restore the reserve entry in these specific error paths. This routine makes use of a new function vma_add_reservation() which will add a reserve entry for a specific address/page. In general, these error paths were rarely (if ever) taken on most architectures. However, powerpc contained arch specific code that that resulted in an extra fault and execution of these error paths on all private mappings. Fixes: 67961f9db8c4 ("mm/hugetlb: fix huge page reserve accounting for private mappings) Link: http://lkml.kernel.org/r/1476933077-23091-2-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 21:46:32 +03:00
*/
mm/hugetlb: expand restore_reserve_on_error functionality The routine restore_reserve_on_error is called to restore reservation information when an error occurs after page allocation. The routine alloc_huge_page modifies the mapping reserve map and potentially the reserve count during allocation. If code calling alloc_huge_page encounters an error after allocation and needs to free the page, the reservation information needs to be adjusted. Currently, restore_reserve_on_error only takes action on pages for which the reserve count was adjusted(HPageRestoreReserve flag). There is nothing wrong with these adjustments. However, alloc_huge_page ALWAYS modifies the reserve map during allocation even if the reserve count is not adjusted. This can cause issues as observed during development of this patch [1]. One specific series of operations causing an issue is: - Create a shared hugetlb mapping Reservations for all pages created by default - Fault in a page in the mapping Reservation exists so reservation count is decremented - Punch a hole in the file/mapping at index previously faulted Reservation and any associated pages will be removed - Allocate a page to fill the hole No reservation entry, so reserve count unmodified Reservation entry added to map by alloc_huge_page - Error after allocation and before instantiating the page Reservation entry remains in map - Allocate a page to fill the hole Reservation entry exists, so decrement reservation count This will cause a reservation count underflow as the reservation count was decremented twice for the same index. A user would observe a very large number for HugePages_Rsvd in /proc/meminfo. This would also likely cause subsequent allocations of hugetlb pages to fail as it would 'appear' that all pages are reserved. This sequence of operations is unlikely to happen, however they were easily reproduced and observed using hacked up code as described in [1]. Address the issue by having the routine restore_reserve_on_error take action on pages where HPageRestoreReserve is not set. In this case, we need to remove any reserve map entry created by alloc_huge_page. A new helper routine vma_del_reservation assists with this operation. There are three callers of alloc_huge_page which do not currently call restore_reserve_on error before freeing a page on error paths. Add those missing calls. [1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/ Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com Fixes: 96b96a96ddee ("mm/hugetlb: fix huge page reservation leak in private mapping error paths" Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:29 +03:00
void restore_reserve_on_error(struct hstate *h, struct vm_area_struct *vma,
unsigned long address, struct page *page)
mm/hugetlb: fix huge page reservation leak in private mapping error paths Error paths in hugetlb_cow() and hugetlb_no_page() may free a newly allocated huge page. If a reservation was associated with the huge page, alloc_huge_page() consumed the reservation while allocating. When the newly allocated page is freed in free_huge_page(), it will increment the global reservation count. However, the reservation entry in the reserve map will remain. This is not an issue for shared mappings as the entry in the reserve map indicates a reservation exists. But, an entry in a private mapping reserve map indicates the reservation was consumed and no longer exists. This results in an inconsistency between the reserve map and the global reservation count. This 'leaks' a reserved huge page. Create a new routine restore_reserve_on_error() to restore the reserve entry in these specific error paths. This routine makes use of a new function vma_add_reservation() which will add a reserve entry for a specific address/page. In general, these error paths were rarely (if ever) taken on most architectures. However, powerpc contained arch specific code that that resulted in an extra fault and execution of these error paths on all private mappings. Fixes: 67961f9db8c4 ("mm/hugetlb: fix huge page reserve accounting for private mappings) Link: http://lkml.kernel.org/r/1476933077-23091-2-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 21:46:32 +03:00
{
mm/hugetlb: expand restore_reserve_on_error functionality The routine restore_reserve_on_error is called to restore reservation information when an error occurs after page allocation. The routine alloc_huge_page modifies the mapping reserve map and potentially the reserve count during allocation. If code calling alloc_huge_page encounters an error after allocation and needs to free the page, the reservation information needs to be adjusted. Currently, restore_reserve_on_error only takes action on pages for which the reserve count was adjusted(HPageRestoreReserve flag). There is nothing wrong with these adjustments. However, alloc_huge_page ALWAYS modifies the reserve map during allocation even if the reserve count is not adjusted. This can cause issues as observed during development of this patch [1]. One specific series of operations causing an issue is: - Create a shared hugetlb mapping Reservations for all pages created by default - Fault in a page in the mapping Reservation exists so reservation count is decremented - Punch a hole in the file/mapping at index previously faulted Reservation and any associated pages will be removed - Allocate a page to fill the hole No reservation entry, so reserve count unmodified Reservation entry added to map by alloc_huge_page - Error after allocation and before instantiating the page Reservation entry remains in map - Allocate a page to fill the hole Reservation entry exists, so decrement reservation count This will cause a reservation count underflow as the reservation count was decremented twice for the same index. A user would observe a very large number for HugePages_Rsvd in /proc/meminfo. This would also likely cause subsequent allocations of hugetlb pages to fail as it would 'appear' that all pages are reserved. This sequence of operations is unlikely to happen, however they were easily reproduced and observed using hacked up code as described in [1]. Address the issue by having the routine restore_reserve_on_error take action on pages where HPageRestoreReserve is not set. In this case, we need to remove any reserve map entry created by alloc_huge_page. A new helper routine vma_del_reservation assists with this operation. There are three callers of alloc_huge_page which do not currently call restore_reserve_on error before freeing a page on error paths. Add those missing calls. [1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/ Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com Fixes: 96b96a96ddee ("mm/hugetlb: fix huge page reservation leak in private mapping error paths" Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:29 +03:00
long rc = vma_needs_reservation(h, vma, address);
mm/hugetlb: fix huge page reservation leak in private mapping error paths Error paths in hugetlb_cow() and hugetlb_no_page() may free a newly allocated huge page. If a reservation was associated with the huge page, alloc_huge_page() consumed the reservation while allocating. When the newly allocated page is freed in free_huge_page(), it will increment the global reservation count. However, the reservation entry in the reserve map will remain. This is not an issue for shared mappings as the entry in the reserve map indicates a reservation exists. But, an entry in a private mapping reserve map indicates the reservation was consumed and no longer exists. This results in an inconsistency between the reserve map and the global reservation count. This 'leaks' a reserved huge page. Create a new routine restore_reserve_on_error() to restore the reserve entry in these specific error paths. This routine makes use of a new function vma_add_reservation() which will add a reserve entry for a specific address/page. In general, these error paths were rarely (if ever) taken on most architectures. However, powerpc contained arch specific code that that resulted in an extra fault and execution of these error paths on all private mappings. Fixes: 67961f9db8c4 ("mm/hugetlb: fix huge page reserve accounting for private mappings) Link: http://lkml.kernel.org/r/1476933077-23091-2-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 21:46:32 +03:00
mm/hugetlb: expand restore_reserve_on_error functionality The routine restore_reserve_on_error is called to restore reservation information when an error occurs after page allocation. The routine alloc_huge_page modifies the mapping reserve map and potentially the reserve count during allocation. If code calling alloc_huge_page encounters an error after allocation and needs to free the page, the reservation information needs to be adjusted. Currently, restore_reserve_on_error only takes action on pages for which the reserve count was adjusted(HPageRestoreReserve flag). There is nothing wrong with these adjustments. However, alloc_huge_page ALWAYS modifies the reserve map during allocation even if the reserve count is not adjusted. This can cause issues as observed during development of this patch [1]. One specific series of operations causing an issue is: - Create a shared hugetlb mapping Reservations for all pages created by default - Fault in a page in the mapping Reservation exists so reservation count is decremented - Punch a hole in the file/mapping at index previously faulted Reservation and any associated pages will be removed - Allocate a page to fill the hole No reservation entry, so reserve count unmodified Reservation entry added to map by alloc_huge_page - Error after allocation and before instantiating the page Reservation entry remains in map - Allocate a page to fill the hole Reservation entry exists, so decrement reservation count This will cause a reservation count underflow as the reservation count was decremented twice for the same index. A user would observe a very large number for HugePages_Rsvd in /proc/meminfo. This would also likely cause subsequent allocations of hugetlb pages to fail as it would 'appear' that all pages are reserved. This sequence of operations is unlikely to happen, however they were easily reproduced and observed using hacked up code as described in [1]. Address the issue by having the routine restore_reserve_on_error take action on pages where HPageRestoreReserve is not set. In this case, we need to remove any reserve map entry created by alloc_huge_page. A new helper routine vma_del_reservation assists with this operation. There are three callers of alloc_huge_page which do not currently call restore_reserve_on error before freeing a page on error paths. Add those missing calls. [1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/ Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com Fixes: 96b96a96ddee ("mm/hugetlb: fix huge page reservation leak in private mapping error paths" Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:29 +03:00
if (HPageRestoreReserve(page)) {
if (unlikely(rc < 0))
mm/hugetlb: fix huge page reservation leak in private mapping error paths Error paths in hugetlb_cow() and hugetlb_no_page() may free a newly allocated huge page. If a reservation was associated with the huge page, alloc_huge_page() consumed the reservation while allocating. When the newly allocated page is freed in free_huge_page(), it will increment the global reservation count. However, the reservation entry in the reserve map will remain. This is not an issue for shared mappings as the entry in the reserve map indicates a reservation exists. But, an entry in a private mapping reserve map indicates the reservation was consumed and no longer exists. This results in an inconsistency between the reserve map and the global reservation count. This 'leaks' a reserved huge page. Create a new routine restore_reserve_on_error() to restore the reserve entry in these specific error paths. This routine makes use of a new function vma_add_reservation() which will add a reserve entry for a specific address/page. In general, these error paths were rarely (if ever) taken on most architectures. However, powerpc contained arch specific code that that resulted in an extra fault and execution of these error paths on all private mappings. Fixes: 67961f9db8c4 ("mm/hugetlb: fix huge page reserve accounting for private mappings) Link: http://lkml.kernel.org/r/1476933077-23091-2-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 21:46:32 +03:00
/*
* Rare out of memory condition in reserve map
hugetlb: use page.private for hugetlb specific page flags Patch series "create hugetlb flags to consolidate state", v3. While discussing a series of hugetlb fixes in [1], it became evident that the hugetlb specific page state information is stored in a somewhat haphazard manner. Code dealing with state information would be easier to read, understand and maintain if this information was stored in a consistent manner. This series uses page.private of the hugetlb head page for storing a set of hugetlb specific page flags. Routines are priovided for test, set and clear of the flags. [1] https://lore.kernel.org/r/20210106084739.63318-1-songmuchun@bytedance.com This patch (of 4): As hugetlbfs evolved, state information about hugetlb pages was added. One 'convenient' way of doing this was to use available fields in tail pages. Over time, it has become difficult to know the meaning or contents of fields simply by looking at a small bit of code. Sometimes, the naming is just confusing. For example: The PagePrivate flag indicates a huge page reservation was consumed and needs to be restored if an error is encountered and the page is freed before it is instantiated. The page.private field contains the pointer to a subpool if the page is associated with one. In an effort to make the code more readable, use page.private to contain hugetlb specific page flags. These flags will have test, set and clear functions similar to those used for 'normal' page flags. More importantly, an enum of flag values will be created with names that actually reflect their purpose. In this patch, - Create infrastructure for hugetlb specific page flag functions - Move subpool pointer to page[1].private to make way for flags Create routines with meaningful names to modify subpool field - Use new HPageRestoreReserve flag instead of PagePrivate Conversion of other state information will happen in subsequent patches. Link: https://lkml.kernel.org/r/20210122195231.324857-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210122195231.324857-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:51 +03:00
* manipulation. Clear HPageRestoreReserve so that
mm/hugetlb: fix huge page reservation leak in private mapping error paths Error paths in hugetlb_cow() and hugetlb_no_page() may free a newly allocated huge page. If a reservation was associated with the huge page, alloc_huge_page() consumed the reservation while allocating. When the newly allocated page is freed in free_huge_page(), it will increment the global reservation count. However, the reservation entry in the reserve map will remain. This is not an issue for shared mappings as the entry in the reserve map indicates a reservation exists. But, an entry in a private mapping reserve map indicates the reservation was consumed and no longer exists. This results in an inconsistency between the reserve map and the global reservation count. This 'leaks' a reserved huge page. Create a new routine restore_reserve_on_error() to restore the reserve entry in these specific error paths. This routine makes use of a new function vma_add_reservation() which will add a reserve entry for a specific address/page. In general, these error paths were rarely (if ever) taken on most architectures. However, powerpc contained arch specific code that that resulted in an extra fault and execution of these error paths on all private mappings. Fixes: 67961f9db8c4 ("mm/hugetlb: fix huge page reserve accounting for private mappings) Link: http://lkml.kernel.org/r/1476933077-23091-2-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 21:46:32 +03:00
* global reserve count will not be incremented
* by free_huge_page. This will make it appear
* as though the reservation for this page was
* consumed. This may prevent the task from
* faulting in the page at a later time. This
* is better than inconsistent global huge page
* accounting of reserve counts.
*/
hugetlb: use page.private for hugetlb specific page flags Patch series "create hugetlb flags to consolidate state", v3. While discussing a series of hugetlb fixes in [1], it became evident that the hugetlb specific page state information is stored in a somewhat haphazard manner. Code dealing with state information would be easier to read, understand and maintain if this information was stored in a consistent manner. This series uses page.private of the hugetlb head page for storing a set of hugetlb specific page flags. Routines are priovided for test, set and clear of the flags. [1] https://lore.kernel.org/r/20210106084739.63318-1-songmuchun@bytedance.com This patch (of 4): As hugetlbfs evolved, state information about hugetlb pages was added. One 'convenient' way of doing this was to use available fields in tail pages. Over time, it has become difficult to know the meaning or contents of fields simply by looking at a small bit of code. Sometimes, the naming is just confusing. For example: The PagePrivate flag indicates a huge page reservation was consumed and needs to be restored if an error is encountered and the page is freed before it is instantiated. The page.private field contains the pointer to a subpool if the page is associated with one. In an effort to make the code more readable, use page.private to contain hugetlb specific page flags. These flags will have test, set and clear functions similar to those used for 'normal' page flags. More importantly, an enum of flag values will be created with names that actually reflect their purpose. In this patch, - Create infrastructure for hugetlb specific page flag functions - Move subpool pointer to page[1].private to make way for flags Create routines with meaningful names to modify subpool field - Use new HPageRestoreReserve flag instead of PagePrivate Conversion of other state information will happen in subsequent patches. Link: https://lkml.kernel.org/r/20210122195231.324857-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210122195231.324857-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:51 +03:00
ClearHPageRestoreReserve(page);
mm/hugetlb: expand restore_reserve_on_error functionality The routine restore_reserve_on_error is called to restore reservation information when an error occurs after page allocation. The routine alloc_huge_page modifies the mapping reserve map and potentially the reserve count during allocation. If code calling alloc_huge_page encounters an error after allocation and needs to free the page, the reservation information needs to be adjusted. Currently, restore_reserve_on_error only takes action on pages for which the reserve count was adjusted(HPageRestoreReserve flag). There is nothing wrong with these adjustments. However, alloc_huge_page ALWAYS modifies the reserve map during allocation even if the reserve count is not adjusted. This can cause issues as observed during development of this patch [1]. One specific series of operations causing an issue is: - Create a shared hugetlb mapping Reservations for all pages created by default - Fault in a page in the mapping Reservation exists so reservation count is decremented - Punch a hole in the file/mapping at index previously faulted Reservation and any associated pages will be removed - Allocate a page to fill the hole No reservation entry, so reserve count unmodified Reservation entry added to map by alloc_huge_page - Error after allocation and before instantiating the page Reservation entry remains in map - Allocate a page to fill the hole Reservation entry exists, so decrement reservation count This will cause a reservation count underflow as the reservation count was decremented twice for the same index. A user would observe a very large number for HugePages_Rsvd in /proc/meminfo. This would also likely cause subsequent allocations of hugetlb pages to fail as it would 'appear' that all pages are reserved. This sequence of operations is unlikely to happen, however they were easily reproduced and observed using hacked up code as described in [1]. Address the issue by having the routine restore_reserve_on_error take action on pages where HPageRestoreReserve is not set. In this case, we need to remove any reserve map entry created by alloc_huge_page. A new helper routine vma_del_reservation assists with this operation. There are three callers of alloc_huge_page which do not currently call restore_reserve_on error before freeing a page on error paths. Add those missing calls. [1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/ Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com Fixes: 96b96a96ddee ("mm/hugetlb: fix huge page reservation leak in private mapping error paths" Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:29 +03:00
else if (rc)
(void)vma_add_reservation(h, vma, address);
else
vma_end_reservation(h, vma, address);
} else {
if (!rc) {
/*
* This indicates there is an entry in the reserve map
hugetlb: don't pass page cache pages to restore_reserve_on_error syzbot hit kernel BUG at fs/hugetlbfs/inode.c:532 as described in [1]. This BUG triggers if the HPageRestoreReserve flag is set on a page in the page cache. It should never be set, as the routine huge_add_to_page_cache explicitly clears the flag after adding a page to the cache. The only code other than huge page allocation which sets the flag is restore_reserve_on_error. It will potentially set the flag in rare out of memory conditions. syzbot was injecting errors to cause memory allocation errors which exercised this specific path. The code in restore_reserve_on_error is doing the right thing. However, there are instances where pages in the page cache were being passed to restore_reserve_on_error. This is incorrect, as once a page goes into the cache reservation information will not be modified for the page until it is removed from the cache. Error paths do not remove pages from the cache, so even in the case of error, the page will remain in the cache and no reservation adjustment is needed. Modify routines that potentially call restore_reserve_on_error with a page cache page to no longer do so. Note on fixes tag: Prior to commit 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") the routine would not process page cache pages because the HPageRestoreReserve flag is not set on such pages. Therefore, this issue could not be trigggered. The code added by commit 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") is needed and correct. It exposed incorrect calls to restore_reserve_on_error which is the root cause addressed by this commit. [1] https://lore.kernel.org/linux-mm/00000000000050776d05c9b7c7f0@google.com/ Link: https://lkml.kernel.org/r/20210818213304.37038-1-mike.kravetz@oracle.com Fixes: 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: <syzbot+67654e51e54455f1c585@syzkaller.appspotmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-08-20 05:04:33 +03:00
* not added by alloc_huge_page. We know it was added
mm/hugetlb: expand restore_reserve_on_error functionality The routine restore_reserve_on_error is called to restore reservation information when an error occurs after page allocation. The routine alloc_huge_page modifies the mapping reserve map and potentially the reserve count during allocation. If code calling alloc_huge_page encounters an error after allocation and needs to free the page, the reservation information needs to be adjusted. Currently, restore_reserve_on_error only takes action on pages for which the reserve count was adjusted(HPageRestoreReserve flag). There is nothing wrong with these adjustments. However, alloc_huge_page ALWAYS modifies the reserve map during allocation even if the reserve count is not adjusted. This can cause issues as observed during development of this patch [1]. One specific series of operations causing an issue is: - Create a shared hugetlb mapping Reservations for all pages created by default - Fault in a page in the mapping Reservation exists so reservation count is decremented - Punch a hole in the file/mapping at index previously faulted Reservation and any associated pages will be removed - Allocate a page to fill the hole No reservation entry, so reserve count unmodified Reservation entry added to map by alloc_huge_page - Error after allocation and before instantiating the page Reservation entry remains in map - Allocate a page to fill the hole Reservation entry exists, so decrement reservation count This will cause a reservation count underflow as the reservation count was decremented twice for the same index. A user would observe a very large number for HugePages_Rsvd in /proc/meminfo. This would also likely cause subsequent allocations of hugetlb pages to fail as it would 'appear' that all pages are reserved. This sequence of operations is unlikely to happen, however they were easily reproduced and observed using hacked up code as described in [1]. Address the issue by having the routine restore_reserve_on_error take action on pages where HPageRestoreReserve is not set. In this case, we need to remove any reserve map entry created by alloc_huge_page. A new helper routine vma_del_reservation assists with this operation. There are three callers of alloc_huge_page which do not currently call restore_reserve_on error before freeing a page on error paths. Add those missing calls. [1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/ Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com Fixes: 96b96a96ddee ("mm/hugetlb: fix huge page reservation leak in private mapping error paths" Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:29 +03:00
* before the alloc_huge_page call, otherwise
* HPageRestoreReserve would be set on the page.
* Remove the entry so that a subsequent allocation
* does not consume a reservation.
*/
rc = vma_del_reservation(h, vma, address);
if (rc < 0)
mm/hugetlb: fix huge page reservation leak in private mapping error paths Error paths in hugetlb_cow() and hugetlb_no_page() may free a newly allocated huge page. If a reservation was associated with the huge page, alloc_huge_page() consumed the reservation while allocating. When the newly allocated page is freed in free_huge_page(), it will increment the global reservation count. However, the reservation entry in the reserve map will remain. This is not an issue for shared mappings as the entry in the reserve map indicates a reservation exists. But, an entry in a private mapping reserve map indicates the reservation was consumed and no longer exists. This results in an inconsistency between the reserve map and the global reservation count. This 'leaks' a reserved huge page. Create a new routine restore_reserve_on_error() to restore the reserve entry in these specific error paths. This routine makes use of a new function vma_add_reservation() which will add a reserve entry for a specific address/page. In general, these error paths were rarely (if ever) taken on most architectures. However, powerpc contained arch specific code that that resulted in an extra fault and execution of these error paths on all private mappings. Fixes: 67961f9db8c4 ("mm/hugetlb: fix huge page reserve accounting for private mappings) Link: http://lkml.kernel.org/r/1476933077-23091-2-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 21:46:32 +03:00
/*
mm/hugetlb: expand restore_reserve_on_error functionality The routine restore_reserve_on_error is called to restore reservation information when an error occurs after page allocation. The routine alloc_huge_page modifies the mapping reserve map and potentially the reserve count during allocation. If code calling alloc_huge_page encounters an error after allocation and needs to free the page, the reservation information needs to be adjusted. Currently, restore_reserve_on_error only takes action on pages for which the reserve count was adjusted(HPageRestoreReserve flag). There is nothing wrong with these adjustments. However, alloc_huge_page ALWAYS modifies the reserve map during allocation even if the reserve count is not adjusted. This can cause issues as observed during development of this patch [1]. One specific series of operations causing an issue is: - Create a shared hugetlb mapping Reservations for all pages created by default - Fault in a page in the mapping Reservation exists so reservation count is decremented - Punch a hole in the file/mapping at index previously faulted Reservation and any associated pages will be removed - Allocate a page to fill the hole No reservation entry, so reserve count unmodified Reservation entry added to map by alloc_huge_page - Error after allocation and before instantiating the page Reservation entry remains in map - Allocate a page to fill the hole Reservation entry exists, so decrement reservation count This will cause a reservation count underflow as the reservation count was decremented twice for the same index. A user would observe a very large number for HugePages_Rsvd in /proc/meminfo. This would also likely cause subsequent allocations of hugetlb pages to fail as it would 'appear' that all pages are reserved. This sequence of operations is unlikely to happen, however they were easily reproduced and observed using hacked up code as described in [1]. Address the issue by having the routine restore_reserve_on_error take action on pages where HPageRestoreReserve is not set. In this case, we need to remove any reserve map entry created by alloc_huge_page. A new helper routine vma_del_reservation assists with this operation. There are three callers of alloc_huge_page which do not currently call restore_reserve_on error before freeing a page on error paths. Add those missing calls. [1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/ Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com Fixes: 96b96a96ddee ("mm/hugetlb: fix huge page reservation leak in private mapping error paths" Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:29 +03:00
* VERY rare out of memory condition. Since
* we can not delete the entry, set
* HPageRestoreReserve so that the reserve
* count will be incremented when the page
* is freed. This reserve will be consumed
* on a subsequent allocation.
mm/hugetlb: fix huge page reservation leak in private mapping error paths Error paths in hugetlb_cow() and hugetlb_no_page() may free a newly allocated huge page. If a reservation was associated with the huge page, alloc_huge_page() consumed the reservation while allocating. When the newly allocated page is freed in free_huge_page(), it will increment the global reservation count. However, the reservation entry in the reserve map will remain. This is not an issue for shared mappings as the entry in the reserve map indicates a reservation exists. But, an entry in a private mapping reserve map indicates the reservation was consumed and no longer exists. This results in an inconsistency between the reserve map and the global reservation count. This 'leaks' a reserved huge page. Create a new routine restore_reserve_on_error() to restore the reserve entry in these specific error paths. This routine makes use of a new function vma_add_reservation() which will add a reserve entry for a specific address/page. In general, these error paths were rarely (if ever) taken on most architectures. However, powerpc contained arch specific code that that resulted in an extra fault and execution of these error paths on all private mappings. Fixes: 67961f9db8c4 ("mm/hugetlb: fix huge page reserve accounting for private mappings) Link: http://lkml.kernel.org/r/1476933077-23091-2-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 21:46:32 +03:00
*/
mm/hugetlb: expand restore_reserve_on_error functionality The routine restore_reserve_on_error is called to restore reservation information when an error occurs after page allocation. The routine alloc_huge_page modifies the mapping reserve map and potentially the reserve count during allocation. If code calling alloc_huge_page encounters an error after allocation and needs to free the page, the reservation information needs to be adjusted. Currently, restore_reserve_on_error only takes action on pages for which the reserve count was adjusted(HPageRestoreReserve flag). There is nothing wrong with these adjustments. However, alloc_huge_page ALWAYS modifies the reserve map during allocation even if the reserve count is not adjusted. This can cause issues as observed during development of this patch [1]. One specific series of operations causing an issue is: - Create a shared hugetlb mapping Reservations for all pages created by default - Fault in a page in the mapping Reservation exists so reservation count is decremented - Punch a hole in the file/mapping at index previously faulted Reservation and any associated pages will be removed - Allocate a page to fill the hole No reservation entry, so reserve count unmodified Reservation entry added to map by alloc_huge_page - Error after allocation and before instantiating the page Reservation entry remains in map - Allocate a page to fill the hole Reservation entry exists, so decrement reservation count This will cause a reservation count underflow as the reservation count was decremented twice for the same index. A user would observe a very large number for HugePages_Rsvd in /proc/meminfo. This would also likely cause subsequent allocations of hugetlb pages to fail as it would 'appear' that all pages are reserved. This sequence of operations is unlikely to happen, however they were easily reproduced and observed using hacked up code as described in [1]. Address the issue by having the routine restore_reserve_on_error take action on pages where HPageRestoreReserve is not set. In this case, we need to remove any reserve map entry created by alloc_huge_page. A new helper routine vma_del_reservation assists with this operation. There are three callers of alloc_huge_page which do not currently call restore_reserve_on error before freeing a page on error paths. Add those missing calls. [1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/ Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com Fixes: 96b96a96ddee ("mm/hugetlb: fix huge page reservation leak in private mapping error paths" Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:29 +03:00
SetHPageRestoreReserve(page);
} else if (rc < 0) {
/*
* Rare out of memory condition from
* vma_needs_reservation call. Memory allocation is
* only attempted if a new entry is needed. Therefore,
* this implies there is not an entry in the
* reserve map.
*
* For shared mappings, no entry in the map indicates
* no reservation. We are done.
*/
if (!(vma->vm_flags & VM_MAYSHARE))
/*
* For private mappings, no entry indicates
* a reservation is present. Since we can
* not add an entry, set SetHPageRestoreReserve
* on the page so reserve count will be
* incremented when freed. This reserve will
* be consumed on a subsequent allocation.
*/
SetHPageRestoreReserve(page);
mm/hugetlb: fix huge page reservation leak in private mapping error paths Error paths in hugetlb_cow() and hugetlb_no_page() may free a newly allocated huge page. If a reservation was associated with the huge page, alloc_huge_page() consumed the reservation while allocating. When the newly allocated page is freed in free_huge_page(), it will increment the global reservation count. However, the reservation entry in the reserve map will remain. This is not an issue for shared mappings as the entry in the reserve map indicates a reservation exists. But, an entry in a private mapping reserve map indicates the reservation was consumed and no longer exists. This results in an inconsistency between the reserve map and the global reservation count. This 'leaks' a reserved huge page. Create a new routine restore_reserve_on_error() to restore the reserve entry in these specific error paths. This routine makes use of a new function vma_add_reservation() which will add a reserve entry for a specific address/page. In general, these error paths were rarely (if ever) taken on most architectures. However, powerpc contained arch specific code that that resulted in an extra fault and execution of these error paths on all private mappings. Fixes: 67961f9db8c4 ("mm/hugetlb: fix huge page reserve accounting for private mappings) Link: http://lkml.kernel.org/r/1476933077-23091-2-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 21:46:32 +03:00
} else
mm/hugetlb: expand restore_reserve_on_error functionality The routine restore_reserve_on_error is called to restore reservation information when an error occurs after page allocation. The routine alloc_huge_page modifies the mapping reserve map and potentially the reserve count during allocation. If code calling alloc_huge_page encounters an error after allocation and needs to free the page, the reservation information needs to be adjusted. Currently, restore_reserve_on_error only takes action on pages for which the reserve count was adjusted(HPageRestoreReserve flag). There is nothing wrong with these adjustments. However, alloc_huge_page ALWAYS modifies the reserve map during allocation even if the reserve count is not adjusted. This can cause issues as observed during development of this patch [1]. One specific series of operations causing an issue is: - Create a shared hugetlb mapping Reservations for all pages created by default - Fault in a page in the mapping Reservation exists so reservation count is decremented - Punch a hole in the file/mapping at index previously faulted Reservation and any associated pages will be removed - Allocate a page to fill the hole No reservation entry, so reserve count unmodified Reservation entry added to map by alloc_huge_page - Error after allocation and before instantiating the page Reservation entry remains in map - Allocate a page to fill the hole Reservation entry exists, so decrement reservation count This will cause a reservation count underflow as the reservation count was decremented twice for the same index. A user would observe a very large number for HugePages_Rsvd in /proc/meminfo. This would also likely cause subsequent allocations of hugetlb pages to fail as it would 'appear' that all pages are reserved. This sequence of operations is unlikely to happen, however they were easily reproduced and observed using hacked up code as described in [1]. Address the issue by having the routine restore_reserve_on_error take action on pages where HPageRestoreReserve is not set. In this case, we need to remove any reserve map entry created by alloc_huge_page. A new helper routine vma_del_reservation assists with this operation. There are three callers of alloc_huge_page which do not currently call restore_reserve_on error before freeing a page on error paths. Add those missing calls. [1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/ Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com Fixes: 96b96a96ddee ("mm/hugetlb: fix huge page reservation leak in private mapping error paths" Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:29 +03:00
/*
* No reservation present, do nothing
*/
vma_end_reservation(h, vma, address);
mm/hugetlb: fix huge page reservation leak in private mapping error paths Error paths in hugetlb_cow() and hugetlb_no_page() may free a newly allocated huge page. If a reservation was associated with the huge page, alloc_huge_page() consumed the reservation while allocating. When the newly allocated page is freed in free_huge_page(), it will increment the global reservation count. However, the reservation entry in the reserve map will remain. This is not an issue for shared mappings as the entry in the reserve map indicates a reservation exists. But, an entry in a private mapping reserve map indicates the reservation was consumed and no longer exists. This results in an inconsistency between the reserve map and the global reservation count. This 'leaks' a reserved huge page. Create a new routine restore_reserve_on_error() to restore the reserve entry in these specific error paths. This routine makes use of a new function vma_add_reservation() which will add a reserve entry for a specific address/page. In general, these error paths were rarely (if ever) taken on most architectures. However, powerpc contained arch specific code that that resulted in an extra fault and execution of these error paths on all private mappings. Fixes: 67961f9db8c4 ("mm/hugetlb: fix huge page reserve accounting for private mappings) Link: http://lkml.kernel.org/r/1476933077-23091-2-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jan Stancek <jstancek@redhat.com> Tested-by: Jan Stancek <jstancek@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 21:46:32 +03:00
}
}
mm: make alloc_contig_range handle free hugetlb pages alloc_contig_range will fail if it ever sees a HugeTLB page within the range we are trying to allocate, even when that page is free and can be easily reallocated. This has proved to be problematic for some users of alloc_contic_range, e.g: CMA and virtio-mem, where those would fail the call even when those pages lay in ZONE_MOVABLE and are free. We can do better by trying to replace such page. Free hugepages are tricky to handle so as to no userspace application notices disruption, we need to replace the current free hugepage with a new one. In order to do that, a new function called alloc_and_dissolve_huge_page is introduced. This function will first try to get a new fresh hugepage, and if it succeeds, it will replace the old one in the free hugepage pool. The free page replacement is done under hugetlb_lock, so no external users of hugetlb will notice the change. To allocate the new huge page, we use alloc_buddy_huge_page(), so we do not have to deal with any counters, and prep_new_huge_page() is not called. This is valulable because in case we need to free the new page, we only need to call __free_pages(). Once we know that the page to be replaced is a genuine 0-refcounted huge page, we remove the old page from the freelist by remove_hugetlb_page(). Then, we can call __prep_new_huge_page() and __prep_account_new_huge_page() for the new huge page to properly initialize it and increment the hstate->nr_huge_pages counter (previously decremented by remove_hugetlb_page()). Once done, the page is enqueued by enqueue_huge_page() and it is ready to be used. There is one tricky case when page's refcount is 0 because it is in the process of being released. A missing PageHugeFreed bit will tell us that freeing is in flight so we retry after dropping the hugetlb_lock. The race window should be small and the next retry should make a forward progress. E.g: CPU0 CPU1 free_huge_page() isolate_or_dissolve_huge_page PageHuge() == T alloc_and_dissolve_huge_page alloc_buddy_huge_page() spin_lock_irq(hugetlb_lock) // PageHuge() && !PageHugeFreed && // !PageCount() spin_unlock_irq(hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) update_and_free_page PageHuge() == F __free_pages() 2) enqueue_huge_page SetPageHugeFreed() spin_unlock_irq(&hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) PageHuge() == F (freed by case#1 from CPU0) 2) PageHuge() == T PageHugeFreed() == T - proceed with replacing the page In the case above we retry as the window race is quite small and we have high chances to succeed next time. With regard to the allocation, we restrict it to the node the page belongs to with __GFP_THISNODE, meaning we do not fallback on other node's zones. Note that gigantic hugetlb pages are fenced off since there is a cyclic dependency between them and alloc_contig_range. Link: https://lkml.kernel.org/r/20210419075413.1064-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:26 +03:00
/*
* alloc_and_dissolve_huge_page - Allocate a new page and dissolve the old one
* @h: struct hstate old page belongs to
* @old_page: Old page to dissolve
* @list: List to isolate the page in case we need to
mm: make alloc_contig_range handle free hugetlb pages alloc_contig_range will fail if it ever sees a HugeTLB page within the range we are trying to allocate, even when that page is free and can be easily reallocated. This has proved to be problematic for some users of alloc_contic_range, e.g: CMA and virtio-mem, where those would fail the call even when those pages lay in ZONE_MOVABLE and are free. We can do better by trying to replace such page. Free hugepages are tricky to handle so as to no userspace application notices disruption, we need to replace the current free hugepage with a new one. In order to do that, a new function called alloc_and_dissolve_huge_page is introduced. This function will first try to get a new fresh hugepage, and if it succeeds, it will replace the old one in the free hugepage pool. The free page replacement is done under hugetlb_lock, so no external users of hugetlb will notice the change. To allocate the new huge page, we use alloc_buddy_huge_page(), so we do not have to deal with any counters, and prep_new_huge_page() is not called. This is valulable because in case we need to free the new page, we only need to call __free_pages(). Once we know that the page to be replaced is a genuine 0-refcounted huge page, we remove the old page from the freelist by remove_hugetlb_page(). Then, we can call __prep_new_huge_page() and __prep_account_new_huge_page() for the new huge page to properly initialize it and increment the hstate->nr_huge_pages counter (previously decremented by remove_hugetlb_page()). Once done, the page is enqueued by enqueue_huge_page() and it is ready to be used. There is one tricky case when page's refcount is 0 because it is in the process of being released. A missing PageHugeFreed bit will tell us that freeing is in flight so we retry after dropping the hugetlb_lock. The race window should be small and the next retry should make a forward progress. E.g: CPU0 CPU1 free_huge_page() isolate_or_dissolve_huge_page PageHuge() == T alloc_and_dissolve_huge_page alloc_buddy_huge_page() spin_lock_irq(hugetlb_lock) // PageHuge() && !PageHugeFreed && // !PageCount() spin_unlock_irq(hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) update_and_free_page PageHuge() == F __free_pages() 2) enqueue_huge_page SetPageHugeFreed() spin_unlock_irq(&hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) PageHuge() == F (freed by case#1 from CPU0) 2) PageHuge() == T PageHugeFreed() == T - proceed with replacing the page In the case above we retry as the window race is quite small and we have high chances to succeed next time. With regard to the allocation, we restrict it to the node the page belongs to with __GFP_THISNODE, meaning we do not fallback on other node's zones. Note that gigantic hugetlb pages are fenced off since there is a cyclic dependency between them and alloc_contig_range. Link: https://lkml.kernel.org/r/20210419075413.1064-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:26 +03:00
* Returns 0 on success, otherwise negated error.
*/
static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page,
struct list_head *list)
mm: make alloc_contig_range handle free hugetlb pages alloc_contig_range will fail if it ever sees a HugeTLB page within the range we are trying to allocate, even when that page is free and can be easily reallocated. This has proved to be problematic for some users of alloc_contic_range, e.g: CMA and virtio-mem, where those would fail the call even when those pages lay in ZONE_MOVABLE and are free. We can do better by trying to replace such page. Free hugepages are tricky to handle so as to no userspace application notices disruption, we need to replace the current free hugepage with a new one. In order to do that, a new function called alloc_and_dissolve_huge_page is introduced. This function will first try to get a new fresh hugepage, and if it succeeds, it will replace the old one in the free hugepage pool. The free page replacement is done under hugetlb_lock, so no external users of hugetlb will notice the change. To allocate the new huge page, we use alloc_buddy_huge_page(), so we do not have to deal with any counters, and prep_new_huge_page() is not called. This is valulable because in case we need to free the new page, we only need to call __free_pages(). Once we know that the page to be replaced is a genuine 0-refcounted huge page, we remove the old page from the freelist by remove_hugetlb_page(). Then, we can call __prep_new_huge_page() and __prep_account_new_huge_page() for the new huge page to properly initialize it and increment the hstate->nr_huge_pages counter (previously decremented by remove_hugetlb_page()). Once done, the page is enqueued by enqueue_huge_page() and it is ready to be used. There is one tricky case when page's refcount is 0 because it is in the process of being released. A missing PageHugeFreed bit will tell us that freeing is in flight so we retry after dropping the hugetlb_lock. The race window should be small and the next retry should make a forward progress. E.g: CPU0 CPU1 free_huge_page() isolate_or_dissolve_huge_page PageHuge() == T alloc_and_dissolve_huge_page alloc_buddy_huge_page() spin_lock_irq(hugetlb_lock) // PageHuge() && !PageHugeFreed && // !PageCount() spin_unlock_irq(hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) update_and_free_page PageHuge() == F __free_pages() 2) enqueue_huge_page SetPageHugeFreed() spin_unlock_irq(&hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) PageHuge() == F (freed by case#1 from CPU0) 2) PageHuge() == T PageHugeFreed() == T - proceed with replacing the page In the case above we retry as the window race is quite small and we have high chances to succeed next time. With regard to the allocation, we restrict it to the node the page belongs to with __GFP_THISNODE, meaning we do not fallback on other node's zones. Note that gigantic hugetlb pages are fenced off since there is a cyclic dependency between them and alloc_contig_range. Link: https://lkml.kernel.org/r/20210419075413.1064-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:26 +03:00
{
gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
int nid = page_to_nid(old_page);
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
bool alloc_retry = false;
mm: make alloc_contig_range handle free hugetlb pages alloc_contig_range will fail if it ever sees a HugeTLB page within the range we are trying to allocate, even when that page is free and can be easily reallocated. This has proved to be problematic for some users of alloc_contic_range, e.g: CMA and virtio-mem, where those would fail the call even when those pages lay in ZONE_MOVABLE and are free. We can do better by trying to replace such page. Free hugepages are tricky to handle so as to no userspace application notices disruption, we need to replace the current free hugepage with a new one. In order to do that, a new function called alloc_and_dissolve_huge_page is introduced. This function will first try to get a new fresh hugepage, and if it succeeds, it will replace the old one in the free hugepage pool. The free page replacement is done under hugetlb_lock, so no external users of hugetlb will notice the change. To allocate the new huge page, we use alloc_buddy_huge_page(), so we do not have to deal with any counters, and prep_new_huge_page() is not called. This is valulable because in case we need to free the new page, we only need to call __free_pages(). Once we know that the page to be replaced is a genuine 0-refcounted huge page, we remove the old page from the freelist by remove_hugetlb_page(). Then, we can call __prep_new_huge_page() and __prep_account_new_huge_page() for the new huge page to properly initialize it and increment the hstate->nr_huge_pages counter (previously decremented by remove_hugetlb_page()). Once done, the page is enqueued by enqueue_huge_page() and it is ready to be used. There is one tricky case when page's refcount is 0 because it is in the process of being released. A missing PageHugeFreed bit will tell us that freeing is in flight so we retry after dropping the hugetlb_lock. The race window should be small and the next retry should make a forward progress. E.g: CPU0 CPU1 free_huge_page() isolate_or_dissolve_huge_page PageHuge() == T alloc_and_dissolve_huge_page alloc_buddy_huge_page() spin_lock_irq(hugetlb_lock) // PageHuge() && !PageHugeFreed && // !PageCount() spin_unlock_irq(hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) update_and_free_page PageHuge() == F __free_pages() 2) enqueue_huge_page SetPageHugeFreed() spin_unlock_irq(&hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) PageHuge() == F (freed by case#1 from CPU0) 2) PageHuge() == T PageHugeFreed() == T - proceed with replacing the page In the case above we retry as the window race is quite small and we have high chances to succeed next time. With regard to the allocation, we restrict it to the node the page belongs to with __GFP_THISNODE, meaning we do not fallback on other node's zones. Note that gigantic hugetlb pages are fenced off since there is a cyclic dependency between them and alloc_contig_range. Link: https://lkml.kernel.org/r/20210419075413.1064-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:26 +03:00
struct page *new_page;
int ret = 0;
/*
* Before dissolving the page, we need to allocate a new one for the
mm: hugetlb: free the vmemmap pages associated with each HugeTLB page Every HugeTLB has more than one struct page structure. We __know__ that we only use the first 4 (__NR_USED_SUBPAGE) struct page structures to store metadata associated with each HugeTLB. There are a lot of struct page structures associated with each HugeTLB page. For tail pages, the value of compound_head is the same. So we can reuse first page of tail page structures. We map the virtual addresses of the remaining pages of tail page structures to the first tail page struct, and then free these page frames. Therefore, we need to reserve two pages as vmemmap areas. When we allocate a HugeTLB page from the buddy, we can free some vmemmap pages associated with each HugeTLB page. It is more appropriate to do it in the prep_new_huge_page(). The free_vmemmap_pages_per_hpage(), which indicates how many vmemmap pages associated with a HugeTLB page can be freed, returns zero for now, which means the feature is disabled. We will enable it once all the infrastructure is there. [willy@infradead.org: fix documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-5-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-5-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Oscar Salvador <osalvador@suse.de> Tested-by: Chen Huang <chenhuang5@huawei.com> Tested-by: Bodeddula Balasubramaniam <bodeddub@amazon.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:13 +03:00
* pool to remain stable. Here, we allocate the page and 'prep' it
* by doing everything but actually updating counters and adding to
* the pool. This simplifies and let us do most of the processing
* under the lock.
mm: make alloc_contig_range handle free hugetlb pages alloc_contig_range will fail if it ever sees a HugeTLB page within the range we are trying to allocate, even when that page is free and can be easily reallocated. This has proved to be problematic for some users of alloc_contic_range, e.g: CMA and virtio-mem, where those would fail the call even when those pages lay in ZONE_MOVABLE and are free. We can do better by trying to replace such page. Free hugepages are tricky to handle so as to no userspace application notices disruption, we need to replace the current free hugepage with a new one. In order to do that, a new function called alloc_and_dissolve_huge_page is introduced. This function will first try to get a new fresh hugepage, and if it succeeds, it will replace the old one in the free hugepage pool. The free page replacement is done under hugetlb_lock, so no external users of hugetlb will notice the change. To allocate the new huge page, we use alloc_buddy_huge_page(), so we do not have to deal with any counters, and prep_new_huge_page() is not called. This is valulable because in case we need to free the new page, we only need to call __free_pages(). Once we know that the page to be replaced is a genuine 0-refcounted huge page, we remove the old page from the freelist by remove_hugetlb_page(). Then, we can call __prep_new_huge_page() and __prep_account_new_huge_page() for the new huge page to properly initialize it and increment the hstate->nr_huge_pages counter (previously decremented by remove_hugetlb_page()). Once done, the page is enqueued by enqueue_huge_page() and it is ready to be used. There is one tricky case when page's refcount is 0 because it is in the process of being released. A missing PageHugeFreed bit will tell us that freeing is in flight so we retry after dropping the hugetlb_lock. The race window should be small and the next retry should make a forward progress. E.g: CPU0 CPU1 free_huge_page() isolate_or_dissolve_huge_page PageHuge() == T alloc_and_dissolve_huge_page alloc_buddy_huge_page() spin_lock_irq(hugetlb_lock) // PageHuge() && !PageHugeFreed && // !PageCount() spin_unlock_irq(hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) update_and_free_page PageHuge() == F __free_pages() 2) enqueue_huge_page SetPageHugeFreed() spin_unlock_irq(&hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) PageHuge() == F (freed by case#1 from CPU0) 2) PageHuge() == T PageHugeFreed() == T - proceed with replacing the page In the case above we retry as the window race is quite small and we have high chances to succeed next time. With regard to the allocation, we restrict it to the node the page belongs to with __GFP_THISNODE, meaning we do not fallback on other node's zones. Note that gigantic hugetlb pages are fenced off since there is a cyclic dependency between them and alloc_contig_range. Link: https://lkml.kernel.org/r/20210419075413.1064-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:26 +03:00
*/
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
alloc_retry:
mm: make alloc_contig_range handle free hugetlb pages alloc_contig_range will fail if it ever sees a HugeTLB page within the range we are trying to allocate, even when that page is free and can be easily reallocated. This has proved to be problematic for some users of alloc_contic_range, e.g: CMA and virtio-mem, where those would fail the call even when those pages lay in ZONE_MOVABLE and are free. We can do better by trying to replace such page. Free hugepages are tricky to handle so as to no userspace application notices disruption, we need to replace the current free hugepage with a new one. In order to do that, a new function called alloc_and_dissolve_huge_page is introduced. This function will first try to get a new fresh hugepage, and if it succeeds, it will replace the old one in the free hugepage pool. The free page replacement is done under hugetlb_lock, so no external users of hugetlb will notice the change. To allocate the new huge page, we use alloc_buddy_huge_page(), so we do not have to deal with any counters, and prep_new_huge_page() is not called. This is valulable because in case we need to free the new page, we only need to call __free_pages(). Once we know that the page to be replaced is a genuine 0-refcounted huge page, we remove the old page from the freelist by remove_hugetlb_page(). Then, we can call __prep_new_huge_page() and __prep_account_new_huge_page() for the new huge page to properly initialize it and increment the hstate->nr_huge_pages counter (previously decremented by remove_hugetlb_page()). Once done, the page is enqueued by enqueue_huge_page() and it is ready to be used. There is one tricky case when page's refcount is 0 because it is in the process of being released. A missing PageHugeFreed bit will tell us that freeing is in flight so we retry after dropping the hugetlb_lock. The race window should be small and the next retry should make a forward progress. E.g: CPU0 CPU1 free_huge_page() isolate_or_dissolve_huge_page PageHuge() == T alloc_and_dissolve_huge_page alloc_buddy_huge_page() spin_lock_irq(hugetlb_lock) // PageHuge() && !PageHugeFreed && // !PageCount() spin_unlock_irq(hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) update_and_free_page PageHuge() == F __free_pages() 2) enqueue_huge_page SetPageHugeFreed() spin_unlock_irq(&hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) PageHuge() == F (freed by case#1 from CPU0) 2) PageHuge() == T PageHugeFreed() == T - proceed with replacing the page In the case above we retry as the window race is quite small and we have high chances to succeed next time. With regard to the allocation, we restrict it to the node the page belongs to with __GFP_THISNODE, meaning we do not fallback on other node's zones. Note that gigantic hugetlb pages are fenced off since there is a cyclic dependency between them and alloc_contig_range. Link: https://lkml.kernel.org/r/20210419075413.1064-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:26 +03:00
new_page = alloc_buddy_huge_page(h, gfp_mask, nid, NULL, NULL);
if (!new_page)
return -ENOMEM;
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
/*
* If all goes well, this page will be directly added to the free
* list in the pool. For this the ref count needs to be zero.
* Attempt to drop now, and retry once if needed. It is VERY
* unlikely there is another ref on the page.
*
* If someone else has a reference to the page, it will be freed
* when they drop their ref. Abuse temporary page flag to accomplish
* this. Retry once if there is an inflated ref count.
*/
SetHPageTemporary(new_page);
if (!put_page_testzero(new_page)) {
if (alloc_retry)
return -EBUSY;
alloc_retry = true;
goto alloc_retry;
}
ClearHPageTemporary(new_page);
mm: hugetlb: free the vmemmap pages associated with each HugeTLB page Every HugeTLB has more than one struct page structure. We __know__ that we only use the first 4 (__NR_USED_SUBPAGE) struct page structures to store metadata associated with each HugeTLB. There are a lot of struct page structures associated with each HugeTLB page. For tail pages, the value of compound_head is the same. So we can reuse first page of tail page structures. We map the virtual addresses of the remaining pages of tail page structures to the first tail page struct, and then free these page frames. Therefore, we need to reserve two pages as vmemmap areas. When we allocate a HugeTLB page from the buddy, we can free some vmemmap pages associated with each HugeTLB page. It is more appropriate to do it in the prep_new_huge_page(). The free_vmemmap_pages_per_hpage(), which indicates how many vmemmap pages associated with a HugeTLB page can be freed, returns zero for now, which means the feature is disabled. We will enable it once all the infrastructure is there. [willy@infradead.org: fix documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-5-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-5-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Oscar Salvador <osalvador@suse.de> Tested-by: Chen Huang <chenhuang5@huawei.com> Tested-by: Bodeddula Balasubramaniam <bodeddub@amazon.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:13 +03:00
__prep_new_huge_page(h, new_page);
mm: make alloc_contig_range handle free hugetlb pages alloc_contig_range will fail if it ever sees a HugeTLB page within the range we are trying to allocate, even when that page is free and can be easily reallocated. This has proved to be problematic for some users of alloc_contic_range, e.g: CMA and virtio-mem, where those would fail the call even when those pages lay in ZONE_MOVABLE and are free. We can do better by trying to replace such page. Free hugepages are tricky to handle so as to no userspace application notices disruption, we need to replace the current free hugepage with a new one. In order to do that, a new function called alloc_and_dissolve_huge_page is introduced. This function will first try to get a new fresh hugepage, and if it succeeds, it will replace the old one in the free hugepage pool. The free page replacement is done under hugetlb_lock, so no external users of hugetlb will notice the change. To allocate the new huge page, we use alloc_buddy_huge_page(), so we do not have to deal with any counters, and prep_new_huge_page() is not called. This is valulable because in case we need to free the new page, we only need to call __free_pages(). Once we know that the page to be replaced is a genuine 0-refcounted huge page, we remove the old page from the freelist by remove_hugetlb_page(). Then, we can call __prep_new_huge_page() and __prep_account_new_huge_page() for the new huge page to properly initialize it and increment the hstate->nr_huge_pages counter (previously decremented by remove_hugetlb_page()). Once done, the page is enqueued by enqueue_huge_page() and it is ready to be used. There is one tricky case when page's refcount is 0 because it is in the process of being released. A missing PageHugeFreed bit will tell us that freeing is in flight so we retry after dropping the hugetlb_lock. The race window should be small and the next retry should make a forward progress. E.g: CPU0 CPU1 free_huge_page() isolate_or_dissolve_huge_page PageHuge() == T alloc_and_dissolve_huge_page alloc_buddy_huge_page() spin_lock_irq(hugetlb_lock) // PageHuge() && !PageHugeFreed && // !PageCount() spin_unlock_irq(hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) update_and_free_page PageHuge() == F __free_pages() 2) enqueue_huge_page SetPageHugeFreed() spin_unlock_irq(&hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) PageHuge() == F (freed by case#1 from CPU0) 2) PageHuge() == T PageHugeFreed() == T - proceed with replacing the page In the case above we retry as the window race is quite small and we have high chances to succeed next time. With regard to the allocation, we restrict it to the node the page belongs to with __GFP_THISNODE, meaning we do not fallback on other node's zones. Note that gigantic hugetlb pages are fenced off since there is a cyclic dependency between them and alloc_contig_range. Link: https://lkml.kernel.org/r/20210419075413.1064-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:26 +03:00
retry:
spin_lock_irq(&hugetlb_lock);
if (!PageHuge(old_page)) {
/*
* Freed from under us. Drop new_page too.
*/
goto free_new;
} else if (page_count(old_page)) {
/*
* Someone has grabbed the page, try to isolate it here.
* Fail with -EBUSY if not possible.
mm: make alloc_contig_range handle free hugetlb pages alloc_contig_range will fail if it ever sees a HugeTLB page within the range we are trying to allocate, even when that page is free and can be easily reallocated. This has proved to be problematic for some users of alloc_contic_range, e.g: CMA and virtio-mem, where those would fail the call even when those pages lay in ZONE_MOVABLE and are free. We can do better by trying to replace such page. Free hugepages are tricky to handle so as to no userspace application notices disruption, we need to replace the current free hugepage with a new one. In order to do that, a new function called alloc_and_dissolve_huge_page is introduced. This function will first try to get a new fresh hugepage, and if it succeeds, it will replace the old one in the free hugepage pool. The free page replacement is done under hugetlb_lock, so no external users of hugetlb will notice the change. To allocate the new huge page, we use alloc_buddy_huge_page(), so we do not have to deal with any counters, and prep_new_huge_page() is not called. This is valulable because in case we need to free the new page, we only need to call __free_pages(). Once we know that the page to be replaced is a genuine 0-refcounted huge page, we remove the old page from the freelist by remove_hugetlb_page(). Then, we can call __prep_new_huge_page() and __prep_account_new_huge_page() for the new huge page to properly initialize it and increment the hstate->nr_huge_pages counter (previously decremented by remove_hugetlb_page()). Once done, the page is enqueued by enqueue_huge_page() and it is ready to be used. There is one tricky case when page's refcount is 0 because it is in the process of being released. A missing PageHugeFreed bit will tell us that freeing is in flight so we retry after dropping the hugetlb_lock. The race window should be small and the next retry should make a forward progress. E.g: CPU0 CPU1 free_huge_page() isolate_or_dissolve_huge_page PageHuge() == T alloc_and_dissolve_huge_page alloc_buddy_huge_page() spin_lock_irq(hugetlb_lock) // PageHuge() && !PageHugeFreed && // !PageCount() spin_unlock_irq(hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) update_and_free_page PageHuge() == F __free_pages() 2) enqueue_huge_page SetPageHugeFreed() spin_unlock_irq(&hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) PageHuge() == F (freed by case#1 from CPU0) 2) PageHuge() == T PageHugeFreed() == T - proceed with replacing the page In the case above we retry as the window race is quite small and we have high chances to succeed next time. With regard to the allocation, we restrict it to the node the page belongs to with __GFP_THISNODE, meaning we do not fallback on other node's zones. Note that gigantic hugetlb pages are fenced off since there is a cyclic dependency between them and alloc_contig_range. Link: https://lkml.kernel.org/r/20210419075413.1064-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:26 +03:00
*/
spin_unlock_irq(&hugetlb_lock);
if (!isolate_huge_page(old_page, list))
ret = -EBUSY;
spin_lock_irq(&hugetlb_lock);
mm: make alloc_contig_range handle free hugetlb pages alloc_contig_range will fail if it ever sees a HugeTLB page within the range we are trying to allocate, even when that page is free and can be easily reallocated. This has proved to be problematic for some users of alloc_contic_range, e.g: CMA and virtio-mem, where those would fail the call even when those pages lay in ZONE_MOVABLE and are free. We can do better by trying to replace such page. Free hugepages are tricky to handle so as to no userspace application notices disruption, we need to replace the current free hugepage with a new one. In order to do that, a new function called alloc_and_dissolve_huge_page is introduced. This function will first try to get a new fresh hugepage, and if it succeeds, it will replace the old one in the free hugepage pool. The free page replacement is done under hugetlb_lock, so no external users of hugetlb will notice the change. To allocate the new huge page, we use alloc_buddy_huge_page(), so we do not have to deal with any counters, and prep_new_huge_page() is not called. This is valulable because in case we need to free the new page, we only need to call __free_pages(). Once we know that the page to be replaced is a genuine 0-refcounted huge page, we remove the old page from the freelist by remove_hugetlb_page(). Then, we can call __prep_new_huge_page() and __prep_account_new_huge_page() for the new huge page to properly initialize it and increment the hstate->nr_huge_pages counter (previously decremented by remove_hugetlb_page()). Once done, the page is enqueued by enqueue_huge_page() and it is ready to be used. There is one tricky case when page's refcount is 0 because it is in the process of being released. A missing PageHugeFreed bit will tell us that freeing is in flight so we retry after dropping the hugetlb_lock. The race window should be small and the next retry should make a forward progress. E.g: CPU0 CPU1 free_huge_page() isolate_or_dissolve_huge_page PageHuge() == T alloc_and_dissolve_huge_page alloc_buddy_huge_page() spin_lock_irq(hugetlb_lock) // PageHuge() && !PageHugeFreed && // !PageCount() spin_unlock_irq(hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) update_and_free_page PageHuge() == F __free_pages() 2) enqueue_huge_page SetPageHugeFreed() spin_unlock_irq(&hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) PageHuge() == F (freed by case#1 from CPU0) 2) PageHuge() == T PageHugeFreed() == T - proceed with replacing the page In the case above we retry as the window race is quite small and we have high chances to succeed next time. With regard to the allocation, we restrict it to the node the page belongs to with __GFP_THISNODE, meaning we do not fallback on other node's zones. Note that gigantic hugetlb pages are fenced off since there is a cyclic dependency between them and alloc_contig_range. Link: https://lkml.kernel.org/r/20210419075413.1064-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:26 +03:00
goto free_new;
} else if (!HPageFreed(old_page)) {
/*
* Page's refcount is 0 but it has not been enqueued in the
* freelist yet. Race window is small, so we can succeed here if
* we retry.
*/
spin_unlock_irq(&hugetlb_lock);
cond_resched();
goto retry;
} else {
/*
* Ok, old_page is still a genuine free hugepage. Remove it from
* the freelist and decrease the counters. These will be
* incremented again when calling __prep_account_new_huge_page()
* and enqueue_huge_page() for new_page. The counters will remain
* stable since this happens under the lock.
*/
remove_hugetlb_page(h, old_page, false);
/*
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
* Ref count on new page is already zero as it was dropped
* earlier. It can be directly added to the pool free list.
mm: make alloc_contig_range handle free hugetlb pages alloc_contig_range will fail if it ever sees a HugeTLB page within the range we are trying to allocate, even when that page is free and can be easily reallocated. This has proved to be problematic for some users of alloc_contic_range, e.g: CMA and virtio-mem, where those would fail the call even when those pages lay in ZONE_MOVABLE and are free. We can do better by trying to replace such page. Free hugepages are tricky to handle so as to no userspace application notices disruption, we need to replace the current free hugepage with a new one. In order to do that, a new function called alloc_and_dissolve_huge_page is introduced. This function will first try to get a new fresh hugepage, and if it succeeds, it will replace the old one in the free hugepage pool. The free page replacement is done under hugetlb_lock, so no external users of hugetlb will notice the change. To allocate the new huge page, we use alloc_buddy_huge_page(), so we do not have to deal with any counters, and prep_new_huge_page() is not called. This is valulable because in case we need to free the new page, we only need to call __free_pages(). Once we know that the page to be replaced is a genuine 0-refcounted huge page, we remove the old page from the freelist by remove_hugetlb_page(). Then, we can call __prep_new_huge_page() and __prep_account_new_huge_page() for the new huge page to properly initialize it and increment the hstate->nr_huge_pages counter (previously decremented by remove_hugetlb_page()). Once done, the page is enqueued by enqueue_huge_page() and it is ready to be used. There is one tricky case when page's refcount is 0 because it is in the process of being released. A missing PageHugeFreed bit will tell us that freeing is in flight so we retry after dropping the hugetlb_lock. The race window should be small and the next retry should make a forward progress. E.g: CPU0 CPU1 free_huge_page() isolate_or_dissolve_huge_page PageHuge() == T alloc_and_dissolve_huge_page alloc_buddy_huge_page() spin_lock_irq(hugetlb_lock) // PageHuge() && !PageHugeFreed && // !PageCount() spin_unlock_irq(hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) update_and_free_page PageHuge() == F __free_pages() 2) enqueue_huge_page SetPageHugeFreed() spin_unlock_irq(&hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) PageHuge() == F (freed by case#1 from CPU0) 2) PageHuge() == T PageHugeFreed() == T - proceed with replacing the page In the case above we retry as the window race is quite small and we have high chances to succeed next time. With regard to the allocation, we restrict it to the node the page belongs to with __GFP_THISNODE, meaning we do not fallback on other node's zones. Note that gigantic hugetlb pages are fenced off since there is a cyclic dependency between them and alloc_contig_range. Link: https://lkml.kernel.org/r/20210419075413.1064-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:26 +03:00
*/
__prep_account_new_huge_page(h, nid);
enqueue_huge_page(h, new_page);
/*
* Pages have been replaced, we can safely free the old one.
*/
spin_unlock_irq(&hugetlb_lock);
mm: hugetlb: defer freeing of HugeTLB pages In the subsequent patch, we should allocate the vmemmap pages when freeing a HugeTLB page. But update_and_free_page() can be called under any context, so we cannot use GFP_KERNEL to allocate vmemmap pages. However, we can defer the actual freeing in a kworker to prevent from using GFP_ATOMIC to allocate the vmemmap pages. The __update_and_free_page() is where the call to allocate vmemmmap pages will be inserted. Link: https://lkml.kernel.org/r/20210510030027.56044-6-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:17 +03:00
update_and_free_page(h, old_page, false);
mm: make alloc_contig_range handle free hugetlb pages alloc_contig_range will fail if it ever sees a HugeTLB page within the range we are trying to allocate, even when that page is free and can be easily reallocated. This has proved to be problematic for some users of alloc_contic_range, e.g: CMA and virtio-mem, where those would fail the call even when those pages lay in ZONE_MOVABLE and are free. We can do better by trying to replace such page. Free hugepages are tricky to handle so as to no userspace application notices disruption, we need to replace the current free hugepage with a new one. In order to do that, a new function called alloc_and_dissolve_huge_page is introduced. This function will first try to get a new fresh hugepage, and if it succeeds, it will replace the old one in the free hugepage pool. The free page replacement is done under hugetlb_lock, so no external users of hugetlb will notice the change. To allocate the new huge page, we use alloc_buddy_huge_page(), so we do not have to deal with any counters, and prep_new_huge_page() is not called. This is valulable because in case we need to free the new page, we only need to call __free_pages(). Once we know that the page to be replaced is a genuine 0-refcounted huge page, we remove the old page from the freelist by remove_hugetlb_page(). Then, we can call __prep_new_huge_page() and __prep_account_new_huge_page() for the new huge page to properly initialize it and increment the hstate->nr_huge_pages counter (previously decremented by remove_hugetlb_page()). Once done, the page is enqueued by enqueue_huge_page() and it is ready to be used. There is one tricky case when page's refcount is 0 because it is in the process of being released. A missing PageHugeFreed bit will tell us that freeing is in flight so we retry after dropping the hugetlb_lock. The race window should be small and the next retry should make a forward progress. E.g: CPU0 CPU1 free_huge_page() isolate_or_dissolve_huge_page PageHuge() == T alloc_and_dissolve_huge_page alloc_buddy_huge_page() spin_lock_irq(hugetlb_lock) // PageHuge() && !PageHugeFreed && // !PageCount() spin_unlock_irq(hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) update_and_free_page PageHuge() == F __free_pages() 2) enqueue_huge_page SetPageHugeFreed() spin_unlock_irq(&hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) PageHuge() == F (freed by case#1 from CPU0) 2) PageHuge() == T PageHugeFreed() == T - proceed with replacing the page In the case above we retry as the window race is quite small and we have high chances to succeed next time. With regard to the allocation, we restrict it to the node the page belongs to with __GFP_THISNODE, meaning we do not fallback on other node's zones. Note that gigantic hugetlb pages are fenced off since there is a cyclic dependency between them and alloc_contig_range. Link: https://lkml.kernel.org/r/20210419075413.1064-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:26 +03:00
}
return ret;
free_new:
spin_unlock_irq(&hugetlb_lock);
hugetlb: drop ref count earlier after page allocation When discussing the possibility of inflated page ref counts, Muuchun Song pointed out this potential issue [1]. It is true that any code could potentially take a reference on a compound page after allocation and before it is converted to and put into use as a hugetlb page. Specifically, this could be done by any users of get_page_unless_zero. There are three areas of concern within hugetlb code. 1) When adding pages to the pool. In this case, new pages are allocated added to the pool by calling put_page to invoke the hugetlb destructor (free_huge_page). If there is an inflated ref count on the page, it will not be immediately added to the free list. It will only be added to the free list when the temporary ref count is dropped. This is deemed acceptable and will not be addressed. 2) A page is allocated for immediate use normally as a surplus page or migration target. In this case, the user of the page will also hold a reference. There is no issue as this is just like normal page ref counting. 3) A page is allocated and MUST be added to the free list to satisfy a reservation. One such example is gather_surplus_pages as pointed out by Muchun in [1]. More specifically, this case covers callers of enqueue_huge_page where the page reference count must be zero. This patch covers this third case. Three routines call enqueue_huge_page when the page reference count could potentially be inflated. They are: gather_surplus_pages, alloc_and_dissolve_huge_page and add_hugetlb_page. add_hugetlb_page is called on error paths when a huge page can not be freed due to the inability to allocate vmemmap pages. In this case, the temporairly inflated ref count is not an issue. When the ref is dropped the appropriate action will be taken. Instead of VM_BUG_ON if the ref count does not drop to zero, simply return. In gather_surplus_pages and alloc_and_dissolve_huge_page the caller expects a page (or pages) to be put on the free lists. In this case we must ensure there are no temporary ref counts. We do this by calling put_page_testzero() earlier and not using pages without a zero ref count. The temporary page flag (HPageTemporary) is used in such cases so that as soon as the inflated ref count is dropped the page will be freed. [1] https://lore.kernel.org/linux-mm/CAMZfGtVMn3daKrJwZMaVOGOaJU+B4dS--x_oPmGQMD=c=QNGEg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210809184832.18342-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:47 +03:00
/* Page has a zero ref count, but needs a ref to be freed */
set_page_refcounted(new_page);
mm: hugetlb: defer freeing of HugeTLB pages In the subsequent patch, we should allocate the vmemmap pages when freeing a HugeTLB page. But update_and_free_page() can be called under any context, so we cannot use GFP_KERNEL to allocate vmemmap pages. However, we can defer the actual freeing in a kworker to prevent from using GFP_ATOMIC to allocate the vmemmap pages. The __update_and_free_page() is where the call to allocate vmemmmap pages will be inserted. Link: https://lkml.kernel.org/r/20210510030027.56044-6-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:17 +03:00
update_and_free_page(h, new_page, false);
mm: make alloc_contig_range handle free hugetlb pages alloc_contig_range will fail if it ever sees a HugeTLB page within the range we are trying to allocate, even when that page is free and can be easily reallocated. This has proved to be problematic for some users of alloc_contic_range, e.g: CMA and virtio-mem, where those would fail the call even when those pages lay in ZONE_MOVABLE and are free. We can do better by trying to replace such page. Free hugepages are tricky to handle so as to no userspace application notices disruption, we need to replace the current free hugepage with a new one. In order to do that, a new function called alloc_and_dissolve_huge_page is introduced. This function will first try to get a new fresh hugepage, and if it succeeds, it will replace the old one in the free hugepage pool. The free page replacement is done under hugetlb_lock, so no external users of hugetlb will notice the change. To allocate the new huge page, we use alloc_buddy_huge_page(), so we do not have to deal with any counters, and prep_new_huge_page() is not called. This is valulable because in case we need to free the new page, we only need to call __free_pages(). Once we know that the page to be replaced is a genuine 0-refcounted huge page, we remove the old page from the freelist by remove_hugetlb_page(). Then, we can call __prep_new_huge_page() and __prep_account_new_huge_page() for the new huge page to properly initialize it and increment the hstate->nr_huge_pages counter (previously decremented by remove_hugetlb_page()). Once done, the page is enqueued by enqueue_huge_page() and it is ready to be used. There is one tricky case when page's refcount is 0 because it is in the process of being released. A missing PageHugeFreed bit will tell us that freeing is in flight so we retry after dropping the hugetlb_lock. The race window should be small and the next retry should make a forward progress. E.g: CPU0 CPU1 free_huge_page() isolate_or_dissolve_huge_page PageHuge() == T alloc_and_dissolve_huge_page alloc_buddy_huge_page() spin_lock_irq(hugetlb_lock) // PageHuge() && !PageHugeFreed && // !PageCount() spin_unlock_irq(hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) update_and_free_page PageHuge() == F __free_pages() 2) enqueue_huge_page SetPageHugeFreed() spin_unlock_irq(&hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) PageHuge() == F (freed by case#1 from CPU0) 2) PageHuge() == T PageHugeFreed() == T - proceed with replacing the page In the case above we retry as the window race is quite small and we have high chances to succeed next time. With regard to the allocation, we restrict it to the node the page belongs to with __GFP_THISNODE, meaning we do not fallback on other node's zones. Note that gigantic hugetlb pages are fenced off since there is a cyclic dependency between them and alloc_contig_range. Link: https://lkml.kernel.org/r/20210419075413.1064-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:26 +03:00
return ret;
}
int isolate_or_dissolve_huge_page(struct page *page, struct list_head *list)
mm: make alloc_contig_range handle free hugetlb pages alloc_contig_range will fail if it ever sees a HugeTLB page within the range we are trying to allocate, even when that page is free and can be easily reallocated. This has proved to be problematic for some users of alloc_contic_range, e.g: CMA and virtio-mem, where those would fail the call even when those pages lay in ZONE_MOVABLE and are free. We can do better by trying to replace such page. Free hugepages are tricky to handle so as to no userspace application notices disruption, we need to replace the current free hugepage with a new one. In order to do that, a new function called alloc_and_dissolve_huge_page is introduced. This function will first try to get a new fresh hugepage, and if it succeeds, it will replace the old one in the free hugepage pool. The free page replacement is done under hugetlb_lock, so no external users of hugetlb will notice the change. To allocate the new huge page, we use alloc_buddy_huge_page(), so we do not have to deal with any counters, and prep_new_huge_page() is not called. This is valulable because in case we need to free the new page, we only need to call __free_pages(). Once we know that the page to be replaced is a genuine 0-refcounted huge page, we remove the old page from the freelist by remove_hugetlb_page(). Then, we can call __prep_new_huge_page() and __prep_account_new_huge_page() for the new huge page to properly initialize it and increment the hstate->nr_huge_pages counter (previously decremented by remove_hugetlb_page()). Once done, the page is enqueued by enqueue_huge_page() and it is ready to be used. There is one tricky case when page's refcount is 0 because it is in the process of being released. A missing PageHugeFreed bit will tell us that freeing is in flight so we retry after dropping the hugetlb_lock. The race window should be small and the next retry should make a forward progress. E.g: CPU0 CPU1 free_huge_page() isolate_or_dissolve_huge_page PageHuge() == T alloc_and_dissolve_huge_page alloc_buddy_huge_page() spin_lock_irq(hugetlb_lock) // PageHuge() && !PageHugeFreed && // !PageCount() spin_unlock_irq(hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) update_and_free_page PageHuge() == F __free_pages() 2) enqueue_huge_page SetPageHugeFreed() spin_unlock_irq(&hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) PageHuge() == F (freed by case#1 from CPU0) 2) PageHuge() == T PageHugeFreed() == T - proceed with replacing the page In the case above we retry as the window race is quite small and we have high chances to succeed next time. With regard to the allocation, we restrict it to the node the page belongs to with __GFP_THISNODE, meaning we do not fallback on other node's zones. Note that gigantic hugetlb pages are fenced off since there is a cyclic dependency between them and alloc_contig_range. Link: https://lkml.kernel.org/r/20210419075413.1064-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:26 +03:00
{
struct hstate *h;
struct page *head;
int ret = -EBUSY;
mm: make alloc_contig_range handle free hugetlb pages alloc_contig_range will fail if it ever sees a HugeTLB page within the range we are trying to allocate, even when that page is free and can be easily reallocated. This has proved to be problematic for some users of alloc_contic_range, e.g: CMA and virtio-mem, where those would fail the call even when those pages lay in ZONE_MOVABLE and are free. We can do better by trying to replace such page. Free hugepages are tricky to handle so as to no userspace application notices disruption, we need to replace the current free hugepage with a new one. In order to do that, a new function called alloc_and_dissolve_huge_page is introduced. This function will first try to get a new fresh hugepage, and if it succeeds, it will replace the old one in the free hugepage pool. The free page replacement is done under hugetlb_lock, so no external users of hugetlb will notice the change. To allocate the new huge page, we use alloc_buddy_huge_page(), so we do not have to deal with any counters, and prep_new_huge_page() is not called. This is valulable because in case we need to free the new page, we only need to call __free_pages(). Once we know that the page to be replaced is a genuine 0-refcounted huge page, we remove the old page from the freelist by remove_hugetlb_page(). Then, we can call __prep_new_huge_page() and __prep_account_new_huge_page() for the new huge page to properly initialize it and increment the hstate->nr_huge_pages counter (previously decremented by remove_hugetlb_page()). Once done, the page is enqueued by enqueue_huge_page() and it is ready to be used. There is one tricky case when page's refcount is 0 because it is in the process of being released. A missing PageHugeFreed bit will tell us that freeing is in flight so we retry after dropping the hugetlb_lock. The race window should be small and the next retry should make a forward progress. E.g: CPU0 CPU1 free_huge_page() isolate_or_dissolve_huge_page PageHuge() == T alloc_and_dissolve_huge_page alloc_buddy_huge_page() spin_lock_irq(hugetlb_lock) // PageHuge() && !PageHugeFreed && // !PageCount() spin_unlock_irq(hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) update_and_free_page PageHuge() == F __free_pages() 2) enqueue_huge_page SetPageHugeFreed() spin_unlock_irq(&hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) PageHuge() == F (freed by case#1 from CPU0) 2) PageHuge() == T PageHugeFreed() == T - proceed with replacing the page In the case above we retry as the window race is quite small and we have high chances to succeed next time. With regard to the allocation, we restrict it to the node the page belongs to with __GFP_THISNODE, meaning we do not fallback on other node's zones. Note that gigantic hugetlb pages are fenced off since there is a cyclic dependency between them and alloc_contig_range. Link: https://lkml.kernel.org/r/20210419075413.1064-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:26 +03:00
/*
* The page might have been dissolved from under our feet, so make sure
* to carefully check the state under the lock.
* Return success when racing as if we dissolved the page ourselves.
*/
spin_lock_irq(&hugetlb_lock);
if (PageHuge(page)) {
head = compound_head(page);
h = page_hstate(head);
} else {
spin_unlock_irq(&hugetlb_lock);
return 0;
}
spin_unlock_irq(&hugetlb_lock);
/*
* Fence off gigantic pages as there is a cyclic dependency between
* alloc_contig_range and them. Return -ENOMEM as this has the effect
* of bailing out right away without further retrying.
*/
if (hstate_is_gigantic(h))
return -ENOMEM;
if (page_count(head) && isolate_huge_page(head, list))
ret = 0;
else if (!page_count(head))
ret = alloc_and_dissolve_huge_page(h, head, list);
return ret;
mm: make alloc_contig_range handle free hugetlb pages alloc_contig_range will fail if it ever sees a HugeTLB page within the range we are trying to allocate, even when that page is free and can be easily reallocated. This has proved to be problematic for some users of alloc_contic_range, e.g: CMA and virtio-mem, where those would fail the call even when those pages lay in ZONE_MOVABLE and are free. We can do better by trying to replace such page. Free hugepages are tricky to handle so as to no userspace application notices disruption, we need to replace the current free hugepage with a new one. In order to do that, a new function called alloc_and_dissolve_huge_page is introduced. This function will first try to get a new fresh hugepage, and if it succeeds, it will replace the old one in the free hugepage pool. The free page replacement is done under hugetlb_lock, so no external users of hugetlb will notice the change. To allocate the new huge page, we use alloc_buddy_huge_page(), so we do not have to deal with any counters, and prep_new_huge_page() is not called. This is valulable because in case we need to free the new page, we only need to call __free_pages(). Once we know that the page to be replaced is a genuine 0-refcounted huge page, we remove the old page from the freelist by remove_hugetlb_page(). Then, we can call __prep_new_huge_page() and __prep_account_new_huge_page() for the new huge page to properly initialize it and increment the hstate->nr_huge_pages counter (previously decremented by remove_hugetlb_page()). Once done, the page is enqueued by enqueue_huge_page() and it is ready to be used. There is one tricky case when page's refcount is 0 because it is in the process of being released. A missing PageHugeFreed bit will tell us that freeing is in flight so we retry after dropping the hugetlb_lock. The race window should be small and the next retry should make a forward progress. E.g: CPU0 CPU1 free_huge_page() isolate_or_dissolve_huge_page PageHuge() == T alloc_and_dissolve_huge_page alloc_buddy_huge_page() spin_lock_irq(hugetlb_lock) // PageHuge() && !PageHugeFreed && // !PageCount() spin_unlock_irq(hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) update_and_free_page PageHuge() == F __free_pages() 2) enqueue_huge_page SetPageHugeFreed() spin_unlock_irq(&hugetlb_lock) spin_lock_irq(hugetlb_lock) 1) PageHuge() == F (freed by case#1 from CPU0) 2) PageHuge() == T PageHugeFreed() == T - proceed with replacing the page In the case above we retry as the window race is quite small and we have high chances to succeed next time. With regard to the allocation, we restrict it to the node the page belongs to with __GFP_THISNODE, meaning we do not fallback on other node's zones. Note that gigantic hugetlb pages are fenced off since there is a cyclic dependency between them and alloc_contig_range. Link: https://lkml.kernel.org/r/20210419075413.1064-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:26 +03:00
}
struct page *alloc_huge_page(struct vm_area_struct *vma,
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
unsigned long addr, int avoid_reserve)
{
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
struct hugepage_subpool *spool = subpool_vma(vma);
struct hstate *h = hstate_vma(vma);
hugetlb: split alloc_huge_page into private and shared components Hugetlbfs implements a quota system which can limit the amount of memory that can be used by the filesystem. Before allocating a new huge page for a file, the quota is checked and debited. The quota is then credited when truncating the file. I found a few bugs in the code for both MAP_PRIVATE and MAP_SHARED mappings. Before detailing the problems and my proposed solutions, we should agree on a definition of quotas that properly addresses both private and shared pages. Since the purpose of quotas is to limit total memory consumption on a per-filesystem basis, I argue that all pages allocated by the fs (private and shared) should be charged against quota. Private Mappings ================ The current code will debit quota for private pages sometimes, but will never credit it. At a minimum, this causes a leak in the quota accounting which renders the accounting essentially useless as it is. Shared pages have a one to one mapping with a hugetlbfs file and are easy to account by debiting on allocation and crediting on truncate. Private pages are anonymous in nature and have a many to one relationship with their hugetlbfs files (due to copy on write). Because private pages are not indexed by the mapping's radix tree, thier quota cannot be credited at file truncation time. Crediting must be done when the page is unmapped and freed. Shared Pages ============ I discovered an issue concerning the interaction between the MAP_SHARED reservation system and quotas. Since quota is not checked until page instantiation, an over-quota mmap/reservation will initially succeed. When instantiating the first over-quota page, the program will receive SIGBUS. This is inconsistent since the reservation is supposed to be a guarantee. The solution is to debit the full amount of quota at reservation time and credit the unused portion when the reservation is released. This patch series brings quotas back in line by making the following modifications: * Private pages - Debit quota in alloc_huge_page() - Credit quota in free_huge_page() * Shared pages - Debit quota for entire reservation at mmap time - Credit quota for instantiated pages in free_huge_page() - Credit quota for unused reservation at munmap time This patch: The shared page reservation and dynamic pool resizing features have made the allocation of private vs. shared huge pages quite different. By splitting out the private/shared-specific portions of the process into their own functions, readability is greatly improved. alloc_huge_page now calls the proper helper and performs common operations. [akpm@linux-foundation.org: coding-style cleanups] Signed-off-by: Adam Litke <agl@us.ibm.com> Cc: Ken Chen <kenchen@google.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: David Gibson <hermes@gibson.dropbear.id.au> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-11-15 03:59:37 +03:00
struct page *page;
long map_chg, map_commit;
long gbl_chg;
int ret, idx;
struct hugetlb_cgroup *h_cg;
bool deferred_reserve;
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
idx = hstate_index(h);
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
/*
* Examine the region/reserve map to determine if the process
* has a reservation for the page to be allocated. A return
* code of zero indicates a reservation exists (no change).
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
*/
map_chg = gbl_chg = vma_needs_reservation(h, vma, addr);
if (map_chg < 0)
return ERR_PTR(-ENOMEM);
/*
* Processes that did not create the mapping will have no
* reserves as indicated by the region/reserve map. Check
* that the allocation will not exceed the subpool limit.
* Allocations for MAP_NORESERVE mappings also need to be
* checked against any subpool limit.
*/
if (map_chg || avoid_reserve) {
gbl_chg = hugepage_subpool_get_pages(spool, 1);
if (gbl_chg < 0) {
vma_end_reservation(h, vma, addr);
return ERR_PTR(-ENOSPC);
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
}
/*
* Even though there was no reservation in the region/reserve
* map, there could be reservations associated with the
* subpool that can be used. This would be indicated if the
* return value of hugepage_subpool_get_pages() is zero.
* However, if avoid_reserve is specified we still avoid even
* the subpool reservations.
*/
if (avoid_reserve)
gbl_chg = 1;
}
/* If this allocation is not consuming a reservation, charge it now.
*/
deferred_reserve = map_chg || avoid_reserve;
if (deferred_reserve) {
ret = hugetlb_cgroup_charge_cgroup_rsvd(
idx, pages_per_huge_page(h), &h_cg);
if (ret)
goto out_subpool_put;
}
ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
if (ret)
goto out_uncharge_cgroup_reservation;
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
/*
* glb_chg is passed to indicate whether or not a page must be taken
* from the global free pool (global change). gbl_chg == 0 indicates
* a reservation exists for the allocation.
*/
page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg);
if (!page) {
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
page = alloc_buddy_huge_page_with_mpol(h, vma, addr);
if (!page)
goto out_uncharge_cgroup;
if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
hugetlb: use page.private for hugetlb specific page flags Patch series "create hugetlb flags to consolidate state", v3. While discussing a series of hugetlb fixes in [1], it became evident that the hugetlb specific page state information is stored in a somewhat haphazard manner. Code dealing with state information would be easier to read, understand and maintain if this information was stored in a consistent manner. This series uses page.private of the hugetlb head page for storing a set of hugetlb specific page flags. Routines are priovided for test, set and clear of the flags. [1] https://lore.kernel.org/r/20210106084739.63318-1-songmuchun@bytedance.com This patch (of 4): As hugetlbfs evolved, state information about hugetlb pages was added. One 'convenient' way of doing this was to use available fields in tail pages. Over time, it has become difficult to know the meaning or contents of fields simply by looking at a small bit of code. Sometimes, the naming is just confusing. For example: The PagePrivate flag indicates a huge page reservation was consumed and needs to be restored if an error is encountered and the page is freed before it is instantiated. The page.private field contains the pointer to a subpool if the page is associated with one. In an effort to make the code more readable, use page.private to contain hugetlb specific page flags. These flags will have test, set and clear functions similar to those used for 'normal' page flags. More importantly, an enum of flag values will be created with names that actually reflect their purpose. In this patch, - Create infrastructure for hugetlb specific page flag functions - Move subpool pointer to page[1].private to make way for flags Create routines with meaningful names to modify subpool field - Use new HPageRestoreReserve flag instead of PagePrivate Conversion of other state information will happen in subsequent patches. Link: https://lkml.kernel.org/r/20210122195231.324857-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210122195231.324857-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:51 +03:00
SetHPageRestoreReserve(page);
h->resv_huge_pages--;
}
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
list_add(&page->lru, &h->hugepage_activelist);
/* Fall through */
}
hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
/* If allocation is not consuming a reservation, also store the
* hugetlb_cgroup pointer on the page.
*/
if (deferred_reserve) {
hugetlb_cgroup_commit_charge_rsvd(idx, pages_per_huge_page(h),
h_cg, page);
}
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
hugetlb: split alloc_huge_page into private and shared components Hugetlbfs implements a quota system which can limit the amount of memory that can be used by the filesystem. Before allocating a new huge page for a file, the quota is checked and debited. The quota is then credited when truncating the file. I found a few bugs in the code for both MAP_PRIVATE and MAP_SHARED mappings. Before detailing the problems and my proposed solutions, we should agree on a definition of quotas that properly addresses both private and shared pages. Since the purpose of quotas is to limit total memory consumption on a per-filesystem basis, I argue that all pages allocated by the fs (private and shared) should be charged against quota. Private Mappings ================ The current code will debit quota for private pages sometimes, but will never credit it. At a minimum, this causes a leak in the quota accounting which renders the accounting essentially useless as it is. Shared pages have a one to one mapping with a hugetlbfs file and are easy to account by debiting on allocation and crediting on truncate. Private pages are anonymous in nature and have a many to one relationship with their hugetlbfs files (due to copy on write). Because private pages are not indexed by the mapping's radix tree, thier quota cannot be credited at file truncation time. Crediting must be done when the page is unmapped and freed. Shared Pages ============ I discovered an issue concerning the interaction between the MAP_SHARED reservation system and quotas. Since quota is not checked until page instantiation, an over-quota mmap/reservation will initially succeed. When instantiating the first over-quota page, the program will receive SIGBUS. This is inconsistent since the reservation is supposed to be a guarantee. The solution is to debit the full amount of quota at reservation time and credit the unused portion when the reservation is released. This patch series brings quotas back in line by making the following modifications: * Private pages - Debit quota in alloc_huge_page() - Credit quota in free_huge_page() * Shared pages - Debit quota for entire reservation at mmap time - Credit quota for instantiated pages in free_huge_page() - Credit quota for unused reservation at munmap time This patch: The shared page reservation and dynamic pool resizing features have made the allocation of private vs. shared huge pages quite different. By splitting out the private/shared-specific portions of the process into their own functions, readability is greatly improved. alloc_huge_page now calls the proper helper and performs common operations. [akpm@linux-foundation.org: coding-style cleanups] Signed-off-by: Adam Litke <agl@us.ibm.com> Cc: Ken Chen <kenchen@google.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: David Gibson <hermes@gibson.dropbear.id.au> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-11-15 03:59:37 +03:00
hugetlb: use page.private for hugetlb specific page flags Patch series "create hugetlb flags to consolidate state", v3. While discussing a series of hugetlb fixes in [1], it became evident that the hugetlb specific page state information is stored in a somewhat haphazard manner. Code dealing with state information would be easier to read, understand and maintain if this information was stored in a consistent manner. This series uses page.private of the hugetlb head page for storing a set of hugetlb specific page flags. Routines are priovided for test, set and clear of the flags. [1] https://lore.kernel.org/r/20210106084739.63318-1-songmuchun@bytedance.com This patch (of 4): As hugetlbfs evolved, state information about hugetlb pages was added. One 'convenient' way of doing this was to use available fields in tail pages. Over time, it has become difficult to know the meaning or contents of fields simply by looking at a small bit of code. Sometimes, the naming is just confusing. For example: The PagePrivate flag indicates a huge page reservation was consumed and needs to be restored if an error is encountered and the page is freed before it is instantiated. The page.private field contains the pointer to a subpool if the page is associated with one. In an effort to make the code more readable, use page.private to contain hugetlb specific page flags. These flags will have test, set and clear functions similar to those used for 'normal' page flags. More importantly, an enum of flag values will be created with names that actually reflect their purpose. In this patch, - Create infrastructure for hugetlb specific page flag functions - Move subpool pointer to page[1].private to make way for flags Create routines with meaningful names to modify subpool field - Use new HPageRestoreReserve flag instead of PagePrivate Conversion of other state information will happen in subsequent patches. Link: https://lkml.kernel.org/r/20210122195231.324857-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210122195231.324857-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:51 +03:00
hugetlb_set_page_subpool(page, spool);
map_commit = vma_commit_reservation(h, vma, addr);
if (unlikely(map_chg > map_commit)) {
/*
* The page was added to the reservation map between
* vma_needs_reservation and vma_commit_reservation.
* This indicates a race with hugetlb_reserve_pages.
* Adjust for the subpool count incremented above AND
* in hugetlb_reserve_pages for the same page. Also,
* the reservation count added in hugetlb_reserve_pages
* no longer applies.
*/
long rsv_adjust;
rsv_adjust = hugepage_subpool_put_pages(spool, 1);
hugetlb_acct_memory(h, -rsv_adjust);
hugetlb_cgroup: fix reservation accounting Michal Privoznik was using "free page reporting" in QEMU/virtio-balloon with hugetlbfs and hit the warning below. QEMU with free page hinting uses fallocate(FALLOC_FL_PUNCH_HOLE) to discard pages that are reported as free by a VM. The reporting granularity is in pageblock granularity. So when the guest reports 2M chunks, we fallocate(FALLOC_FL_PUNCH_HOLE) one huge page in QEMU. WARNING: CPU: 7 PID: 6636 at mm/page_counter.c:57 page_counter_uncharge+0x4b/0x50 Modules linked in: ... CPU: 7 PID: 6636 Comm: qemu-system-x86 Not tainted 5.9.0 #137 Hardware name: Gigabyte Technology Co., Ltd. X570 AORUS PRO/X570 AORUS PRO, BIOS F21 07/31/2020 RIP: 0010:page_counter_uncharge+0x4b/0x50 ... Call Trace: hugetlb_cgroup_uncharge_file_region+0x4b/0x80 region_del+0x1d3/0x300 hugetlb_unreserve_pages+0x39/0xb0 remove_inode_hugepages+0x1a8/0x3d0 hugetlbfs_fallocate+0x3c4/0x5c0 vfs_fallocate+0x146/0x290 __x64_sys_fallocate+0x3e/0x70 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Investigation of the issue uncovered bugs in hugetlb cgroup reservation accounting. This patch addresses the found issues. Fixes: 075a61d07a8e ("hugetlb_cgroup: add accounting for shared mappings") Reported-by: Michal Privoznik <mprivozn@redhat.com> Co-developed-by: David Hildenbrand <david@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Michal Privoznik <mprivozn@redhat.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Cc: <stable@vger.kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Tejun Heo <tj@kernel.org> Link: https://lkml.kernel.org/r/20201021204426.36069-1-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-11-02 04:07:27 +03:00
if (deferred_reserve)
hugetlb_cgroup_uncharge_page_rsvd(hstate_index(h),
pages_per_huge_page(h), page);
}
return page;
out_uncharge_cgroup:
hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
out_uncharge_cgroup_reservation:
if (deferred_reserve)
hugetlb_cgroup_uncharge_cgroup_rsvd(idx, pages_per_huge_page(h),
h_cg);
out_subpool_put:
if (map_chg || avoid_reserve)
hugepage_subpool_put_pages(spool, 1);
vma_end_reservation(h, vma, addr);
return ERR_PTR(-ENOSPC);
[PATCH] hugepage: Strict page reservation for hugepage inodes These days, hugepages are demand-allocated at first fault time. There's a somewhat dubious (and racy) heuristic when making a new mmap() to check if there are enough available hugepages to fully satisfy that mapping. A particularly obvious case where the heuristic breaks down is where a process maps its hugepages not as a single chunk, but as a bunch of individually mmap()ed (or shmat()ed) blocks without touching and instantiating the pages in between allocations. In this case the size of each block is compared against the total number of available hugepages. It's thus easy for the process to become overcommitted, because each block mapping will succeed, although the total number of hugepages required by all blocks exceeds the number available. In particular, this defeats such a program which will detect a mapping failure and adjust its hugepage usage downward accordingly. The patch below addresses this problem, by strictly reserving a number of physical hugepages for hugepage inodes which have been mapped, but not instatiated. MAP_SHARED mappings are thus "safe" - they will fail on mmap(), not later with an OOM SIGKILL. MAP_PRIVATE mappings can still trigger an OOM. (Actually SHARED mappings can technically still OOM, but only if the sysadmin explicitly reduces the hugepage pool between mapping and instantiation) This patch appears to address the problem at hand - it allows DB2 to start correctly, for instance, which previously suffered the failure described above. This patch causes no regressions on the libhugetblfs testsuite, and makes a test (designed to catch this problem) pass which previously failed (ppc64, POWER5). Signed-off-by: David Gibson <dwg@au1.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 11:08:55 +03:00
}
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
int alloc_bootmem_huge_page(struct hstate *h, int nid)
__attribute__ ((weak, alias("__alloc_bootmem_huge_page")));
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
int __alloc_bootmem_huge_page(struct hstate *h, int nid)
{
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
struct huge_bootmem_page *m = NULL; /* initialize for clang */
int nr_nodes, node;
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
/* do node specific alloc */
if (nid != NUMA_NO_NODE) {
m = memblock_alloc_try_nid_raw(huge_page_size(h), huge_page_size(h),
0, MEMBLOCK_ALLOC_ACCESSIBLE, nid);
if (!m)
return 0;
goto found;
}
/* allocate from next node when distributing huge pages */
for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) {
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
m = memblock_alloc_try_nid_raw(
huge_page_size(h), huge_page_size(h),
memblock: replace BOOTMEM_ALLOC_* with MEMBLOCK variants Drop BOOTMEM_ALLOC_ACCESSIBLE and BOOTMEM_ALLOC_ANYWHERE in favor of identical MEMBLOCK definitions. Link: http://lkml.kernel.org/r/1536927045-23536-29-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Zankel <chris@zankel.net> Cc: "David S. Miller" <davem@davemloft.net> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Ingo Molnar <mingo@redhat.com> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Jonas Bonn <jonas@southpole.se> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Ley Foon Tan <lftan@altera.com> Cc: Mark Salter <msalter@redhat.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Palmer Dabbelt <palmer@sifive.com> Cc: Paul Burton <paul.burton@mips.com> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Serge Semin <fancer.lancer@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-31 01:09:44 +03:00
0, MEMBLOCK_ALLOC_ACCESSIBLE, node);
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
/*
* Use the beginning of the huge page to store the
* huge_bootmem_page struct (until gather_bootmem
* puts them into the mem_map).
*/
if (!m)
return 0;
goto found;
}
found:
/* Put them into a private list first because mem_map is not up yet */
INIT_LIST_HEAD(&m->list);
list_add(&m->list, &huge_boot_pages);
m->hstate = h;
return 1;
}
hugetlb: remove prep_compound_huge_page cleanup Patch series "Fix prep_compound_gigantic_page ref count adjustment". These patches address the possible race between prep_compound_gigantic_page and __page_cache_add_speculative as described by Jann Horn in [1]. The first patch simply removes the unnecessary/obsolete helper routine prep_compound_huge_page to make the actual fix a little simpler. The second patch is the actual fix and has a detailed explanation in the commit message. This potential issue has existed for almost 10 years and I am unaware of anyone actually hitting the race. I did not cc stable, but would be happy to squash the patches and send to stable if anyone thinks that is a good idea. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ This patch (of 2): I could not think of a reliable way to recreate the issue for testing. Rather, I 'simulated errors' to exercise all the error paths. The routine prep_compound_huge_page is a simple wrapper to call either prep_compound_gigantic_page or prep_compound_page. However, it is only called from gather_bootmem_prealloc which only processes gigantic pages. Eliminate the routine and call prep_compound_gigantic_page directly. Link: https://lkml.kernel.org/r/20210622021423.154662-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210622021423.154662-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Youquan Song <youquan.song@intel.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:31 +03:00
/*
* Put bootmem huge pages into the standard lists after mem_map is up.
* Note: This only applies to gigantic (order > MAX_ORDER) pages.
*/
static void __init gather_bootmem_prealloc(void)
{
struct huge_bootmem_page *m;
list_for_each_entry(m, &huge_boot_pages, list) {
struct page *page = virt_to_page(m);
struct hstate *h = m->hstate;
hugetlb: remove prep_compound_huge_page cleanup Patch series "Fix prep_compound_gigantic_page ref count adjustment". These patches address the possible race between prep_compound_gigantic_page and __page_cache_add_speculative as described by Jann Horn in [1]. The first patch simply removes the unnecessary/obsolete helper routine prep_compound_huge_page to make the actual fix a little simpler. The second patch is the actual fix and has a detailed explanation in the commit message. This potential issue has existed for almost 10 years and I am unaware of anyone actually hitting the race. I did not cc stable, but would be happy to squash the patches and send to stable if anyone thinks that is a good idea. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ This patch (of 2): I could not think of a reliable way to recreate the issue for testing. Rather, I 'simulated errors' to exercise all the error paths. The routine prep_compound_huge_page is a simple wrapper to call either prep_compound_gigantic_page or prep_compound_page. However, it is only called from gather_bootmem_prealloc which only processes gigantic pages. Eliminate the routine and call prep_compound_gigantic_page directly. Link: https://lkml.kernel.org/r/20210622021423.154662-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210622021423.154662-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Youquan Song <youquan.song@intel.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:31 +03:00
VM_BUG_ON(!hstate_is_gigantic(h));
WARN_ON(page_count(page) != 1);
hugetlb: address ref count racing in prep_compound_gigantic_page In [1], Jann Horn points out a possible race between prep_compound_gigantic_page and __page_cache_add_speculative. The root cause of the possible race is prep_compound_gigantic_page uncondittionally setting the ref count of pages to zero. It does this because prep_compound_gigantic_page is handed a 'group' of pages from an allocator and needs to convert that group of pages to a compound page. The ref count of each page in this 'group' is one as set by the allocator. However, the ref count of compound page tail pages must be zero. The potential race comes about when ref counted pages are returned from the allocator. When this happens, other mm code could also take a reference on the page. __page_cache_add_speculative is one such example. Therefore, prep_compound_gigantic_page can not just set the ref count of pages to zero as it does today. Doing so would lose the reference taken by any other code. This would lead to BUGs in code checking ref counts and could possibly even lead to memory corruption. There are two possible ways to address this issue. 1) Make all allocators of gigantic groups of pages be able to return a properly constructed compound page. 2) Make prep_compound_gigantic_page be more careful when constructing a compound page. This patch takes approach 2. In prep_compound_gigantic_page, use cmpxchg to only set ref count to zero if it is one. If the cmpxchg fails, call synchronize_rcu() in the hope that the extra ref count will be driopped during a rcu grace period. This is not a performance critical code path and the wait should be accceptable. If the ref count is still inflated after the grace period, then undo any modifications made and return an error. Currently prep_compound_gigantic_page is type void and does not return errors. Modify the two callers to check for and handle error returns. On error, the caller must free the 'group' of pages as they can not be used to form a gigantic page. After freeing pages, the runtime caller (alloc_fresh_huge_page) will retry the allocation once. Boot time allocations can not be retried. The routine prep_compound_page also unconditionally sets the ref count of compound page tail pages to zero. However, in this case the buddy allocator is constructing a compound page from freshly allocated pages. The ref count on those freshly allocated pages is already zero, so the set_page_count(p, 0) is unnecessary and could lead to confusion. Just remove it. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210622021423.154662-3-mike.kravetz@oracle.com Fixes: 58a84aa92723 ("thp: set compound tail page _count to zero") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jann Horn <jannh@google.com> Cc: Youquan Song <youquan.song@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:34 +03:00
if (prep_compound_gigantic_page(page, huge_page_order(h))) {
WARN_ON(PageReserved(page));
prep_new_huge_page(h, page, page_to_nid(page));
put_page(page); /* add to the hugepage allocator */
} else {
/* VERY unlikely inflated ref count on a tail page */
hugetlb: address ref count racing in prep_compound_gigantic_page In [1], Jann Horn points out a possible race between prep_compound_gigantic_page and __page_cache_add_speculative. The root cause of the possible race is prep_compound_gigantic_page uncondittionally setting the ref count of pages to zero. It does this because prep_compound_gigantic_page is handed a 'group' of pages from an allocator and needs to convert that group of pages to a compound page. The ref count of each page in this 'group' is one as set by the allocator. However, the ref count of compound page tail pages must be zero. The potential race comes about when ref counted pages are returned from the allocator. When this happens, other mm code could also take a reference on the page. __page_cache_add_speculative is one such example. Therefore, prep_compound_gigantic_page can not just set the ref count of pages to zero as it does today. Doing so would lose the reference taken by any other code. This would lead to BUGs in code checking ref counts and could possibly even lead to memory corruption. There are two possible ways to address this issue. 1) Make all allocators of gigantic groups of pages be able to return a properly constructed compound page. 2) Make prep_compound_gigantic_page be more careful when constructing a compound page. This patch takes approach 2. In prep_compound_gigantic_page, use cmpxchg to only set ref count to zero if it is one. If the cmpxchg fails, call synchronize_rcu() in the hope that the extra ref count will be driopped during a rcu grace period. This is not a performance critical code path and the wait should be accceptable. If the ref count is still inflated after the grace period, then undo any modifications made and return an error. Currently prep_compound_gigantic_page is type void and does not return errors. Modify the two callers to check for and handle error returns. On error, the caller must free the 'group' of pages as they can not be used to form a gigantic page. After freeing pages, the runtime caller (alloc_fresh_huge_page) will retry the allocation once. Boot time allocations can not be retried. The routine prep_compound_page also unconditionally sets the ref count of compound page tail pages to zero. However, in this case the buddy allocator is constructing a compound page from freshly allocated pages. The ref count on those freshly allocated pages is already zero, so the set_page_count(p, 0) is unnecessary and could lead to confusion. Just remove it. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210622021423.154662-3-mike.kravetz@oracle.com Fixes: 58a84aa92723 ("thp: set compound tail page _count to zero") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jann Horn <jannh@google.com> Cc: Youquan Song <youquan.song@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:34 +03:00
free_gigantic_page(page, huge_page_order(h));
}
mm, hugetlb: unify core page allocation accounting and initialization Patch series "mm, hugetlb: allocation API and migration improvements" Motivation: this is a follow up for [3] for the allocation API and [4] for the hugetlb migration. It wasn't really easy to split those into two separate patch series as they share some code. My primary motivation to touch this code is to make the gigantic pages migration working. The giga pages allocation code is just too fragile and hacked into the hugetlb code now. This series tries to move giga pages closer to the first class citizen. We are not there yet but having 5 patches is quite a lot already and it will already make the code much easier to follow. I will come with other changes on top after this sees some review. The first two patches should be trivial to review. The third patch changes the way how we migrate huge pages. Newly allocated pages are a subject of the overcommit check and they participate surplus accounting which is quite unfortunate as the changelog explains. This patch doesn't change anything wrt. giga pages. Patch #4 removes the surplus accounting hack from __alloc_surplus_huge_page. I hope I didn't miss anything there and a deeper review is really due there. Patch #5 finally unifies allocation paths and giga pages shouldn't be any special anymore. There is also some renaming going on as well. This patch (of 6): hugetlb allocator has two entry points to the page allocator - alloc_fresh_huge_page_node - __hugetlb_alloc_buddy_huge_page The two differ very subtly in two aspects. The first one doesn't care about HTLB_BUDDY_* stats and it doesn't initialize the huge page. prep_new_huge_page is not used because it not only initializes hugetlb specific stuff but because it also put_page and releases the page to the hugetlb pool which is not what is required in some contexts. This makes things more complicated than necessary. Simplify things by a) removing the page allocator entry point duplicity and only keep __hugetlb_alloc_buddy_huge_page and b) make prep_new_huge_page more reusable by removing the put_page which moves the page to the allocator pool. All current callers are updated to call put_page explicitly. Later patches will add new callers which won't need it. This patch shouldn't introduce any functional change. Link: http://lkml.kernel.org/r/20180103093213.26329-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:41 +03:00
mm: fix negative commitlimit when gigantic hugepages are allocated When 1GB hugepages are allocated on a system, free(1) reports less available memory than what really is installed in the box. Also, if the total size of hugepages allocated on a system is over half of the total memory size, CommitLimit becomes a negative number. The problem is that gigantic hugepages (order > MAX_ORDER) can only be allocated at boot with bootmem, thus its frames are not accounted to 'totalram_pages'. However, they are accounted to hugetlb_total_pages() What happens to turn CommitLimit into a negative number is this calculation, in fs/proc/meminfo.c: allowed = ((totalram_pages - hugetlb_total_pages()) * sysctl_overcommit_ratio / 100) + total_swap_pages; A similar calculation occurs in __vm_enough_memory() in mm/mmap.c. Also, every vm statistic which depends on 'totalram_pages' will render confusing values, as if system were 'missing' some part of its memory. Impact of this bug: When gigantic hugepages are allocated and sysctl_overcommit_memory == OVERCOMMIT_NEVER. In a such situation, __vm_enough_memory() goes through the mentioned 'allowed' calculation and might end up mistakenly returning -ENOMEM, thus forcing the system to start reclaiming pages earlier than it would be ususal, and this could cause detrimental impact to overall system's performance, depending on the workload. Besides the aforementioned scenario, I can only think of this causing annoyances with memory reports from /proc/meminfo and free(1). [akpm@linux-foundation.org: standardize comment layout] Reported-by: Russ Anderson <rja@sgi.com> Signed-off-by: Rafael Aquini <aquini@linux.com> Acked-by: Russ Anderson <rja@sgi.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-06-16 02:08:39 +04:00
/*
hugetlb: remove prep_compound_huge_page cleanup Patch series "Fix prep_compound_gigantic_page ref count adjustment". These patches address the possible race between prep_compound_gigantic_page and __page_cache_add_speculative as described by Jann Horn in [1]. The first patch simply removes the unnecessary/obsolete helper routine prep_compound_huge_page to make the actual fix a little simpler. The second patch is the actual fix and has a detailed explanation in the commit message. This potential issue has existed for almost 10 years and I am unaware of anyone actually hitting the race. I did not cc stable, but would be happy to squash the patches and send to stable if anyone thinks that is a good idea. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ This patch (of 2): I could not think of a reliable way to recreate the issue for testing. Rather, I 'simulated errors' to exercise all the error paths. The routine prep_compound_huge_page is a simple wrapper to call either prep_compound_gigantic_page or prep_compound_page. However, it is only called from gather_bootmem_prealloc which only processes gigantic pages. Eliminate the routine and call prep_compound_gigantic_page directly. Link: https://lkml.kernel.org/r/20210622021423.154662-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210622021423.154662-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Youquan Song <youquan.song@intel.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:31 +03:00
* We need to restore the 'stolen' pages to totalram_pages
* in order to fix confusing memory reports from free(1) and
* other side-effects, like CommitLimit going negative.
mm: fix negative commitlimit when gigantic hugepages are allocated When 1GB hugepages are allocated on a system, free(1) reports less available memory than what really is installed in the box. Also, if the total size of hugepages allocated on a system is over half of the total memory size, CommitLimit becomes a negative number. The problem is that gigantic hugepages (order > MAX_ORDER) can only be allocated at boot with bootmem, thus its frames are not accounted to 'totalram_pages'. However, they are accounted to hugetlb_total_pages() What happens to turn CommitLimit into a negative number is this calculation, in fs/proc/meminfo.c: allowed = ((totalram_pages - hugetlb_total_pages()) * sysctl_overcommit_ratio / 100) + total_swap_pages; A similar calculation occurs in __vm_enough_memory() in mm/mmap.c. Also, every vm statistic which depends on 'totalram_pages' will render confusing values, as if system were 'missing' some part of its memory. Impact of this bug: When gigantic hugepages are allocated and sysctl_overcommit_memory == OVERCOMMIT_NEVER. In a such situation, __vm_enough_memory() goes through the mentioned 'allowed' calculation and might end up mistakenly returning -ENOMEM, thus forcing the system to start reclaiming pages earlier than it would be ususal, and this could cause detrimental impact to overall system's performance, depending on the workload. Besides the aforementioned scenario, I can only think of this causing annoyances with memory reports from /proc/meminfo and free(1). [akpm@linux-foundation.org: standardize comment layout] Reported-by: Russ Anderson <rja@sgi.com> Signed-off-by: Rafael Aquini <aquini@linux.com> Acked-by: Russ Anderson <rja@sgi.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-06-16 02:08:39 +04:00
*/
hugetlb: remove prep_compound_huge_page cleanup Patch series "Fix prep_compound_gigantic_page ref count adjustment". These patches address the possible race between prep_compound_gigantic_page and __page_cache_add_speculative as described by Jann Horn in [1]. The first patch simply removes the unnecessary/obsolete helper routine prep_compound_huge_page to make the actual fix a little simpler. The second patch is the actual fix and has a detailed explanation in the commit message. This potential issue has existed for almost 10 years and I am unaware of anyone actually hitting the race. I did not cc stable, but would be happy to squash the patches and send to stable if anyone thinks that is a good idea. [1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/ This patch (of 2): I could not think of a reliable way to recreate the issue for testing. Rather, I 'simulated errors' to exercise all the error paths. The routine prep_compound_huge_page is a simple wrapper to call either prep_compound_gigantic_page or prep_compound_page. However, it is only called from gather_bootmem_prealloc which only processes gigantic pages. Eliminate the routine and call prep_compound_gigantic_page directly. Link: https://lkml.kernel.org/r/20210622021423.154662-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210622021423.154662-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Youquan Song <youquan.song@intel.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:31 +03:00
adjust_managed_page_count(page, pages_per_huge_page(h));
cond_resched();
}
}
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
static void __init hugetlb_hstate_alloc_pages_onenode(struct hstate *h, int nid)
{
unsigned long i;
char buf[32];
for (i = 0; i < h->max_huge_pages_node[nid]; ++i) {
if (hstate_is_gigantic(h)) {
if (!alloc_bootmem_huge_page(h, nid))
break;
} else {
struct page *page;
gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
page = alloc_fresh_huge_page(h, gfp_mask, nid,
&node_states[N_MEMORY], NULL);
if (!page)
break;
put_page(page); /* free it into the hugepage allocator */
}
cond_resched();
}
if (i == h->max_huge_pages_node[nid])
return;
string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
pr_warn("HugeTLB: allocating %u of page size %s failed node%d. Only allocated %lu hugepages.\n",
h->max_huge_pages_node[nid], buf, nid, i);
h->max_huge_pages -= (h->max_huge_pages_node[nid] - i);
h->max_huge_pages_node[nid] = i;
}
static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
{
unsigned long i;
nodemask_t *node_alloc_noretry;
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
bool node_specific_alloc = false;
/* skip gigantic hugepages allocation if hugetlb_cma enabled */
if (hstate_is_gigantic(h) && hugetlb_cma_size) {
pr_warn_once("HugeTLB: hugetlb_cma is enabled, skip boot time allocation\n");
return;
}
/* do node specific alloc */
hugetlb: fix wrong use of nr_online_nodes Patch series "hugetlb: Fix some incorrect behavior", v3. This series fix three bugs of hugetlb: 1) Invalid use of nr_online_nodes; 2) Inconsistency between 1G hugepage and 2M hugepage; 3) Useless information in dmesg. This patch (of 4): Certain systems are designed to have sparse/discontiguous nodes. In this case, nr_online_nodes can not be used to walk through numa node. Also, a valid node may be greater than nr_online_nodes. However, in hugetlb, it is assumed that nodes are contiguous. For sparse/discontiguous nodes, the current code may treat a valid node as invalid, and will fail to allocate all hugepages on a valid node that "nid >= nr_online_nodes". As David suggested: if (tmp >= nr_online_nodes) goto invalid; Just imagine node 0 and node 2 are online, and node 1 is offline. Assuming that "node < 2" is valid is wrong. Recheck all the places that use nr_online_nodes, and repair them one by one. [liupeng256@huawei.com: v4] Link: https://lkml.kernel.org/r/20220416103526.3287348-1-liupeng256@huawei.com Link: https://lkml.kernel.org/r/20220413032915.251254-1-liupeng256@huawei.com Link: https://lkml.kernel.org/r/20220413032915.251254-2-liupeng256@huawei.com Fixes: 4178158ef8ca ("hugetlbfs: fix issue of preallocation of gigantic pages can't work") Fixes: b5389086ad7b ("hugetlbfs: extend the definition of hugepages parameter to support node allocation") Fixes: e79ce9832316 ("hugetlbfs: fix a truncation issue in hugepages parameter") Fixes: f9317f77a6e0 ("hugetlb: clean up potential spectre issue warnings") Signed-off-by: Peng Liu <liupeng256@huawei.com> Suggested-by: David Hildenbrand <david@redhat.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Liu Yuntao <liuyuntao10@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-04-30 00:36:57 +03:00
for_each_online_node(i) {
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
if (h->max_huge_pages_node[i] > 0) {
hugetlb_hstate_alloc_pages_onenode(h, i);
node_specific_alloc = true;
}
}
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
if (node_specific_alloc)
return;
/* below will do all node balanced alloc */
if (!hstate_is_gigantic(h)) {
/*
* Bit mask controlling how hard we retry per-node allocations.
* Ignore errors as lower level routines can deal with
* node_alloc_noretry == NULL. If this kmalloc fails at boot
* time, we are likely in bigger trouble.
*/
node_alloc_noretry = kmalloc(sizeof(*node_alloc_noretry),
GFP_KERNEL);
} else {
/* allocations done at boot time */
node_alloc_noretry = NULL;
}
/* bit mask controlling how hard we retry per-node allocations */
if (node_alloc_noretry)
nodes_clear(*node_alloc_noretry);
for (i = 0; i < h->max_huge_pages; ++i) {
if (hstate_is_gigantic(h)) {
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
if (!alloc_bootmem_huge_page(h, NUMA_NO_NODE))
break;
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
} else if (!alloc_pool_huge_page(h,
&node_states[N_MEMORY],
node_alloc_noretry))
break;
cond_resched();
}
mm/hugetlb.c: warn the user when issues arise on boot due to hugepages When the user specifies too many hugepages or an invalid default_hugepagesz the communication to the user is implicit in the allocation message. This patch adds a warning when the desired page count is not allocated and prints an error when the default_hugepagesz is invalid on boot. During boot hugepages will allocate until there is a fraction of the hugepage size left. That is, we allocate until either the request is satisfied or memory for the pages is exhausted. When memory for the pages is exhausted, it will most likely lead to the system failing with the OOM manager not finding enough (or anything) to kill (unless you're using really big hugepages in the order of 100s of MB or in the GBs). The user will most likely see the OOM messages much later in the boot sequence than the implicitly stated message. Worse yet, you may even get an OOM for each processor which causes many pages of OOMs on modern systems. Although these messages will be printed earlier than the OOM messages, at least giving the user errors and warnings will highlight the configuration as an issue. I'm trying to point the user in the right direction by providing a more robust statement of what is failing. During the sysctl or echo command, the user can check the results much easier than if the system hangs during boot and the scenario of having nothing to OOM for kernel memory is highly unlikely. Mike said: "Before sending out this patch, I asked Liam off list why he was doing it. Was it something he just thought would be useful? Or, was there some type of user situation/need. He said that he had been called in to assist on several occasions when a system OOMed during boot. In almost all of these situations, the user had grossly misconfigured huge pages. DB users want to pre-allocate just the right amount of huge pages, but sometimes they can be really off. In such situations, the huge page init code just allocates as many huge pages as it can and reports the number allocated. There is no indication that it quit allocating because it ran out of memory. Of course, a user could compare the number in the message to what they requested on the command line to determine if they got all the huge pages they requested. The thought was that it would be useful to at least flag this situation. That way, the user might be able to better relate the huge page allocation failure to the OOM. I'm not sure if the e-mail discussion made it obvious that this is something he has seen on several occasions. I see Michal's point that this will only flag the situation where someone configures huge pages very badly. And, a more extensive look at the situation of misconfiguring huge pages might be in order. But, this has happened on several occasions which led to the creation of this patch" [akpm@linux-foundation.org: reposition memfmt() to avoid forward declaration] Link: http://lkml.kernel.org/r/20170603005413.10380-1-Liam.Howlett@Oracle.com Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: zhongjiang <zhongjiang@huawei.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-11 01:48:15 +03:00
if (i < h->max_huge_pages) {
char buf[32];
string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
mm/hugetlb.c: warn the user when issues arise on boot due to hugepages When the user specifies too many hugepages or an invalid default_hugepagesz the communication to the user is implicit in the allocation message. This patch adds a warning when the desired page count is not allocated and prints an error when the default_hugepagesz is invalid on boot. During boot hugepages will allocate until there is a fraction of the hugepage size left. That is, we allocate until either the request is satisfied or memory for the pages is exhausted. When memory for the pages is exhausted, it will most likely lead to the system failing with the OOM manager not finding enough (or anything) to kill (unless you're using really big hugepages in the order of 100s of MB or in the GBs). The user will most likely see the OOM messages much later in the boot sequence than the implicitly stated message. Worse yet, you may even get an OOM for each processor which causes many pages of OOMs on modern systems. Although these messages will be printed earlier than the OOM messages, at least giving the user errors and warnings will highlight the configuration as an issue. I'm trying to point the user in the right direction by providing a more robust statement of what is failing. During the sysctl or echo command, the user can check the results much easier than if the system hangs during boot and the scenario of having nothing to OOM for kernel memory is highly unlikely. Mike said: "Before sending out this patch, I asked Liam off list why he was doing it. Was it something he just thought would be useful? Or, was there some type of user situation/need. He said that he had been called in to assist on several occasions when a system OOMed during boot. In almost all of these situations, the user had grossly misconfigured huge pages. DB users want to pre-allocate just the right amount of huge pages, but sometimes they can be really off. In such situations, the huge page init code just allocates as many huge pages as it can and reports the number allocated. There is no indication that it quit allocating because it ran out of memory. Of course, a user could compare the number in the message to what they requested on the command line to determine if they got all the huge pages they requested. The thought was that it would be useful to at least flag this situation. That way, the user might be able to better relate the huge page allocation failure to the OOM. I'm not sure if the e-mail discussion made it obvious that this is something he has seen on several occasions. I see Michal's point that this will only flag the situation where someone configures huge pages very badly. And, a more extensive look at the situation of misconfiguring huge pages might be in order. But, this has happened on several occasions which led to the creation of this patch" [akpm@linux-foundation.org: reposition memfmt() to avoid forward declaration] Link: http://lkml.kernel.org/r/20170603005413.10380-1-Liam.Howlett@Oracle.com Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: zhongjiang <zhongjiang@huawei.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-11 01:48:15 +03:00
pr_warn("HugeTLB: allocating %lu of page size %s failed. Only allocated %lu hugepages.\n",
h->max_huge_pages, buf, i);
h->max_huge_pages = i;
}
kfree(node_alloc_noretry);
}
static void __init hugetlb_init_hstates(void)
{
hugetlb: add demote hugetlb page sysfs interfaces Patch series "hugetlb: add demote/split page functionality", v4. The concurrent use of multiple hugetlb page sizes on a single system is becoming more common. One of the reasons is better TLB support for gigantic page sizes on x86 hardware. In addition, hugetlb pages are being used to back VMs in hosting environments. When using hugetlb pages to back VMs, it is often desirable to preallocate hugetlb pools. This avoids the delay and uncertainty of allocating hugetlb pages at VM startup. In addition, preallocating huge pages minimizes the issue of memory fragmentation that increases the longer the system is up and running. In such environments, a combination of larger and smaller hugetlb pages are preallocated in anticipation of backing VMs of various sizes. Over time, the preallocated pool of smaller hugetlb pages may become depleted while larger hugetlb pages still remain. In such situations, it is desirable to convert larger hugetlb pages to smaller hugetlb pages. Converting larger to smaller hugetlb pages can be accomplished today by first freeing the larger page to the buddy allocator and then allocating the smaller pages. For example, to convert 50 GB pages on x86: gb_pages=`cat .../hugepages-1048576kB/nr_hugepages` m2_pages=`cat .../hugepages-2048kB/nr_hugepages` echo $(($gb_pages - 50)) > .../hugepages-1048576kB/nr_hugepages echo $(($m2_pages + 25600)) > .../hugepages-2048kB/nr_hugepages On an idle system this operation is fairly reliable and results are as expected. The number of 2MB pages is increased as expected and the time of the operation is a second or two. However, when there is activity on the system the following issues arise: 1) This process can take quite some time, especially if allocation of the smaller pages is not immediate and requires migration/compaction. 2) There is no guarantee that the total size of smaller pages allocated will match the size of the larger page which was freed. This is because the area freed by the larger page could quickly be fragmented. In a test environment with a load that continually fills the page cache with clean pages, results such as the following can be observed: Unexpected number of 2MB pages allocated: Expected 25600, have 19944 real 0m42.092s user 0m0.008s sys 0m41.467s To address these issues, introduce the concept of hugetlb page demotion. Demotion provides a means of 'in place' splitting of a hugetlb page to pages of a smaller size. This avoids freeing pages to buddy and then trying to allocate from buddy. Page demotion is controlled via sysfs files that reside in the per-hugetlb page size and per node directories. - demote_size Target page size for demotion, a smaller huge page size. File can be written to chose a smaller huge page size if multiple are available. - demote Writable number of hugetlb pages to be demoted To demote 50 GB huge pages, one would: cat .../hugepages-1048576kB/free_hugepages /* optional, verify free pages */ cat .../hugepages-1048576kB/demote_size /* optional, verify target size */ echo 50 > .../hugepages-1048576kB/demote Only hugetlb pages which are free at the time of the request can be demoted. Demotion does not add to the complexity of surplus pages and honors reserved huge pages. Therefore, when a value is written to the sysfs demote file, that value is only the maximum number of pages which will be demoted. It is possible fewer will actually be demoted. The recently introduced per-hstate mutex is used to synchronize demote operations with other operations that modify hugetlb pools. Real world use cases -------------------- The above scenario describes a real world use case where hugetlb pages are used to back VMs on x86. Both issues of long allocation times and not necessarily getting the expected number of smaller huge pages after a free and allocate cycle have been experienced. The occurrence of these issues is dependent on other activity within the host and can not be predicted. This patch (of 5): Two new sysfs files are added to demote hugtlb pages. These files are both per-hugetlb page size and per node. Files are: demote_size - The size in Kb that pages are demoted to. (read-write) demote - The number of huge pages to demote. (write-only) By default, demote_size is the next smallest huge page size. Valid huge page sizes less than huge page size may be written to this file. When huge pages are demoted, they are demoted to this size. Writing a value to demote will result in an attempt to demote that number of hugetlb pages to an appropriate number of demote_size pages. NOTE: Demote interfaces are only provided for huge page sizes if there is a smaller target demote huge page size. For example, on x86 1GB huge pages will have demote interfaces. 2MB huge pages will not have demote interfaces. This patch does not provide full demote functionality. It only provides the sysfs interfaces. It also provides documentation for the new interfaces. [mike.kravetz@oracle.com: n_mask initialization does not need to be protected by the mutex] Link: https://lkml.kernel.org/r/0530e4ef-2492-5186-f919-5db68edea654@oracle.com Link: https://lkml.kernel.org/r/20211007181918.136982-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: David Rientjes <rientjes@google.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Nghia Le <nghialm78@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:20 +03:00
struct hstate *h, *h2;
for_each_hstate(h) {
if (minimum_order > huge_page_order(h))
minimum_order = huge_page_order(h);
/* oversize hugepages were init'ed in early boot */
if (!hstate_is_gigantic(h))
hugetlb_hstate_alloc_pages(h);
hugetlb: add demote hugetlb page sysfs interfaces Patch series "hugetlb: add demote/split page functionality", v4. The concurrent use of multiple hugetlb page sizes on a single system is becoming more common. One of the reasons is better TLB support for gigantic page sizes on x86 hardware. In addition, hugetlb pages are being used to back VMs in hosting environments. When using hugetlb pages to back VMs, it is often desirable to preallocate hugetlb pools. This avoids the delay and uncertainty of allocating hugetlb pages at VM startup. In addition, preallocating huge pages minimizes the issue of memory fragmentation that increases the longer the system is up and running. In such environments, a combination of larger and smaller hugetlb pages are preallocated in anticipation of backing VMs of various sizes. Over time, the preallocated pool of smaller hugetlb pages may become depleted while larger hugetlb pages still remain. In such situations, it is desirable to convert larger hugetlb pages to smaller hugetlb pages. Converting larger to smaller hugetlb pages can be accomplished today by first freeing the larger page to the buddy allocator and then allocating the smaller pages. For example, to convert 50 GB pages on x86: gb_pages=`cat .../hugepages-1048576kB/nr_hugepages` m2_pages=`cat .../hugepages-2048kB/nr_hugepages` echo $(($gb_pages - 50)) > .../hugepages-1048576kB/nr_hugepages echo $(($m2_pages + 25600)) > .../hugepages-2048kB/nr_hugepages On an idle system this operation is fairly reliable and results are as expected. The number of 2MB pages is increased as expected and the time of the operation is a second or two. However, when there is activity on the system the following issues arise: 1) This process can take quite some time, especially if allocation of the smaller pages is not immediate and requires migration/compaction. 2) There is no guarantee that the total size of smaller pages allocated will match the size of the larger page which was freed. This is because the area freed by the larger page could quickly be fragmented. In a test environment with a load that continually fills the page cache with clean pages, results such as the following can be observed: Unexpected number of 2MB pages allocated: Expected 25600, have 19944 real 0m42.092s user 0m0.008s sys 0m41.467s To address these issues, introduce the concept of hugetlb page demotion. Demotion provides a means of 'in place' splitting of a hugetlb page to pages of a smaller size. This avoids freeing pages to buddy and then trying to allocate from buddy. Page demotion is controlled via sysfs files that reside in the per-hugetlb page size and per node directories. - demote_size Target page size for demotion, a smaller huge page size. File can be written to chose a smaller huge page size if multiple are available. - demote Writable number of hugetlb pages to be demoted To demote 50 GB huge pages, one would: cat .../hugepages-1048576kB/free_hugepages /* optional, verify free pages */ cat .../hugepages-1048576kB/demote_size /* optional, verify target size */ echo 50 > .../hugepages-1048576kB/demote Only hugetlb pages which are free at the time of the request can be demoted. Demotion does not add to the complexity of surplus pages and honors reserved huge pages. Therefore, when a value is written to the sysfs demote file, that value is only the maximum number of pages which will be demoted. It is possible fewer will actually be demoted. The recently introduced per-hstate mutex is used to synchronize demote operations with other operations that modify hugetlb pools. Real world use cases -------------------- The above scenario describes a real world use case where hugetlb pages are used to back VMs on x86. Both issues of long allocation times and not necessarily getting the expected number of smaller huge pages after a free and allocate cycle have been experienced. The occurrence of these issues is dependent on other activity within the host and can not be predicted. This patch (of 5): Two new sysfs files are added to demote hugtlb pages. These files are both per-hugetlb page size and per node. Files are: demote_size - The size in Kb that pages are demoted to. (read-write) demote - The number of huge pages to demote. (write-only) By default, demote_size is the next smallest huge page size. Valid huge page sizes less than huge page size may be written to this file. When huge pages are demoted, they are demoted to this size. Writing a value to demote will result in an attempt to demote that number of hugetlb pages to an appropriate number of demote_size pages. NOTE: Demote interfaces are only provided for huge page sizes if there is a smaller target demote huge page size. For example, on x86 1GB huge pages will have demote interfaces. 2MB huge pages will not have demote interfaces. This patch does not provide full demote functionality. It only provides the sysfs interfaces. It also provides documentation for the new interfaces. [mike.kravetz@oracle.com: n_mask initialization does not need to be protected by the mutex] Link: https://lkml.kernel.org/r/0530e4ef-2492-5186-f919-5db68edea654@oracle.com Link: https://lkml.kernel.org/r/20211007181918.136982-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: David Rientjes <rientjes@google.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Nghia Le <nghialm78@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:20 +03:00
/*
* Set demote order for each hstate. Note that
* h->demote_order is initially 0.
* - We can not demote gigantic pages if runtime freeing
* is not supported, so skip this.
hugetlb: be sure to free demoted CMA pages to CMA When huge page demotion is fully implemented, gigantic pages can be demoted to a smaller huge page size. For example, on x86 a 1G page can be demoted to 512 2M pages. However, gigantic pages can potentially be allocated from CMA. If a gigantic page which was allocated from CMA is demoted, the corresponding demoted pages needs to be returned to CMA. Use the new interface cma_pages_valid() to determine if a non-gigantic hugetlb page should be freed to CMA. Also, clear mapping field of these pages as expected by cma_release. This also requires a change to CMA region creation for gigantic pages. CMA uses a per-region bit map to track allocations. When setting up the region, you specify how many pages each bit represents. Currently, only gigantic pages are allocated/freed from CMA so the region is set up such that one bit represents a gigantic page size allocation. With demote, a gigantic page (allocation) could be split into smaller size pages. And, these smaller size pages will be freed to CMA. So, since the per-region bit map needs to be set up to represent the smallest allocation/free size, it now needs to be set to the smallest huge page size which can be freed to CMA. Unfortunately, we set up the CMA region for huge pages before we set up huge pages sizes (hstates). So, technically we do not know the smallest huge page size as this can change via command line options and architecture specific code. Therefore, at region setup time we use HUGETLB_PAGE_ORDER as the smallest possible huge page size that can be given back to CMA. It is possible that this value is sub-optimal for some architectures/config options. If needed, this can be addressed in follow on work. Link: https://lkml.kernel.org/r/20211007181918.136982-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:27 +03:00
* - If CMA allocation is possible, we can not demote
* HUGETLB_PAGE_ORDER or smaller size pages.
hugetlb: add demote hugetlb page sysfs interfaces Patch series "hugetlb: add demote/split page functionality", v4. The concurrent use of multiple hugetlb page sizes on a single system is becoming more common. One of the reasons is better TLB support for gigantic page sizes on x86 hardware. In addition, hugetlb pages are being used to back VMs in hosting environments. When using hugetlb pages to back VMs, it is often desirable to preallocate hugetlb pools. This avoids the delay and uncertainty of allocating hugetlb pages at VM startup. In addition, preallocating huge pages minimizes the issue of memory fragmentation that increases the longer the system is up and running. In such environments, a combination of larger and smaller hugetlb pages are preallocated in anticipation of backing VMs of various sizes. Over time, the preallocated pool of smaller hugetlb pages may become depleted while larger hugetlb pages still remain. In such situations, it is desirable to convert larger hugetlb pages to smaller hugetlb pages. Converting larger to smaller hugetlb pages can be accomplished today by first freeing the larger page to the buddy allocator and then allocating the smaller pages. For example, to convert 50 GB pages on x86: gb_pages=`cat .../hugepages-1048576kB/nr_hugepages` m2_pages=`cat .../hugepages-2048kB/nr_hugepages` echo $(($gb_pages - 50)) > .../hugepages-1048576kB/nr_hugepages echo $(($m2_pages + 25600)) > .../hugepages-2048kB/nr_hugepages On an idle system this operation is fairly reliable and results are as expected. The number of 2MB pages is increased as expected and the time of the operation is a second or two. However, when there is activity on the system the following issues arise: 1) This process can take quite some time, especially if allocation of the smaller pages is not immediate and requires migration/compaction. 2) There is no guarantee that the total size of smaller pages allocated will match the size of the larger page which was freed. This is because the area freed by the larger page could quickly be fragmented. In a test environment with a load that continually fills the page cache with clean pages, results such as the following can be observed: Unexpected number of 2MB pages allocated: Expected 25600, have 19944 real 0m42.092s user 0m0.008s sys 0m41.467s To address these issues, introduce the concept of hugetlb page demotion. Demotion provides a means of 'in place' splitting of a hugetlb page to pages of a smaller size. This avoids freeing pages to buddy and then trying to allocate from buddy. Page demotion is controlled via sysfs files that reside in the per-hugetlb page size and per node directories. - demote_size Target page size for demotion, a smaller huge page size. File can be written to chose a smaller huge page size if multiple are available. - demote Writable number of hugetlb pages to be demoted To demote 50 GB huge pages, one would: cat .../hugepages-1048576kB/free_hugepages /* optional, verify free pages */ cat .../hugepages-1048576kB/demote_size /* optional, verify target size */ echo 50 > .../hugepages-1048576kB/demote Only hugetlb pages which are free at the time of the request can be demoted. Demotion does not add to the complexity of surplus pages and honors reserved huge pages. Therefore, when a value is written to the sysfs demote file, that value is only the maximum number of pages which will be demoted. It is possible fewer will actually be demoted. The recently introduced per-hstate mutex is used to synchronize demote operations with other operations that modify hugetlb pools. Real world use cases -------------------- The above scenario describes a real world use case where hugetlb pages are used to back VMs on x86. Both issues of long allocation times and not necessarily getting the expected number of smaller huge pages after a free and allocate cycle have been experienced. The occurrence of these issues is dependent on other activity within the host and can not be predicted. This patch (of 5): Two new sysfs files are added to demote hugtlb pages. These files are both per-hugetlb page size and per node. Files are: demote_size - The size in Kb that pages are demoted to. (read-write) demote - The number of huge pages to demote. (write-only) By default, demote_size is the next smallest huge page size. Valid huge page sizes less than huge page size may be written to this file. When huge pages are demoted, they are demoted to this size. Writing a value to demote will result in an attempt to demote that number of hugetlb pages to an appropriate number of demote_size pages. NOTE: Demote interfaces are only provided for huge page sizes if there is a smaller target demote huge page size. For example, on x86 1GB huge pages will have demote interfaces. 2MB huge pages will not have demote interfaces. This patch does not provide full demote functionality. It only provides the sysfs interfaces. It also provides documentation for the new interfaces. [mike.kravetz@oracle.com: n_mask initialization does not need to be protected by the mutex] Link: https://lkml.kernel.org/r/0530e4ef-2492-5186-f919-5db68edea654@oracle.com Link: https://lkml.kernel.org/r/20211007181918.136982-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: David Rientjes <rientjes@google.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Nghia Le <nghialm78@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:20 +03:00
*/
if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
continue;
hugetlb: be sure to free demoted CMA pages to CMA When huge page demotion is fully implemented, gigantic pages can be demoted to a smaller huge page size. For example, on x86 a 1G page can be demoted to 512 2M pages. However, gigantic pages can potentially be allocated from CMA. If a gigantic page which was allocated from CMA is demoted, the corresponding demoted pages needs to be returned to CMA. Use the new interface cma_pages_valid() to determine if a non-gigantic hugetlb page should be freed to CMA. Also, clear mapping field of these pages as expected by cma_release. This also requires a change to CMA region creation for gigantic pages. CMA uses a per-region bit map to track allocations. When setting up the region, you specify how many pages each bit represents. Currently, only gigantic pages are allocated/freed from CMA so the region is set up such that one bit represents a gigantic page size allocation. With demote, a gigantic page (allocation) could be split into smaller size pages. And, these smaller size pages will be freed to CMA. So, since the per-region bit map needs to be set up to represent the smallest allocation/free size, it now needs to be set to the smallest huge page size which can be freed to CMA. Unfortunately, we set up the CMA region for huge pages before we set up huge pages sizes (hstates). So, technically we do not know the smallest huge page size as this can change via command line options and architecture specific code. Therefore, at region setup time we use HUGETLB_PAGE_ORDER as the smallest possible huge page size that can be given back to CMA. It is possible that this value is sub-optimal for some architectures/config options. If needed, this can be addressed in follow on work. Link: https://lkml.kernel.org/r/20211007181918.136982-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:27 +03:00
if (hugetlb_cma_size && h->order <= HUGETLB_PAGE_ORDER)
continue;
hugetlb: add demote hugetlb page sysfs interfaces Patch series "hugetlb: add demote/split page functionality", v4. The concurrent use of multiple hugetlb page sizes on a single system is becoming more common. One of the reasons is better TLB support for gigantic page sizes on x86 hardware. In addition, hugetlb pages are being used to back VMs in hosting environments. When using hugetlb pages to back VMs, it is often desirable to preallocate hugetlb pools. This avoids the delay and uncertainty of allocating hugetlb pages at VM startup. In addition, preallocating huge pages minimizes the issue of memory fragmentation that increases the longer the system is up and running. In such environments, a combination of larger and smaller hugetlb pages are preallocated in anticipation of backing VMs of various sizes. Over time, the preallocated pool of smaller hugetlb pages may become depleted while larger hugetlb pages still remain. In such situations, it is desirable to convert larger hugetlb pages to smaller hugetlb pages. Converting larger to smaller hugetlb pages can be accomplished today by first freeing the larger page to the buddy allocator and then allocating the smaller pages. For example, to convert 50 GB pages on x86: gb_pages=`cat .../hugepages-1048576kB/nr_hugepages` m2_pages=`cat .../hugepages-2048kB/nr_hugepages` echo $(($gb_pages - 50)) > .../hugepages-1048576kB/nr_hugepages echo $(($m2_pages + 25600)) > .../hugepages-2048kB/nr_hugepages On an idle system this operation is fairly reliable and results are as expected. The number of 2MB pages is increased as expected and the time of the operation is a second or two. However, when there is activity on the system the following issues arise: 1) This process can take quite some time, especially if allocation of the smaller pages is not immediate and requires migration/compaction. 2) There is no guarantee that the total size of smaller pages allocated will match the size of the larger page which was freed. This is because the area freed by the larger page could quickly be fragmented. In a test environment with a load that continually fills the page cache with clean pages, results such as the following can be observed: Unexpected number of 2MB pages allocated: Expected 25600, have 19944 real 0m42.092s user 0m0.008s sys 0m41.467s To address these issues, introduce the concept of hugetlb page demotion. Demotion provides a means of 'in place' splitting of a hugetlb page to pages of a smaller size. This avoids freeing pages to buddy and then trying to allocate from buddy. Page demotion is controlled via sysfs files that reside in the per-hugetlb page size and per node directories. - demote_size Target page size for demotion, a smaller huge page size. File can be written to chose a smaller huge page size if multiple are available. - demote Writable number of hugetlb pages to be demoted To demote 50 GB huge pages, one would: cat .../hugepages-1048576kB/free_hugepages /* optional, verify free pages */ cat .../hugepages-1048576kB/demote_size /* optional, verify target size */ echo 50 > .../hugepages-1048576kB/demote Only hugetlb pages which are free at the time of the request can be demoted. Demotion does not add to the complexity of surplus pages and honors reserved huge pages. Therefore, when a value is written to the sysfs demote file, that value is only the maximum number of pages which will be demoted. It is possible fewer will actually be demoted. The recently introduced per-hstate mutex is used to synchronize demote operations with other operations that modify hugetlb pools. Real world use cases -------------------- The above scenario describes a real world use case where hugetlb pages are used to back VMs on x86. Both issues of long allocation times and not necessarily getting the expected number of smaller huge pages after a free and allocate cycle have been experienced. The occurrence of these issues is dependent on other activity within the host and can not be predicted. This patch (of 5): Two new sysfs files are added to demote hugtlb pages. These files are both per-hugetlb page size and per node. Files are: demote_size - The size in Kb that pages are demoted to. (read-write) demote - The number of huge pages to demote. (write-only) By default, demote_size is the next smallest huge page size. Valid huge page sizes less than huge page size may be written to this file. When huge pages are demoted, they are demoted to this size. Writing a value to demote will result in an attempt to demote that number of hugetlb pages to an appropriate number of demote_size pages. NOTE: Demote interfaces are only provided for huge page sizes if there is a smaller target demote huge page size. For example, on x86 1GB huge pages will have demote interfaces. 2MB huge pages will not have demote interfaces. This patch does not provide full demote functionality. It only provides the sysfs interfaces. It also provides documentation for the new interfaces. [mike.kravetz@oracle.com: n_mask initialization does not need to be protected by the mutex] Link: https://lkml.kernel.org/r/0530e4ef-2492-5186-f919-5db68edea654@oracle.com Link: https://lkml.kernel.org/r/20211007181918.136982-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: David Rientjes <rientjes@google.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Nghia Le <nghialm78@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:20 +03:00
for_each_hstate(h2) {
if (h2 == h)
continue;
if (h2->order < h->order &&
h2->order > h->demote_order)
h->demote_order = h2->order;
}
}
VM_BUG_ON(minimum_order == UINT_MAX);
}
static void __init report_hugepages(void)
{
struct hstate *h;
for_each_hstate(h) {
char buf[32];
string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n",
buf, h->free_huge_pages);
}
}
#ifdef CONFIG_HIGHMEM
hugetlb: add nodemask arg to huge page alloc, free and surplus adjust functions In preparation for constraining huge page allocation and freeing by the controlling task's numa mempolicy, add a "nodes_allowed" nodemask pointer to the allocate, free and surplus adjustment functions. For now, pass NULL to indicate default behavior--i.e., use node_online_map. A subsqeuent patch will derive a non-default mask from the controlling task's numa mempolicy. Note that this method of updating the global hstate nr_hugepages under the constraint of a nodemask simplifies keeping the global state consistent--especially the number of persistent and surplus pages relative to reservations and overcommit limits. There are undoubtedly other ways to do this, but this works for both interfaces: mempolicy and per node attributes. [rientjes@google.com: fix HIGHMEM compile error] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Reviewed-by: Mel Gorman <mel@csn.ul.ie> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:16 +03:00
static void try_to_free_low(struct hstate *h, unsigned long count,
nodemask_t *nodes_allowed)
{
int i;
hugetlb: call update_and_free_page without hugetlb_lock With the introduction of remove_hugetlb_page(), there is no need for update_and_free_page to hold the hugetlb lock. Change all callers to drop the lock before calling. With additional code modifications, this will allow loops which decrease the huge page pool to drop the hugetlb_lock with each page to reduce long hold times. The ugly unlock/lock cycle in free_pool_huge_page will be removed in a subsequent patch which restructures free_pool_huge_page. Link: https://lkml.kernel.org/r/20210409205254.242291-6-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:59 +03:00
LIST_HEAD(page_list);
lockdep_assert_held(&hugetlb_lock);
if (hstate_is_gigantic(h))
return;
hugetlb: call update_and_free_page without hugetlb_lock With the introduction of remove_hugetlb_page(), there is no need for update_and_free_page to hold the hugetlb lock. Change all callers to drop the lock before calling. With additional code modifications, this will allow loops which decrease the huge page pool to drop the hugetlb_lock with each page to reduce long hold times. The ugly unlock/lock cycle in free_pool_huge_page will be removed in a subsequent patch which restructures free_pool_huge_page. Link: https://lkml.kernel.org/r/20210409205254.242291-6-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:59 +03:00
/*
* Collect pages to be freed on a list, and free after dropping lock
*/
hugetlb: add nodemask arg to huge page alloc, free and surplus adjust functions In preparation for constraining huge page allocation and freeing by the controlling task's numa mempolicy, add a "nodes_allowed" nodemask pointer to the allocate, free and surplus adjustment functions. For now, pass NULL to indicate default behavior--i.e., use node_online_map. A subsqeuent patch will derive a non-default mask from the controlling task's numa mempolicy. Note that this method of updating the global hstate nr_hugepages under the constraint of a nodemask simplifies keeping the global state consistent--especially the number of persistent and surplus pages relative to reservations and overcommit limits. There are undoubtedly other ways to do this, but this works for both interfaces: mempolicy and per node attributes. [rientjes@google.com: fix HIGHMEM compile error] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Reviewed-by: Mel Gorman <mel@csn.ul.ie> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:16 +03:00
for_each_node_mask(i, *nodes_allowed) {
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
struct page *page, *next;
struct list_head *freel = &h->hugepage_freelists[i];
list_for_each_entry_safe(page, next, freel, lru) {
if (count >= h->nr_huge_pages)
hugetlb: call update_and_free_page without hugetlb_lock With the introduction of remove_hugetlb_page(), there is no need for update_and_free_page to hold the hugetlb lock. Change all callers to drop the lock before calling. With additional code modifications, this will allow loops which decrease the huge page pool to drop the hugetlb_lock with each page to reduce long hold times. The ugly unlock/lock cycle in free_pool_huge_page will be removed in a subsequent patch which restructures free_pool_huge_page. Link: https://lkml.kernel.org/r/20210409205254.242291-6-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:59 +03:00
goto out;
if (PageHighMem(page))
continue;
hugetlb: create remove_hugetlb_page() to separate functionality The new remove_hugetlb_page() routine is designed to remove a hugetlb page from hugetlbfs processing. It will remove the page from the active or free list, update global counters and set the compound page destructor to NULL so that PageHuge() will return false for the 'page'. After this call, the 'page' can be treated as a normal compound page or a collection of base size pages. update_and_free_page no longer decrements h->nr_huge_pages{_node} as this is performed in remove_hugetlb_page. The only functionality performed by update_and_free_page is to free the base pages to the lower level allocators. update_and_free_page is typically called after remove_hugetlb_page. remove_hugetlb_page is to be called with the hugetlb_lock held. Creating this routine and separating functionality is in preparation for restructuring code to reduce lock hold times. This commit should not introduce any changes to functionality. Link: https://lkml.kernel.org/r/20210409205254.242291-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:55 +03:00
remove_hugetlb_page(h, page, false);
hugetlb: call update_and_free_page without hugetlb_lock With the introduction of remove_hugetlb_page(), there is no need for update_and_free_page to hold the hugetlb lock. Change all callers to drop the lock before calling. With additional code modifications, this will allow loops which decrease the huge page pool to drop the hugetlb_lock with each page to reduce long hold times. The ugly unlock/lock cycle in free_pool_huge_page will be removed in a subsequent patch which restructures free_pool_huge_page. Link: https://lkml.kernel.org/r/20210409205254.242291-6-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:59 +03:00
list_add(&page->lru, &page_list);
}
}
hugetlb: call update_and_free_page without hugetlb_lock With the introduction of remove_hugetlb_page(), there is no need for update_and_free_page to hold the hugetlb lock. Change all callers to drop the lock before calling. With additional code modifications, this will allow loops which decrease the huge page pool to drop the hugetlb_lock with each page to reduce long hold times. The ugly unlock/lock cycle in free_pool_huge_page will be removed in a subsequent patch which restructures free_pool_huge_page. Link: https://lkml.kernel.org/r/20210409205254.242291-6-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:59 +03:00
out:
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
update_and_free_pages_bulk(h, &page_list);
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
}
#else
hugetlb: add nodemask arg to huge page alloc, free and surplus adjust functions In preparation for constraining huge page allocation and freeing by the controlling task's numa mempolicy, add a "nodes_allowed" nodemask pointer to the allocate, free and surplus adjustment functions. For now, pass NULL to indicate default behavior--i.e., use node_online_map. A subsqeuent patch will derive a non-default mask from the controlling task's numa mempolicy. Note that this method of updating the global hstate nr_hugepages under the constraint of a nodemask simplifies keeping the global state consistent--especially the number of persistent and surplus pages relative to reservations and overcommit limits. There are undoubtedly other ways to do this, but this works for both interfaces: mempolicy and per node attributes. [rientjes@google.com: fix HIGHMEM compile error] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Reviewed-by: Mel Gorman <mel@csn.ul.ie> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:16 +03:00
static inline void try_to_free_low(struct hstate *h, unsigned long count,
nodemask_t *nodes_allowed)
{
}
#endif
mm: introduce PageHuge() for testing huge/gigantic pages A series of patches to enhance the /proc/pagemap interface and to add a userspace executable which can be used to present the pagemap data. Export 10 more flags to end users (and more for kernel developers): 11. KPF_MMAP (pseudo flag) memory mapped page 12. KPF_ANON (pseudo flag) memory mapped page (anonymous) 13. KPF_SWAPCACHE page is in swap cache 14. KPF_SWAPBACKED page is swap/RAM backed 15. KPF_COMPOUND_HEAD (*) 16. KPF_COMPOUND_TAIL (*) 17. KPF_HUGE hugeTLB pages 18. KPF_UNEVICTABLE page is in the unevictable LRU list 19. KPF_HWPOISON hardware detected corruption 20. KPF_NOPAGE (pseudo flag) no page frame at the address (*) For compound pages, exporting _both_ head/tail info enables users to tell where a compound page starts/ends, and its order. a simple demo of the page-types tool # ./page-types -h page-types [options] -r|--raw Raw mode, for kernel developers -a|--addr addr-spec Walk a range of pages -b|--bits bits-spec Walk pages with specified bits -l|--list Show page details in ranges -L|--list-each Show page details one by one -N|--no-summary Don't show summay info -h|--help Show this usage message addr-spec: N one page at offset N (unit: pages) N+M pages range from N to N+M-1 N,M pages range from N to M-1 N, pages range from N to end ,M pages range from 0 to M bits-spec: bit1,bit2 (flags & (bit1|bit2)) != 0 bit1,bit2=bit1 (flags & (bit1|bit2)) == bit1 bit1,~bit2 (flags & (bit1|bit2)) == bit1 =bit1,bit2 flags == (bit1|bit2) bit-names: locked error referenced uptodate dirty lru active slab writeback reclaim buddy mmap anonymous swapcache swapbacked compound_head compound_tail huge unevictable hwpoison nopage reserved(r) mlocked(r) mappedtodisk(r) private(r) private_2(r) owner_private(r) arch(r) uncached(r) readahead(o) slob_free(o) slub_frozen(o) slub_debug(o) (r) raw mode bits (o) overloaded bits # ./page-types flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 487369 1903 _________________________________ 0x0000000000000014 5 0 __R_D____________________________ referenced,dirty 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000000000024 34 0 __R__l___________________________ referenced,lru 0x0000000000000028 3838 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 48 0 ___U_l_______________________I___ uptodate,lru,readahead 0x000000000000002c 6478 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x0000000000000040 8344 32 ______A__________________________ active 0x0000000000000060 1 0 _____lA__________________________ lru,active 0x0000000000000068 348 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x000000000000006c 988 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 503 1 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 30 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types -r flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 468002 1828 _________________________________ 0x0000000100000000 19102 74 _____________________r___________ reserved 0x0000000000008000 41 0 _______________H_________________ compound_head 0x0000000000010000 188 0 ________________T________________ compound_tail 0x0000000000008014 1 0 __R_D__________H_________________ referenced,dirty,compound_head 0x0000000000010014 4 0 __R_D___________T________________ referenced,dirty,compound_tail 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000800000024 34 0 __R__l__________________P________ referenced,lru,private 0x0000000000000028 3794 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 46 0 ___U_l_______________________I___ uptodate,lru,readahead 0x0000000400000028 44 0 ___U_l_________________d_________ uptodate,lru,mappedtodisk 0x0001000400000028 2 0 ___U_l_________________d_____I___ uptodate,lru,mappedtodisk,readahead 0x000000000000002c 6434 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x000000040000002c 14 0 __RU_l_________________d_________ referenced,uptodate,lru,mappedtodisk 0x000000080000002c 30 0 __RU_l__________________P________ referenced,uptodate,lru,private 0x0000000800000040 8124 31 ______A_________________P________ active,private 0x0000000000000040 219 0 ______A__________________________ active 0x0000000800000060 1 0 _____lA_________________P________ lru,active,private 0x0000000000000068 322 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x0000000400000068 13 0 ___U_lA________________d_________ uptodate,lru,active,mappedtodisk 0x0000000800000068 12 0 ___U_lA_________________P________ uptodate,lru,active,private 0x000000000000006c 977 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x000000040000006c 5 0 __RU_lA________________d_________ referenced,uptodate,lru,active,mappedtodisk 0x000000080000006c 3 0 __RU_lA_________________P________ referenced,uptodate,lru,active,private 0x0000000c0000006c 3 0 __RU_lA________________dP________ referenced,uptodate,lru,active,mappedtodisk,private 0x0000000c00000068 1 0 ___U_lA________________dP________ uptodate,lru,active,mappedtodisk,private 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 538 2 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005008 2 0 ___U________a_b__________________ uptodate,anonymous,swapbacked 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x000000000000580c 1 0 __RU_______Ma_b__________________ referenced,uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 29 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types --raw --list --no-summary --bits reserved offset count flags 0 15 _____________________r___________ 31 4 _____________________r___________ 159 97 _____________________r___________ 4096 2067 _____________________r___________ 6752 2390 _____________________r___________ 9355 3 _____________________r___________ 9728 14526 _____________________r___________ This patch: Introduce PageHuge(), which identifies huge/gigantic pages by their dedicated compound destructor functions. Also move prep_compound_gigantic_page() to hugetlb.c and make __free_pages_ok() non-static. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-17 02:32:22 +04:00
/*
* Increment or decrement surplus_huge_pages. Keep node-specific counters
* balanced by operating on them in a round-robin fashion.
* Returns 1 if an adjustment was made.
*/
hugetlb: add nodemask arg to huge page alloc, free and surplus adjust functions In preparation for constraining huge page allocation and freeing by the controlling task's numa mempolicy, add a "nodes_allowed" nodemask pointer to the allocate, free and surplus adjustment functions. For now, pass NULL to indicate default behavior--i.e., use node_online_map. A subsqeuent patch will derive a non-default mask from the controlling task's numa mempolicy. Note that this method of updating the global hstate nr_hugepages under the constraint of a nodemask simplifies keeping the global state consistent--especially the number of persistent and surplus pages relative to reservations and overcommit limits. There are undoubtedly other ways to do this, but this works for both interfaces: mempolicy and per node attributes. [rientjes@google.com: fix HIGHMEM compile error] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Reviewed-by: Mel Gorman <mel@csn.ul.ie> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:16 +03:00
static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
int delta)
mm: introduce PageHuge() for testing huge/gigantic pages A series of patches to enhance the /proc/pagemap interface and to add a userspace executable which can be used to present the pagemap data. Export 10 more flags to end users (and more for kernel developers): 11. KPF_MMAP (pseudo flag) memory mapped page 12. KPF_ANON (pseudo flag) memory mapped page (anonymous) 13. KPF_SWAPCACHE page is in swap cache 14. KPF_SWAPBACKED page is swap/RAM backed 15. KPF_COMPOUND_HEAD (*) 16. KPF_COMPOUND_TAIL (*) 17. KPF_HUGE hugeTLB pages 18. KPF_UNEVICTABLE page is in the unevictable LRU list 19. KPF_HWPOISON hardware detected corruption 20. KPF_NOPAGE (pseudo flag) no page frame at the address (*) For compound pages, exporting _both_ head/tail info enables users to tell where a compound page starts/ends, and its order. a simple demo of the page-types tool # ./page-types -h page-types [options] -r|--raw Raw mode, for kernel developers -a|--addr addr-spec Walk a range of pages -b|--bits bits-spec Walk pages with specified bits -l|--list Show page details in ranges -L|--list-each Show page details one by one -N|--no-summary Don't show summay info -h|--help Show this usage message addr-spec: N one page at offset N (unit: pages) N+M pages range from N to N+M-1 N,M pages range from N to M-1 N, pages range from N to end ,M pages range from 0 to M bits-spec: bit1,bit2 (flags & (bit1|bit2)) != 0 bit1,bit2=bit1 (flags & (bit1|bit2)) == bit1 bit1,~bit2 (flags & (bit1|bit2)) == bit1 =bit1,bit2 flags == (bit1|bit2) bit-names: locked error referenced uptodate dirty lru active slab writeback reclaim buddy mmap anonymous swapcache swapbacked compound_head compound_tail huge unevictable hwpoison nopage reserved(r) mlocked(r) mappedtodisk(r) private(r) private_2(r) owner_private(r) arch(r) uncached(r) readahead(o) slob_free(o) slub_frozen(o) slub_debug(o) (r) raw mode bits (o) overloaded bits # ./page-types flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 487369 1903 _________________________________ 0x0000000000000014 5 0 __R_D____________________________ referenced,dirty 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000000000024 34 0 __R__l___________________________ referenced,lru 0x0000000000000028 3838 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 48 0 ___U_l_______________________I___ uptodate,lru,readahead 0x000000000000002c 6478 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x0000000000000040 8344 32 ______A__________________________ active 0x0000000000000060 1 0 _____lA__________________________ lru,active 0x0000000000000068 348 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x000000000000006c 988 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 503 1 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 30 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types -r flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 468002 1828 _________________________________ 0x0000000100000000 19102 74 _____________________r___________ reserved 0x0000000000008000 41 0 _______________H_________________ compound_head 0x0000000000010000 188 0 ________________T________________ compound_tail 0x0000000000008014 1 0 __R_D__________H_________________ referenced,dirty,compound_head 0x0000000000010014 4 0 __R_D___________T________________ referenced,dirty,compound_tail 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000800000024 34 0 __R__l__________________P________ referenced,lru,private 0x0000000000000028 3794 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 46 0 ___U_l_______________________I___ uptodate,lru,readahead 0x0000000400000028 44 0 ___U_l_________________d_________ uptodate,lru,mappedtodisk 0x0001000400000028 2 0 ___U_l_________________d_____I___ uptodate,lru,mappedtodisk,readahead 0x000000000000002c 6434 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x000000040000002c 14 0 __RU_l_________________d_________ referenced,uptodate,lru,mappedtodisk 0x000000080000002c 30 0 __RU_l__________________P________ referenced,uptodate,lru,private 0x0000000800000040 8124 31 ______A_________________P________ active,private 0x0000000000000040 219 0 ______A__________________________ active 0x0000000800000060 1 0 _____lA_________________P________ lru,active,private 0x0000000000000068 322 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x0000000400000068 13 0 ___U_lA________________d_________ uptodate,lru,active,mappedtodisk 0x0000000800000068 12 0 ___U_lA_________________P________ uptodate,lru,active,private 0x000000000000006c 977 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x000000040000006c 5 0 __RU_lA________________d_________ referenced,uptodate,lru,active,mappedtodisk 0x000000080000006c 3 0 __RU_lA_________________P________ referenced,uptodate,lru,active,private 0x0000000c0000006c 3 0 __RU_lA________________dP________ referenced,uptodate,lru,active,mappedtodisk,private 0x0000000c00000068 1 0 ___U_lA________________dP________ uptodate,lru,active,mappedtodisk,private 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 538 2 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005008 2 0 ___U________a_b__________________ uptodate,anonymous,swapbacked 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x000000000000580c 1 0 __RU_______Ma_b__________________ referenced,uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 29 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types --raw --list --no-summary --bits reserved offset count flags 0 15 _____________________r___________ 31 4 _____________________r___________ 159 97 _____________________r___________ 4096 2067 _____________________r___________ 6752 2390 _____________________r___________ 9355 3 _____________________r___________ 9728 14526 _____________________r___________ This patch: Introduce PageHuge(), which identifies huge/gigantic pages by their dedicated compound destructor functions. Also move prep_compound_gigantic_page() to hugetlb.c and make __free_pages_ok() non-static. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-17 02:32:22 +04:00
{
int nr_nodes, node;
mm: introduce PageHuge() for testing huge/gigantic pages A series of patches to enhance the /proc/pagemap interface and to add a userspace executable which can be used to present the pagemap data. Export 10 more flags to end users (and more for kernel developers): 11. KPF_MMAP (pseudo flag) memory mapped page 12. KPF_ANON (pseudo flag) memory mapped page (anonymous) 13. KPF_SWAPCACHE page is in swap cache 14. KPF_SWAPBACKED page is swap/RAM backed 15. KPF_COMPOUND_HEAD (*) 16. KPF_COMPOUND_TAIL (*) 17. KPF_HUGE hugeTLB pages 18. KPF_UNEVICTABLE page is in the unevictable LRU list 19. KPF_HWPOISON hardware detected corruption 20. KPF_NOPAGE (pseudo flag) no page frame at the address (*) For compound pages, exporting _both_ head/tail info enables users to tell where a compound page starts/ends, and its order. a simple demo of the page-types tool # ./page-types -h page-types [options] -r|--raw Raw mode, for kernel developers -a|--addr addr-spec Walk a range of pages -b|--bits bits-spec Walk pages with specified bits -l|--list Show page details in ranges -L|--list-each Show page details one by one -N|--no-summary Don't show summay info -h|--help Show this usage message addr-spec: N one page at offset N (unit: pages) N+M pages range from N to N+M-1 N,M pages range from N to M-1 N, pages range from N to end ,M pages range from 0 to M bits-spec: bit1,bit2 (flags & (bit1|bit2)) != 0 bit1,bit2=bit1 (flags & (bit1|bit2)) == bit1 bit1,~bit2 (flags & (bit1|bit2)) == bit1 =bit1,bit2 flags == (bit1|bit2) bit-names: locked error referenced uptodate dirty lru active slab writeback reclaim buddy mmap anonymous swapcache swapbacked compound_head compound_tail huge unevictable hwpoison nopage reserved(r) mlocked(r) mappedtodisk(r) private(r) private_2(r) owner_private(r) arch(r) uncached(r) readahead(o) slob_free(o) slub_frozen(o) slub_debug(o) (r) raw mode bits (o) overloaded bits # ./page-types flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 487369 1903 _________________________________ 0x0000000000000014 5 0 __R_D____________________________ referenced,dirty 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000000000024 34 0 __R__l___________________________ referenced,lru 0x0000000000000028 3838 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 48 0 ___U_l_______________________I___ uptodate,lru,readahead 0x000000000000002c 6478 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x0000000000000040 8344 32 ______A__________________________ active 0x0000000000000060 1 0 _____lA__________________________ lru,active 0x0000000000000068 348 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x000000000000006c 988 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 503 1 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 30 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types -r flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 468002 1828 _________________________________ 0x0000000100000000 19102 74 _____________________r___________ reserved 0x0000000000008000 41 0 _______________H_________________ compound_head 0x0000000000010000 188 0 ________________T________________ compound_tail 0x0000000000008014 1 0 __R_D__________H_________________ referenced,dirty,compound_head 0x0000000000010014 4 0 __R_D___________T________________ referenced,dirty,compound_tail 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000800000024 34 0 __R__l__________________P________ referenced,lru,private 0x0000000000000028 3794 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 46 0 ___U_l_______________________I___ uptodate,lru,readahead 0x0000000400000028 44 0 ___U_l_________________d_________ uptodate,lru,mappedtodisk 0x0001000400000028 2 0 ___U_l_________________d_____I___ uptodate,lru,mappedtodisk,readahead 0x000000000000002c 6434 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x000000040000002c 14 0 __RU_l_________________d_________ referenced,uptodate,lru,mappedtodisk 0x000000080000002c 30 0 __RU_l__________________P________ referenced,uptodate,lru,private 0x0000000800000040 8124 31 ______A_________________P________ active,private 0x0000000000000040 219 0 ______A__________________________ active 0x0000000800000060 1 0 _____lA_________________P________ lru,active,private 0x0000000000000068 322 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x0000000400000068 13 0 ___U_lA________________d_________ uptodate,lru,active,mappedtodisk 0x0000000800000068 12 0 ___U_lA_________________P________ uptodate,lru,active,private 0x000000000000006c 977 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x000000040000006c 5 0 __RU_lA________________d_________ referenced,uptodate,lru,active,mappedtodisk 0x000000080000006c 3 0 __RU_lA_________________P________ referenced,uptodate,lru,active,private 0x0000000c0000006c 3 0 __RU_lA________________dP________ referenced,uptodate,lru,active,mappedtodisk,private 0x0000000c00000068 1 0 ___U_lA________________dP________ uptodate,lru,active,mappedtodisk,private 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 538 2 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005008 2 0 ___U________a_b__________________ uptodate,anonymous,swapbacked 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x000000000000580c 1 0 __RU_______Ma_b__________________ referenced,uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 29 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types --raw --list --no-summary --bits reserved offset count flags 0 15 _____________________r___________ 31 4 _____________________r___________ 159 97 _____________________r___________ 4096 2067 _____________________r___________ 6752 2390 _____________________r___________ 9355 3 _____________________r___________ 9728 14526 _____________________r___________ This patch: Introduce PageHuge(), which identifies huge/gigantic pages by their dedicated compound destructor functions. Also move prep_compound_gigantic_page() to hugetlb.c and make __free_pages_ok() non-static. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-17 02:32:22 +04:00
lockdep_assert_held(&hugetlb_lock);
mm: introduce PageHuge() for testing huge/gigantic pages A series of patches to enhance the /proc/pagemap interface and to add a userspace executable which can be used to present the pagemap data. Export 10 more flags to end users (and more for kernel developers): 11. KPF_MMAP (pseudo flag) memory mapped page 12. KPF_ANON (pseudo flag) memory mapped page (anonymous) 13. KPF_SWAPCACHE page is in swap cache 14. KPF_SWAPBACKED page is swap/RAM backed 15. KPF_COMPOUND_HEAD (*) 16. KPF_COMPOUND_TAIL (*) 17. KPF_HUGE hugeTLB pages 18. KPF_UNEVICTABLE page is in the unevictable LRU list 19. KPF_HWPOISON hardware detected corruption 20. KPF_NOPAGE (pseudo flag) no page frame at the address (*) For compound pages, exporting _both_ head/tail info enables users to tell where a compound page starts/ends, and its order. a simple demo of the page-types tool # ./page-types -h page-types [options] -r|--raw Raw mode, for kernel developers -a|--addr addr-spec Walk a range of pages -b|--bits bits-spec Walk pages with specified bits -l|--list Show page details in ranges -L|--list-each Show page details one by one -N|--no-summary Don't show summay info -h|--help Show this usage message addr-spec: N one page at offset N (unit: pages) N+M pages range from N to N+M-1 N,M pages range from N to M-1 N, pages range from N to end ,M pages range from 0 to M bits-spec: bit1,bit2 (flags & (bit1|bit2)) != 0 bit1,bit2=bit1 (flags & (bit1|bit2)) == bit1 bit1,~bit2 (flags & (bit1|bit2)) == bit1 =bit1,bit2 flags == (bit1|bit2) bit-names: locked error referenced uptodate dirty lru active slab writeback reclaim buddy mmap anonymous swapcache swapbacked compound_head compound_tail huge unevictable hwpoison nopage reserved(r) mlocked(r) mappedtodisk(r) private(r) private_2(r) owner_private(r) arch(r) uncached(r) readahead(o) slob_free(o) slub_frozen(o) slub_debug(o) (r) raw mode bits (o) overloaded bits # ./page-types flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 487369 1903 _________________________________ 0x0000000000000014 5 0 __R_D____________________________ referenced,dirty 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000000000024 34 0 __R__l___________________________ referenced,lru 0x0000000000000028 3838 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 48 0 ___U_l_______________________I___ uptodate,lru,readahead 0x000000000000002c 6478 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x0000000000000040 8344 32 ______A__________________________ active 0x0000000000000060 1 0 _____lA__________________________ lru,active 0x0000000000000068 348 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x000000000000006c 988 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 503 1 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 30 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types -r flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 468002 1828 _________________________________ 0x0000000100000000 19102 74 _____________________r___________ reserved 0x0000000000008000 41 0 _______________H_________________ compound_head 0x0000000000010000 188 0 ________________T________________ compound_tail 0x0000000000008014 1 0 __R_D__________H_________________ referenced,dirty,compound_head 0x0000000000010014 4 0 __R_D___________T________________ referenced,dirty,compound_tail 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000800000024 34 0 __R__l__________________P________ referenced,lru,private 0x0000000000000028 3794 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 46 0 ___U_l_______________________I___ uptodate,lru,readahead 0x0000000400000028 44 0 ___U_l_________________d_________ uptodate,lru,mappedtodisk 0x0001000400000028 2 0 ___U_l_________________d_____I___ uptodate,lru,mappedtodisk,readahead 0x000000000000002c 6434 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x000000040000002c 14 0 __RU_l_________________d_________ referenced,uptodate,lru,mappedtodisk 0x000000080000002c 30 0 __RU_l__________________P________ referenced,uptodate,lru,private 0x0000000800000040 8124 31 ______A_________________P________ active,private 0x0000000000000040 219 0 ______A__________________________ active 0x0000000800000060 1 0 _____lA_________________P________ lru,active,private 0x0000000000000068 322 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x0000000400000068 13 0 ___U_lA________________d_________ uptodate,lru,active,mappedtodisk 0x0000000800000068 12 0 ___U_lA_________________P________ uptodate,lru,active,private 0x000000000000006c 977 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x000000040000006c 5 0 __RU_lA________________d_________ referenced,uptodate,lru,active,mappedtodisk 0x000000080000006c 3 0 __RU_lA_________________P________ referenced,uptodate,lru,active,private 0x0000000c0000006c 3 0 __RU_lA________________dP________ referenced,uptodate,lru,active,mappedtodisk,private 0x0000000c00000068 1 0 ___U_lA________________dP________ uptodate,lru,active,mappedtodisk,private 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 538 2 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005008 2 0 ___U________a_b__________________ uptodate,anonymous,swapbacked 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x000000000000580c 1 0 __RU_______Ma_b__________________ referenced,uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 29 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types --raw --list --no-summary --bits reserved offset count flags 0 15 _____________________r___________ 31 4 _____________________r___________ 159 97 _____________________r___________ 4096 2067 _____________________r___________ 6752 2390 _____________________r___________ 9355 3 _____________________r___________ 9728 14526 _____________________r___________ This patch: Introduce PageHuge(), which identifies huge/gigantic pages by their dedicated compound destructor functions. Also move prep_compound_gigantic_page() to hugetlb.c and make __free_pages_ok() non-static. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-17 02:32:22 +04:00
VM_BUG_ON(delta != -1 && delta != 1);
if (delta < 0) {
for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
if (h->surplus_huge_pages_node[node])
goto found;
}
} else {
for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
if (h->surplus_huge_pages_node[node] <
h->nr_huge_pages_node[node])
goto found;
}
}
return 0;
mm: introduce PageHuge() for testing huge/gigantic pages A series of patches to enhance the /proc/pagemap interface and to add a userspace executable which can be used to present the pagemap data. Export 10 more flags to end users (and more for kernel developers): 11. KPF_MMAP (pseudo flag) memory mapped page 12. KPF_ANON (pseudo flag) memory mapped page (anonymous) 13. KPF_SWAPCACHE page is in swap cache 14. KPF_SWAPBACKED page is swap/RAM backed 15. KPF_COMPOUND_HEAD (*) 16. KPF_COMPOUND_TAIL (*) 17. KPF_HUGE hugeTLB pages 18. KPF_UNEVICTABLE page is in the unevictable LRU list 19. KPF_HWPOISON hardware detected corruption 20. KPF_NOPAGE (pseudo flag) no page frame at the address (*) For compound pages, exporting _both_ head/tail info enables users to tell where a compound page starts/ends, and its order. a simple demo of the page-types tool # ./page-types -h page-types [options] -r|--raw Raw mode, for kernel developers -a|--addr addr-spec Walk a range of pages -b|--bits bits-spec Walk pages with specified bits -l|--list Show page details in ranges -L|--list-each Show page details one by one -N|--no-summary Don't show summay info -h|--help Show this usage message addr-spec: N one page at offset N (unit: pages) N+M pages range from N to N+M-1 N,M pages range from N to M-1 N, pages range from N to end ,M pages range from 0 to M bits-spec: bit1,bit2 (flags & (bit1|bit2)) != 0 bit1,bit2=bit1 (flags & (bit1|bit2)) == bit1 bit1,~bit2 (flags & (bit1|bit2)) == bit1 =bit1,bit2 flags == (bit1|bit2) bit-names: locked error referenced uptodate dirty lru active slab writeback reclaim buddy mmap anonymous swapcache swapbacked compound_head compound_tail huge unevictable hwpoison nopage reserved(r) mlocked(r) mappedtodisk(r) private(r) private_2(r) owner_private(r) arch(r) uncached(r) readahead(o) slob_free(o) slub_frozen(o) slub_debug(o) (r) raw mode bits (o) overloaded bits # ./page-types flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 487369 1903 _________________________________ 0x0000000000000014 5 0 __R_D____________________________ referenced,dirty 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000000000024 34 0 __R__l___________________________ referenced,lru 0x0000000000000028 3838 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 48 0 ___U_l_______________________I___ uptodate,lru,readahead 0x000000000000002c 6478 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x0000000000000040 8344 32 ______A__________________________ active 0x0000000000000060 1 0 _____lA__________________________ lru,active 0x0000000000000068 348 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x000000000000006c 988 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 503 1 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 30 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types -r flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 468002 1828 _________________________________ 0x0000000100000000 19102 74 _____________________r___________ reserved 0x0000000000008000 41 0 _______________H_________________ compound_head 0x0000000000010000 188 0 ________________T________________ compound_tail 0x0000000000008014 1 0 __R_D__________H_________________ referenced,dirty,compound_head 0x0000000000010014 4 0 __R_D___________T________________ referenced,dirty,compound_tail 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000800000024 34 0 __R__l__________________P________ referenced,lru,private 0x0000000000000028 3794 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 46 0 ___U_l_______________________I___ uptodate,lru,readahead 0x0000000400000028 44 0 ___U_l_________________d_________ uptodate,lru,mappedtodisk 0x0001000400000028 2 0 ___U_l_________________d_____I___ uptodate,lru,mappedtodisk,readahead 0x000000000000002c 6434 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x000000040000002c 14 0 __RU_l_________________d_________ referenced,uptodate,lru,mappedtodisk 0x000000080000002c 30 0 __RU_l__________________P________ referenced,uptodate,lru,private 0x0000000800000040 8124 31 ______A_________________P________ active,private 0x0000000000000040 219 0 ______A__________________________ active 0x0000000800000060 1 0 _____lA_________________P________ lru,active,private 0x0000000000000068 322 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x0000000400000068 13 0 ___U_lA________________d_________ uptodate,lru,active,mappedtodisk 0x0000000800000068 12 0 ___U_lA_________________P________ uptodate,lru,active,private 0x000000000000006c 977 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x000000040000006c 5 0 __RU_lA________________d_________ referenced,uptodate,lru,active,mappedtodisk 0x000000080000006c 3 0 __RU_lA_________________P________ referenced,uptodate,lru,active,private 0x0000000c0000006c 3 0 __RU_lA________________dP________ referenced,uptodate,lru,active,mappedtodisk,private 0x0000000c00000068 1 0 ___U_lA________________dP________ uptodate,lru,active,mappedtodisk,private 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 538 2 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005008 2 0 ___U________a_b__________________ uptodate,anonymous,swapbacked 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x000000000000580c 1 0 __RU_______Ma_b__________________ referenced,uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 29 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types --raw --list --no-summary --bits reserved offset count flags 0 15 _____________________r___________ 31 4 _____________________r___________ 159 97 _____________________r___________ 4096 2067 _____________________r___________ 6752 2390 _____________________r___________ 9355 3 _____________________r___________ 9728 14526 _____________________r___________ This patch: Introduce PageHuge(), which identifies huge/gigantic pages by their dedicated compound destructor functions. Also move prep_compound_gigantic_page() to hugetlb.c and make __free_pages_ok() non-static. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-17 02:32:22 +04:00
found:
h->surplus_huge_pages += delta;
h->surplus_huge_pages_node[node] += delta;
return 1;
mm: introduce PageHuge() for testing huge/gigantic pages A series of patches to enhance the /proc/pagemap interface and to add a userspace executable which can be used to present the pagemap data. Export 10 more flags to end users (and more for kernel developers): 11. KPF_MMAP (pseudo flag) memory mapped page 12. KPF_ANON (pseudo flag) memory mapped page (anonymous) 13. KPF_SWAPCACHE page is in swap cache 14. KPF_SWAPBACKED page is swap/RAM backed 15. KPF_COMPOUND_HEAD (*) 16. KPF_COMPOUND_TAIL (*) 17. KPF_HUGE hugeTLB pages 18. KPF_UNEVICTABLE page is in the unevictable LRU list 19. KPF_HWPOISON hardware detected corruption 20. KPF_NOPAGE (pseudo flag) no page frame at the address (*) For compound pages, exporting _both_ head/tail info enables users to tell where a compound page starts/ends, and its order. a simple demo of the page-types tool # ./page-types -h page-types [options] -r|--raw Raw mode, for kernel developers -a|--addr addr-spec Walk a range of pages -b|--bits bits-spec Walk pages with specified bits -l|--list Show page details in ranges -L|--list-each Show page details one by one -N|--no-summary Don't show summay info -h|--help Show this usage message addr-spec: N one page at offset N (unit: pages) N+M pages range from N to N+M-1 N,M pages range from N to M-1 N, pages range from N to end ,M pages range from 0 to M bits-spec: bit1,bit2 (flags & (bit1|bit2)) != 0 bit1,bit2=bit1 (flags & (bit1|bit2)) == bit1 bit1,~bit2 (flags & (bit1|bit2)) == bit1 =bit1,bit2 flags == (bit1|bit2) bit-names: locked error referenced uptodate dirty lru active slab writeback reclaim buddy mmap anonymous swapcache swapbacked compound_head compound_tail huge unevictable hwpoison nopage reserved(r) mlocked(r) mappedtodisk(r) private(r) private_2(r) owner_private(r) arch(r) uncached(r) readahead(o) slob_free(o) slub_frozen(o) slub_debug(o) (r) raw mode bits (o) overloaded bits # ./page-types flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 487369 1903 _________________________________ 0x0000000000000014 5 0 __R_D____________________________ referenced,dirty 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000000000024 34 0 __R__l___________________________ referenced,lru 0x0000000000000028 3838 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 48 0 ___U_l_______________________I___ uptodate,lru,readahead 0x000000000000002c 6478 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x0000000000000040 8344 32 ______A__________________________ active 0x0000000000000060 1 0 _____lA__________________________ lru,active 0x0000000000000068 348 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x000000000000006c 988 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 503 1 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 30 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types -r flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000000 468002 1828 _________________________________ 0x0000000100000000 19102 74 _____________________r___________ reserved 0x0000000000008000 41 0 _______________H_________________ compound_head 0x0000000000010000 188 0 ________________T________________ compound_tail 0x0000000000008014 1 0 __R_D__________H_________________ referenced,dirty,compound_head 0x0000000000010014 4 0 __R_D___________T________________ referenced,dirty,compound_tail 0x0000000000000020 1 0 _____l___________________________ lru 0x0000000800000024 34 0 __R__l__________________P________ referenced,lru,private 0x0000000000000028 3794 14 ___U_l___________________________ uptodate,lru 0x0001000000000028 46 0 ___U_l_______________________I___ uptodate,lru,readahead 0x0000000400000028 44 0 ___U_l_________________d_________ uptodate,lru,mappedtodisk 0x0001000400000028 2 0 ___U_l_________________d_____I___ uptodate,lru,mappedtodisk,readahead 0x000000000000002c 6434 25 __RU_l___________________________ referenced,uptodate,lru 0x000100000000002c 47 0 __RU_l_______________________I___ referenced,uptodate,lru,readahead 0x000000040000002c 14 0 __RU_l_________________d_________ referenced,uptodate,lru,mappedtodisk 0x000000080000002c 30 0 __RU_l__________________P________ referenced,uptodate,lru,private 0x0000000800000040 8124 31 ______A_________________P________ active,private 0x0000000000000040 219 0 ______A__________________________ active 0x0000000800000060 1 0 _____lA_________________P________ lru,active,private 0x0000000000000068 322 1 ___U_lA__________________________ uptodate,lru,active 0x0001000000000068 12 0 ___U_lA______________________I___ uptodate,lru,active,readahead 0x0000000400000068 13 0 ___U_lA________________d_________ uptodate,lru,active,mappedtodisk 0x0000000800000068 12 0 ___U_lA_________________P________ uptodate,lru,active,private 0x000000000000006c 977 3 __RU_lA__________________________ referenced,uptodate,lru,active 0x000100000000006c 48 0 __RU_lA______________________I___ referenced,uptodate,lru,active,readahead 0x000000040000006c 5 0 __RU_lA________________d_________ referenced,uptodate,lru,active,mappedtodisk 0x000000080000006c 3 0 __RU_lA_________________P________ referenced,uptodate,lru,active,private 0x0000000c0000006c 3 0 __RU_lA________________dP________ referenced,uptodate,lru,active,mappedtodisk,private 0x0000000c00000068 1 0 ___U_lA________________dP________ uptodate,lru,active,mappedtodisk,private 0x0000000000004078 1 0 ___UDlA_______b__________________ uptodate,dirty,lru,active,swapbacked 0x000000000000407c 34 0 __RUDlA_______b__________________ referenced,uptodate,dirty,lru,active,swapbacked 0x0000000000000400 538 2 __________B______________________ buddy 0x0000000000000804 1 0 __R________M_____________________ referenced,mmap 0x0000000000000828 1029 4 ___U_l_____M_____________________ uptodate,lru,mmap 0x0001000000000828 43 0 ___U_l_____M_________________I___ uptodate,lru,mmap,readahead 0x000000000000082c 382 1 __RU_l_____M_____________________ referenced,uptodate,lru,mmap 0x000100000000082c 12 0 __RU_l_____M_________________I___ referenced,uptodate,lru,mmap,readahead 0x0000000000000868 192 0 ___U_lA____M_____________________ uptodate,lru,active,mmap 0x0001000000000868 12 0 ___U_lA____M_________________I___ uptodate,lru,active,mmap,readahead 0x000000000000086c 800 3 __RU_lA____M_____________________ referenced,uptodate,lru,active,mmap 0x000100000000086c 31 0 __RU_lA____M_________________I___ referenced,uptodate,lru,active,mmap,readahead 0x0000000000004878 2 0 ___UDlA____M__b__________________ uptodate,dirty,lru,active,mmap,swapbacked 0x0000000000001000 492 1 ____________a____________________ anonymous 0x0000000000005008 2 0 ___U________a_b__________________ uptodate,anonymous,swapbacked 0x0000000000005808 4 0 ___U_______Ma_b__________________ uptodate,mmap,anonymous,swapbacked 0x000000000000580c 1 0 __RU_______Ma_b__________________ referenced,uptodate,mmap,anonymous,swapbacked 0x0000000000005868 2839 11 ___U_lA____Ma_b__________________ uptodate,lru,active,mmap,anonymous,swapbacked 0x000000000000586c 29 0 __RU_lA____Ma_b__________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types --raw --list --no-summary --bits reserved offset count flags 0 15 _____________________r___________ 31 4 _____________________r___________ 159 97 _____________________r___________ 4096 2067 _____________________r___________ 6752 2390 _____________________r___________ 9355 3 _____________________r___________ 9728 14526 _____________________r___________ This patch: Introduce PageHuge(), which identifies huge/gigantic pages by their dedicated compound destructor functions. Also move prep_compound_gigantic_page() to hugetlb.c and make __free_pages_ok() non-static. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-17 02:32:22 +04:00
}
#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
hugetlbfs: fix potential over/underflow setting node specific nr_hugepages The number of node specific huge pages can be set via a file such as: /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages When a node specific value is specified, the global number of huge pages must also be adjusted. This adjustment is calculated as the specified node specific value + (global value - current node value). If the node specific value provided by the user is large enough, this calculation could overflow an unsigned long leading to a smaller than expected number of huge pages. To fix, check the calculation for overflow. If overflow is detected, use ULONG_MAX as the requested value. This is inline with the user request to allocate as many huge pages as possible. It was also noticed that the above calculation was done outside the hugetlb_lock. Therefore, the values could be inconsistent and result in underflow. To fix, the calculation is moved within the routine set_max_huge_pages() where the lock is held. In addition, the code in __nr_hugepages_store_common() which tries to handle the case of not being able to allocate a node mask would likely result in incorrect behavior. Luckily, it is very unlikely we will ever take this path. If we do, simply return ENOMEM. Link: http://lkml.kernel.org/r/20190328220533.19884-1-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jing Xiangfeng <jingxiangfeng@huawei.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Alex Ghiti <alex@ghiti.fr> Cc: Jing Xiangfeng <jingxiangfeng@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 03:19:20 +03:00
static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
nodemask_t *nodes_allowed)
{
unsigned long min_count, ret;
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
struct page *page;
LIST_HEAD(page_list);
NODEMASK_ALLOC(nodemask_t, node_alloc_noretry, GFP_KERNEL);
/*
* Bit mask controlling how hard we retry per-node allocations.
* If we can not allocate the bit mask, do not attempt to allocate
* the requested huge pages.
*/
if (node_alloc_noretry)
nodes_clear(*node_alloc_noretry);
else
return -ENOMEM;
hugetlb: add per-hstate mutex to synchronize user adjustments The helper routine hstate_next_node_to_alloc accesses and modifies the hstate variable next_nid_to_alloc. The helper is used by the routines alloc_pool_huge_page and adjust_pool_surplus. adjust_pool_surplus is called with hugetlb_lock held. However, alloc_pool_huge_page can not be called with the hugetlb lock held as it will call the page allocator. Two instances of alloc_pool_huge_page could be run in parallel or alloc_pool_huge_page could run in parallel with adjust_pool_surplus which may result in the variable next_nid_to_alloc becoming invalid for the caller and pages being allocated on the wrong node. Both alloc_pool_huge_page and adjust_pool_surplus are only called from the routine set_max_huge_pages after boot. set_max_huge_pages is only called as the reusult of a user writing to the proc/sysfs nr_hugepages, or nr_hugepages_mempolicy file to adjust the number of hugetlb pages. It makes little sense to allow multiple adjustment to the number of hugetlb pages in parallel. Add a mutex to the hstate and use it to only allow one hugetlb page adjustment at a time. This will synchronize modifications to the next_nid_to_alloc variable. Link: https://lkml.kernel.org/r/20210409205254.242291-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:52 +03:00
/*
* resize_lock mutex prevents concurrent adjustments to number of
* pages in hstate via the proc/sysfs interfaces.
*/
mutex_lock(&h->resize_lock);
mm: hugetlb: defer freeing of HugeTLB pages In the subsequent patch, we should allocate the vmemmap pages when freeing a HugeTLB page. But update_and_free_page() can be called under any context, so we cannot use GFP_KERNEL to allocate vmemmap pages. However, we can defer the actual freeing in a kworker to prevent from using GFP_ATOMIC to allocate the vmemmap pages. The __update_and_free_page() is where the call to allocate vmemmmap pages will be inserted. Link: https://lkml.kernel.org/r/20210510030027.56044-6-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:17 +03:00
flush_free_hpage_work(h);
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
hugetlbfs: fix potential over/underflow setting node specific nr_hugepages The number of node specific huge pages can be set via a file such as: /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages When a node specific value is specified, the global number of huge pages must also be adjusted. This adjustment is calculated as the specified node specific value + (global value - current node value). If the node specific value provided by the user is large enough, this calculation could overflow an unsigned long leading to a smaller than expected number of huge pages. To fix, check the calculation for overflow. If overflow is detected, use ULONG_MAX as the requested value. This is inline with the user request to allocate as many huge pages as possible. It was also noticed that the above calculation was done outside the hugetlb_lock. Therefore, the values could be inconsistent and result in underflow. To fix, the calculation is moved within the routine set_max_huge_pages() where the lock is held. In addition, the code in __nr_hugepages_store_common() which tries to handle the case of not being able to allocate a node mask would likely result in incorrect behavior. Luckily, it is very unlikely we will ever take this path. If we do, simply return ENOMEM. Link: http://lkml.kernel.org/r/20190328220533.19884-1-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jing Xiangfeng <jingxiangfeng@huawei.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Alex Ghiti <alex@ghiti.fr> Cc: Jing Xiangfeng <jingxiangfeng@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 03:19:20 +03:00
/*
* Check for a node specific request.
* Changing node specific huge page count may require a corresponding
* change to the global count. In any case, the passed node mask
* (nodes_allowed) will restrict alloc/free to the specified node.
*/
if (nid != NUMA_NO_NODE) {
unsigned long old_count = count;
count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
/*
* User may have specified a large count value which caused the
* above calculation to overflow. In this case, they wanted
* to allocate as many huge pages as possible. Set count to
* largest possible value to align with their intention.
*/
if (count < old_count)
count = ULONG_MAX;
}
/*
* Gigantic pages runtime allocation depend on the capability for large
* page range allocation.
* If the system does not provide this feature, return an error when
* the user tries to allocate gigantic pages but let the user free the
* boottime allocated gigantic pages.
*/
if (hstate_is_gigantic(h) && !IS_ENABLED(CONFIG_CONTIG_ALLOC)) {
if (count > persistent_huge_pages(h)) {
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
hugetlb: add per-hstate mutex to synchronize user adjustments The helper routine hstate_next_node_to_alloc accesses and modifies the hstate variable next_nid_to_alloc. The helper is used by the routines alloc_pool_huge_page and adjust_pool_surplus. adjust_pool_surplus is called with hugetlb_lock held. However, alloc_pool_huge_page can not be called with the hugetlb lock held as it will call the page allocator. Two instances of alloc_pool_huge_page could be run in parallel or alloc_pool_huge_page could run in parallel with adjust_pool_surplus which may result in the variable next_nid_to_alloc becoming invalid for the caller and pages being allocated on the wrong node. Both alloc_pool_huge_page and adjust_pool_surplus are only called from the routine set_max_huge_pages after boot. set_max_huge_pages is only called as the reusult of a user writing to the proc/sysfs nr_hugepages, or nr_hugepages_mempolicy file to adjust the number of hugetlb pages. It makes little sense to allow multiple adjustment to the number of hugetlb pages in parallel. Add a mutex to the hstate and use it to only allow one hugetlb page adjustment at a time. This will synchronize modifications to the next_nid_to_alloc variable. Link: https://lkml.kernel.org/r/20210409205254.242291-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:52 +03:00
mutex_unlock(&h->resize_lock);
NODEMASK_FREE(node_alloc_noretry);
return -EINVAL;
}
/* Fall through to decrease pool */
}
/*
* Increase the pool size
* First take pages out of surplus state. Then make up the
* remaining difference by allocating fresh huge pages.
hugetlb: introduce nr_overcommit_hugepages sysctl hugetlb: introduce nr_overcommit_hugepages sysctl While examining the code to support /proc/sys/vm/hugetlb_dynamic_pool, I became convinced that having a boolean sysctl was insufficient: 1) To support per-node control of hugepages, I have previously submitted patches to add a sysfs attribute related to nr_hugepages. However, with a boolean global value and per-mount quota enforcement constraining the dynamic pool, adding corresponding control of the dynamic pool on a per-node basis seems inconsistent to me. 2) Administration of the hugetlb dynamic pool with multiple hugetlbfs mount points is, arguably, more arduous than it needs to be. Each quota would need to be set separately, and the sum would need to be monitored. To ease the administration, and to help make the way for per-node control of the static & dynamic hugepage pool, I added a separate sysctl, nr_overcommit_hugepages. This value serves as a high watermark for the overall hugepage pool, while nr_hugepages serves as a low watermark. The boolean sysctl can then be removed, as the condition nr_overcommit_hugepages > 0 indicates the same administrative setting as hugetlb_dynamic_pool == 1 Quotas still serve as local enforcement of the size of the pool on a per-mount basis. A few caveats: 1) There is a race whereby the global surplus huge page counter is incremented before a hugepage has allocated. Another process could then try grow the pool, and fail to convert a surplus huge page to a normal huge page and instead allocate a fresh huge page. I believe this is benign, as no memory is leaked (the actual pages are still tracked correctly) and the counters won't go out of sync. 2) Shrinking the static pool while a surplus is in effect will allow the number of surplus huge pages to exceed the overcommit value. As long as this condition holds, however, no more surplus huge pages will be allowed on the system until one of the two sysctls are increased sufficiently, or the surplus huge pages go out of use and are freed. Successfully tested on x86_64 with the current libhugetlbfs snapshot, modified to use the new sysctl. Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Acked-by: Adam Litke <agl@us.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-12-18 03:20:12 +03:00
*
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
* We might race with alloc_surplus_huge_page() here and be unable
hugetlb: introduce nr_overcommit_hugepages sysctl hugetlb: introduce nr_overcommit_hugepages sysctl While examining the code to support /proc/sys/vm/hugetlb_dynamic_pool, I became convinced that having a boolean sysctl was insufficient: 1) To support per-node control of hugepages, I have previously submitted patches to add a sysfs attribute related to nr_hugepages. However, with a boolean global value and per-mount quota enforcement constraining the dynamic pool, adding corresponding control of the dynamic pool on a per-node basis seems inconsistent to me. 2) Administration of the hugetlb dynamic pool with multiple hugetlbfs mount points is, arguably, more arduous than it needs to be. Each quota would need to be set separately, and the sum would need to be monitored. To ease the administration, and to help make the way for per-node control of the static & dynamic hugepage pool, I added a separate sysctl, nr_overcommit_hugepages. This value serves as a high watermark for the overall hugepage pool, while nr_hugepages serves as a low watermark. The boolean sysctl can then be removed, as the condition nr_overcommit_hugepages > 0 indicates the same administrative setting as hugetlb_dynamic_pool == 1 Quotas still serve as local enforcement of the size of the pool on a per-mount basis. A few caveats: 1) There is a race whereby the global surplus huge page counter is incremented before a hugepage has allocated. Another process could then try grow the pool, and fail to convert a surplus huge page to a normal huge page and instead allocate a fresh huge page. I believe this is benign, as no memory is leaked (the actual pages are still tracked correctly) and the counters won't go out of sync. 2) Shrinking the static pool while a surplus is in effect will allow the number of surplus huge pages to exceed the overcommit value. As long as this condition holds, however, no more surplus huge pages will be allowed on the system until one of the two sysctls are increased sufficiently, or the surplus huge pages go out of use and are freed. Successfully tested on x86_64 with the current libhugetlbfs snapshot, modified to use the new sysctl. Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Acked-by: Adam Litke <agl@us.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-12-18 03:20:12 +03:00
* to convert a surplus huge page to a normal huge page. That is
* not critical, though, it just means the overall size of the
* pool might be one hugepage larger than it needs to be, but
* within all the constraints specified by the sysctls.
*/
while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
hugetlb: add nodemask arg to huge page alloc, free and surplus adjust functions In preparation for constraining huge page allocation and freeing by the controlling task's numa mempolicy, add a "nodes_allowed" nodemask pointer to the allocate, free and surplus adjustment functions. For now, pass NULL to indicate default behavior--i.e., use node_online_map. A subsqeuent patch will derive a non-default mask from the controlling task's numa mempolicy. Note that this method of updating the global hstate nr_hugepages under the constraint of a nodemask simplifies keeping the global state consistent--especially the number of persistent and surplus pages relative to reservations and overcommit limits. There are undoubtedly other ways to do this, but this works for both interfaces: mempolicy and per node attributes. [rientjes@google.com: fix HIGHMEM compile error] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Reviewed-by: Mel Gorman <mel@csn.ul.ie> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:16 +03:00
if (!adjust_pool_surplus(h, nodes_allowed, -1))
break;
}
while (count > persistent_huge_pages(h)) {
/*
* If this allocation races such that we no longer need the
* page, free_huge_page will handle it by freeing the page
* and reducing the surplus.
*/
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
/* yield cpu to avoid soft lockup */
cond_resched();
ret = alloc_pool_huge_page(h, nodes_allowed,
node_alloc_noretry);
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
if (!ret)
goto out;
/* Bail for signals. Probably ctrl-c from user */
if (signal_pending(current))
goto out;
}
/*
* Decrease the pool size
* First return free pages to the buddy allocator (being careful
* to keep enough around to satisfy reservations). Then place
* pages into surplus state as needed so the pool will shrink
* to the desired size as pages become free.
hugetlb: introduce nr_overcommit_hugepages sysctl hugetlb: introduce nr_overcommit_hugepages sysctl While examining the code to support /proc/sys/vm/hugetlb_dynamic_pool, I became convinced that having a boolean sysctl was insufficient: 1) To support per-node control of hugepages, I have previously submitted patches to add a sysfs attribute related to nr_hugepages. However, with a boolean global value and per-mount quota enforcement constraining the dynamic pool, adding corresponding control of the dynamic pool on a per-node basis seems inconsistent to me. 2) Administration of the hugetlb dynamic pool with multiple hugetlbfs mount points is, arguably, more arduous than it needs to be. Each quota would need to be set separately, and the sum would need to be monitored. To ease the administration, and to help make the way for per-node control of the static & dynamic hugepage pool, I added a separate sysctl, nr_overcommit_hugepages. This value serves as a high watermark for the overall hugepage pool, while nr_hugepages serves as a low watermark. The boolean sysctl can then be removed, as the condition nr_overcommit_hugepages > 0 indicates the same administrative setting as hugetlb_dynamic_pool == 1 Quotas still serve as local enforcement of the size of the pool on a per-mount basis. A few caveats: 1) There is a race whereby the global surplus huge page counter is incremented before a hugepage has allocated. Another process could then try grow the pool, and fail to convert a surplus huge page to a normal huge page and instead allocate a fresh huge page. I believe this is benign, as no memory is leaked (the actual pages are still tracked correctly) and the counters won't go out of sync. 2) Shrinking the static pool while a surplus is in effect will allow the number of surplus huge pages to exceed the overcommit value. As long as this condition holds, however, no more surplus huge pages will be allowed on the system until one of the two sysctls are increased sufficiently, or the surplus huge pages go out of use and are freed. Successfully tested on x86_64 with the current libhugetlbfs snapshot, modified to use the new sysctl. Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Acked-by: Adam Litke <agl@us.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-12-18 03:20:12 +03:00
*
* By placing pages into the surplus state independent of the
* overcommit value, we are allowing the surplus pool size to
* exceed overcommit. There are few sane options here. Since
mm, hugetlb: further simplify hugetlb allocation API Hugetlb allocator has several layer of allocation functions depending and the purpose of the allocation. There are two allocators depending on whether the page can be allocated from the page allocator or we need a contiguous allocator. This is currently opencoded in alloc_fresh_huge_page which is the only path that might allocate giga pages which require the later allocator. Create alloc_fresh_huge_page which hides this implementation detail and use it in all callers which hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page). This shouldn't introduce any funtional change because both migration and surplus allocators exlude giga pages explicitly. While we are at it let's do some renaming. The current scheme is not consistent and overly painfull to read and understand. Get rid of prefix underscores from most functions. There is no real reason to make names longer. * alloc_fresh_huge_page is the new layer to abstract underlying allocator * __hugetlb_alloc_buddy_huge_page becomes shorter and neater alloc_buddy_huge_page. * Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put the new page directly to the pool * alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code as it uses alloc_fresh_huge_page now * others lose their excessive prefix underscores to make names shorter [dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:56 +03:00
* alloc_surplus_huge_page() is checking the global counter,
hugetlb: introduce nr_overcommit_hugepages sysctl hugetlb: introduce nr_overcommit_hugepages sysctl While examining the code to support /proc/sys/vm/hugetlb_dynamic_pool, I became convinced that having a boolean sysctl was insufficient: 1) To support per-node control of hugepages, I have previously submitted patches to add a sysfs attribute related to nr_hugepages. However, with a boolean global value and per-mount quota enforcement constraining the dynamic pool, adding corresponding control of the dynamic pool on a per-node basis seems inconsistent to me. 2) Administration of the hugetlb dynamic pool with multiple hugetlbfs mount points is, arguably, more arduous than it needs to be. Each quota would need to be set separately, and the sum would need to be monitored. To ease the administration, and to help make the way for per-node control of the static & dynamic hugepage pool, I added a separate sysctl, nr_overcommit_hugepages. This value serves as a high watermark for the overall hugepage pool, while nr_hugepages serves as a low watermark. The boolean sysctl can then be removed, as the condition nr_overcommit_hugepages > 0 indicates the same administrative setting as hugetlb_dynamic_pool == 1 Quotas still serve as local enforcement of the size of the pool on a per-mount basis. A few caveats: 1) There is a race whereby the global surplus huge page counter is incremented before a hugepage has allocated. Another process could then try grow the pool, and fail to convert a surplus huge page to a normal huge page and instead allocate a fresh huge page. I believe this is benign, as no memory is leaked (the actual pages are still tracked correctly) and the counters won't go out of sync. 2) Shrinking the static pool while a surplus is in effect will allow the number of surplus huge pages to exceed the overcommit value. As long as this condition holds, however, no more surplus huge pages will be allowed on the system until one of the two sysctls are increased sufficiently, or the surplus huge pages go out of use and are freed. Successfully tested on x86_64 with the current libhugetlbfs snapshot, modified to use the new sysctl. Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Acked-by: Adam Litke <agl@us.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-12-18 03:20:12 +03:00
* though, we'll note that we're not allowed to exceed surplus
* and won't grow the pool anywhere else. Not until one of the
* sysctls are changed, or the surplus pages go out of use.
*/
min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
min_count = max(count, min_count);
hugetlb: add nodemask arg to huge page alloc, free and surplus adjust functions In preparation for constraining huge page allocation and freeing by the controlling task's numa mempolicy, add a "nodes_allowed" nodemask pointer to the allocate, free and surplus adjustment functions. For now, pass NULL to indicate default behavior--i.e., use node_online_map. A subsqeuent patch will derive a non-default mask from the controlling task's numa mempolicy. Note that this method of updating the global hstate nr_hugepages under the constraint of a nodemask simplifies keeping the global state consistent--especially the number of persistent and surplus pages relative to reservations and overcommit limits. There are undoubtedly other ways to do this, but this works for both interfaces: mempolicy and per node attributes. [rientjes@google.com: fix HIGHMEM compile error] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Reviewed-by: Mel Gorman <mel@csn.ul.ie> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:16 +03:00
try_to_free_low(h, min_count, nodes_allowed);
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
/*
* Collect pages to be removed on list without dropping lock
*/
while (min_count < persistent_huge_pages(h)) {
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
page = remove_pool_huge_page(h, nodes_allowed, 0);
if (!page)
break;
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
list_add(&page->lru, &page_list);
}
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
/* free the pages after dropping lock */
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
update_and_free_pages_bulk(h, &page_list);
mm: hugetlb: defer freeing of HugeTLB pages In the subsequent patch, we should allocate the vmemmap pages when freeing a HugeTLB page. But update_and_free_page() can be called under any context, so we cannot use GFP_KERNEL to allocate vmemmap pages. However, we can defer the actual freeing in a kworker to prevent from using GFP_ATOMIC to allocate the vmemmap pages. The __update_and_free_page() is where the call to allocate vmemmmap pages will be inserted. Link: https://lkml.kernel.org/r/20210510030027.56044-6-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Chen Huang <chenhuang5@huawei.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:17 +03:00
flush_free_hpage_work(h);
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
hugetlb: change free_pool_huge_page to remove_pool_huge_page free_pool_huge_page was called with hugetlb_lock held. It would remove a hugetlb page, and then free the corresponding pages to the lower level allocators such as buddy. free_pool_huge_page was called in a loop to remove hugetlb pages and these loops could hold the hugetlb_lock for a considerable time. Create new routine remove_pool_huge_page to replace free_pool_huge_page. remove_pool_huge_page will remove the hugetlb page, and it must be called with the hugetlb_lock held. It will return the removed page and it is the responsibility of the caller to free the page to the lower level allocators. The hugetlb_lock is dropped before freeing to these allocators which results in shorter lock hold times. Add new helper routine to call update_and_free_page for a list of pages. Note: Some changes to the routine return_unused_surplus_pages are in need of explanation. Commit e5bbc8a6c992 ("mm/hugetlb.c: fix reservation race when freeing surplus pages") modified this routine to address a race which could occur when dropping the hugetlb_lock in the loop that removes pool pages. Accounting changes introduced in that commit were subtle and took some thought to understand. This commit removes the cond_resched_lock() and the potential race. Therefore, remove the subtle code and restore the more straight forward accounting effectively reverting the commit. Link: https://lkml.kernel.org/r/20210409205254.242291-7-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:03 +03:00
while (count < persistent_huge_pages(h)) {
hugetlb: add nodemask arg to huge page alloc, free and surplus adjust functions In preparation for constraining huge page allocation and freeing by the controlling task's numa mempolicy, add a "nodes_allowed" nodemask pointer to the allocate, free and surplus adjustment functions. For now, pass NULL to indicate default behavior--i.e., use node_online_map. A subsqeuent patch will derive a non-default mask from the controlling task's numa mempolicy. Note that this method of updating the global hstate nr_hugepages under the constraint of a nodemask simplifies keeping the global state consistent--especially the number of persistent and surplus pages relative to reservations and overcommit limits. There are undoubtedly other ways to do this, but this works for both interfaces: mempolicy and per node attributes. [rientjes@google.com: fix HIGHMEM compile error] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Reviewed-by: Mel Gorman <mel@csn.ul.ie> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:16 +03:00
if (!adjust_pool_surplus(h, nodes_allowed, 1))
break;
}
out:
h->max_huge_pages = persistent_huge_pages(h);
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
hugetlb: add per-hstate mutex to synchronize user adjustments The helper routine hstate_next_node_to_alloc accesses and modifies the hstate variable next_nid_to_alloc. The helper is used by the routines alloc_pool_huge_page and adjust_pool_surplus. adjust_pool_surplus is called with hugetlb_lock held. However, alloc_pool_huge_page can not be called with the hugetlb lock held as it will call the page allocator. Two instances of alloc_pool_huge_page could be run in parallel or alloc_pool_huge_page could run in parallel with adjust_pool_surplus which may result in the variable next_nid_to_alloc becoming invalid for the caller and pages being allocated on the wrong node. Both alloc_pool_huge_page and adjust_pool_surplus are only called from the routine set_max_huge_pages after boot. set_max_huge_pages is only called as the reusult of a user writing to the proc/sysfs nr_hugepages, or nr_hugepages_mempolicy file to adjust the number of hugetlb pages. It makes little sense to allow multiple adjustment to the number of hugetlb pages in parallel. Add a mutex to the hstate and use it to only allow one hugetlb page adjustment at a time. This will synchronize modifications to the next_nid_to_alloc variable. Link: https://lkml.kernel.org/r/20210409205254.242291-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:52 +03:00
mutex_unlock(&h->resize_lock);
NODEMASK_FREE(node_alloc_noretry);
return 0;
}
static int demote_free_huge_page(struct hstate *h, struct page *page)
{
int i, nid = page_to_nid(page);
struct hstate *target_hstate;
int rc = 0;
target_hstate = size_to_hstate(PAGE_SIZE << h->demote_order);
remove_hugetlb_page_for_demote(h, page, false);
spin_unlock_irq(&hugetlb_lock);
rc = hugetlb_vmemmap_alloc(h, page);
if (rc) {
/* Allocation of vmemmmap failed, we can not demote page */
spin_lock_irq(&hugetlb_lock);
set_page_refcounted(page);
add_hugetlb_page(h, page, false);
return rc;
}
/*
* Use destroy_compound_hugetlb_page_for_demote for all huge page
* sizes as it will not ref count pages.
*/
destroy_compound_hugetlb_page_for_demote(page, huge_page_order(h));
/*
* Taking target hstate mutex synchronizes with set_max_huge_pages.
* Without the mutex, pages added to target hstate could be marked
* as surplus.
*
* Note that we already hold h->resize_lock. To prevent deadlock,
* use the convention of always taking larger size hstate mutex first.
*/
mutex_lock(&target_hstate->resize_lock);
for (i = 0; i < pages_per_huge_page(h);
i += pages_per_huge_page(target_hstate)) {
if (hstate_is_gigantic(target_hstate))
prep_compound_gigantic_page_for_demote(page + i,
target_hstate->order);
else
prep_compound_page(page + i, target_hstate->order);
set_page_private(page + i, 0);
set_page_refcounted(page + i);
prep_new_huge_page(target_hstate, page + i, nid);
put_page(page + i);
}
mutex_unlock(&target_hstate->resize_lock);
spin_lock_irq(&hugetlb_lock);
/*
* Not absolutely necessary, but for consistency update max_huge_pages
* based on pool changes for the demoted page.
*/
h->max_huge_pages--;
target_hstate->max_huge_pages += pages_per_huge_page(h);
return rc;
}
hugetlb: add demote hugetlb page sysfs interfaces Patch series "hugetlb: add demote/split page functionality", v4. The concurrent use of multiple hugetlb page sizes on a single system is becoming more common. One of the reasons is better TLB support for gigantic page sizes on x86 hardware. In addition, hugetlb pages are being used to back VMs in hosting environments. When using hugetlb pages to back VMs, it is often desirable to preallocate hugetlb pools. This avoids the delay and uncertainty of allocating hugetlb pages at VM startup. In addition, preallocating huge pages minimizes the issue of memory fragmentation that increases the longer the system is up and running. In such environments, a combination of larger and smaller hugetlb pages are preallocated in anticipation of backing VMs of various sizes. Over time, the preallocated pool of smaller hugetlb pages may become depleted while larger hugetlb pages still remain. In such situations, it is desirable to convert larger hugetlb pages to smaller hugetlb pages. Converting larger to smaller hugetlb pages can be accomplished today by first freeing the larger page to the buddy allocator and then allocating the smaller pages. For example, to convert 50 GB pages on x86: gb_pages=`cat .../hugepages-1048576kB/nr_hugepages` m2_pages=`cat .../hugepages-2048kB/nr_hugepages` echo $(($gb_pages - 50)) > .../hugepages-1048576kB/nr_hugepages echo $(($m2_pages + 25600)) > .../hugepages-2048kB/nr_hugepages On an idle system this operation is fairly reliable and results are as expected. The number of 2MB pages is increased as expected and the time of the operation is a second or two. However, when there is activity on the system the following issues arise: 1) This process can take quite some time, especially if allocation of the smaller pages is not immediate and requires migration/compaction. 2) There is no guarantee that the total size of smaller pages allocated will match the size of the larger page which was freed. This is because the area freed by the larger page could quickly be fragmented. In a test environment with a load that continually fills the page cache with clean pages, results such as the following can be observed: Unexpected number of 2MB pages allocated: Expected 25600, have 19944 real 0m42.092s user 0m0.008s sys 0m41.467s To address these issues, introduce the concept of hugetlb page demotion. Demotion provides a means of 'in place' splitting of a hugetlb page to pages of a smaller size. This avoids freeing pages to buddy and then trying to allocate from buddy. Page demotion is controlled via sysfs files that reside in the per-hugetlb page size and per node directories. - demote_size Target page size for demotion, a smaller huge page size. File can be written to chose a smaller huge page size if multiple are available. - demote Writable number of hugetlb pages to be demoted To demote 50 GB huge pages, one would: cat .../hugepages-1048576kB/free_hugepages /* optional, verify free pages */ cat .../hugepages-1048576kB/demote_size /* optional, verify target size */ echo 50 > .../hugepages-1048576kB/demote Only hugetlb pages which are free at the time of the request can be demoted. Demotion does not add to the complexity of surplus pages and honors reserved huge pages. Therefore, when a value is written to the sysfs demote file, that value is only the maximum number of pages which will be demoted. It is possible fewer will actually be demoted. The recently introduced per-hstate mutex is used to synchronize demote operations with other operations that modify hugetlb pools. Real world use cases -------------------- The above scenario describes a real world use case where hugetlb pages are used to back VMs on x86. Both issues of long allocation times and not necessarily getting the expected number of smaller huge pages after a free and allocate cycle have been experienced. The occurrence of these issues is dependent on other activity within the host and can not be predicted. This patch (of 5): Two new sysfs files are added to demote hugtlb pages. These files are both per-hugetlb page size and per node. Files are: demote_size - The size in Kb that pages are demoted to. (read-write) demote - The number of huge pages to demote. (write-only) By default, demote_size is the next smallest huge page size. Valid huge page sizes less than huge page size may be written to this file. When huge pages are demoted, they are demoted to this size. Writing a value to demote will result in an attempt to demote that number of hugetlb pages to an appropriate number of demote_size pages. NOTE: Demote interfaces are only provided for huge page sizes if there is a smaller target demote huge page size. For example, on x86 1GB huge pages will have demote interfaces. 2MB huge pages will not have demote interfaces. This patch does not provide full demote functionality. It only provides the sysfs interfaces. It also provides documentation for the new interfaces. [mike.kravetz@oracle.com: n_mask initialization does not need to be protected by the mutex] Link: https://lkml.kernel.org/r/0530e4ef-2492-5186-f919-5db68edea654@oracle.com Link: https://lkml.kernel.org/r/20211007181918.136982-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: David Rientjes <rientjes@google.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Nghia Le <nghialm78@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:20 +03:00
static int demote_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
__must_hold(&hugetlb_lock)
{
int nr_nodes, node;
struct page *page;
hugetlb: add demote hugetlb page sysfs interfaces Patch series "hugetlb: add demote/split page functionality", v4. The concurrent use of multiple hugetlb page sizes on a single system is becoming more common. One of the reasons is better TLB support for gigantic page sizes on x86 hardware. In addition, hugetlb pages are being used to back VMs in hosting environments. When using hugetlb pages to back VMs, it is often desirable to preallocate hugetlb pools. This avoids the delay and uncertainty of allocating hugetlb pages at VM startup. In addition, preallocating huge pages minimizes the issue of memory fragmentation that increases the longer the system is up and running. In such environments, a combination of larger and smaller hugetlb pages are preallocated in anticipation of backing VMs of various sizes. Over time, the preallocated pool of smaller hugetlb pages may become depleted while larger hugetlb pages still remain. In such situations, it is desirable to convert larger hugetlb pages to smaller hugetlb pages. Converting larger to smaller hugetlb pages can be accomplished today by first freeing the larger page to the buddy allocator and then allocating the smaller pages. For example, to convert 50 GB pages on x86: gb_pages=`cat .../hugepages-1048576kB/nr_hugepages` m2_pages=`cat .../hugepages-2048kB/nr_hugepages` echo $(($gb_pages - 50)) > .../hugepages-1048576kB/nr_hugepages echo $(($m2_pages + 25600)) > .../hugepages-2048kB/nr_hugepages On an idle system this operation is fairly reliable and results are as expected. The number of 2MB pages is increased as expected and the time of the operation is a second or two. However, when there is activity on the system the following issues arise: 1) This process can take quite some time, especially if allocation of the smaller pages is not immediate and requires migration/compaction. 2) There is no guarantee that the total size of smaller pages allocated will match the size of the larger page which was freed. This is because the area freed by the larger page could quickly be fragmented. In a test environment with a load that continually fills the page cache with clean pages, results such as the following can be observed: Unexpected number of 2MB pages allocated: Expected 25600, have 19944 real 0m42.092s user 0m0.008s sys 0m41.467s To address these issues, introduce the concept of hugetlb page demotion. Demotion provides a means of 'in place' splitting of a hugetlb page to pages of a smaller size. This avoids freeing pages to buddy and then trying to allocate from buddy. Page demotion is controlled via sysfs files that reside in the per-hugetlb page size and per node directories. - demote_size Target page size for demotion, a smaller huge page size. File can be written to chose a smaller huge page size if multiple are available. - demote Writable number of hugetlb pages to be demoted To demote 50 GB huge pages, one would: cat .../hugepages-1048576kB/free_hugepages /* optional, verify free pages */ cat .../hugepages-1048576kB/demote_size /* optional, verify target size */ echo 50 > .../hugepages-1048576kB/demote Only hugetlb pages which are free at the time of the request can be demoted. Demotion does not add to the complexity of surplus pages and honors reserved huge pages. Therefore, when a value is written to the sysfs demote file, that value is only the maximum number of pages which will be demoted. It is possible fewer will actually be demoted. The recently introduced per-hstate mutex is used to synchronize demote operations with other operations that modify hugetlb pools. Real world use cases -------------------- The above scenario describes a real world use case where hugetlb pages are used to back VMs on x86. Both issues of long allocation times and not necessarily getting the expected number of smaller huge pages after a free and allocate cycle have been experienced. The occurrence of these issues is dependent on other activity within the host and can not be predicted. This patch (of 5): Two new sysfs files are added to demote hugtlb pages. These files are both per-hugetlb page size and per node. Files are: demote_size - The size in Kb that pages are demoted to. (read-write) demote - The number of huge pages to demote. (write-only) By default, demote_size is the next smallest huge page size. Valid huge page sizes less than huge page size may be written to this file. When huge pages are demoted, they are demoted to this size. Writing a value to demote will result in an attempt to demote that number of hugetlb pages to an appropriate number of demote_size pages. NOTE: Demote interfaces are only provided for huge page sizes if there is a smaller target demote huge page size. For example, on x86 1GB huge pages will have demote interfaces. 2MB huge pages will not have demote interfaces. This patch does not provide full demote functionality. It only provides the sysfs interfaces. It also provides documentation for the new interfaces. [mike.kravetz@oracle.com: n_mask initialization does not need to be protected by the mutex] Link: https://lkml.kernel.org/r/0530e4ef-2492-5186-f919-5db68edea654@oracle.com Link: https://lkml.kernel.org/r/20211007181918.136982-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: David Rientjes <rientjes@google.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Nghia Le <nghialm78@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:20 +03:00
lockdep_assert_held(&hugetlb_lock);
/* We should never get here if no demote order */
if (!h->demote_order) {
pr_warn("HugeTLB: NULL demote order passed to demote_pool_huge_page.\n");
return -EINVAL; /* internal error */
}
for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
list_for_each_entry(page, &h->hugepage_freelists[node], lru) {
if (PageHWPoison(page))
continue;
return demote_free_huge_page(h, page);
}
}
/*
* Only way to get here is if all pages on free lists are poisoned.
* Return -EBUSY so that caller will not retry.
*/
return -EBUSY;
hugetlb: add demote hugetlb page sysfs interfaces Patch series "hugetlb: add demote/split page functionality", v4. The concurrent use of multiple hugetlb page sizes on a single system is becoming more common. One of the reasons is better TLB support for gigantic page sizes on x86 hardware. In addition, hugetlb pages are being used to back VMs in hosting environments. When using hugetlb pages to back VMs, it is often desirable to preallocate hugetlb pools. This avoids the delay and uncertainty of allocating hugetlb pages at VM startup. In addition, preallocating huge pages minimizes the issue of memory fragmentation that increases the longer the system is up and running. In such environments, a combination of larger and smaller hugetlb pages are preallocated in anticipation of backing VMs of various sizes. Over time, the preallocated pool of smaller hugetlb pages may become depleted while larger hugetlb pages still remain. In such situations, it is desirable to convert larger hugetlb pages to smaller hugetlb pages. Converting larger to smaller hugetlb pages can be accomplished today by first freeing the larger page to the buddy allocator and then allocating the smaller pages. For example, to convert 50 GB pages on x86: gb_pages=`cat .../hugepages-1048576kB/nr_hugepages` m2_pages=`cat .../hugepages-2048kB/nr_hugepages` echo $(($gb_pages - 50)) > .../hugepages-1048576kB/nr_hugepages echo $(($m2_pages + 25600)) > .../hugepages-2048kB/nr_hugepages On an idle system this operation is fairly reliable and results are as expected. The number of 2MB pages is increased as expected and the time of the operation is a second or two. However, when there is activity on the system the following issues arise: 1) This process can take quite some time, especially if allocation of the smaller pages is not immediate and requires migration/compaction. 2) There is no guarantee that the total size of smaller pages allocated will match the size of the larger page which was freed. This is because the area freed by the larger page could quickly be fragmented. In a test environment with a load that continually fills the page cache with clean pages, results such as the following can be observed: Unexpected number of 2MB pages allocated: Expected 25600, have 19944 real 0m42.092s user 0m0.008s sys 0m41.467s To address these issues, introduce the concept of hugetlb page demotion. Demotion provides a means of 'in place' splitting of a hugetlb page to pages of a smaller size. This avoids freeing pages to buddy and then trying to allocate from buddy. Page demotion is controlled via sysfs files that reside in the per-hugetlb page size and per node directories. - demote_size Target page size for demotion, a smaller huge page size. File can be written to chose a smaller huge page size if multiple are available. - demote Writable number of hugetlb pages to be demoted To demote 50 GB huge pages, one would: cat .../hugepages-1048576kB/free_hugepages /* optional, verify free pages */ cat .../hugepages-1048576kB/demote_size /* optional, verify target size */ echo 50 > .../hugepages-1048576kB/demote Only hugetlb pages which are free at the time of the request can be demoted. Demotion does not add to the complexity of surplus pages and honors reserved huge pages. Therefore, when a value is written to the sysfs demote file, that value is only the maximum number of pages which will be demoted. It is possible fewer will actually be demoted. The recently introduced per-hstate mutex is used to synchronize demote operations with other operations that modify hugetlb pools. Real world use cases -------------------- The above scenario describes a real world use case where hugetlb pages are used to back VMs on x86. Both issues of long allocation times and not necessarily getting the expected number of smaller huge pages after a free and allocate cycle have been experienced. The occurrence of these issues is dependent on other activity within the host and can not be predicted. This patch (of 5): Two new sysfs files are added to demote hugtlb pages. These files are both per-hugetlb page size and per node. Files are: demote_size - The size in Kb that pages are demoted to. (read-write) demote - The number of huge pages to demote. (write-only) By default, demote_size is the next smallest huge page size. Valid huge page sizes less than huge page size may be written to this file. When huge pages are demoted, they are demoted to this size. Writing a value to demote will result in an attempt to demote that number of hugetlb pages to an appropriate number of demote_size pages. NOTE: Demote interfaces are only provided for huge page sizes if there is a smaller target demote huge page size. For example, on x86 1GB huge pages will have demote interfaces. 2MB huge pages will not have demote interfaces. This patch does not provide full demote functionality. It only provides the sysfs interfaces. It also provides documentation for the new interfaces. [mike.kravetz@oracle.com: n_mask initialization does not need to be protected by the mutex] Link: https://lkml.kernel.org/r/0530e4ef-2492-5186-f919-5db68edea654@oracle.com Link: https://lkml.kernel.org/r/20211007181918.136982-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: David Rientjes <rientjes@google.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Nghia Le <nghialm78@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:20 +03:00
}
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
#define HSTATE_ATTR_RO(_name) \
static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
hugetlb: add demote hugetlb page sysfs interfaces Patch series "hugetlb: add demote/split page functionality", v4. The concurrent use of multiple hugetlb page sizes on a single system is becoming more common. One of the reasons is better TLB support for gigantic page sizes on x86 hardware. In addition, hugetlb pages are being used to back VMs in hosting environments. When using hugetlb pages to back VMs, it is often desirable to preallocate hugetlb pools. This avoids the delay and uncertainty of allocating hugetlb pages at VM startup. In addition, preallocating huge pages minimizes the issue of memory fragmentation that increases the longer the system is up and running. In such environments, a combination of larger and smaller hugetlb pages are preallocated in anticipation of backing VMs of various sizes. Over time, the preallocated pool of smaller hugetlb pages may become depleted while larger hugetlb pages still remain. In such situations, it is desirable to convert larger hugetlb pages to smaller hugetlb pages. Converting larger to smaller hugetlb pages can be accomplished today by first freeing the larger page to the buddy allocator and then allocating the smaller pages. For example, to convert 50 GB pages on x86: gb_pages=`cat .../hugepages-1048576kB/nr_hugepages` m2_pages=`cat .../hugepages-2048kB/nr_hugepages` echo $(($gb_pages - 50)) > .../hugepages-1048576kB/nr_hugepages echo $(($m2_pages + 25600)) > .../hugepages-2048kB/nr_hugepages On an idle system this operation is fairly reliable and results are as expected. The number of 2MB pages is increased as expected and the time of the operation is a second or two. However, when there is activity on the system the following issues arise: 1) This process can take quite some time, especially if allocation of the smaller pages is not immediate and requires migration/compaction. 2) There is no guarantee that the total size of smaller pages allocated will match the size of the larger page which was freed. This is because the area freed by the larger page could quickly be fragmented. In a test environment with a load that continually fills the page cache with clean pages, results such as the following can be observed: Unexpected number of 2MB pages allocated: Expected 25600, have 19944 real 0m42.092s user 0m0.008s sys 0m41.467s To address these issues, introduce the concept of hugetlb page demotion. Demotion provides a means of 'in place' splitting of a hugetlb page to pages of a smaller size. This avoids freeing pages to buddy and then trying to allocate from buddy. Page demotion is controlled via sysfs files that reside in the per-hugetlb page size and per node directories. - demote_size Target page size for demotion, a smaller huge page size. File can be written to chose a smaller huge page size if multiple are available. - demote Writable number of hugetlb pages to be demoted To demote 50 GB huge pages, one would: cat .../hugepages-1048576kB/free_hugepages /* optional, verify free pages */ cat .../hugepages-1048576kB/demote_size /* optional, verify target size */ echo 50 > .../hugepages-1048576kB/demote Only hugetlb pages which are free at the time of the request can be demoted. Demotion does not add to the complexity of surplus pages and honors reserved huge pages. Therefore, when a value is written to the sysfs demote file, that value is only the maximum number of pages which will be demoted. It is possible fewer will actually be demoted. The recently introduced per-hstate mutex is used to synchronize demote operations with other operations that modify hugetlb pools. Real world use cases -------------------- The above scenario describes a real world use case where hugetlb pages are used to back VMs on x86. Both issues of long allocation times and not necessarily getting the expected number of smaller huge pages after a free and allocate cycle have been experienced. The occurrence of these issues is dependent on other activity within the host and can not be predicted. This patch (of 5): Two new sysfs files are added to demote hugtlb pages. These files are both per-hugetlb page size and per node. Files are: demote_size - The size in Kb that pages are demoted to. (read-write) demote - The number of huge pages to demote. (write-only) By default, demote_size is the next smallest huge page size. Valid huge page sizes less than huge page size may be written to this file. When huge pages are demoted, they are demoted to this size. Writing a value to demote will result in an attempt to demote that number of hugetlb pages to an appropriate number of demote_size pages. NOTE: Demote interfaces are only provided for huge page sizes if there is a smaller target demote huge page size. For example, on x86 1GB huge pages will have demote interfaces. 2MB huge pages will not have demote interfaces. This patch does not provide full demote functionality. It only provides the sysfs interfaces. It also provides documentation for the new interfaces. [mike.kravetz@oracle.com: n_mask initialization does not need to be protected by the mutex] Link: https://lkml.kernel.org/r/0530e4ef-2492-5186-f919-5db68edea654@oracle.com Link: https://lkml.kernel.org/r/20211007181918.136982-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: David Rientjes <rientjes@google.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Nghia Le <nghialm78@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:20 +03:00
#define HSTATE_ATTR_WO(_name) \
static struct kobj_attribute _name##_attr = __ATTR_WO(_name)
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
#define HSTATE_ATTR(_name) \
static struct kobj_attribute _name##_attr = __ATTR_RW(_name)
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
static struct kobject *hugepages_kobj;
static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
{
int i;
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
for (i = 0; i < HUGE_MAX_HSTATE; i++)
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
if (hstate_kobjs[i] == kobj) {
if (nidp)
*nidp = NUMA_NO_NODE;
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
return &hstates[i];
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
}
return kobj_to_node_hstate(kobj, nidp);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
}
hugetlb: derive huge pages nodes allowed from task mempolicy This patch derives a "nodes_allowed" node mask from the numa mempolicy of the task modifying the number of persistent huge pages to control the allocation, freeing and adjusting of surplus huge pages when the pool page count is modified via the new sysctl or sysfs attribute "nr_hugepages_mempolicy". The nodes_allowed mask is derived as follows: * For "default" [NULL] task mempolicy, a NULL nodemask_t pointer is produced. This will cause the hugetlb subsystem to use node_online_map as the "nodes_allowed". This preserves the behavior before this patch. * For "preferred" mempolicy, including explicit local allocation, a nodemask with the single preferred node will be produced. "local" policy will NOT track any internode migrations of the task adjusting nr_hugepages. * For "bind" and "interleave" policy, the mempolicy's nodemask will be used. * Other than to inform the construction of the nodes_allowed node mask, the actual mempolicy mode is ignored. That is, all modes behave like interleave over the resulting nodes_allowed mask with no "fallback". See the updated documentation [next patch] for more information about the implications of this patch. Examples: Starting with: Node 0 HugePages_Total: 0 Node 1 HugePages_Total: 0 Node 2 HugePages_Total: 0 Node 3 HugePages_Total: 0 Default behavior [with or without this patch] balances persistent hugepage allocation across nodes [with sufficient contiguous memory]: sysctl vm.nr_hugepages[_mempolicy]=32 yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 8 Node 3 HugePages_Total: 8 Of course, we only have nr_hugepages_mempolicy with the patch, but with default mempolicy, nr_hugepages_mempolicy behaves the same as nr_hugepages. Applying mempolicy--e.g., with numactl [using '-m' a.k.a. '--membind' because it allows multiple nodes to be specified and it's easy to type]--we can allocate huge pages on individual nodes or sets of nodes. So, starting from the condition above, with 8 huge pages per node, add 8 more to node 2 using: numactl -m 2 sysctl vm.nr_hugepages_mempolicy=40 This yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The incremental 8 huge pages were restricted to node 2 by the specified mempolicy. Similarly, we can use mempolicy to free persistent huge pages from specified nodes: numactl -m 0,1 sysctl vm.nr_hugepages_mempolicy=32 yields: Node 0 HugePages_Total: 4 Node 1 HugePages_Total: 4 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The 8 huge pages freed were balanced over nodes 0 and 1. [rientjes@google.com: accomodate reworked NODEMASK_ALLOC] Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:21 +03:00
static ssize_t nr_hugepages_show_common(struct kobject *kobj,
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
struct kobj_attribute *attr, char *buf)
{
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
struct hstate *h;
unsigned long nr_huge_pages;
int nid;
h = kobj_to_hstate(kobj, &nid);
if (nid == NUMA_NO_NODE)
nr_huge_pages = h->nr_huge_pages;
else
nr_huge_pages = h->nr_huge_pages_node[nid];
return sysfs_emit(buf, "%lu\n", nr_huge_pages);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
}
static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
struct hstate *h, int nid,
unsigned long count, size_t len)
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
{
int err;
nodemask_t nodes_allowed, *n_mask;
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
return -EINVAL;
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
if (nid == NUMA_NO_NODE) {
/*
* global hstate attribute
*/
if (!(obey_mempolicy &&
init_nodemask_of_mempolicy(&nodes_allowed)))
n_mask = &node_states[N_MEMORY];
else
n_mask = &nodes_allowed;
} else {
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
/*
hugetlbfs: fix potential over/underflow setting node specific nr_hugepages The number of node specific huge pages can be set via a file such as: /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages When a node specific value is specified, the global number of huge pages must also be adjusted. This adjustment is calculated as the specified node specific value + (global value - current node value). If the node specific value provided by the user is large enough, this calculation could overflow an unsigned long leading to a smaller than expected number of huge pages. To fix, check the calculation for overflow. If overflow is detected, use ULONG_MAX as the requested value. This is inline with the user request to allocate as many huge pages as possible. It was also noticed that the above calculation was done outside the hugetlb_lock. Therefore, the values could be inconsistent and result in underflow. To fix, the calculation is moved within the routine set_max_huge_pages() where the lock is held. In addition, the code in __nr_hugepages_store_common() which tries to handle the case of not being able to allocate a node mask would likely result in incorrect behavior. Luckily, it is very unlikely we will ever take this path. If we do, simply return ENOMEM. Link: http://lkml.kernel.org/r/20190328220533.19884-1-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jing Xiangfeng <jingxiangfeng@huawei.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Alex Ghiti <alex@ghiti.fr> Cc: Jing Xiangfeng <jingxiangfeng@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 03:19:20 +03:00
* Node specific request. count adjustment happens in
* set_max_huge_pages() after acquiring hugetlb_lock.
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
*/
init_nodemask_of_node(&nodes_allowed, nid);
n_mask = &nodes_allowed;
hugetlbfs: fix potential over/underflow setting node specific nr_hugepages The number of node specific huge pages can be set via a file such as: /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages When a node specific value is specified, the global number of huge pages must also be adjusted. This adjustment is calculated as the specified node specific value + (global value - current node value). If the node specific value provided by the user is large enough, this calculation could overflow an unsigned long leading to a smaller than expected number of huge pages. To fix, check the calculation for overflow. If overflow is detected, use ULONG_MAX as the requested value. This is inline with the user request to allocate as many huge pages as possible. It was also noticed that the above calculation was done outside the hugetlb_lock. Therefore, the values could be inconsistent and result in underflow. To fix, the calculation is moved within the routine set_max_huge_pages() where the lock is held. In addition, the code in __nr_hugepages_store_common() which tries to handle the case of not being able to allocate a node mask would likely result in incorrect behavior. Luckily, it is very unlikely we will ever take this path. If we do, simply return ENOMEM. Link: http://lkml.kernel.org/r/20190328220533.19884-1-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Jing Xiangfeng <jingxiangfeng@huawei.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Alex Ghiti <alex@ghiti.fr> Cc: Jing Xiangfeng <jingxiangfeng@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 03:19:20 +03:00
}
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
err = set_max_huge_pages(h, count, nid, n_mask);
hugetlb: derive huge pages nodes allowed from task mempolicy This patch derives a "nodes_allowed" node mask from the numa mempolicy of the task modifying the number of persistent huge pages to control the allocation, freeing and adjusting of surplus huge pages when the pool page count is modified via the new sysctl or sysfs attribute "nr_hugepages_mempolicy". The nodes_allowed mask is derived as follows: * For "default" [NULL] task mempolicy, a NULL nodemask_t pointer is produced. This will cause the hugetlb subsystem to use node_online_map as the "nodes_allowed". This preserves the behavior before this patch. * For "preferred" mempolicy, including explicit local allocation, a nodemask with the single preferred node will be produced. "local" policy will NOT track any internode migrations of the task adjusting nr_hugepages. * For "bind" and "interleave" policy, the mempolicy's nodemask will be used. * Other than to inform the construction of the nodes_allowed node mask, the actual mempolicy mode is ignored. That is, all modes behave like interleave over the resulting nodes_allowed mask with no "fallback". See the updated documentation [next patch] for more information about the implications of this patch. Examples: Starting with: Node 0 HugePages_Total: 0 Node 1 HugePages_Total: 0 Node 2 HugePages_Total: 0 Node 3 HugePages_Total: 0 Default behavior [with or without this patch] balances persistent hugepage allocation across nodes [with sufficient contiguous memory]: sysctl vm.nr_hugepages[_mempolicy]=32 yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 8 Node 3 HugePages_Total: 8 Of course, we only have nr_hugepages_mempolicy with the patch, but with default mempolicy, nr_hugepages_mempolicy behaves the same as nr_hugepages. Applying mempolicy--e.g., with numactl [using '-m' a.k.a. '--membind' because it allows multiple nodes to be specified and it's easy to type]--we can allocate huge pages on individual nodes or sets of nodes. So, starting from the condition above, with 8 huge pages per node, add 8 more to node 2 using: numactl -m 2 sysctl vm.nr_hugepages_mempolicy=40 This yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The incremental 8 huge pages were restricted to node 2 by the specified mempolicy. Similarly, we can use mempolicy to free persistent huge pages from specified nodes: numactl -m 0,1 sysctl vm.nr_hugepages_mempolicy=32 yields: Node 0 HugePages_Total: 4 Node 1 HugePages_Total: 4 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The 8 huge pages freed were balanced over nodes 0 and 1. [rientjes@google.com: accomodate reworked NODEMASK_ALLOC] Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:21 +03:00
return err ? err : len;
hugetlb: derive huge pages nodes allowed from task mempolicy This patch derives a "nodes_allowed" node mask from the numa mempolicy of the task modifying the number of persistent huge pages to control the allocation, freeing and adjusting of surplus huge pages when the pool page count is modified via the new sysctl or sysfs attribute "nr_hugepages_mempolicy". The nodes_allowed mask is derived as follows: * For "default" [NULL] task mempolicy, a NULL nodemask_t pointer is produced. This will cause the hugetlb subsystem to use node_online_map as the "nodes_allowed". This preserves the behavior before this patch. * For "preferred" mempolicy, including explicit local allocation, a nodemask with the single preferred node will be produced. "local" policy will NOT track any internode migrations of the task adjusting nr_hugepages. * For "bind" and "interleave" policy, the mempolicy's nodemask will be used. * Other than to inform the construction of the nodes_allowed node mask, the actual mempolicy mode is ignored. That is, all modes behave like interleave over the resulting nodes_allowed mask with no "fallback". See the updated documentation [next patch] for more information about the implications of this patch. Examples: Starting with: Node 0 HugePages_Total: 0 Node 1 HugePages_Total: 0 Node 2 HugePages_Total: 0 Node 3 HugePages_Total: 0 Default behavior [with or without this patch] balances persistent hugepage allocation across nodes [with sufficient contiguous memory]: sysctl vm.nr_hugepages[_mempolicy]=32 yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 8 Node 3 HugePages_Total: 8 Of course, we only have nr_hugepages_mempolicy with the patch, but with default mempolicy, nr_hugepages_mempolicy behaves the same as nr_hugepages. Applying mempolicy--e.g., with numactl [using '-m' a.k.a. '--membind' because it allows multiple nodes to be specified and it's easy to type]--we can allocate huge pages on individual nodes or sets of nodes. So, starting from the condition above, with 8 huge pages per node, add 8 more to node 2 using: numactl -m 2 sysctl vm.nr_hugepages_mempolicy=40 This yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The incremental 8 huge pages were restricted to node 2 by the specified mempolicy. Similarly, we can use mempolicy to free persistent huge pages from specified nodes: numactl -m 0,1 sysctl vm.nr_hugepages_mempolicy=32 yields: Node 0 HugePages_Total: 4 Node 1 HugePages_Total: 4 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The 8 huge pages freed were balanced over nodes 0 and 1. [rientjes@google.com: accomodate reworked NODEMASK_ALLOC] Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:21 +03:00
}
static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
struct kobject *kobj, const char *buf,
size_t len)
{
struct hstate *h;
unsigned long count;
int nid;
int err;
err = kstrtoul(buf, 10, &count);
if (err)
return err;
h = kobj_to_hstate(kobj, &nid);
return __nr_hugepages_store_common(obey_mempolicy, h, nid, count, len);
}
hugetlb: derive huge pages nodes allowed from task mempolicy This patch derives a "nodes_allowed" node mask from the numa mempolicy of the task modifying the number of persistent huge pages to control the allocation, freeing and adjusting of surplus huge pages when the pool page count is modified via the new sysctl or sysfs attribute "nr_hugepages_mempolicy". The nodes_allowed mask is derived as follows: * For "default" [NULL] task mempolicy, a NULL nodemask_t pointer is produced. This will cause the hugetlb subsystem to use node_online_map as the "nodes_allowed". This preserves the behavior before this patch. * For "preferred" mempolicy, including explicit local allocation, a nodemask with the single preferred node will be produced. "local" policy will NOT track any internode migrations of the task adjusting nr_hugepages. * For "bind" and "interleave" policy, the mempolicy's nodemask will be used. * Other than to inform the construction of the nodes_allowed node mask, the actual mempolicy mode is ignored. That is, all modes behave like interleave over the resulting nodes_allowed mask with no "fallback". See the updated documentation [next patch] for more information about the implications of this patch. Examples: Starting with: Node 0 HugePages_Total: 0 Node 1 HugePages_Total: 0 Node 2 HugePages_Total: 0 Node 3 HugePages_Total: 0 Default behavior [with or without this patch] balances persistent hugepage allocation across nodes [with sufficient contiguous memory]: sysctl vm.nr_hugepages[_mempolicy]=32 yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 8 Node 3 HugePages_Total: 8 Of course, we only have nr_hugepages_mempolicy with the patch, but with default mempolicy, nr_hugepages_mempolicy behaves the same as nr_hugepages. Applying mempolicy--e.g., with numactl [using '-m' a.k.a. '--membind' because it allows multiple nodes to be specified and it's easy to type]--we can allocate huge pages on individual nodes or sets of nodes. So, starting from the condition above, with 8 huge pages per node, add 8 more to node 2 using: numactl -m 2 sysctl vm.nr_hugepages_mempolicy=40 This yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The incremental 8 huge pages were restricted to node 2 by the specified mempolicy. Similarly, we can use mempolicy to free persistent huge pages from specified nodes: numactl -m 0,1 sysctl vm.nr_hugepages_mempolicy=32 yields: Node 0 HugePages_Total: 4 Node 1 HugePages_Total: 4 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The 8 huge pages freed were balanced over nodes 0 and 1. [rientjes@google.com: accomodate reworked NODEMASK_ALLOC] Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:21 +03:00
static ssize_t nr_hugepages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return nr_hugepages_show_common(kobj, attr, buf);
}
static ssize_t nr_hugepages_store(struct kobject *kobj,
struct kobj_attribute *attr, const char *buf, size_t len)
{
return nr_hugepages_store_common(false, kobj, buf, len);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
}
HSTATE_ATTR(nr_hugepages);
hugetlb: derive huge pages nodes allowed from task mempolicy This patch derives a "nodes_allowed" node mask from the numa mempolicy of the task modifying the number of persistent huge pages to control the allocation, freeing and adjusting of surplus huge pages when the pool page count is modified via the new sysctl or sysfs attribute "nr_hugepages_mempolicy". The nodes_allowed mask is derived as follows: * For "default" [NULL] task mempolicy, a NULL nodemask_t pointer is produced. This will cause the hugetlb subsystem to use node_online_map as the "nodes_allowed". This preserves the behavior before this patch. * For "preferred" mempolicy, including explicit local allocation, a nodemask with the single preferred node will be produced. "local" policy will NOT track any internode migrations of the task adjusting nr_hugepages. * For "bind" and "interleave" policy, the mempolicy's nodemask will be used. * Other than to inform the construction of the nodes_allowed node mask, the actual mempolicy mode is ignored. That is, all modes behave like interleave over the resulting nodes_allowed mask with no "fallback". See the updated documentation [next patch] for more information about the implications of this patch. Examples: Starting with: Node 0 HugePages_Total: 0 Node 1 HugePages_Total: 0 Node 2 HugePages_Total: 0 Node 3 HugePages_Total: 0 Default behavior [with or without this patch] balances persistent hugepage allocation across nodes [with sufficient contiguous memory]: sysctl vm.nr_hugepages[_mempolicy]=32 yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 8 Node 3 HugePages_Total: 8 Of course, we only have nr_hugepages_mempolicy with the patch, but with default mempolicy, nr_hugepages_mempolicy behaves the same as nr_hugepages. Applying mempolicy--e.g., with numactl [using '-m' a.k.a. '--membind' because it allows multiple nodes to be specified and it's easy to type]--we can allocate huge pages on individual nodes or sets of nodes. So, starting from the condition above, with 8 huge pages per node, add 8 more to node 2 using: numactl -m 2 sysctl vm.nr_hugepages_mempolicy=40 This yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The incremental 8 huge pages were restricted to node 2 by the specified mempolicy. Similarly, we can use mempolicy to free persistent huge pages from specified nodes: numactl -m 0,1 sysctl vm.nr_hugepages_mempolicy=32 yields: Node 0 HugePages_Total: 4 Node 1 HugePages_Total: 4 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The 8 huge pages freed were balanced over nodes 0 and 1. [rientjes@google.com: accomodate reworked NODEMASK_ALLOC] Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:21 +03:00
#ifdef CONFIG_NUMA
/*
* hstate attribute for optionally mempolicy-based constraint on persistent
* huge page alloc/free.
*/
static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
hugetlb: derive huge pages nodes allowed from task mempolicy This patch derives a "nodes_allowed" node mask from the numa mempolicy of the task modifying the number of persistent huge pages to control the allocation, freeing and adjusting of surplus huge pages when the pool page count is modified via the new sysctl or sysfs attribute "nr_hugepages_mempolicy". The nodes_allowed mask is derived as follows: * For "default" [NULL] task mempolicy, a NULL nodemask_t pointer is produced. This will cause the hugetlb subsystem to use node_online_map as the "nodes_allowed". This preserves the behavior before this patch. * For "preferred" mempolicy, including explicit local allocation, a nodemask with the single preferred node will be produced. "local" policy will NOT track any internode migrations of the task adjusting nr_hugepages. * For "bind" and "interleave" policy, the mempolicy's nodemask will be used. * Other than to inform the construction of the nodes_allowed node mask, the actual mempolicy mode is ignored. That is, all modes behave like interleave over the resulting nodes_allowed mask with no "fallback". See the updated documentation [next patch] for more information about the implications of this patch. Examples: Starting with: Node 0 HugePages_Total: 0 Node 1 HugePages_Total: 0 Node 2 HugePages_Total: 0 Node 3 HugePages_Total: 0 Default behavior [with or without this patch] balances persistent hugepage allocation across nodes [with sufficient contiguous memory]: sysctl vm.nr_hugepages[_mempolicy]=32 yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 8 Node 3 HugePages_Total: 8 Of course, we only have nr_hugepages_mempolicy with the patch, but with default mempolicy, nr_hugepages_mempolicy behaves the same as nr_hugepages. Applying mempolicy--e.g., with numactl [using '-m' a.k.a. '--membind' because it allows multiple nodes to be specified and it's easy to type]--we can allocate huge pages on individual nodes or sets of nodes. So, starting from the condition above, with 8 huge pages per node, add 8 more to node 2 using: numactl -m 2 sysctl vm.nr_hugepages_mempolicy=40 This yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The incremental 8 huge pages were restricted to node 2 by the specified mempolicy. Similarly, we can use mempolicy to free persistent huge pages from specified nodes: numactl -m 0,1 sysctl vm.nr_hugepages_mempolicy=32 yields: Node 0 HugePages_Total: 4 Node 1 HugePages_Total: 4 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The 8 huge pages freed were balanced over nodes 0 and 1. [rientjes@google.com: accomodate reworked NODEMASK_ALLOC] Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:21 +03:00
{
return nr_hugepages_show_common(kobj, attr, buf);
}
static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
struct kobj_attribute *attr, const char *buf, size_t len)
{
return nr_hugepages_store_common(true, kobj, buf, len);
hugetlb: derive huge pages nodes allowed from task mempolicy This patch derives a "nodes_allowed" node mask from the numa mempolicy of the task modifying the number of persistent huge pages to control the allocation, freeing and adjusting of surplus huge pages when the pool page count is modified via the new sysctl or sysfs attribute "nr_hugepages_mempolicy". The nodes_allowed mask is derived as follows: * For "default" [NULL] task mempolicy, a NULL nodemask_t pointer is produced. This will cause the hugetlb subsystem to use node_online_map as the "nodes_allowed". This preserves the behavior before this patch. * For "preferred" mempolicy, including explicit local allocation, a nodemask with the single preferred node will be produced. "local" policy will NOT track any internode migrations of the task adjusting nr_hugepages. * For "bind" and "interleave" policy, the mempolicy's nodemask will be used. * Other than to inform the construction of the nodes_allowed node mask, the actual mempolicy mode is ignored. That is, all modes behave like interleave over the resulting nodes_allowed mask with no "fallback". See the updated documentation [next patch] for more information about the implications of this patch. Examples: Starting with: Node 0 HugePages_Total: 0 Node 1 HugePages_Total: 0 Node 2 HugePages_Total: 0 Node 3 HugePages_Total: 0 Default behavior [with or without this patch] balances persistent hugepage allocation across nodes [with sufficient contiguous memory]: sysctl vm.nr_hugepages[_mempolicy]=32 yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 8 Node 3 HugePages_Total: 8 Of course, we only have nr_hugepages_mempolicy with the patch, but with default mempolicy, nr_hugepages_mempolicy behaves the same as nr_hugepages. Applying mempolicy--e.g., with numactl [using '-m' a.k.a. '--membind' because it allows multiple nodes to be specified and it's easy to type]--we can allocate huge pages on individual nodes or sets of nodes. So, starting from the condition above, with 8 huge pages per node, add 8 more to node 2 using: numactl -m 2 sysctl vm.nr_hugepages_mempolicy=40 This yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The incremental 8 huge pages were restricted to node 2 by the specified mempolicy. Similarly, we can use mempolicy to free persistent huge pages from specified nodes: numactl -m 0,1 sysctl vm.nr_hugepages_mempolicy=32 yields: Node 0 HugePages_Total: 4 Node 1 HugePages_Total: 4 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The 8 huge pages freed were balanced over nodes 0 and 1. [rientjes@google.com: accomodate reworked NODEMASK_ALLOC] Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:21 +03:00
}
HSTATE_ATTR(nr_hugepages_mempolicy);
#endif
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
struct hstate *h = kobj_to_hstate(kobj, NULL);
return sysfs_emit(buf, "%lu\n", h->nr_overcommit_huge_pages);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
}
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
struct kobj_attribute *attr, const char *buf, size_t count)
{
int err;
unsigned long input;
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
struct hstate *h = kobj_to_hstate(kobj, NULL);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
if (hstate_is_gigantic(h))
return -EINVAL;
err = kstrtoul(buf, 10, &input);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
if (err)
return err;
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
h->nr_overcommit_huge_pages = input;
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
return count;
}
HSTATE_ATTR(nr_overcommit_hugepages);
static ssize_t free_hugepages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
struct hstate *h;
unsigned long free_huge_pages;
int nid;
h = kobj_to_hstate(kobj, &nid);
if (nid == NUMA_NO_NODE)
free_huge_pages = h->free_huge_pages;
else
free_huge_pages = h->free_huge_pages_node[nid];
return sysfs_emit(buf, "%lu\n", free_huge_pages);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
}
HSTATE_ATTR_RO(free_hugepages);
static ssize_t resv_hugepages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
struct hstate *h = kobj_to_hstate(kobj, NULL);
return sysfs_emit(buf, "%lu\n", h->resv_huge_pages);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
}
HSTATE_ATTR_RO(resv_hugepages);
static ssize_t surplus_hugepages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
struct hstate *h;
unsigned long surplus_huge_pages;
int nid;
h = kobj_to_hstate(kobj, &nid);
if (nid == NUMA_NO_NODE)
surplus_huge_pages = h->surplus_huge_pages;
else
surplus_huge_pages = h->surplus_huge_pages_node[nid];
return sysfs_emit(buf, "%lu\n", surplus_huge_pages);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
}
HSTATE_ATTR_RO(surplus_hugepages);
hugetlb: add demote hugetlb page sysfs interfaces Patch series "hugetlb: add demote/split page functionality", v4. The concurrent use of multiple hugetlb page sizes on a single system is becoming more common. One of the reasons is better TLB support for gigantic page sizes on x86 hardware. In addition, hugetlb pages are being used to back VMs in hosting environments. When using hugetlb pages to back VMs, it is often desirable to preallocate hugetlb pools. This avoids the delay and uncertainty of allocating hugetlb pages at VM startup. In addition, preallocating huge pages minimizes the issue of memory fragmentation that increases the longer the system is up and running. In such environments, a combination of larger and smaller hugetlb pages are preallocated in anticipation of backing VMs of various sizes. Over time, the preallocated pool of smaller hugetlb pages may become depleted while larger hugetlb pages still remain. In such situations, it is desirable to convert larger hugetlb pages to smaller hugetlb pages. Converting larger to smaller hugetlb pages can be accomplished today by first freeing the larger page to the buddy allocator and then allocating the smaller pages. For example, to convert 50 GB pages on x86: gb_pages=`cat .../hugepages-1048576kB/nr_hugepages` m2_pages=`cat .../hugepages-2048kB/nr_hugepages` echo $(($gb_pages - 50)) > .../hugepages-1048576kB/nr_hugepages echo $(($m2_pages + 25600)) > .../hugepages-2048kB/nr_hugepages On an idle system this operation is fairly reliable and results are as expected. The number of 2MB pages is increased as expected and the time of the operation is a second or two. However, when there is activity on the system the following issues arise: 1) This process can take quite some time, especially if allocation of the smaller pages is not immediate and requires migration/compaction. 2) There is no guarantee that the total size of smaller pages allocated will match the size of the larger page which was freed. This is because the area freed by the larger page could quickly be fragmented. In a test environment with a load that continually fills the page cache with clean pages, results such as the following can be observed: Unexpected number of 2MB pages allocated: Expected 25600, have 19944 real 0m42.092s user 0m0.008s sys 0m41.467s To address these issues, introduce the concept of hugetlb page demotion. Demotion provides a means of 'in place' splitting of a hugetlb page to pages of a smaller size. This avoids freeing pages to buddy and then trying to allocate from buddy. Page demotion is controlled via sysfs files that reside in the per-hugetlb page size and per node directories. - demote_size Target page size for demotion, a smaller huge page size. File can be written to chose a smaller huge page size if multiple are available. - demote Writable number of hugetlb pages to be demoted To demote 50 GB huge pages, one would: cat .../hugepages-1048576kB/free_hugepages /* optional, verify free pages */ cat .../hugepages-1048576kB/demote_size /* optional, verify target size */ echo 50 > .../hugepages-1048576kB/demote Only hugetlb pages which are free at the time of the request can be demoted. Demotion does not add to the complexity of surplus pages and honors reserved huge pages. Therefore, when a value is written to the sysfs demote file, that value is only the maximum number of pages which will be demoted. It is possible fewer will actually be demoted. The recently introduced per-hstate mutex is used to synchronize demote operations with other operations that modify hugetlb pools. Real world use cases -------------------- The above scenario describes a real world use case where hugetlb pages are used to back VMs on x86. Both issues of long allocation times and not necessarily getting the expected number of smaller huge pages after a free and allocate cycle have been experienced. The occurrence of these issues is dependent on other activity within the host and can not be predicted. This patch (of 5): Two new sysfs files are added to demote hugtlb pages. These files are both per-hugetlb page size and per node. Files are: demote_size - The size in Kb that pages are demoted to. (read-write) demote - The number of huge pages to demote. (write-only) By default, demote_size is the next smallest huge page size. Valid huge page sizes less than huge page size may be written to this file. When huge pages are demoted, they are demoted to this size. Writing a value to demote will result in an attempt to demote that number of hugetlb pages to an appropriate number of demote_size pages. NOTE: Demote interfaces are only provided for huge page sizes if there is a smaller target demote huge page size. For example, on x86 1GB huge pages will have demote interfaces. 2MB huge pages will not have demote interfaces. This patch does not provide full demote functionality. It only provides the sysfs interfaces. It also provides documentation for the new interfaces. [mike.kravetz@oracle.com: n_mask initialization does not need to be protected by the mutex] Link: https://lkml.kernel.org/r/0530e4ef-2492-5186-f919-5db68edea654@oracle.com Link: https://lkml.kernel.org/r/20211007181918.136982-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: David Rientjes <rientjes@google.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Nghia Le <nghialm78@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:20 +03:00
static ssize_t demote_store(struct kobject *kobj,
struct kobj_attribute *attr, const char *buf, size_t len)
{
unsigned long nr_demote;
unsigned long nr_available;
nodemask_t nodes_allowed, *n_mask;
struct hstate *h;
int err = 0;
int nid;
err = kstrtoul(buf, 10, &nr_demote);
if (err)
return err;
h = kobj_to_hstate(kobj, &nid);
if (nid != NUMA_NO_NODE) {
init_nodemask_of_node(&nodes_allowed, nid);
n_mask = &nodes_allowed;
} else {
n_mask = &node_states[N_MEMORY];
}
/* Synchronize with other sysfs operations modifying huge pages */
mutex_lock(&h->resize_lock);
spin_lock_irq(&hugetlb_lock);
while (nr_demote) {
/*
* Check for available pages to demote each time thorough the
* loop as demote_pool_huge_page will drop hugetlb_lock.
*/
if (nid != NUMA_NO_NODE)
nr_available = h->free_huge_pages_node[nid];
else
nr_available = h->free_huge_pages;
nr_available -= h->resv_huge_pages;
if (!nr_available)
break;
err = demote_pool_huge_page(h, n_mask);
if (err)
break;
nr_demote--;
}
spin_unlock_irq(&hugetlb_lock);
mutex_unlock(&h->resize_lock);
if (err)
return err;
return len;
}
HSTATE_ATTR_WO(demote);
static ssize_t demote_size_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
int nid;
struct hstate *h = kobj_to_hstate(kobj, &nid);
unsigned long demote_size = (PAGE_SIZE << h->demote_order) / SZ_1K;
return sysfs_emit(buf, "%lukB\n", demote_size);
}
static ssize_t demote_size_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
struct hstate *h, *demote_hstate;
unsigned long demote_size;
unsigned int demote_order;
int nid;
demote_size = (unsigned long)memparse(buf, NULL);
demote_hstate = size_to_hstate(demote_size);
if (!demote_hstate)
return -EINVAL;
demote_order = demote_hstate->order;
hugetlb: be sure to free demoted CMA pages to CMA When huge page demotion is fully implemented, gigantic pages can be demoted to a smaller huge page size. For example, on x86 a 1G page can be demoted to 512 2M pages. However, gigantic pages can potentially be allocated from CMA. If a gigantic page which was allocated from CMA is demoted, the corresponding demoted pages needs to be returned to CMA. Use the new interface cma_pages_valid() to determine if a non-gigantic hugetlb page should be freed to CMA. Also, clear mapping field of these pages as expected by cma_release. This also requires a change to CMA region creation for gigantic pages. CMA uses a per-region bit map to track allocations. When setting up the region, you specify how many pages each bit represents. Currently, only gigantic pages are allocated/freed from CMA so the region is set up such that one bit represents a gigantic page size allocation. With demote, a gigantic page (allocation) could be split into smaller size pages. And, these smaller size pages will be freed to CMA. So, since the per-region bit map needs to be set up to represent the smallest allocation/free size, it now needs to be set to the smallest huge page size which can be freed to CMA. Unfortunately, we set up the CMA region for huge pages before we set up huge pages sizes (hstates). So, technically we do not know the smallest huge page size as this can change via command line options and architecture specific code. Therefore, at region setup time we use HUGETLB_PAGE_ORDER as the smallest possible huge page size that can be given back to CMA. It is possible that this value is sub-optimal for some architectures/config options. If needed, this can be addressed in follow on work. Link: https://lkml.kernel.org/r/20211007181918.136982-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:27 +03:00
if (demote_order < HUGETLB_PAGE_ORDER)
return -EINVAL;
hugetlb: add demote hugetlb page sysfs interfaces Patch series "hugetlb: add demote/split page functionality", v4. The concurrent use of multiple hugetlb page sizes on a single system is becoming more common. One of the reasons is better TLB support for gigantic page sizes on x86 hardware. In addition, hugetlb pages are being used to back VMs in hosting environments. When using hugetlb pages to back VMs, it is often desirable to preallocate hugetlb pools. This avoids the delay and uncertainty of allocating hugetlb pages at VM startup. In addition, preallocating huge pages minimizes the issue of memory fragmentation that increases the longer the system is up and running. In such environments, a combination of larger and smaller hugetlb pages are preallocated in anticipation of backing VMs of various sizes. Over time, the preallocated pool of smaller hugetlb pages may become depleted while larger hugetlb pages still remain. In such situations, it is desirable to convert larger hugetlb pages to smaller hugetlb pages. Converting larger to smaller hugetlb pages can be accomplished today by first freeing the larger page to the buddy allocator and then allocating the smaller pages. For example, to convert 50 GB pages on x86: gb_pages=`cat .../hugepages-1048576kB/nr_hugepages` m2_pages=`cat .../hugepages-2048kB/nr_hugepages` echo $(($gb_pages - 50)) > .../hugepages-1048576kB/nr_hugepages echo $(($m2_pages + 25600)) > .../hugepages-2048kB/nr_hugepages On an idle system this operation is fairly reliable and results are as expected. The number of 2MB pages is increased as expected and the time of the operation is a second or two. However, when there is activity on the system the following issues arise: 1) This process can take quite some time, especially if allocation of the smaller pages is not immediate and requires migration/compaction. 2) There is no guarantee that the total size of smaller pages allocated will match the size of the larger page which was freed. This is because the area freed by the larger page could quickly be fragmented. In a test environment with a load that continually fills the page cache with clean pages, results such as the following can be observed: Unexpected number of 2MB pages allocated: Expected 25600, have 19944 real 0m42.092s user 0m0.008s sys 0m41.467s To address these issues, introduce the concept of hugetlb page demotion. Demotion provides a means of 'in place' splitting of a hugetlb page to pages of a smaller size. This avoids freeing pages to buddy and then trying to allocate from buddy. Page demotion is controlled via sysfs files that reside in the per-hugetlb page size and per node directories. - demote_size Target page size for demotion, a smaller huge page size. File can be written to chose a smaller huge page size if multiple are available. - demote Writable number of hugetlb pages to be demoted To demote 50 GB huge pages, one would: cat .../hugepages-1048576kB/free_hugepages /* optional, verify free pages */ cat .../hugepages-1048576kB/demote_size /* optional, verify target size */ echo 50 > .../hugepages-1048576kB/demote Only hugetlb pages which are free at the time of the request can be demoted. Demotion does not add to the complexity of surplus pages and honors reserved huge pages. Therefore, when a value is written to the sysfs demote file, that value is only the maximum number of pages which will be demoted. It is possible fewer will actually be demoted. The recently introduced per-hstate mutex is used to synchronize demote operations with other operations that modify hugetlb pools. Real world use cases -------------------- The above scenario describes a real world use case where hugetlb pages are used to back VMs on x86. Both issues of long allocation times and not necessarily getting the expected number of smaller huge pages after a free and allocate cycle have been experienced. The occurrence of these issues is dependent on other activity within the host and can not be predicted. This patch (of 5): Two new sysfs files are added to demote hugtlb pages. These files are both per-hugetlb page size and per node. Files are: demote_size - The size in Kb that pages are demoted to. (read-write) demote - The number of huge pages to demote. (write-only) By default, demote_size is the next smallest huge page size. Valid huge page sizes less than huge page size may be written to this file. When huge pages are demoted, they are demoted to this size. Writing a value to demote will result in an attempt to demote that number of hugetlb pages to an appropriate number of demote_size pages. NOTE: Demote interfaces are only provided for huge page sizes if there is a smaller target demote huge page size. For example, on x86 1GB huge pages will have demote interfaces. 2MB huge pages will not have demote interfaces. This patch does not provide full demote functionality. It only provides the sysfs interfaces. It also provides documentation for the new interfaces. [mike.kravetz@oracle.com: n_mask initialization does not need to be protected by the mutex] Link: https://lkml.kernel.org/r/0530e4ef-2492-5186-f919-5db68edea654@oracle.com Link: https://lkml.kernel.org/r/20211007181918.136982-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: David Rientjes <rientjes@google.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Nghia Le <nghialm78@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:20 +03:00
/* demote order must be smaller than hstate order */
h = kobj_to_hstate(kobj, &nid);
if (demote_order >= h->order)
return -EINVAL;
/* resize_lock synchronizes access to demote size and writes */
mutex_lock(&h->resize_lock);
h->demote_order = demote_order;
mutex_unlock(&h->resize_lock);
return count;
}
HSTATE_ATTR(demote_size);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
static struct attribute *hstate_attrs[] = {
&nr_hugepages_attr.attr,
&nr_overcommit_hugepages_attr.attr,
&free_hugepages_attr.attr,
&resv_hugepages_attr.attr,
&surplus_hugepages_attr.attr,
hugetlb: derive huge pages nodes allowed from task mempolicy This patch derives a "nodes_allowed" node mask from the numa mempolicy of the task modifying the number of persistent huge pages to control the allocation, freeing and adjusting of surplus huge pages when the pool page count is modified via the new sysctl or sysfs attribute "nr_hugepages_mempolicy". The nodes_allowed mask is derived as follows: * For "default" [NULL] task mempolicy, a NULL nodemask_t pointer is produced. This will cause the hugetlb subsystem to use node_online_map as the "nodes_allowed". This preserves the behavior before this patch. * For "preferred" mempolicy, including explicit local allocation, a nodemask with the single preferred node will be produced. "local" policy will NOT track any internode migrations of the task adjusting nr_hugepages. * For "bind" and "interleave" policy, the mempolicy's nodemask will be used. * Other than to inform the construction of the nodes_allowed node mask, the actual mempolicy mode is ignored. That is, all modes behave like interleave over the resulting nodes_allowed mask with no "fallback". See the updated documentation [next patch] for more information about the implications of this patch. Examples: Starting with: Node 0 HugePages_Total: 0 Node 1 HugePages_Total: 0 Node 2 HugePages_Total: 0 Node 3 HugePages_Total: 0 Default behavior [with or without this patch] balances persistent hugepage allocation across nodes [with sufficient contiguous memory]: sysctl vm.nr_hugepages[_mempolicy]=32 yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 8 Node 3 HugePages_Total: 8 Of course, we only have nr_hugepages_mempolicy with the patch, but with default mempolicy, nr_hugepages_mempolicy behaves the same as nr_hugepages. Applying mempolicy--e.g., with numactl [using '-m' a.k.a. '--membind' because it allows multiple nodes to be specified and it's easy to type]--we can allocate huge pages on individual nodes or sets of nodes. So, starting from the condition above, with 8 huge pages per node, add 8 more to node 2 using: numactl -m 2 sysctl vm.nr_hugepages_mempolicy=40 This yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The incremental 8 huge pages were restricted to node 2 by the specified mempolicy. Similarly, we can use mempolicy to free persistent huge pages from specified nodes: numactl -m 0,1 sysctl vm.nr_hugepages_mempolicy=32 yields: Node 0 HugePages_Total: 4 Node 1 HugePages_Total: 4 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The 8 huge pages freed were balanced over nodes 0 and 1. [rientjes@google.com: accomodate reworked NODEMASK_ALLOC] Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:21 +03:00
#ifdef CONFIG_NUMA
&nr_hugepages_mempolicy_attr.attr,
#endif
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
NULL,
};
static const struct attribute_group hstate_attr_group = {
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
.attrs = hstate_attrs,
};
hugetlb: add demote hugetlb page sysfs interfaces Patch series "hugetlb: add demote/split page functionality", v4. The concurrent use of multiple hugetlb page sizes on a single system is becoming more common. One of the reasons is better TLB support for gigantic page sizes on x86 hardware. In addition, hugetlb pages are being used to back VMs in hosting environments. When using hugetlb pages to back VMs, it is often desirable to preallocate hugetlb pools. This avoids the delay and uncertainty of allocating hugetlb pages at VM startup. In addition, preallocating huge pages minimizes the issue of memory fragmentation that increases the longer the system is up and running. In such environments, a combination of larger and smaller hugetlb pages are preallocated in anticipation of backing VMs of various sizes. Over time, the preallocated pool of smaller hugetlb pages may become depleted while larger hugetlb pages still remain. In such situations, it is desirable to convert larger hugetlb pages to smaller hugetlb pages. Converting larger to smaller hugetlb pages can be accomplished today by first freeing the larger page to the buddy allocator and then allocating the smaller pages. For example, to convert 50 GB pages on x86: gb_pages=`cat .../hugepages-1048576kB/nr_hugepages` m2_pages=`cat .../hugepages-2048kB/nr_hugepages` echo $(($gb_pages - 50)) > .../hugepages-1048576kB/nr_hugepages echo $(($m2_pages + 25600)) > .../hugepages-2048kB/nr_hugepages On an idle system this operation is fairly reliable and results are as expected. The number of 2MB pages is increased as expected and the time of the operation is a second or two. However, when there is activity on the system the following issues arise: 1) This process can take quite some time, especially if allocation of the smaller pages is not immediate and requires migration/compaction. 2) There is no guarantee that the total size of smaller pages allocated will match the size of the larger page which was freed. This is because the area freed by the larger page could quickly be fragmented. In a test environment with a load that continually fills the page cache with clean pages, results such as the following can be observed: Unexpected number of 2MB pages allocated: Expected 25600, have 19944 real 0m42.092s user 0m0.008s sys 0m41.467s To address these issues, introduce the concept of hugetlb page demotion. Demotion provides a means of 'in place' splitting of a hugetlb page to pages of a smaller size. This avoids freeing pages to buddy and then trying to allocate from buddy. Page demotion is controlled via sysfs files that reside in the per-hugetlb page size and per node directories. - demote_size Target page size for demotion, a smaller huge page size. File can be written to chose a smaller huge page size if multiple are available. - demote Writable number of hugetlb pages to be demoted To demote 50 GB huge pages, one would: cat .../hugepages-1048576kB/free_hugepages /* optional, verify free pages */ cat .../hugepages-1048576kB/demote_size /* optional, verify target size */ echo 50 > .../hugepages-1048576kB/demote Only hugetlb pages which are free at the time of the request can be demoted. Demotion does not add to the complexity of surplus pages and honors reserved huge pages. Therefore, when a value is written to the sysfs demote file, that value is only the maximum number of pages which will be demoted. It is possible fewer will actually be demoted. The recently introduced per-hstate mutex is used to synchronize demote operations with other operations that modify hugetlb pools. Real world use cases -------------------- The above scenario describes a real world use case where hugetlb pages are used to back VMs on x86. Both issues of long allocation times and not necessarily getting the expected number of smaller huge pages after a free and allocate cycle have been experienced. The occurrence of these issues is dependent on other activity within the host and can not be predicted. This patch (of 5): Two new sysfs files are added to demote hugtlb pages. These files are both per-hugetlb page size and per node. Files are: demote_size - The size in Kb that pages are demoted to. (read-write) demote - The number of huge pages to demote. (write-only) By default, demote_size is the next smallest huge page size. Valid huge page sizes less than huge page size may be written to this file. When huge pages are demoted, they are demoted to this size. Writing a value to demote will result in an attempt to demote that number of hugetlb pages to an appropriate number of demote_size pages. NOTE: Demote interfaces are only provided for huge page sizes if there is a smaller target demote huge page size. For example, on x86 1GB huge pages will have demote interfaces. 2MB huge pages will not have demote interfaces. This patch does not provide full demote functionality. It only provides the sysfs interfaces. It also provides documentation for the new interfaces. [mike.kravetz@oracle.com: n_mask initialization does not need to be protected by the mutex] Link: https://lkml.kernel.org/r/0530e4ef-2492-5186-f919-5db68edea654@oracle.com Link: https://lkml.kernel.org/r/20211007181918.136982-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: David Rientjes <rientjes@google.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Nghia Le <nghialm78@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:20 +03:00
static struct attribute *hstate_demote_attrs[] = {
&demote_size_attr.attr,
&demote_attr.attr,
NULL,
};
static const struct attribute_group hstate_demote_attr_group = {
.attrs = hstate_demote_attrs,
};
static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
struct kobject **hstate_kobjs,
const struct attribute_group *hstate_attr_group)
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
{
int retval;
int hi = hstate_index(h);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
if (!hstate_kobjs[hi])
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
return -ENOMEM;
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
if (retval) {
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
kobject_put(hstate_kobjs[hi]);
hstate_kobjs[hi] = NULL;
}
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
hugetlb: add demote hugetlb page sysfs interfaces Patch series "hugetlb: add demote/split page functionality", v4. The concurrent use of multiple hugetlb page sizes on a single system is becoming more common. One of the reasons is better TLB support for gigantic page sizes on x86 hardware. In addition, hugetlb pages are being used to back VMs in hosting environments. When using hugetlb pages to back VMs, it is often desirable to preallocate hugetlb pools. This avoids the delay and uncertainty of allocating hugetlb pages at VM startup. In addition, preallocating huge pages minimizes the issue of memory fragmentation that increases the longer the system is up and running. In such environments, a combination of larger and smaller hugetlb pages are preallocated in anticipation of backing VMs of various sizes. Over time, the preallocated pool of smaller hugetlb pages may become depleted while larger hugetlb pages still remain. In such situations, it is desirable to convert larger hugetlb pages to smaller hugetlb pages. Converting larger to smaller hugetlb pages can be accomplished today by first freeing the larger page to the buddy allocator and then allocating the smaller pages. For example, to convert 50 GB pages on x86: gb_pages=`cat .../hugepages-1048576kB/nr_hugepages` m2_pages=`cat .../hugepages-2048kB/nr_hugepages` echo $(($gb_pages - 50)) > .../hugepages-1048576kB/nr_hugepages echo $(($m2_pages + 25600)) > .../hugepages-2048kB/nr_hugepages On an idle system this operation is fairly reliable and results are as expected. The number of 2MB pages is increased as expected and the time of the operation is a second or two. However, when there is activity on the system the following issues arise: 1) This process can take quite some time, especially if allocation of the smaller pages is not immediate and requires migration/compaction. 2) There is no guarantee that the total size of smaller pages allocated will match the size of the larger page which was freed. This is because the area freed by the larger page could quickly be fragmented. In a test environment with a load that continually fills the page cache with clean pages, results such as the following can be observed: Unexpected number of 2MB pages allocated: Expected 25600, have 19944 real 0m42.092s user 0m0.008s sys 0m41.467s To address these issues, introduce the concept of hugetlb page demotion. Demotion provides a means of 'in place' splitting of a hugetlb page to pages of a smaller size. This avoids freeing pages to buddy and then trying to allocate from buddy. Page demotion is controlled via sysfs files that reside in the per-hugetlb page size and per node directories. - demote_size Target page size for demotion, a smaller huge page size. File can be written to chose a smaller huge page size if multiple are available. - demote Writable number of hugetlb pages to be demoted To demote 50 GB huge pages, one would: cat .../hugepages-1048576kB/free_hugepages /* optional, verify free pages */ cat .../hugepages-1048576kB/demote_size /* optional, verify target size */ echo 50 > .../hugepages-1048576kB/demote Only hugetlb pages which are free at the time of the request can be demoted. Demotion does not add to the complexity of surplus pages and honors reserved huge pages. Therefore, when a value is written to the sysfs demote file, that value is only the maximum number of pages which will be demoted. It is possible fewer will actually be demoted. The recently introduced per-hstate mutex is used to synchronize demote operations with other operations that modify hugetlb pools. Real world use cases -------------------- The above scenario describes a real world use case where hugetlb pages are used to back VMs on x86. Both issues of long allocation times and not necessarily getting the expected number of smaller huge pages after a free and allocate cycle have been experienced. The occurrence of these issues is dependent on other activity within the host and can not be predicted. This patch (of 5): Two new sysfs files are added to demote hugtlb pages. These files are both per-hugetlb page size and per node. Files are: demote_size - The size in Kb that pages are demoted to. (read-write) demote - The number of huge pages to demote. (write-only) By default, demote_size is the next smallest huge page size. Valid huge page sizes less than huge page size may be written to this file. When huge pages are demoted, they are demoted to this size. Writing a value to demote will result in an attempt to demote that number of hugetlb pages to an appropriate number of demote_size pages. NOTE: Demote interfaces are only provided for huge page sizes if there is a smaller target demote huge page size. For example, on x86 1GB huge pages will have demote interfaces. 2MB huge pages will not have demote interfaces. This patch does not provide full demote functionality. It only provides the sysfs interfaces. It also provides documentation for the new interfaces. [mike.kravetz@oracle.com: n_mask initialization does not need to be protected by the mutex] Link: https://lkml.kernel.org/r/0530e4ef-2492-5186-f919-5db68edea654@oracle.com Link: https://lkml.kernel.org/r/20211007181918.136982-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: David Rientjes <rientjes@google.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Nghia Le <nghialm78@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:20 +03:00
if (h->demote_order) {
if (sysfs_create_group(hstate_kobjs[hi],
&hstate_demote_attr_group))
pr_warn("HugeTLB unable to create demote interfaces for %s\n", h->name);
}
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
return retval;
}
static void __init hugetlb_sysfs_init(void)
{
struct hstate *h;
int err;
hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
if (!hugepages_kobj)
return;
for_each_hstate(h) {
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
hstate_kobjs, &hstate_attr_group);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
if (err)
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
pr_err("HugeTLB: Unable to add hstate %s", h->name);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
}
}
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
#ifdef CONFIG_NUMA
/*
* node_hstate/s - associate per node hstate attributes, via their kobjects,
* with node devices in node_devices[] using a parallel array. The array
* index of a node device or _hstate == node id.
* This is here to avoid any static dependency of the node device driver, in
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
* the base kernel, on the hugetlb module.
*/
struct node_hstate {
struct kobject *hugepages_kobj;
struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
};
static struct node_hstate node_hstates[MAX_NUMNODES];
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
/*
* A subset of global hstate attributes for node devices
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
*/
static struct attribute *per_node_hstate_attrs[] = {
&nr_hugepages_attr.attr,
&free_hugepages_attr.attr,
&surplus_hugepages_attr.attr,
NULL,
};
static const struct attribute_group per_node_hstate_attr_group = {
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
.attrs = per_node_hstate_attrs,
};
/*
* kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
* Returns node id via non-NULL nidp.
*/
static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
{
int nid;
for (nid = 0; nid < nr_node_ids; nid++) {
struct node_hstate *nhs = &node_hstates[nid];
int i;
for (i = 0; i < HUGE_MAX_HSTATE; i++)
if (nhs->hstate_kobjs[i] == kobj) {
if (nidp)
*nidp = nid;
return &hstates[i];
}
}
BUG();
return NULL;
}
/*
* Unregister hstate attributes from a single node device.
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
* No-op if no hstate attributes attached.
*/
static void hugetlb_unregister_node(struct node *node)
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
{
struct hstate *h;
struct node_hstate *nhs = &node_hstates[node->dev.id];
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
if (!nhs->hugepages_kobj)
return; /* no hstate attributes */
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
for_each_hstate(h) {
int idx = hstate_index(h);
if (nhs->hstate_kobjs[idx]) {
kobject_put(nhs->hstate_kobjs[idx]);
nhs->hstate_kobjs[idx] = NULL;
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
}
}
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
kobject_put(nhs->hugepages_kobj);
nhs->hugepages_kobj = NULL;
}
/*
* Register hstate attributes for a single node device.
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
* No-op if attributes already registered.
*/
static void hugetlb_register_node(struct node *node)
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
{
struct hstate *h;
struct node_hstate *nhs = &node_hstates[node->dev.id];
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
int err;
if (nhs->hugepages_kobj)
return; /* already allocated */
nhs->hugepages_kobj = kobject_create_and_add("hugepages",
&node->dev.kobj);
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
if (!nhs->hugepages_kobj)
return;
for_each_hstate(h) {
err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
nhs->hstate_kobjs,
&per_node_hstate_attr_group);
if (err) {
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
pr_err("HugeTLB: Unable to add hstate %s for node %d\n",
h->name, node->dev.id);
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
hugetlb_unregister_node(node);
break;
}
}
}
/*
* hugetlb init time: register hstate attributes for all registered node
* devices of nodes that have memory. All on-line nodes should have
* registered their associated device by this time.
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
*/
static void __init hugetlb_register_all_nodes(void)
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
{
int nid;
for_each_node_state(nid, N_MEMORY) {
struct node *node = node_devices[nid];
if (node->dev.id == nid)
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
hugetlb_register_node(node);
}
/*
* Let the node device driver know we're here so it can
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
* [un]register hstate attributes on node hotplug.
*/
register_hugetlbfs_with_node(hugetlb_register_node,
hugetlb_unregister_node);
}
#else /* !CONFIG_NUMA */
static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
{
BUG();
if (nidp)
*nidp = -1;
return NULL;
}
static void hugetlb_register_all_nodes(void) { }
#endif
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
static int __init hugetlb_init(void)
{
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
int i;
hugetlb: use page.private for hugetlb specific page flags Patch series "create hugetlb flags to consolidate state", v3. While discussing a series of hugetlb fixes in [1], it became evident that the hugetlb specific page state information is stored in a somewhat haphazard manner. Code dealing with state information would be easier to read, understand and maintain if this information was stored in a consistent manner. This series uses page.private of the hugetlb head page for storing a set of hugetlb specific page flags. Routines are priovided for test, set and clear of the flags. [1] https://lore.kernel.org/r/20210106084739.63318-1-songmuchun@bytedance.com This patch (of 4): As hugetlbfs evolved, state information about hugetlb pages was added. One 'convenient' way of doing this was to use available fields in tail pages. Over time, it has become difficult to know the meaning or contents of fields simply by looking at a small bit of code. Sometimes, the naming is just confusing. For example: The PagePrivate flag indicates a huge page reservation was consumed and needs to be restored if an error is encountered and the page is freed before it is instantiated. The page.private field contains the pointer to a subpool if the page is associated with one. In an effort to make the code more readable, use page.private to contain hugetlb specific page flags. These flags will have test, set and clear functions similar to those used for 'normal' page flags. More importantly, an enum of flag values will be created with names that actually reflect their purpose. In this patch, - Create infrastructure for hugetlb specific page flag functions - Move subpool pointer to page[1].private to make way for flags Create routines with meaningful names to modify subpool field - Use new HPageRestoreReserve flag instead of PagePrivate Conversion of other state information will happen in subsequent patches. Link: https://lkml.kernel.org/r/20210122195231.324857-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210122195231.324857-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:51 +03:00
BUILD_BUG_ON(sizeof_field(struct page, private) * BITS_PER_BYTE <
__NR_HPAGEFLAGS);
if (!hugepages_supported()) {
if (hugetlb_max_hstate || default_hstate_max_huge_pages)
pr_warn("HugeTLB: huge pages not supported, ignoring associated command-line parameters\n");
return 0;
}
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
/*
* Make sure HPAGE_SIZE (HUGETLB_PAGE_ORDER) hstate exists. Some
* architectures depend on setup being done here.
*/
hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
if (!parsed_default_hugepagesz) {
/*
* If we did not parse a default huge page size, set
* default_hstate_idx to HPAGE_SIZE hstate. And, if the
* number of huge pages for this default size was implicitly
* specified, set that here as well.
* Note that the implicit setting will overwrite an explicit
* setting. A warning will be printed in this case.
*/
default_hstate_idx = hstate_index(size_to_hstate(HPAGE_SIZE));
if (default_hstate_max_huge_pages) {
if (default_hstate.max_huge_pages) {
char buf[32];
string_get_size(huge_page_size(&default_hstate),
1, STRING_UNITS_2, buf, 32);
pr_warn("HugeTLB: Ignoring hugepages=%lu associated with %s page size\n",
default_hstate.max_huge_pages, buf);
pr_warn("HugeTLB: Using hugepages=%lu for number of default huge pages\n",
default_hstate_max_huge_pages);
}
default_hstate.max_huge_pages =
default_hstate_max_huge_pages;
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
hugetlb: fix wrong use of nr_online_nodes Patch series "hugetlb: Fix some incorrect behavior", v3. This series fix three bugs of hugetlb: 1) Invalid use of nr_online_nodes; 2) Inconsistency between 1G hugepage and 2M hugepage; 3) Useless information in dmesg. This patch (of 4): Certain systems are designed to have sparse/discontiguous nodes. In this case, nr_online_nodes can not be used to walk through numa node. Also, a valid node may be greater than nr_online_nodes. However, in hugetlb, it is assumed that nodes are contiguous. For sparse/discontiguous nodes, the current code may treat a valid node as invalid, and will fail to allocate all hugepages on a valid node that "nid >= nr_online_nodes". As David suggested: if (tmp >= nr_online_nodes) goto invalid; Just imagine node 0 and node 2 are online, and node 1 is offline. Assuming that "node < 2" is valid is wrong. Recheck all the places that use nr_online_nodes, and repair them one by one. [liupeng256@huawei.com: v4] Link: https://lkml.kernel.org/r/20220416103526.3287348-1-liupeng256@huawei.com Link: https://lkml.kernel.org/r/20220413032915.251254-1-liupeng256@huawei.com Link: https://lkml.kernel.org/r/20220413032915.251254-2-liupeng256@huawei.com Fixes: 4178158ef8ca ("hugetlbfs: fix issue of preallocation of gigantic pages can't work") Fixes: b5389086ad7b ("hugetlbfs: extend the definition of hugepages parameter to support node allocation") Fixes: e79ce9832316 ("hugetlbfs: fix a truncation issue in hugepages parameter") Fixes: f9317f77a6e0 ("hugetlb: clean up potential spectre issue warnings") Signed-off-by: Peng Liu <liupeng256@huawei.com> Suggested-by: David Hildenbrand <david@redhat.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Liu Yuntao <liuyuntao10@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-04-30 00:36:57 +03:00
for_each_online_node(i)
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
default_hstate.max_huge_pages_node[i] =
default_hugepages_in_node[i];
mm/hugetlb.c: warn the user when issues arise on boot due to hugepages When the user specifies too many hugepages or an invalid default_hugepagesz the communication to the user is implicit in the allocation message. This patch adds a warning when the desired page count is not allocated and prints an error when the default_hugepagesz is invalid on boot. During boot hugepages will allocate until there is a fraction of the hugepage size left. That is, we allocate until either the request is satisfied or memory for the pages is exhausted. When memory for the pages is exhausted, it will most likely lead to the system failing with the OOM manager not finding enough (or anything) to kill (unless you're using really big hugepages in the order of 100s of MB or in the GBs). The user will most likely see the OOM messages much later in the boot sequence than the implicitly stated message. Worse yet, you may even get an OOM for each processor which causes many pages of OOMs on modern systems. Although these messages will be printed earlier than the OOM messages, at least giving the user errors and warnings will highlight the configuration as an issue. I'm trying to point the user in the right direction by providing a more robust statement of what is failing. During the sysctl or echo command, the user can check the results much easier than if the system hangs during boot and the scenario of having nothing to OOM for kernel memory is highly unlikely. Mike said: "Before sending out this patch, I asked Liam off list why he was doing it. Was it something he just thought would be useful? Or, was there some type of user situation/need. He said that he had been called in to assist on several occasions when a system OOMed during boot. In almost all of these situations, the user had grossly misconfigured huge pages. DB users want to pre-allocate just the right amount of huge pages, but sometimes they can be really off. In such situations, the huge page init code just allocates as many huge pages as it can and reports the number allocated. There is no indication that it quit allocating because it ran out of memory. Of course, a user could compare the number in the message to what they requested on the command line to determine if they got all the huge pages they requested. The thought was that it would be useful to at least flag this situation. That way, the user might be able to better relate the huge page allocation failure to the OOM. I'm not sure if the e-mail discussion made it obvious that this is something he has seen on several occasions. I see Michal's point that this will only flag the situation where someone configures huge pages very badly. And, a more extensive look at the situation of misconfiguring huge pages might be in order. But, this has happened on several occasions which led to the creation of this patch" [akpm@linux-foundation.org: reposition memfmt() to avoid forward declaration] Link: http://lkml.kernel.org/r/20170603005413.10380-1-Liam.Howlett@Oracle.com Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: zhongjiang <zhongjiang@huawei.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-11 01:48:15 +03:00
}
mm/hugetlb.c: fix incorrect proc nr_hugepages value Currently incorrect default hugepage pool size is reported by proc nr_hugepages when number of pages for the default huge page size is specified twice. When multiple huge page sizes are supported, /proc/sys/vm/nr_hugepages indicates the current number of pre-allocated huge pages of the default size. Basically /proc/sys/vm/nr_hugepages displays default_hstate-> max_huge_pages and after boot time pre-allocation, max_huge_pages should equal the number of pre-allocated pages (nr_hugepages). Test case: Note that this is specific to x86 architecture. Boot the kernel with command line option 'default_hugepagesz=1G hugepages=X hugepagesz=2M hugepages=Y hugepagesz=1G hugepages=Z'. After boot, 'cat /proc/sys/vm/nr_hugepages' and 'sysctl -a | grep hugepages' returns the value X. However, dmesg output shows that Z huge pages were pre-allocated. So, the root cause of the problem here is that the global variable default_hstate_max_huge_pages is set if a default huge page size is specified (directly or indirectly) on the command line. After the command line processing in hugetlb_init, if default_hstate_max_huge_pages is set, the value is assigned to default_hstae.max_huge_pages. However, default_hstate.max_huge_pages may have already been set based on the number of pre-allocated huge pages of default_hstate size. The solution to this problem is if hstate->max_huge_pages is already set then it should not set as a result of global max_huge_pages value. Basically if the value of the variable hugepages is set multiple times on a command line for a specific supported hugepagesize then proc layer should consider the last specified value. Signed-off-by: Vaishali Thakkar <vaishali.thakkar@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-02-18 00:11:26 +03:00
}
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
hugetlb_cma_check();
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
hugetlb_init_hstates();
gather_bootmem_prealloc();
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
report_hugepages();
hugetlb_sysfs_init();
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
hugetlb_register_all_nodes();
hugetlb_cgroup_file_init();
hugetlb: add per node hstate attributes Add the per huge page size control/query attributes to the per node sysdevs: /sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/ nr_hugepages - r/w free_huge_pages - r/o surplus_huge_pages - r/o The patch attempts to re-use/share as much of the existing global hstate attribute initialization and handling, and the "nodes_allowed" constraint processing as possible. Calling set_max_huge_pages() with no node indicates a change to global hstate parameters. In this case, any non-default task mempolicy will be used to generate the nodes_allowed mask. A valid node id indicates an update to that node's hstate parameters, and the count argument specifies the target count for the specified node. From this info, we compute the target global count for the hstate and construct a nodes_allowed node mask contain only the specified node. Setting the node specific nr_hugepages via the per node attribute effectively ignores any task mempolicy or cpuset constraints. With this patch: (me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB ./ ../ free_hugepages nr_hugepages surplus_hugepages Starting from: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 0 Node 2 HugePages_Free: 0 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 0 Allocate 16 persistent huge pages on node 2: (me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages [Note that this is equivalent to: numactl -m 2 hugeadmin --pool-pages-min 2M:+16 ] Yields: Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 16 Node 2 HugePages_Free: 16 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 vm.nr_hugepages = 16 Global controls work as expected--reduce pool to 8 persistent huge pages: (me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages Node 0 HugePages_Total: 0 Node 0 HugePages_Free: 0 Node 0 HugePages_Surp: 0 Node 1 HugePages_Total: 0 Node 1 HugePages_Free: 0 Node 1 HugePages_Surp: 0 Node 2 HugePages_Total: 8 Node 2 HugePages_Free: 8 Node 2 HugePages_Surp: 0 Node 3 HugePages_Total: 0 Node 3 HugePages_Free: 0 Node 3 HugePages_Surp: 0 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:25 +03:00
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
#ifdef CONFIG_SMP
num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus());
#else
num_fault_mutexes = 1;
#endif
hugetlb_fault_mutex_table =
treewide: kmalloc() -> kmalloc_array() The kmalloc() function has a 2-factor argument form, kmalloc_array(). This patch replaces cases of: kmalloc(a * b, gfp) with: kmalloc_array(a * b, gfp) as well as handling cases of: kmalloc(a * b * c, gfp) with: kmalloc(array3_size(a, b, c), gfp) as it's slightly less ugly than: kmalloc_array(array_size(a, b), c, gfp) This does, however, attempt to ignore constant size factors like: kmalloc(4 * 1024, gfp) though any constants defined via macros get caught up in the conversion. Any factors with a sizeof() of "unsigned char", "char", and "u8" were dropped, since they're redundant. The tools/ directory was manually excluded, since it has its own implementation of kmalloc(). The Coccinelle script used for this was: // Fix redundant parens around sizeof(). @@ type TYPE; expression THING, E; @@ ( kmalloc( - (sizeof(TYPE)) * E + sizeof(TYPE) * E , ...) | kmalloc( - (sizeof(THING)) * E + sizeof(THING) * E , ...) ) // Drop single-byte sizes and redundant parens. @@ expression COUNT; typedef u8; typedef __u8; @@ ( kmalloc( - sizeof(u8) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(__u8) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(char) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(unsigned char) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(u8) * COUNT + COUNT , ...) | kmalloc( - sizeof(__u8) * COUNT + COUNT , ...) | kmalloc( - sizeof(char) * COUNT + COUNT , ...) | kmalloc( - sizeof(unsigned char) * COUNT + COUNT , ...) ) // 2-factor product with sizeof(type/expression) and identifier or constant. @@ type TYPE; expression THING; identifier COUNT_ID; constant COUNT_CONST; @@ ( - kmalloc + kmalloc_array ( - sizeof(TYPE) * (COUNT_ID) + COUNT_ID, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * COUNT_ID + COUNT_ID, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * (COUNT_CONST) + COUNT_CONST, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * COUNT_CONST + COUNT_CONST, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * (COUNT_ID) + COUNT_ID, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * COUNT_ID + COUNT_ID, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * (COUNT_CONST) + COUNT_CONST, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * COUNT_CONST + COUNT_CONST, sizeof(THING) , ...) ) // 2-factor product, only identifiers. @@ identifier SIZE, COUNT; @@ - kmalloc + kmalloc_array ( - SIZE * COUNT + COUNT, SIZE , ...) // 3-factor product with 1 sizeof(type) or sizeof(expression), with // redundant parens removed. @@ expression THING; identifier STRIDE, COUNT; type TYPE; @@ ( kmalloc( - sizeof(TYPE) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(TYPE) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(TYPE) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(TYPE) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(THING) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kmalloc( - sizeof(THING) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kmalloc( - sizeof(THING) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kmalloc( - sizeof(THING) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) ) // 3-factor product with 2 sizeof(variable), with redundant parens removed. @@ expression THING1, THING2; identifier COUNT; type TYPE1, TYPE2; @@ ( kmalloc( - sizeof(TYPE1) * sizeof(TYPE2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kmalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kmalloc( - sizeof(THING1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kmalloc( - sizeof(THING1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kmalloc( - sizeof(TYPE1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) | kmalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) ) // 3-factor product, only identifiers, with redundant parens removed. @@ identifier STRIDE, SIZE, COUNT; @@ ( kmalloc( - (COUNT) * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - (COUNT) * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - (COUNT) * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - (COUNT) * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) ) // Any remaining multi-factor products, first at least 3-factor products, // when they're not all constants... @@ expression E1, E2, E3; constant C1, C2, C3; @@ ( kmalloc(C1 * C2 * C3, ...) | kmalloc( - (E1) * E2 * E3 + array3_size(E1, E2, E3) , ...) | kmalloc( - (E1) * (E2) * E3 + array3_size(E1, E2, E3) , ...) | kmalloc( - (E1) * (E2) * (E3) + array3_size(E1, E2, E3) , ...) | kmalloc( - E1 * E2 * E3 + array3_size(E1, E2, E3) , ...) ) // And then all remaining 2 factors products when they're not all constants, // keeping sizeof() as the second factor argument. @@ expression THING, E1, E2; type TYPE; constant C1, C2, C3; @@ ( kmalloc(sizeof(THING) * C2, ...) | kmalloc(sizeof(TYPE) * C2, ...) | kmalloc(C1 * C2 * C3, ...) | kmalloc(C1 * C2, ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * (E2) + E2, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * E2 + E2, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * (E2) + E2, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * E2 + E2, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - (E1) * E2 + E1, E2 , ...) | - kmalloc + kmalloc_array ( - (E1) * (E2) + E1, E2 , ...) | - kmalloc + kmalloc_array ( - E1 * E2 + E1, E2 , ...) ) Signed-off-by: Kees Cook <keescook@chromium.org>
2018-06-12 23:55:00 +03:00
kmalloc_array(num_fault_mutexes, sizeof(struct mutex),
GFP_KERNEL);
BUG_ON(!hugetlb_fault_mutex_table);
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
for (i = 0; i < num_fault_mutexes; i++)
mutex_init(&hugetlb_fault_mutex_table[i]);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
return 0;
}
hugetlb: make mm and fs code explicitly non-modular The Kconfig currently controlling compilation of this code is: config HUGETLBFS bool "HugeTLB file system support" ...meaning that it currently is not being built as a module by anyone. Lets remove the modular code that is essentially orphaned, so that when reading the driver there is no doubt it is builtin-only. Since module_init translates to device_initcall in the non-modular case, the init ordering gets moved to earlier levels when we use the more appropriate initcalls here. Originally I had the fs part and the mm part as separate commits, just by happenstance of the nature of how I detected these non-modular use cases. But that can possibly introduce regressions if the patch merge ordering puts the fs part 1st -- as the 0-day testing reported a splat at mount time. Investigating with "initcall_debug" showed that the delta was init_hugetlbfs_fs being called _before_ hugetlb_init instead of after. So both the fs change and the mm change are here together. In addition, it worked before due to luck of link order, since they were both in the same initcall category. So we now have the fs part using fs_initcall, and the mm part using subsys_initcall, which puts it one bucket earlier. It now passes the basic sanity test that failed in earlier 0-day testing. We delete the MODULE_LICENSE tag and capture that information at the top of the file alongside author comments, etc. We don't replace module.h with init.h since the file already has that. Also note that MODULE_ALIAS is a no-op for non-modular code. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Reported-by: kernel test robot <ying.huang@linux.intel.com> Cc: Nadia Yvette Chambers <nyc@holomorphy.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-15 02:21:52 +03:00
subsys_initcall(hugetlb_init);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
hugetlbfs: add arch_hugetlb_valid_size Patch series "Clean up hugetlb boot command line processing", v4. Longpeng(Mike) reported a weird message from hugetlb command line processing and proposed a solution [1]. While the proposed patch does address the specific issue, there are other related issues in command line processing. As hugetlbfs evolved, updates to command line processing have been made to meet immediate needs and not necessarily in a coordinated manner. The result is that some processing is done in arch specific code, some is done in arch independent code and coordination is problematic. Semantics can vary between architectures. The patch series does the following: - Define arch specific arch_hugetlb_valid_size routine used to validate passed huge page sizes. - Move hugepagesz= command line parsing out of arch specific code and into an arch independent routine. - Clean up command line processing to follow desired semantics and document those semantics. [1] https://lore.kernel.org/linux-mm/20200305033014.1152-1-longpeng2@huawei.com This patch (of 3): The architecture independent routine hugetlb_default_setup sets up the default huge pages size. It has no way to verify if the passed value is valid, so it accepts it and attempts to validate at a later time. This requires undocumented cooperation between the arch specific and arch independent code. For architectures that support more than one huge page size, provide a routine arch_hugetlb_valid_size to validate a huge page size. hugetlb_default_setup can use this to validate passed values. arch_hugetlb_valid_size will also be used in a subsequent patch to move processing of the "hugepagesz=" in arch specific code to a common routine in arch independent code. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200428205614.246260-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-2-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:34 +03:00
/* Overwritten by architectures with more huge page sizes */
bool __init __attribute((weak)) arch_hugetlb_valid_size(unsigned long size)
mm/hugetlb: introduce hugetlb_bad_size() When any unsupported hugepage size is specified, 'hugepagesz=' and 'hugepages=' should be ignored during command line parsing until any supported hugepage size is found. But currently incorrect number of hugepages are allocated when unsupported size is specified as it fails to ignore the 'hugepages=' command. Test case: Note that this is specific to x86 architecture. Boot the kernel with command line option 'hugepagesz=256M hugepages=X'. After boot, dmesg output shows that X number of hugepages of the size 2M is pre-allocated instead of 0. So, to handle such command line options, introduce new routine hugetlb_bad_size. The routine hugetlb_bad_size sets the global variable parsed_valid_hugepagesz. We are using parsed_valid_hugepagesz to save the state when unsupported hugepagesize is found so that we can ignore the 'hugepages=' parameters after that and then reset the variable when supported hugepage size is found. The routine hugetlb_bad_size can be called while setting 'hugepagesz=' parameter in an architecture specific code. Signed-off-by: Vaishali Thakkar <vaishali.thakkar@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com> Cc: Dominik Dingel <dingel@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: James Hogan <james.hogan@imgtec.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-20 03:11:04 +03:00
{
hugetlbfs: add arch_hugetlb_valid_size Patch series "Clean up hugetlb boot command line processing", v4. Longpeng(Mike) reported a weird message from hugetlb command line processing and proposed a solution [1]. While the proposed patch does address the specific issue, there are other related issues in command line processing. As hugetlbfs evolved, updates to command line processing have been made to meet immediate needs and not necessarily in a coordinated manner. The result is that some processing is done in arch specific code, some is done in arch independent code and coordination is problematic. Semantics can vary between architectures. The patch series does the following: - Define arch specific arch_hugetlb_valid_size routine used to validate passed huge page sizes. - Move hugepagesz= command line parsing out of arch specific code and into an arch independent routine. - Clean up command line processing to follow desired semantics and document those semantics. [1] https://lore.kernel.org/linux-mm/20200305033014.1152-1-longpeng2@huawei.com This patch (of 3): The architecture independent routine hugetlb_default_setup sets up the default huge pages size. It has no way to verify if the passed value is valid, so it accepts it and attempts to validate at a later time. This requires undocumented cooperation between the arch specific and arch independent code. For architectures that support more than one huge page size, provide a routine arch_hugetlb_valid_size to validate a huge page size. hugetlb_default_setup can use this to validate passed values. arch_hugetlb_valid_size will also be used in a subsequent patch to move processing of the "hugepagesz=" in arch specific code to a common routine in arch independent code. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200428205614.246260-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-2-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:34 +03:00
return size == HPAGE_SIZE;
mm/hugetlb: introduce hugetlb_bad_size() When any unsupported hugepage size is specified, 'hugepagesz=' and 'hugepages=' should be ignored during command line parsing until any supported hugepage size is found. But currently incorrect number of hugepages are allocated when unsupported size is specified as it fails to ignore the 'hugepages=' command. Test case: Note that this is specific to x86 architecture. Boot the kernel with command line option 'hugepagesz=256M hugepages=X'. After boot, dmesg output shows that X number of hugepages of the size 2M is pre-allocated instead of 0. So, to handle such command line options, introduce new routine hugetlb_bad_size. The routine hugetlb_bad_size sets the global variable parsed_valid_hugepagesz. We are using parsed_valid_hugepagesz to save the state when unsupported hugepagesize is found so that we can ignore the 'hugepages=' parameters after that and then reset the variable when supported hugepage size is found. The routine hugetlb_bad_size can be called while setting 'hugepagesz=' parameter in an architecture specific code. Signed-off-by: Vaishali Thakkar <vaishali.thakkar@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com> Cc: Dominik Dingel <dingel@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: James Hogan <james.hogan@imgtec.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-20 03:11:04 +03:00
}
void __init hugetlb_add_hstate(unsigned int order)
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
{
struct hstate *h;
unsigned long i;
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
if (size_to_hstate(PAGE_SIZE << order)) {
return;
}
hugetlb: rename max_hstate to hugetlb_max_hstate This patchset implements a cgroup resource controller for HugeTLB pages. The controller allows to limit the HugeTLB usage per control group and enforces the controller limit during page fault. Since HugeTLB doesn't support page reclaim, enforcing the limit at page fault time implies that, the application will get SIGBUS signal if it tries to access HugeTLB pages beyond its limit. This requires the application to know beforehand how much HugeTLB pages it would require for its use. The goal is to control how many HugeTLB pages a group of task can allocate. It can be looked at as an extension of the existing quota interface which limits the number of HugeTLB pages per hugetlbfs superblock. HPC job scheduler requires jobs to specify their resource requirements in the job file. Once their requirements can be met, job schedulers like (SLURM) will schedule the job. We need to make sure that the jobs won't consume more resources than requested. If they do we should either error out or kill the application. This patch: Rename max_hstate to hugetlb_max_hstate. We will be using this from other subsystems like hugetlb controller in later patches. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-08-01 03:41:54 +04:00
BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
BUG_ON(order == 0);
hugetlb: rename max_hstate to hugetlb_max_hstate This patchset implements a cgroup resource controller for HugeTLB pages. The controller allows to limit the HugeTLB usage per control group and enforces the controller limit during page fault. Since HugeTLB doesn't support page reclaim, enforcing the limit at page fault time implies that, the application will get SIGBUS signal if it tries to access HugeTLB pages beyond its limit. This requires the application to know beforehand how much HugeTLB pages it would require for its use. The goal is to control how many HugeTLB pages a group of task can allocate. It can be looked at as an extension of the existing quota interface which limits the number of HugeTLB pages per hugetlbfs superblock. HPC job scheduler requires jobs to specify their resource requirements in the job file. Once their requirements can be met, job schedulers like (SLURM) will schedule the job. We need to make sure that the jobs won't consume more resources than requested. If they do we should either error out or kill the application. This patch: Rename max_hstate to hugetlb_max_hstate. We will be using this from other subsystems like hugetlb controller in later patches. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-08-01 03:41:54 +04:00
h = &hstates[hugetlb_max_hstate++];
hugetlb: add per-hstate mutex to synchronize user adjustments The helper routine hstate_next_node_to_alloc accesses and modifies the hstate variable next_nid_to_alloc. The helper is used by the routines alloc_pool_huge_page and adjust_pool_surplus. adjust_pool_surplus is called with hugetlb_lock held. However, alloc_pool_huge_page can not be called with the hugetlb lock held as it will call the page allocator. Two instances of alloc_pool_huge_page could be run in parallel or alloc_pool_huge_page could run in parallel with adjust_pool_surplus which may result in the variable next_nid_to_alloc becoming invalid for the caller and pages being allocated on the wrong node. Both alloc_pool_huge_page and adjust_pool_surplus are only called from the routine set_max_huge_pages after boot. set_max_huge_pages is only called as the reusult of a user writing to the proc/sysfs nr_hugepages, or nr_hugepages_mempolicy file to adjust the number of hugetlb pages. It makes little sense to allow multiple adjustment to the number of hugetlb pages in parallel. Add a mutex to the hstate and use it to only allow one hugetlb page adjustment at a time. This will synchronize modifications to the next_nid_to_alloc variable. Link: https://lkml.kernel.org/r/20210409205254.242291-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:34:52 +03:00
mutex_init(&h->resize_lock);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
h->order = order;
h->mask = ~(huge_page_size(h) - 1);
for (i = 0; i < MAX_NUMNODES; ++i)
INIT_LIST_HEAD(&h->hugepage_freelists[i]);
INIT_LIST_HEAD(&h->hugepage_activelist);
h->next_nid_to_alloc = first_memory_node;
h->next_nid_to_free = first_memory_node;
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
huge_page_size(h)/1024);
mm: hugetlb: introduce nr_free_vmemmap_pages in the struct hstate All the infrastructure is ready, so we introduce nr_free_vmemmap_pages field in the hstate to indicate how many vmemmap pages associated with a HugeTLB page that can be freed to buddy allocator. And initialize it in the hugetlb_vmemmap_init(). This patch is actual enablement of the feature. There are only (RESERVE_VMEMMAP_SIZE / sizeof(struct page)) struct page structs that can be used when CONFIG_HUGETLB_PAGE_FREE_VMEMMAP, so add a BUILD_BUG_ON to catch invalid usage of the tail struct page. Link: https://lkml.kernel.org/r/20210510030027.56044-10-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Tested-by: Chen Huang <chenhuang5@huawei.com> Tested-by: Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:47:33 +03:00
hugetlb_vmemmap_init(h);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
parsed_hstate = h;
}
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
bool __init __weak hugetlb_node_alloc_supported(void)
{
return true;
}
static void __init hugepages_clear_pages_in_node(void)
{
if (!hugetlb_max_hstate) {
default_hstate_max_huge_pages = 0;
memset(default_hugepages_in_node, 0,
MAX_NUMNODES * sizeof(unsigned int));
} else {
parsed_hstate->max_huge_pages = 0;
memset(parsed_hstate->max_huge_pages_node, 0,
MAX_NUMNODES * sizeof(unsigned int));
}
}
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
/*
* hugepages command line processing
* hugepages normally follows a valid hugepagsz or default_hugepagsz
* specification. If not, ignore the hugepages value. hugepages can also
* be the first huge page command line option in which case it implicitly
* specifies the number of huge pages for the default size.
*/
static int __init hugepages_setup(char *s)
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
{
unsigned long *mhp;
static unsigned long *last_mhp;
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
int node = NUMA_NO_NODE;
int count;
unsigned long tmp;
char *p = s;
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
mm/hugetlb: introduce hugetlb_bad_size() When any unsupported hugepage size is specified, 'hugepagesz=' and 'hugepages=' should be ignored during command line parsing until any supported hugepage size is found. But currently incorrect number of hugepages are allocated when unsupported size is specified as it fails to ignore the 'hugepages=' command. Test case: Note that this is specific to x86 architecture. Boot the kernel with command line option 'hugepagesz=256M hugepages=X'. After boot, dmesg output shows that X number of hugepages of the size 2M is pre-allocated instead of 0. So, to handle such command line options, introduce new routine hugetlb_bad_size. The routine hugetlb_bad_size sets the global variable parsed_valid_hugepagesz. We are using parsed_valid_hugepagesz to save the state when unsupported hugepagesize is found so that we can ignore the 'hugepages=' parameters after that and then reset the variable when supported hugepage size is found. The routine hugetlb_bad_size can be called while setting 'hugepagesz=' parameter in an architecture specific code. Signed-off-by: Vaishali Thakkar <vaishali.thakkar@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com> Cc: Dominik Dingel <dingel@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: James Hogan <james.hogan@imgtec.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-20 03:11:04 +03:00
if (!parsed_valid_hugepagesz) {
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
pr_warn("HugeTLB: hugepages=%s does not follow a valid hugepagesz, ignoring\n", s);
mm/hugetlb: introduce hugetlb_bad_size() When any unsupported hugepage size is specified, 'hugepagesz=' and 'hugepages=' should be ignored during command line parsing until any supported hugepage size is found. But currently incorrect number of hugepages are allocated when unsupported size is specified as it fails to ignore the 'hugepages=' command. Test case: Note that this is specific to x86 architecture. Boot the kernel with command line option 'hugepagesz=256M hugepages=X'. After boot, dmesg output shows that X number of hugepages of the size 2M is pre-allocated instead of 0. So, to handle such command line options, introduce new routine hugetlb_bad_size. The routine hugetlb_bad_size sets the global variable parsed_valid_hugepagesz. We are using parsed_valid_hugepagesz to save the state when unsupported hugepagesize is found so that we can ignore the 'hugepages=' parameters after that and then reset the variable when supported hugepage size is found. The routine hugetlb_bad_size can be called while setting 'hugepagesz=' parameter in an architecture specific code. Signed-off-by: Vaishali Thakkar <vaishali.thakkar@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com> Cc: Dominik Dingel <dingel@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: James Hogan <james.hogan@imgtec.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-20 03:11:04 +03:00
parsed_valid_hugepagesz = true;
return 1;
mm/hugetlb: introduce hugetlb_bad_size() When any unsupported hugepage size is specified, 'hugepagesz=' and 'hugepages=' should be ignored during command line parsing until any supported hugepage size is found. But currently incorrect number of hugepages are allocated when unsupported size is specified as it fails to ignore the 'hugepages=' command. Test case: Note that this is specific to x86 architecture. Boot the kernel with command line option 'hugepagesz=256M hugepages=X'. After boot, dmesg output shows that X number of hugepages of the size 2M is pre-allocated instead of 0. So, to handle such command line options, introduce new routine hugetlb_bad_size. The routine hugetlb_bad_size sets the global variable parsed_valid_hugepagesz. We are using parsed_valid_hugepagesz to save the state when unsupported hugepagesize is found so that we can ignore the 'hugepages=' parameters after that and then reset the variable when supported hugepage size is found. The routine hugetlb_bad_size can be called while setting 'hugepagesz=' parameter in an architecture specific code. Signed-off-by: Vaishali Thakkar <vaishali.thakkar@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com> Cc: Dominik Dingel <dingel@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: James Hogan <james.hogan@imgtec.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-20 03:11:04 +03:00
}
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
/*
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
* !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter
* yet, so this hugepages= parameter goes to the "default hstate".
* Otherwise, it goes with the previously parsed hugepagesz or
* default_hugepagesz.
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
*/
mm/hugetlb: introduce hugetlb_bad_size() When any unsupported hugepage size is specified, 'hugepagesz=' and 'hugepages=' should be ignored during command line parsing until any supported hugepage size is found. But currently incorrect number of hugepages are allocated when unsupported size is specified as it fails to ignore the 'hugepages=' command. Test case: Note that this is specific to x86 architecture. Boot the kernel with command line option 'hugepagesz=256M hugepages=X'. After boot, dmesg output shows that X number of hugepages of the size 2M is pre-allocated instead of 0. So, to handle such command line options, introduce new routine hugetlb_bad_size. The routine hugetlb_bad_size sets the global variable parsed_valid_hugepagesz. We are using parsed_valid_hugepagesz to save the state when unsupported hugepagesize is found so that we can ignore the 'hugepages=' parameters after that and then reset the variable when supported hugepage size is found. The routine hugetlb_bad_size can be called while setting 'hugepagesz=' parameter in an architecture specific code. Signed-off-by: Vaishali Thakkar <vaishali.thakkar@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com> Cc: Dominik Dingel <dingel@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: James Hogan <james.hogan@imgtec.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-20 03:11:04 +03:00
else if (!hugetlb_max_hstate)
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
mhp = &default_hstate_max_huge_pages;
else
mhp = &parsed_hstate->max_huge_pages;
if (mhp == last_mhp) {
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
pr_warn("HugeTLB: hugepages= specified twice without interleaving hugepagesz=, ignoring hugepages=%s\n", s);
return 1;
}
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
while (*p) {
count = 0;
if (sscanf(p, "%lu%n", &tmp, &count) != 1)
goto invalid;
/* Parameter is node format */
if (p[count] == ':') {
if (!hugetlb_node_alloc_supported()) {
pr_warn("HugeTLB: architecture can't support node specific alloc, ignoring!\n");
return 1;
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
}
hugetlb: fix wrong use of nr_online_nodes Patch series "hugetlb: Fix some incorrect behavior", v3. This series fix three bugs of hugetlb: 1) Invalid use of nr_online_nodes; 2) Inconsistency between 1G hugepage and 2M hugepage; 3) Useless information in dmesg. This patch (of 4): Certain systems are designed to have sparse/discontiguous nodes. In this case, nr_online_nodes can not be used to walk through numa node. Also, a valid node may be greater than nr_online_nodes. However, in hugetlb, it is assumed that nodes are contiguous. For sparse/discontiguous nodes, the current code may treat a valid node as invalid, and will fail to allocate all hugepages on a valid node that "nid >= nr_online_nodes". As David suggested: if (tmp >= nr_online_nodes) goto invalid; Just imagine node 0 and node 2 are online, and node 1 is offline. Assuming that "node < 2" is valid is wrong. Recheck all the places that use nr_online_nodes, and repair them one by one. [liupeng256@huawei.com: v4] Link: https://lkml.kernel.org/r/20220416103526.3287348-1-liupeng256@huawei.com Link: https://lkml.kernel.org/r/20220413032915.251254-1-liupeng256@huawei.com Link: https://lkml.kernel.org/r/20220413032915.251254-2-liupeng256@huawei.com Fixes: 4178158ef8ca ("hugetlbfs: fix issue of preallocation of gigantic pages can't work") Fixes: b5389086ad7b ("hugetlbfs: extend the definition of hugepages parameter to support node allocation") Fixes: e79ce9832316 ("hugetlbfs: fix a truncation issue in hugepages parameter") Fixes: f9317f77a6e0 ("hugetlb: clean up potential spectre issue warnings") Signed-off-by: Peng Liu <liupeng256@huawei.com> Suggested-by: David Hildenbrand <david@redhat.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Liu Yuntao <liuyuntao10@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-04-30 00:36:57 +03:00
if (tmp >= MAX_NUMNODES || !node_online(tmp))
goto invalid;
hugetlb: fix wrong use of nr_online_nodes Patch series "hugetlb: Fix some incorrect behavior", v3. This series fix three bugs of hugetlb: 1) Invalid use of nr_online_nodes; 2) Inconsistency between 1G hugepage and 2M hugepage; 3) Useless information in dmesg. This patch (of 4): Certain systems are designed to have sparse/discontiguous nodes. In this case, nr_online_nodes can not be used to walk through numa node. Also, a valid node may be greater than nr_online_nodes. However, in hugetlb, it is assumed that nodes are contiguous. For sparse/discontiguous nodes, the current code may treat a valid node as invalid, and will fail to allocate all hugepages on a valid node that "nid >= nr_online_nodes". As David suggested: if (tmp >= nr_online_nodes) goto invalid; Just imagine node 0 and node 2 are online, and node 1 is offline. Assuming that "node < 2" is valid is wrong. Recheck all the places that use nr_online_nodes, and repair them one by one. [liupeng256@huawei.com: v4] Link: https://lkml.kernel.org/r/20220416103526.3287348-1-liupeng256@huawei.com Link: https://lkml.kernel.org/r/20220413032915.251254-1-liupeng256@huawei.com Link: https://lkml.kernel.org/r/20220413032915.251254-2-liupeng256@huawei.com Fixes: 4178158ef8ca ("hugetlbfs: fix issue of preallocation of gigantic pages can't work") Fixes: b5389086ad7b ("hugetlbfs: extend the definition of hugepages parameter to support node allocation") Fixes: e79ce9832316 ("hugetlbfs: fix a truncation issue in hugepages parameter") Fixes: f9317f77a6e0 ("hugetlb: clean up potential spectre issue warnings") Signed-off-by: Peng Liu <liupeng256@huawei.com> Suggested-by: David Hildenbrand <david@redhat.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Liu Yuntao <liuyuntao10@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-04-30 00:36:57 +03:00
node = array_index_nospec(tmp, MAX_NUMNODES);
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
p += count + 1;
/* Parse hugepages */
if (sscanf(p, "%lu%n", &tmp, &count) != 1)
goto invalid;
if (!hugetlb_max_hstate)
default_hugepages_in_node[node] = tmp;
else
parsed_hstate->max_huge_pages_node[node] = tmp;
*mhp += tmp;
/* Go to parse next node*/
if (p[count] == ',')
p += count + 1;
else
break;
} else {
if (p != s)
goto invalid;
*mhp = tmp;
break;
}
}
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
/*
* Global state is always initialized later in hugetlb_init.
* But we need to allocate gigantic hstates here early to still
* use the bootmem allocator.
*/
if (hugetlb_max_hstate && hstate_is_gigantic(parsed_hstate))
hugetlb_hstate_alloc_pages(parsed_hstate);
last_mhp = mhp;
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
return 1;
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
invalid:
pr_warn("HugeTLB: Invalid hugepages parameter %s\n", p);
hugepages_clear_pages_in_node();
return 1;
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
}
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
__setup("hugepages=", hugepages_setup);
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
/*
* hugepagesz command line processing
* A specific huge page size can only be specified once with hugepagesz.
* hugepagesz is followed by hugepages on the command line. The global
* variable 'parsed_valid_hugepagesz' is used to determine if prior
* hugepagesz argument was valid.
*/
hugetlbfs: move hugepagesz= parsing to arch independent code Now that architectures provide arch_hugetlb_valid_size(), parsing of "hugepagesz=" can be done in architecture independent code. Create a single routine to handle hugepagesz= parsing and remove all arch specific routines. We can also remove the interface hugetlb_bad_size() as this is no longer used outside arch independent code. This also provides consistent behavior of hugetlbfs command line options. The hugepagesz= option should only be specified once for a specific size, but some architectures allow multiple instances. This appears to be more of an oversight when code was added by some architectures to set up ALL huge pages sizes. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Reviewed-by: Peter Xu <peterx@redhat.com> Acked-by: Mina Almasry <almasrymina@google.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-3-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-3-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:38 +03:00
static int __init hugepagesz_setup(char *s)
{
hugetlbfs: move hugepagesz= parsing to arch independent code Now that architectures provide arch_hugetlb_valid_size(), parsing of "hugepagesz=" can be done in architecture independent code. Create a single routine to handle hugepagesz= parsing and remove all arch specific routines. We can also remove the interface hugetlb_bad_size() as this is no longer used outside arch independent code. This also provides consistent behavior of hugetlbfs command line options. The hugepagesz= option should only be specified once for a specific size, but some architectures allow multiple instances. This appears to be more of an oversight when code was added by some architectures to set up ALL huge pages sizes. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Reviewed-by: Peter Xu <peterx@redhat.com> Acked-by: Mina Almasry <almasrymina@google.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-3-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-3-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:38 +03:00
unsigned long size;
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
struct hstate *h;
parsed_valid_hugepagesz = false;
hugetlbfs: move hugepagesz= parsing to arch independent code Now that architectures provide arch_hugetlb_valid_size(), parsing of "hugepagesz=" can be done in architecture independent code. Create a single routine to handle hugepagesz= parsing and remove all arch specific routines. We can also remove the interface hugetlb_bad_size() as this is no longer used outside arch independent code. This also provides consistent behavior of hugetlbfs command line options. The hugepagesz= option should only be specified once for a specific size, but some architectures allow multiple instances. This appears to be more of an oversight when code was added by some architectures to set up ALL huge pages sizes. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Reviewed-by: Peter Xu <peterx@redhat.com> Acked-by: Mina Almasry <almasrymina@google.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-3-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-3-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:38 +03:00
size = (unsigned long)memparse(s, NULL);
if (!arch_hugetlb_valid_size(size)) {
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
pr_err("HugeTLB: unsupported hugepagesz=%s\n", s);
return 1;
hugetlbfs: move hugepagesz= parsing to arch independent code Now that architectures provide arch_hugetlb_valid_size(), parsing of "hugepagesz=" can be done in architecture independent code. Create a single routine to handle hugepagesz= parsing and remove all arch specific routines. We can also remove the interface hugetlb_bad_size() as this is no longer used outside arch independent code. This also provides consistent behavior of hugetlbfs command line options. The hugepagesz= option should only be specified once for a specific size, but some architectures allow multiple instances. This appears to be more of an oversight when code was added by some architectures to set up ALL huge pages sizes. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Reviewed-by: Peter Xu <peterx@redhat.com> Acked-by: Mina Almasry <almasrymina@google.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-3-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-3-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:38 +03:00
}
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
h = size_to_hstate(size);
if (h) {
/*
* hstate for this size already exists. This is normally
* an error, but is allowed if the existing hstate is the
* default hstate. More specifically, it is only allowed if
* the number of huge pages for the default hstate was not
* previously specified.
*/
if (!parsed_default_hugepagesz || h != &default_hstate ||
default_hstate.max_huge_pages) {
pr_warn("HugeTLB: hugepagesz=%s specified twice, ignoring\n", s);
return 1;
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
}
/*
* No need to call hugetlb_add_hstate() as hstate already
* exists. But, do set parsed_hstate so that a following
* hugepages= parameter will be applied to this hstate.
*/
parsed_hstate = h;
parsed_valid_hugepagesz = true;
return 1;
hugetlbfs: remove hugetlb_add_hstate() warning for existing hstate hugetlb_add_hstate() prints a warning if the hstate already exists. This was originally done as part of kernel command line parsing. If 'hugepagesz=' was specified more than once, the warning pr_warn("hugepagesz= specified twice, ignoring\n"); would be printed. Some architectures want to enable all huge page sizes. They would call hugetlb_add_hstate for all supported sizes. However, this was done after command line processing and as a result hstates could have already been created for some sizes. To make sure no warning were printed, there would often be code like: if (!size_to_hstate(size) hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT) The only time we want to print the warning is as the result of command line processing. So, remove the warning from hugetlb_add_hstate and add it to the single arch independent routine processing "hugepagesz=". After this, calls to size_to_hstate() in arch specific code can be removed and hugetlb_add_hstate can be called without worrying about warning messages. [mike.kravetz@oracle.com: fix hugetlb initialization] Link: http://lkml.kernel.org/r/4c36c6ce-3774-78fa-abc4-b7346bf24348@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Anders Roxell <anders.roxell@linaro.org> Acked-by: Mina Almasry <almasrymina@google.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-4-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-4-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:42 +03:00
}
hugetlbfs: move hugepagesz= parsing to arch independent code Now that architectures provide arch_hugetlb_valid_size(), parsing of "hugepagesz=" can be done in architecture independent code. Create a single routine to handle hugepagesz= parsing and remove all arch specific routines. We can also remove the interface hugetlb_bad_size() as this is no longer used outside arch independent code. This also provides consistent behavior of hugetlbfs command line options. The hugepagesz= option should only be specified once for a specific size, but some architectures allow multiple instances. This appears to be more of an oversight when code was added by some architectures to set up ALL huge pages sizes. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Reviewed-by: Peter Xu <peterx@redhat.com> Acked-by: Mina Almasry <almasrymina@google.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-3-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-3-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:38 +03:00
hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
parsed_valid_hugepagesz = true;
return 1;
}
hugetlbfs: move hugepagesz= parsing to arch independent code Now that architectures provide arch_hugetlb_valid_size(), parsing of "hugepagesz=" can be done in architecture independent code. Create a single routine to handle hugepagesz= parsing and remove all arch specific routines. We can also remove the interface hugetlb_bad_size() as this is no longer used outside arch independent code. This also provides consistent behavior of hugetlbfs command line options. The hugepagesz= option should only be specified once for a specific size, but some architectures allow multiple instances. This appears to be more of an oversight when code was added by some architectures to set up ALL huge pages sizes. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Reviewed-by: Peter Xu <peterx@redhat.com> Acked-by: Mina Almasry <almasrymina@google.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-3-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-3-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:38 +03:00
__setup("hugepagesz=", hugepagesz_setup);
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
/*
* default_hugepagesz command line input
* Only one instance of default_hugepagesz allowed on command line.
*/
hugetlbfs: add arch_hugetlb_valid_size Patch series "Clean up hugetlb boot command line processing", v4. Longpeng(Mike) reported a weird message from hugetlb command line processing and proposed a solution [1]. While the proposed patch does address the specific issue, there are other related issues in command line processing. As hugetlbfs evolved, updates to command line processing have been made to meet immediate needs and not necessarily in a coordinated manner. The result is that some processing is done in arch specific code, some is done in arch independent code and coordination is problematic. Semantics can vary between architectures. The patch series does the following: - Define arch specific arch_hugetlb_valid_size routine used to validate passed huge page sizes. - Move hugepagesz= command line parsing out of arch specific code and into an arch independent routine. - Clean up command line processing to follow desired semantics and document those semantics. [1] https://lore.kernel.org/linux-mm/20200305033014.1152-1-longpeng2@huawei.com This patch (of 3): The architecture independent routine hugetlb_default_setup sets up the default huge pages size. It has no way to verify if the passed value is valid, so it accepts it and attempts to validate at a later time. This requires undocumented cooperation between the arch specific and arch independent code. For architectures that support more than one huge page size, provide a routine arch_hugetlb_valid_size to validate a huge page size. hugetlb_default_setup can use this to validate passed values. arch_hugetlb_valid_size will also be used in a subsequent patch to move processing of the "hugepagesz=" in arch specific code to a common routine in arch independent code. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200428205614.246260-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-2-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:34 +03:00
static int __init default_hugepagesz_setup(char *s)
{
hugetlbfs: add arch_hugetlb_valid_size Patch series "Clean up hugetlb boot command line processing", v4. Longpeng(Mike) reported a weird message from hugetlb command line processing and proposed a solution [1]. While the proposed patch does address the specific issue, there are other related issues in command line processing. As hugetlbfs evolved, updates to command line processing have been made to meet immediate needs and not necessarily in a coordinated manner. The result is that some processing is done in arch specific code, some is done in arch independent code and coordination is problematic. Semantics can vary between architectures. The patch series does the following: - Define arch specific arch_hugetlb_valid_size routine used to validate passed huge page sizes. - Move hugepagesz= command line parsing out of arch specific code and into an arch independent routine. - Clean up command line processing to follow desired semantics and document those semantics. [1] https://lore.kernel.org/linux-mm/20200305033014.1152-1-longpeng2@huawei.com This patch (of 3): The architecture independent routine hugetlb_default_setup sets up the default huge pages size. It has no way to verify if the passed value is valid, so it accepts it and attempts to validate at a later time. This requires undocumented cooperation between the arch specific and arch independent code. For architectures that support more than one huge page size, provide a routine arch_hugetlb_valid_size to validate a huge page size. hugetlb_default_setup can use this to validate passed values. arch_hugetlb_valid_size will also be used in a subsequent patch to move processing of the "hugepagesz=" in arch specific code to a common routine in arch independent code. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200428205614.246260-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-2-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:34 +03:00
unsigned long size;
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
int i;
hugetlbfs: add arch_hugetlb_valid_size Patch series "Clean up hugetlb boot command line processing", v4. Longpeng(Mike) reported a weird message from hugetlb command line processing and proposed a solution [1]. While the proposed patch does address the specific issue, there are other related issues in command line processing. As hugetlbfs evolved, updates to command line processing have been made to meet immediate needs and not necessarily in a coordinated manner. The result is that some processing is done in arch specific code, some is done in arch independent code and coordination is problematic. Semantics can vary between architectures. The patch series does the following: - Define arch specific arch_hugetlb_valid_size routine used to validate passed huge page sizes. - Move hugepagesz= command line parsing out of arch specific code and into an arch independent routine. - Clean up command line processing to follow desired semantics and document those semantics. [1] https://lore.kernel.org/linux-mm/20200305033014.1152-1-longpeng2@huawei.com This patch (of 3): The architecture independent routine hugetlb_default_setup sets up the default huge pages size. It has no way to verify if the passed value is valid, so it accepts it and attempts to validate at a later time. This requires undocumented cooperation between the arch specific and arch independent code. For architectures that support more than one huge page size, provide a routine arch_hugetlb_valid_size to validate a huge page size. hugetlb_default_setup can use this to validate passed values. arch_hugetlb_valid_size will also be used in a subsequent patch to move processing of the "hugepagesz=" in arch specific code to a common routine in arch independent code. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200428205614.246260-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-2-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:34 +03:00
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
parsed_valid_hugepagesz = false;
if (parsed_default_hugepagesz) {
pr_err("HugeTLB: default_hugepagesz previously specified, ignoring %s\n", s);
return 1;
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
}
hugetlbfs: add arch_hugetlb_valid_size Patch series "Clean up hugetlb boot command line processing", v4. Longpeng(Mike) reported a weird message from hugetlb command line processing and proposed a solution [1]. While the proposed patch does address the specific issue, there are other related issues in command line processing. As hugetlbfs evolved, updates to command line processing have been made to meet immediate needs and not necessarily in a coordinated manner. The result is that some processing is done in arch specific code, some is done in arch independent code and coordination is problematic. Semantics can vary between architectures. The patch series does the following: - Define arch specific arch_hugetlb_valid_size routine used to validate passed huge page sizes. - Move hugepagesz= command line parsing out of arch specific code and into an arch independent routine. - Clean up command line processing to follow desired semantics and document those semantics. [1] https://lore.kernel.org/linux-mm/20200305033014.1152-1-longpeng2@huawei.com This patch (of 3): The architecture independent routine hugetlb_default_setup sets up the default huge pages size. It has no way to verify if the passed value is valid, so it accepts it and attempts to validate at a later time. This requires undocumented cooperation between the arch specific and arch independent code. For architectures that support more than one huge page size, provide a routine arch_hugetlb_valid_size to validate a huge page size. hugetlb_default_setup can use this to validate passed values. arch_hugetlb_valid_size will also be used in a subsequent patch to move processing of the "hugepagesz=" in arch specific code to a common routine in arch independent code. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200428205614.246260-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-2-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:34 +03:00
size = (unsigned long)memparse(s, NULL);
if (!arch_hugetlb_valid_size(size)) {
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
pr_err("HugeTLB: unsupported default_hugepagesz=%s\n", s);
return 1;
hugetlbfs: add arch_hugetlb_valid_size Patch series "Clean up hugetlb boot command line processing", v4. Longpeng(Mike) reported a weird message from hugetlb command line processing and proposed a solution [1]. While the proposed patch does address the specific issue, there are other related issues in command line processing. As hugetlbfs evolved, updates to command line processing have been made to meet immediate needs and not necessarily in a coordinated manner. The result is that some processing is done in arch specific code, some is done in arch independent code and coordination is problematic. Semantics can vary between architectures. The patch series does the following: - Define arch specific arch_hugetlb_valid_size routine used to validate passed huge page sizes. - Move hugepagesz= command line parsing out of arch specific code and into an arch independent routine. - Clean up command line processing to follow desired semantics and document those semantics. [1] https://lore.kernel.org/linux-mm/20200305033014.1152-1-longpeng2@huawei.com This patch (of 3): The architecture independent routine hugetlb_default_setup sets up the default huge pages size. It has no way to verify if the passed value is valid, so it accepts it and attempts to validate at a later time. This requires undocumented cooperation between the arch specific and arch independent code. For architectures that support more than one huge page size, provide a routine arch_hugetlb_valid_size to validate a huge page size. hugetlb_default_setup can use this to validate passed values. arch_hugetlb_valid_size will also be used in a subsequent patch to move processing of the "hugepagesz=" in arch specific code to a common routine in arch independent code. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200428205614.246260-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-2-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:34 +03:00
}
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
parsed_valid_hugepagesz = true;
parsed_default_hugepagesz = true;
default_hstate_idx = hstate_index(size_to_hstate(size));
/*
* The number of default huge pages (for this size) could have been
* specified as the first hugetlb parameter: hugepages=X. If so,
* then default_hstate_max_huge_pages is set. If the default huge
* page size is gigantic (>= MAX_ORDER), then the pages must be
* allocated here from bootmem allocator.
*/
if (default_hstate_max_huge_pages) {
default_hstate.max_huge_pages = default_hstate_max_huge_pages;
hugetlb: fix wrong use of nr_online_nodes Patch series "hugetlb: Fix some incorrect behavior", v3. This series fix three bugs of hugetlb: 1) Invalid use of nr_online_nodes; 2) Inconsistency between 1G hugepage and 2M hugepage; 3) Useless information in dmesg. This patch (of 4): Certain systems are designed to have sparse/discontiguous nodes. In this case, nr_online_nodes can not be used to walk through numa node. Also, a valid node may be greater than nr_online_nodes. However, in hugetlb, it is assumed that nodes are contiguous. For sparse/discontiguous nodes, the current code may treat a valid node as invalid, and will fail to allocate all hugepages on a valid node that "nid >= nr_online_nodes". As David suggested: if (tmp >= nr_online_nodes) goto invalid; Just imagine node 0 and node 2 are online, and node 1 is offline. Assuming that "node < 2" is valid is wrong. Recheck all the places that use nr_online_nodes, and repair them one by one. [liupeng256@huawei.com: v4] Link: https://lkml.kernel.org/r/20220416103526.3287348-1-liupeng256@huawei.com Link: https://lkml.kernel.org/r/20220413032915.251254-1-liupeng256@huawei.com Link: https://lkml.kernel.org/r/20220413032915.251254-2-liupeng256@huawei.com Fixes: 4178158ef8ca ("hugetlbfs: fix issue of preallocation of gigantic pages can't work") Fixes: b5389086ad7b ("hugetlbfs: extend the definition of hugepages parameter to support node allocation") Fixes: e79ce9832316 ("hugetlbfs: fix a truncation issue in hugepages parameter") Fixes: f9317f77a6e0 ("hugetlb: clean up potential spectre issue warnings") Signed-off-by: Peng Liu <liupeng256@huawei.com> Suggested-by: David Hildenbrand <david@redhat.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Liu Yuntao <liuyuntao10@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-04-30 00:36:57 +03:00
for_each_online_node(i)
hugetlbfs: extend the definition of hugepages parameter to support node allocation We can specify the number of hugepages to allocate at boot. But the hugepages is balanced in all nodes at present. In some scenarios, we only need hugepages in one node. For example: DPDK needs hugepages which are in the same node as NIC. If DPDK needs four hugepages of 1G size in node1 and system has 16 numa nodes we must reserve 64 hugepages on the kernel cmdline. But only four hugepages are used. The others should be free after boot. If the system memory is low(for example: 64G), it will be an impossible task. So extend the hugepages parameter to support specifying hugepages on a specific node. For example add following parameter: hugepagesz=1G hugepages=0:1,1:3 It will allocate 1 hugepage in node0 and 3 hugepages in node1. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:43:28 +03:00
default_hstate.max_huge_pages_node[i] =
default_hugepages_in_node[i];
hugetlbfs: clean up command line processing With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Xu <peterx@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:46 +03:00
if (hstate_is_gigantic(&default_hstate))
hugetlb_hstate_alloc_pages(&default_hstate);
default_hstate_max_huge_pages = 0;
}
return 1;
}
hugetlbfs: add arch_hugetlb_valid_size Patch series "Clean up hugetlb boot command line processing", v4. Longpeng(Mike) reported a weird message from hugetlb command line processing and proposed a solution [1]. While the proposed patch does address the specific issue, there are other related issues in command line processing. As hugetlbfs evolved, updates to command line processing have been made to meet immediate needs and not necessarily in a coordinated manner. The result is that some processing is done in arch specific code, some is done in arch independent code and coordination is problematic. Semantics can vary between architectures. The patch series does the following: - Define arch specific arch_hugetlb_valid_size routine used to validate passed huge page sizes. - Move hugepagesz= command line parsing out of arch specific code and into an arch independent routine. - Clean up command line processing to follow desired semantics and document those semantics. [1] https://lore.kernel.org/linux-mm/20200305033014.1152-1-longpeng2@huawei.com This patch (of 3): The architecture independent routine hugetlb_default_setup sets up the default huge pages size. It has no way to verify if the passed value is valid, so it accepts it and attempts to validate at a later time. This requires undocumented cooperation between the arch specific and arch independent code. For architectures that support more than one huge page size, provide a routine arch_hugetlb_valid_size to validate a huge page size. hugetlb_default_setup can use this to validate passed values. arch_hugetlb_valid_size will also be used in a subsequent patch to move processing of the "hugepagesz=" in arch specific code to a common routine in arch independent code. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] Acked-by: Will Deacon <will@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Longpeng <longpeng2@huawei.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Qian Cai <cai@lca.pw> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200428205614.246260-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200428205614.246260-2-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-1-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20200417185049.275845-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:34 +03:00
__setup("default_hugepagesz=", default_hugepagesz_setup);
hugetlb: new sysfs interface Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:44 +04:00
static unsigned int allowed_mems_nr(struct hstate *h)
{
int node;
unsigned int nr = 0;
nodemask_t *mpol_allowed;
unsigned int *array = h->free_huge_pages_node;
gfp_t gfp_mask = htlb_alloc_mask(h);
mpol_allowed = policy_nodemask_current(gfp_mask);
for_each_node_mask(node, cpuset_current_mems_allowed) {
if (!mpol_allowed || node_isset(node, *mpol_allowed))
nr += array[node];
}
return nr;
}
#ifdef CONFIG_SYSCTL
mm/hugetlb: fix a race between hugetlb sysctl handlers There is a race between the assignment of `table->data` and write value to the pointer of `table->data` in the __do_proc_doulongvec_minmax() on the other thread. CPU0: CPU1: proc_sys_write hugetlb_sysctl_handler proc_sys_call_handler hugetlb_sysctl_handler_common hugetlb_sysctl_handler table->data = &tmp; hugetlb_sysctl_handler_common table->data = &tmp; proc_doulongvec_minmax do_proc_doulongvec_minmax sysctl_head_finish __do_proc_doulongvec_minmax unuse_table i = table->data; *i = val; // corrupt CPU1's stack Fix this by duplicating the `table`, and only update the duplicate of it. And introduce a helper of proc_hugetlb_doulongvec_minmax() to simplify the code. The following oops was seen: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page Code: Bad RIP value. ... Call Trace: ? set_max_huge_pages+0x3da/0x4f0 ? alloc_pool_huge_page+0x150/0x150 ? proc_doulongvec_minmax+0x46/0x60 ? hugetlb_sysctl_handler_common+0x1c7/0x200 ? nr_hugepages_store+0x20/0x20 ? copy_fd_bitmaps+0x170/0x170 ? hugetlb_sysctl_handler+0x1e/0x20 ? proc_sys_call_handler+0x2f1/0x300 ? unregister_sysctl_table+0xb0/0xb0 ? __fd_install+0x78/0x100 ? proc_sys_write+0x14/0x20 ? __vfs_write+0x4d/0x90 ? vfs_write+0xef/0x240 ? ksys_write+0xc0/0x160 ? __ia32_sys_read+0x50/0x50 ? __close_fd+0x129/0x150 ? __x64_sys_write+0x43/0x50 ? do_syscall_64+0x6c/0x200 ? entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fixes: e5ff215941d5 ("hugetlb: multiple hstates for multiple page sizes") Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Andi Kleen <ak@linux.intel.com> Link: http://lkml.kernel.org/r/20200828031146.43035-1-songmuchun@bytedance.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-09-05 02:36:13 +03:00
static int proc_hugetlb_doulongvec_minmax(struct ctl_table *table, int write,
void *buffer, size_t *length,
loff_t *ppos, unsigned long *out)
{
struct ctl_table dup_table;
/*
* In order to avoid races with __do_proc_doulongvec_minmax(), we
* can duplicate the @table and alter the duplicate of it.
*/
dup_table = *table;
dup_table.data = out;
return proc_doulongvec_minmax(&dup_table, write, buffer, length, ppos);
}
hugetlb: derive huge pages nodes allowed from task mempolicy This patch derives a "nodes_allowed" node mask from the numa mempolicy of the task modifying the number of persistent huge pages to control the allocation, freeing and adjusting of surplus huge pages when the pool page count is modified via the new sysctl or sysfs attribute "nr_hugepages_mempolicy". The nodes_allowed mask is derived as follows: * For "default" [NULL] task mempolicy, a NULL nodemask_t pointer is produced. This will cause the hugetlb subsystem to use node_online_map as the "nodes_allowed". This preserves the behavior before this patch. * For "preferred" mempolicy, including explicit local allocation, a nodemask with the single preferred node will be produced. "local" policy will NOT track any internode migrations of the task adjusting nr_hugepages. * For "bind" and "interleave" policy, the mempolicy's nodemask will be used. * Other than to inform the construction of the nodes_allowed node mask, the actual mempolicy mode is ignored. That is, all modes behave like interleave over the resulting nodes_allowed mask with no "fallback". See the updated documentation [next patch] for more information about the implications of this patch. Examples: Starting with: Node 0 HugePages_Total: 0 Node 1 HugePages_Total: 0 Node 2 HugePages_Total: 0 Node 3 HugePages_Total: 0 Default behavior [with or without this patch] balances persistent hugepage allocation across nodes [with sufficient contiguous memory]: sysctl vm.nr_hugepages[_mempolicy]=32 yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 8 Node 3 HugePages_Total: 8 Of course, we only have nr_hugepages_mempolicy with the patch, but with default mempolicy, nr_hugepages_mempolicy behaves the same as nr_hugepages. Applying mempolicy--e.g., with numactl [using '-m' a.k.a. '--membind' because it allows multiple nodes to be specified and it's easy to type]--we can allocate huge pages on individual nodes or sets of nodes. So, starting from the condition above, with 8 huge pages per node, add 8 more to node 2 using: numactl -m 2 sysctl vm.nr_hugepages_mempolicy=40 This yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The incremental 8 huge pages were restricted to node 2 by the specified mempolicy. Similarly, we can use mempolicy to free persistent huge pages from specified nodes: numactl -m 0,1 sysctl vm.nr_hugepages_mempolicy=32 yields: Node 0 HugePages_Total: 4 Node 1 HugePages_Total: 4 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The 8 huge pages freed were balanced over nodes 0 and 1. [rientjes@google.com: accomodate reworked NODEMASK_ALLOC] Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:21 +03:00
static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
{
struct hstate *h = &default_hstate;
unsigned long tmp = h->max_huge_pages;
int ret;
hugetlb: ensure hugepage access is denied if hugepages are not supported Currently, I am seeing the following when I `mount -t hugetlbfs /none /dev/hugetlbfs`, and then simply do a `ls /dev/hugetlbfs`. I think it's related to the fact that hugetlbfs is properly not correctly setting itself up in this state?: Unable to handle kernel paging request for data at address 0x00000031 Faulting instruction address: 0xc000000000245710 Oops: Kernel access of bad area, sig: 11 [#1] SMP NR_CPUS=2048 NUMA pSeries .... In KVM guests on Power, in a guest not backed by hugepages, we see the following: AnonHugePages: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 64 kB HPAGE_SHIFT == 0 in this configuration, which indicates that hugepages are not supported at boot-time, but this is only checked in hugetlb_init(). Extract the check to a helper function, and use it in a few relevant places. This does make hugetlbfs not supported (not registered at all) in this environment. I believe this is fine, as there are no valid hugepages and that won't change at runtime. [akpm@linux-foundation.org: use pr_info(), per Mel] [akpm@linux-foundation.org: fix build when HPAGE_SHIFT is undefined] Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-05-06 23:50:00 +04:00
if (!hugepages_supported())
return -EOPNOTSUPP;
hugetlb: ensure hugepage access is denied if hugepages are not supported Currently, I am seeing the following when I `mount -t hugetlbfs /none /dev/hugetlbfs`, and then simply do a `ls /dev/hugetlbfs`. I think it's related to the fact that hugetlbfs is properly not correctly setting itself up in this state?: Unable to handle kernel paging request for data at address 0x00000031 Faulting instruction address: 0xc000000000245710 Oops: Kernel access of bad area, sig: 11 [#1] SMP NR_CPUS=2048 NUMA pSeries .... In KVM guests on Power, in a guest not backed by hugepages, we see the following: AnonHugePages: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 64 kB HPAGE_SHIFT == 0 in this configuration, which indicates that hugepages are not supported at boot-time, but this is only checked in hugetlb_init(). Extract the check to a helper function, and use it in a few relevant places. This does make hugetlbfs not supported (not registered at all) in this environment. I believe this is fine, as there are no valid hugepages and that won't change at runtime. [akpm@linux-foundation.org: use pr_info(), per Mel] [akpm@linux-foundation.org: fix build when HPAGE_SHIFT is undefined] Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-05-06 23:50:00 +04:00
mm/hugetlb: fix a race between hugetlb sysctl handlers There is a race between the assignment of `table->data` and write value to the pointer of `table->data` in the __do_proc_doulongvec_minmax() on the other thread. CPU0: CPU1: proc_sys_write hugetlb_sysctl_handler proc_sys_call_handler hugetlb_sysctl_handler_common hugetlb_sysctl_handler table->data = &tmp; hugetlb_sysctl_handler_common table->data = &tmp; proc_doulongvec_minmax do_proc_doulongvec_minmax sysctl_head_finish __do_proc_doulongvec_minmax unuse_table i = table->data; *i = val; // corrupt CPU1's stack Fix this by duplicating the `table`, and only update the duplicate of it. And introduce a helper of proc_hugetlb_doulongvec_minmax() to simplify the code. The following oops was seen: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page Code: Bad RIP value. ... Call Trace: ? set_max_huge_pages+0x3da/0x4f0 ? alloc_pool_huge_page+0x150/0x150 ? proc_doulongvec_minmax+0x46/0x60 ? hugetlb_sysctl_handler_common+0x1c7/0x200 ? nr_hugepages_store+0x20/0x20 ? copy_fd_bitmaps+0x170/0x170 ? hugetlb_sysctl_handler+0x1e/0x20 ? proc_sys_call_handler+0x2f1/0x300 ? unregister_sysctl_table+0xb0/0xb0 ? __fd_install+0x78/0x100 ? proc_sys_write+0x14/0x20 ? __vfs_write+0x4d/0x90 ? vfs_write+0xef/0x240 ? ksys_write+0xc0/0x160 ? __ia32_sys_read+0x50/0x50 ? __close_fd+0x129/0x150 ? __x64_sys_write+0x43/0x50 ? do_syscall_64+0x6c/0x200 ? entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fixes: e5ff215941d5 ("hugetlb: multiple hstates for multiple page sizes") Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Andi Kleen <ak@linux.intel.com> Link: http://lkml.kernel.org/r/20200828031146.43035-1-songmuchun@bytedance.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-09-05 02:36:13 +03:00
ret = proc_hugetlb_doulongvec_minmax(table, write, buffer, length, ppos,
&tmp);
if (ret)
goto out;
if (write)
ret = __nr_hugepages_store_common(obey_mempolicy, h,
NUMA_NO_NODE, tmp, *length);
out:
return ret;
}
hugetlb: derive huge pages nodes allowed from task mempolicy This patch derives a "nodes_allowed" node mask from the numa mempolicy of the task modifying the number of persistent huge pages to control the allocation, freeing and adjusting of surplus huge pages when the pool page count is modified via the new sysctl or sysfs attribute "nr_hugepages_mempolicy". The nodes_allowed mask is derived as follows: * For "default" [NULL] task mempolicy, a NULL nodemask_t pointer is produced. This will cause the hugetlb subsystem to use node_online_map as the "nodes_allowed". This preserves the behavior before this patch. * For "preferred" mempolicy, including explicit local allocation, a nodemask with the single preferred node will be produced. "local" policy will NOT track any internode migrations of the task adjusting nr_hugepages. * For "bind" and "interleave" policy, the mempolicy's nodemask will be used. * Other than to inform the construction of the nodes_allowed node mask, the actual mempolicy mode is ignored. That is, all modes behave like interleave over the resulting nodes_allowed mask with no "fallback". See the updated documentation [next patch] for more information about the implications of this patch. Examples: Starting with: Node 0 HugePages_Total: 0 Node 1 HugePages_Total: 0 Node 2 HugePages_Total: 0 Node 3 HugePages_Total: 0 Default behavior [with or without this patch] balances persistent hugepage allocation across nodes [with sufficient contiguous memory]: sysctl vm.nr_hugepages[_mempolicy]=32 yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 8 Node 3 HugePages_Total: 8 Of course, we only have nr_hugepages_mempolicy with the patch, but with default mempolicy, nr_hugepages_mempolicy behaves the same as nr_hugepages. Applying mempolicy--e.g., with numactl [using '-m' a.k.a. '--membind' because it allows multiple nodes to be specified and it's easy to type]--we can allocate huge pages on individual nodes or sets of nodes. So, starting from the condition above, with 8 huge pages per node, add 8 more to node 2 using: numactl -m 2 sysctl vm.nr_hugepages_mempolicy=40 This yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The incremental 8 huge pages were restricted to node 2 by the specified mempolicy. Similarly, we can use mempolicy to free persistent huge pages from specified nodes: numactl -m 0,1 sysctl vm.nr_hugepages_mempolicy=32 yields: Node 0 HugePages_Total: 4 Node 1 HugePages_Total: 4 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The 8 huge pages freed were balanced over nodes 0 and 1. [rientjes@google.com: accomodate reworked NODEMASK_ALLOC] Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:21 +03:00
int hugetlb_sysctl_handler(struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
hugetlb: derive huge pages nodes allowed from task mempolicy This patch derives a "nodes_allowed" node mask from the numa mempolicy of the task modifying the number of persistent huge pages to control the allocation, freeing and adjusting of surplus huge pages when the pool page count is modified via the new sysctl or sysfs attribute "nr_hugepages_mempolicy". The nodes_allowed mask is derived as follows: * For "default" [NULL] task mempolicy, a NULL nodemask_t pointer is produced. This will cause the hugetlb subsystem to use node_online_map as the "nodes_allowed". This preserves the behavior before this patch. * For "preferred" mempolicy, including explicit local allocation, a nodemask with the single preferred node will be produced. "local" policy will NOT track any internode migrations of the task adjusting nr_hugepages. * For "bind" and "interleave" policy, the mempolicy's nodemask will be used. * Other than to inform the construction of the nodes_allowed node mask, the actual mempolicy mode is ignored. That is, all modes behave like interleave over the resulting nodes_allowed mask with no "fallback". See the updated documentation [next patch] for more information about the implications of this patch. Examples: Starting with: Node 0 HugePages_Total: 0 Node 1 HugePages_Total: 0 Node 2 HugePages_Total: 0 Node 3 HugePages_Total: 0 Default behavior [with or without this patch] balances persistent hugepage allocation across nodes [with sufficient contiguous memory]: sysctl vm.nr_hugepages[_mempolicy]=32 yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 8 Node 3 HugePages_Total: 8 Of course, we only have nr_hugepages_mempolicy with the patch, but with default mempolicy, nr_hugepages_mempolicy behaves the same as nr_hugepages. Applying mempolicy--e.g., with numactl [using '-m' a.k.a. '--membind' because it allows multiple nodes to be specified and it's easy to type]--we can allocate huge pages on individual nodes or sets of nodes. So, starting from the condition above, with 8 huge pages per node, add 8 more to node 2 using: numactl -m 2 sysctl vm.nr_hugepages_mempolicy=40 This yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The incremental 8 huge pages were restricted to node 2 by the specified mempolicy. Similarly, we can use mempolicy to free persistent huge pages from specified nodes: numactl -m 0,1 sysctl vm.nr_hugepages_mempolicy=32 yields: Node 0 HugePages_Total: 4 Node 1 HugePages_Total: 4 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The 8 huge pages freed were balanced over nodes 0 and 1. [rientjes@google.com: accomodate reworked NODEMASK_ALLOC] Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:21 +03:00
{
return hugetlb_sysctl_handler_common(false, table, write,
buffer, length, ppos);
}
#ifdef CONFIG_NUMA
int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
hugetlb: derive huge pages nodes allowed from task mempolicy This patch derives a "nodes_allowed" node mask from the numa mempolicy of the task modifying the number of persistent huge pages to control the allocation, freeing and adjusting of surplus huge pages when the pool page count is modified via the new sysctl or sysfs attribute "nr_hugepages_mempolicy". The nodes_allowed mask is derived as follows: * For "default" [NULL] task mempolicy, a NULL nodemask_t pointer is produced. This will cause the hugetlb subsystem to use node_online_map as the "nodes_allowed". This preserves the behavior before this patch. * For "preferred" mempolicy, including explicit local allocation, a nodemask with the single preferred node will be produced. "local" policy will NOT track any internode migrations of the task adjusting nr_hugepages. * For "bind" and "interleave" policy, the mempolicy's nodemask will be used. * Other than to inform the construction of the nodes_allowed node mask, the actual mempolicy mode is ignored. That is, all modes behave like interleave over the resulting nodes_allowed mask with no "fallback". See the updated documentation [next patch] for more information about the implications of this patch. Examples: Starting with: Node 0 HugePages_Total: 0 Node 1 HugePages_Total: 0 Node 2 HugePages_Total: 0 Node 3 HugePages_Total: 0 Default behavior [with or without this patch] balances persistent hugepage allocation across nodes [with sufficient contiguous memory]: sysctl vm.nr_hugepages[_mempolicy]=32 yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 8 Node 3 HugePages_Total: 8 Of course, we only have nr_hugepages_mempolicy with the patch, but with default mempolicy, nr_hugepages_mempolicy behaves the same as nr_hugepages. Applying mempolicy--e.g., with numactl [using '-m' a.k.a. '--membind' because it allows multiple nodes to be specified and it's easy to type]--we can allocate huge pages on individual nodes or sets of nodes. So, starting from the condition above, with 8 huge pages per node, add 8 more to node 2 using: numactl -m 2 sysctl vm.nr_hugepages_mempolicy=40 This yields: Node 0 HugePages_Total: 8 Node 1 HugePages_Total: 8 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The incremental 8 huge pages were restricted to node 2 by the specified mempolicy. Similarly, we can use mempolicy to free persistent huge pages from specified nodes: numactl -m 0,1 sysctl vm.nr_hugepages_mempolicy=32 yields: Node 0 HugePages_Total: 4 Node 1 HugePages_Total: 4 Node 2 HugePages_Total: 16 Node 3 HugePages_Total: 8 The 8 huge pages freed were balanced over nodes 0 and 1. [rientjes@google.com: accomodate reworked NODEMASK_ALLOC] Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:58:21 +03:00
{
return hugetlb_sysctl_handler_common(true, table, write,
buffer, length, ppos);
}
#endif /* CONFIG_NUMA */
int hugetlb_overcommit_handler(struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
{
struct hstate *h = &default_hstate;
unsigned long tmp;
int ret;
hugetlb: ensure hugepage access is denied if hugepages are not supported Currently, I am seeing the following when I `mount -t hugetlbfs /none /dev/hugetlbfs`, and then simply do a `ls /dev/hugetlbfs`. I think it's related to the fact that hugetlbfs is properly not correctly setting itself up in this state?: Unable to handle kernel paging request for data at address 0x00000031 Faulting instruction address: 0xc000000000245710 Oops: Kernel access of bad area, sig: 11 [#1] SMP NR_CPUS=2048 NUMA pSeries .... In KVM guests on Power, in a guest not backed by hugepages, we see the following: AnonHugePages: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 64 kB HPAGE_SHIFT == 0 in this configuration, which indicates that hugepages are not supported at boot-time, but this is only checked in hugetlb_init(). Extract the check to a helper function, and use it in a few relevant places. This does make hugetlbfs not supported (not registered at all) in this environment. I believe this is fine, as there are no valid hugepages and that won't change at runtime. [akpm@linux-foundation.org: use pr_info(), per Mel] [akpm@linux-foundation.org: fix build when HPAGE_SHIFT is undefined] Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-05-06 23:50:00 +04:00
if (!hugepages_supported())
return -EOPNOTSUPP;
hugetlb: ensure hugepage access is denied if hugepages are not supported Currently, I am seeing the following when I `mount -t hugetlbfs /none /dev/hugetlbfs`, and then simply do a `ls /dev/hugetlbfs`. I think it's related to the fact that hugetlbfs is properly not correctly setting itself up in this state?: Unable to handle kernel paging request for data at address 0x00000031 Faulting instruction address: 0xc000000000245710 Oops: Kernel access of bad area, sig: 11 [#1] SMP NR_CPUS=2048 NUMA pSeries .... In KVM guests on Power, in a guest not backed by hugepages, we see the following: AnonHugePages: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 64 kB HPAGE_SHIFT == 0 in this configuration, which indicates that hugepages are not supported at boot-time, but this is only checked in hugetlb_init(). Extract the check to a helper function, and use it in a few relevant places. This does make hugetlbfs not supported (not registered at all) in this environment. I believe this is fine, as there are no valid hugepages and that won't change at runtime. [akpm@linux-foundation.org: use pr_info(), per Mel] [akpm@linux-foundation.org: fix build when HPAGE_SHIFT is undefined] Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-05-06 23:50:00 +04:00
tmp = h->nr_overcommit_huge_pages;
if (write && hstate_is_gigantic(h))
return -EINVAL;
mm/hugetlb: fix a race between hugetlb sysctl handlers There is a race between the assignment of `table->data` and write value to the pointer of `table->data` in the __do_proc_doulongvec_minmax() on the other thread. CPU0: CPU1: proc_sys_write hugetlb_sysctl_handler proc_sys_call_handler hugetlb_sysctl_handler_common hugetlb_sysctl_handler table->data = &tmp; hugetlb_sysctl_handler_common table->data = &tmp; proc_doulongvec_minmax do_proc_doulongvec_minmax sysctl_head_finish __do_proc_doulongvec_minmax unuse_table i = table->data; *i = val; // corrupt CPU1's stack Fix this by duplicating the `table`, and only update the duplicate of it. And introduce a helper of proc_hugetlb_doulongvec_minmax() to simplify the code. The following oops was seen: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page Code: Bad RIP value. ... Call Trace: ? set_max_huge_pages+0x3da/0x4f0 ? alloc_pool_huge_page+0x150/0x150 ? proc_doulongvec_minmax+0x46/0x60 ? hugetlb_sysctl_handler_common+0x1c7/0x200 ? nr_hugepages_store+0x20/0x20 ? copy_fd_bitmaps+0x170/0x170 ? hugetlb_sysctl_handler+0x1e/0x20 ? proc_sys_call_handler+0x2f1/0x300 ? unregister_sysctl_table+0xb0/0xb0 ? __fd_install+0x78/0x100 ? proc_sys_write+0x14/0x20 ? __vfs_write+0x4d/0x90 ? vfs_write+0xef/0x240 ? ksys_write+0xc0/0x160 ? __ia32_sys_read+0x50/0x50 ? __close_fd+0x129/0x150 ? __x64_sys_write+0x43/0x50 ? do_syscall_64+0x6c/0x200 ? entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fixes: e5ff215941d5 ("hugetlb: multiple hstates for multiple page sizes") Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Andi Kleen <ak@linux.intel.com> Link: http://lkml.kernel.org/r/20200828031146.43035-1-songmuchun@bytedance.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-09-05 02:36:13 +03:00
ret = proc_hugetlb_doulongvec_minmax(table, write, buffer, length, ppos,
&tmp);
if (ret)
goto out;
if (write) {
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
h->nr_overcommit_huge_pages = tmp;
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
}
out:
return ret;
}
#endif /* CONFIG_SYSCTL */
void hugetlb_report_meminfo(struct seq_file *m)
{
mm: show total hugetlb memory consumption in /proc/meminfo Currently we display some hugepage statistics (total, free, etc) in /proc/meminfo, but only for default hugepage size (e.g. 2Mb). If hugepages of different sizes are used (like 2Mb and 1Gb on x86-64), /proc/meminfo output can be confusing, as non-default sized hugepages are not reflected at all, and there are no signs that they are existing and consuming system memory. To solve this problem, let's display the total amount of memory, consumed by hugetlb pages of all sized (both free and used). Let's call it "Hugetlb", and display size in kB to match generic /proc/meminfo style. For example, (1024 2Mb pages and 2 1Gb pages are pre-allocated): $ cat /proc/meminfo MemTotal: 8168984 kB MemFree: 3789276 kB <...> CmaFree: 0 kB HugePages_Total: 1024 HugePages_Free: 1024 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB Hugetlb: 4194304 kB DirectMap4k: 32632 kB DirectMap2M: 4161536 kB DirectMap1G: 6291456 kB Also, this patch updates corresponding docs to reflect Hugetlb entry meaning and difference between Hugetlb and HugePages_Total * Hugepagesize. Link: http://lkml.kernel.org/r/20171115231409.12131-1-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:16:22 +03:00
struct hstate *h;
unsigned long total = 0;
hugetlb: ensure hugepage access is denied if hugepages are not supported Currently, I am seeing the following when I `mount -t hugetlbfs /none /dev/hugetlbfs`, and then simply do a `ls /dev/hugetlbfs`. I think it's related to the fact that hugetlbfs is properly not correctly setting itself up in this state?: Unable to handle kernel paging request for data at address 0x00000031 Faulting instruction address: 0xc000000000245710 Oops: Kernel access of bad area, sig: 11 [#1] SMP NR_CPUS=2048 NUMA pSeries .... In KVM guests on Power, in a guest not backed by hugepages, we see the following: AnonHugePages: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 64 kB HPAGE_SHIFT == 0 in this configuration, which indicates that hugepages are not supported at boot-time, but this is only checked in hugetlb_init(). Extract the check to a helper function, and use it in a few relevant places. This does make hugetlbfs not supported (not registered at all) in this environment. I believe this is fine, as there are no valid hugepages and that won't change at runtime. [akpm@linux-foundation.org: use pr_info(), per Mel] [akpm@linux-foundation.org: fix build when HPAGE_SHIFT is undefined] Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-05-06 23:50:00 +04:00
if (!hugepages_supported())
return;
mm: show total hugetlb memory consumption in /proc/meminfo Currently we display some hugepage statistics (total, free, etc) in /proc/meminfo, but only for default hugepage size (e.g. 2Mb). If hugepages of different sizes are used (like 2Mb and 1Gb on x86-64), /proc/meminfo output can be confusing, as non-default sized hugepages are not reflected at all, and there are no signs that they are existing and consuming system memory. To solve this problem, let's display the total amount of memory, consumed by hugetlb pages of all sized (both free and used). Let's call it "Hugetlb", and display size in kB to match generic /proc/meminfo style. For example, (1024 2Mb pages and 2 1Gb pages are pre-allocated): $ cat /proc/meminfo MemTotal: 8168984 kB MemFree: 3789276 kB <...> CmaFree: 0 kB HugePages_Total: 1024 HugePages_Free: 1024 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB Hugetlb: 4194304 kB DirectMap4k: 32632 kB DirectMap2M: 4161536 kB DirectMap1G: 6291456 kB Also, this patch updates corresponding docs to reflect Hugetlb entry meaning and difference between Hugetlb and HugePages_Total * Hugepagesize. Link: http://lkml.kernel.org/r/20171115231409.12131-1-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:16:22 +03:00
for_each_hstate(h) {
unsigned long count = h->nr_huge_pages;
total += huge_page_size(h) * count;
mm: show total hugetlb memory consumption in /proc/meminfo Currently we display some hugepage statistics (total, free, etc) in /proc/meminfo, but only for default hugepage size (e.g. 2Mb). If hugepages of different sizes are used (like 2Mb and 1Gb on x86-64), /proc/meminfo output can be confusing, as non-default sized hugepages are not reflected at all, and there are no signs that they are existing and consuming system memory. To solve this problem, let's display the total amount of memory, consumed by hugetlb pages of all sized (both free and used). Let's call it "Hugetlb", and display size in kB to match generic /proc/meminfo style. For example, (1024 2Mb pages and 2 1Gb pages are pre-allocated): $ cat /proc/meminfo MemTotal: 8168984 kB MemFree: 3789276 kB <...> CmaFree: 0 kB HugePages_Total: 1024 HugePages_Free: 1024 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB Hugetlb: 4194304 kB DirectMap4k: 32632 kB DirectMap2M: 4161536 kB DirectMap1G: 6291456 kB Also, this patch updates corresponding docs to reflect Hugetlb entry meaning and difference between Hugetlb and HugePages_Total * Hugepagesize. Link: http://lkml.kernel.org/r/20171115231409.12131-1-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:16:22 +03:00
if (h == &default_hstate)
seq_printf(m,
"HugePages_Total: %5lu\n"
"HugePages_Free: %5lu\n"
"HugePages_Rsvd: %5lu\n"
"HugePages_Surp: %5lu\n"
"Hugepagesize: %8lu kB\n",
count,
h->free_huge_pages,
h->resv_huge_pages,
h->surplus_huge_pages,
huge_page_size(h) / SZ_1K);
mm: show total hugetlb memory consumption in /proc/meminfo Currently we display some hugepage statistics (total, free, etc) in /proc/meminfo, but only for default hugepage size (e.g. 2Mb). If hugepages of different sizes are used (like 2Mb and 1Gb on x86-64), /proc/meminfo output can be confusing, as non-default sized hugepages are not reflected at all, and there are no signs that they are existing and consuming system memory. To solve this problem, let's display the total amount of memory, consumed by hugetlb pages of all sized (both free and used). Let's call it "Hugetlb", and display size in kB to match generic /proc/meminfo style. For example, (1024 2Mb pages and 2 1Gb pages are pre-allocated): $ cat /proc/meminfo MemTotal: 8168984 kB MemFree: 3789276 kB <...> CmaFree: 0 kB HugePages_Total: 1024 HugePages_Free: 1024 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB Hugetlb: 4194304 kB DirectMap4k: 32632 kB DirectMap2M: 4161536 kB DirectMap1G: 6291456 kB Also, this patch updates corresponding docs to reflect Hugetlb entry meaning and difference between Hugetlb and HugePages_Total * Hugepagesize. Link: http://lkml.kernel.org/r/20171115231409.12131-1-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:16:22 +03:00
}
seq_printf(m, "Hugetlb: %8lu kB\n", total / SZ_1K);
}
int hugetlb_report_node_meminfo(char *buf, int len, int nid)
{
struct hstate *h = &default_hstate;
hugetlb: ensure hugepage access is denied if hugepages are not supported Currently, I am seeing the following when I `mount -t hugetlbfs /none /dev/hugetlbfs`, and then simply do a `ls /dev/hugetlbfs`. I think it's related to the fact that hugetlbfs is properly not correctly setting itself up in this state?: Unable to handle kernel paging request for data at address 0x00000031 Faulting instruction address: 0xc000000000245710 Oops: Kernel access of bad area, sig: 11 [#1] SMP NR_CPUS=2048 NUMA pSeries .... In KVM guests on Power, in a guest not backed by hugepages, we see the following: AnonHugePages: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 64 kB HPAGE_SHIFT == 0 in this configuration, which indicates that hugepages are not supported at boot-time, but this is only checked in hugetlb_init(). Extract the check to a helper function, and use it in a few relevant places. This does make hugetlbfs not supported (not registered at all) in this environment. I believe this is fine, as there are no valid hugepages and that won't change at runtime. [akpm@linux-foundation.org: use pr_info(), per Mel] [akpm@linux-foundation.org: fix build when HPAGE_SHIFT is undefined] Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-05-06 23:50:00 +04:00
if (!hugepages_supported())
return 0;
return sysfs_emit_at(buf, len,
"Node %d HugePages_Total: %5u\n"
"Node %d HugePages_Free: %5u\n"
"Node %d HugePages_Surp: %5u\n",
nid, h->nr_huge_pages_node[nid],
nid, h->free_huge_pages_node[nid],
nid, h->surplus_huge_pages_node[nid]);
}
void hugetlb_show_meminfo(void)
{
struct hstate *h;
int nid;
hugetlb: ensure hugepage access is denied if hugepages are not supported Currently, I am seeing the following when I `mount -t hugetlbfs /none /dev/hugetlbfs`, and then simply do a `ls /dev/hugetlbfs`. I think it's related to the fact that hugetlbfs is properly not correctly setting itself up in this state?: Unable to handle kernel paging request for data at address 0x00000031 Faulting instruction address: 0xc000000000245710 Oops: Kernel access of bad area, sig: 11 [#1] SMP NR_CPUS=2048 NUMA pSeries .... In KVM guests on Power, in a guest not backed by hugepages, we see the following: AnonHugePages: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 64 kB HPAGE_SHIFT == 0 in this configuration, which indicates that hugepages are not supported at boot-time, but this is only checked in hugetlb_init(). Extract the check to a helper function, and use it in a few relevant places. This does make hugetlbfs not supported (not registered at all) in this environment. I believe this is fine, as there are no valid hugepages and that won't change at runtime. [akpm@linux-foundation.org: use pr_info(), per Mel] [akpm@linux-foundation.org: fix build when HPAGE_SHIFT is undefined] Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-05-06 23:50:00 +04:00
if (!hugepages_supported())
return;
for_each_node_state(nid, N_MEMORY)
for_each_hstate(h)
pr_info("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n",
nid,
h->nr_huge_pages_node[nid],
h->free_huge_pages_node[nid],
h->surplus_huge_pages_node[nid],
huge_page_size(h) / SZ_1K);
}
void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm)
{
seq_printf(m, "HugetlbPages:\t%8lu kB\n",
atomic_long_read(&mm->hugetlb_usage) << (PAGE_SHIFT - 10));
}
/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
unsigned long hugetlb_total_pages(void)
{
struct hstate *h;
unsigned long nr_total_pages = 0;
for_each_hstate(h)
nr_total_pages += h->nr_huge_pages * pages_per_huge_page(h);
return nr_total_pages;
}
static int hugetlb_acct_memory(struct hstate *h, long delta)
hugetlb: move hugetlb_acct_memory() This is a patchset to give reliable behaviour to a process that successfully calls mmap(MAP_PRIVATE) on a hugetlbfs file. Currently, it is possible for the process to be killed due to a small hugepage pool size even if it calls mlock(). MAP_SHARED mappings on hugetlbfs reserve huge pages at mmap() time. This guarantees all future faults against the mapping will succeed. This allows local allocations at first use improving NUMA locality whilst retaining reliability. MAP_PRIVATE mappings do not reserve pages. This can result in an application being SIGKILLed later if a huge page is not available at fault time. This makes huge pages usage very ill-advised in some cases as the unexpected application failure cannot be detected and handled as it is immediately fatal. Although an application may force instantiation of the pages using mlock(), this may lead to poor memory placement and the process may still be killed when performing COW. This patchset introduces a reliability guarantee for the process which creates a private mapping, i.e. the process that calls mmap() on a hugetlbfs file successfully. The first patch of the set is purely mechanical code move to make later diffs easier to read. The second patch will guarantee faults up until the process calls fork(). After patch two, as long as the child keeps the mappings, the parent is no longer guaranteed to be reliable. Patch 3 guarantees that the parent will always successfully COW by unmapping the pages from the child in the event there are insufficient pages in the hugepage pool in allocate a new page, be it via a static or dynamic pool. Existing hugepage-aware applications are unlikely to be affected by this change. For much of hugetlbfs's history, pages were pre-faulted at mmap() time or mmap() failed which acts in a reserve-like manner. If the pool is sized correctly already so that parent and child can fault reliably, the application will not even notice the reserves. It's only when the pool is too small for the application to function perfectly reliably that the reserves come into play. Credit goes to Andy Whitcroft for cleaning up a number of mistakes during review before the patches were released. This patch: A later patch in this set needs to call hugetlb_acct_memory() before it is defined. This patch moves the function without modification. This makes later diffs easier to read. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:22 +04:00
{
int ret = -ENOMEM;
if (!delta)
return 0;
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
hugetlb: move hugetlb_acct_memory() This is a patchset to give reliable behaviour to a process that successfully calls mmap(MAP_PRIVATE) on a hugetlbfs file. Currently, it is possible for the process to be killed due to a small hugepage pool size even if it calls mlock(). MAP_SHARED mappings on hugetlbfs reserve huge pages at mmap() time. This guarantees all future faults against the mapping will succeed. This allows local allocations at first use improving NUMA locality whilst retaining reliability. MAP_PRIVATE mappings do not reserve pages. This can result in an application being SIGKILLed later if a huge page is not available at fault time. This makes huge pages usage very ill-advised in some cases as the unexpected application failure cannot be detected and handled as it is immediately fatal. Although an application may force instantiation of the pages using mlock(), this may lead to poor memory placement and the process may still be killed when performing COW. This patchset introduces a reliability guarantee for the process which creates a private mapping, i.e. the process that calls mmap() on a hugetlbfs file successfully. The first patch of the set is purely mechanical code move to make later diffs easier to read. The second patch will guarantee faults up until the process calls fork(). After patch two, as long as the child keeps the mappings, the parent is no longer guaranteed to be reliable. Patch 3 guarantees that the parent will always successfully COW by unmapping the pages from the child in the event there are insufficient pages in the hugepage pool in allocate a new page, be it via a static or dynamic pool. Existing hugepage-aware applications are unlikely to be affected by this change. For much of hugetlbfs's history, pages were pre-faulted at mmap() time or mmap() failed which acts in a reserve-like manner. If the pool is sized correctly already so that parent and child can fault reliably, the application will not even notice the reserves. It's only when the pool is too small for the application to function perfectly reliably that the reserves come into play. Credit goes to Andy Whitcroft for cleaning up a number of mistakes during review before the patches were released. This patch: A later patch in this set needs to call hugetlb_acct_memory() before it is defined. This patch moves the function without modification. This makes later diffs easier to read. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:22 +04:00
/*
* When cpuset is configured, it breaks the strict hugetlb page
* reservation as the accounting is done on a global variable. Such
* reservation is completely rubbish in the presence of cpuset because
* the reservation is not checked against page availability for the
* current cpuset. Application can still potentially OOM'ed by kernel
* with lack of free htlb page in cpuset that the task is in.
* Attempt to enforce strict accounting with cpuset is almost
* impossible (or too ugly) because cpuset is too fluid that
* task or memory node can be dynamically moved between cpusets.
*
* The change of semantics for shared hugetlb mapping with cpuset is
* undesirable. However, in order to preserve some of the semantics,
* we fall back to check against current free page availability as
* a best attempt and hopefully to minimize the impact of changing
* semantics that cpuset has.
*
* Apart from cpuset, we also have memory policy mechanism that
* also determines from which node the kernel will allocate memory
* in a NUMA system. So similar to cpuset, we also should consider
* the memory policy of the current task. Similar to the description
* above.
hugetlb: move hugetlb_acct_memory() This is a patchset to give reliable behaviour to a process that successfully calls mmap(MAP_PRIVATE) on a hugetlbfs file. Currently, it is possible for the process to be killed due to a small hugepage pool size even if it calls mlock(). MAP_SHARED mappings on hugetlbfs reserve huge pages at mmap() time. This guarantees all future faults against the mapping will succeed. This allows local allocations at first use improving NUMA locality whilst retaining reliability. MAP_PRIVATE mappings do not reserve pages. This can result in an application being SIGKILLed later if a huge page is not available at fault time. This makes huge pages usage very ill-advised in some cases as the unexpected application failure cannot be detected and handled as it is immediately fatal. Although an application may force instantiation of the pages using mlock(), this may lead to poor memory placement and the process may still be killed when performing COW. This patchset introduces a reliability guarantee for the process which creates a private mapping, i.e. the process that calls mmap() on a hugetlbfs file successfully. The first patch of the set is purely mechanical code move to make later diffs easier to read. The second patch will guarantee faults up until the process calls fork(). After patch two, as long as the child keeps the mappings, the parent is no longer guaranteed to be reliable. Patch 3 guarantees that the parent will always successfully COW by unmapping the pages from the child in the event there are insufficient pages in the hugepage pool in allocate a new page, be it via a static or dynamic pool. Existing hugepage-aware applications are unlikely to be affected by this change. For much of hugetlbfs's history, pages were pre-faulted at mmap() time or mmap() failed which acts in a reserve-like manner. If the pool is sized correctly already so that parent and child can fault reliably, the application will not even notice the reserves. It's only when the pool is too small for the application to function perfectly reliably that the reserves come into play. Credit goes to Andy Whitcroft for cleaning up a number of mistakes during review before the patches were released. This patch: A later patch in this set needs to call hugetlb_acct_memory() before it is defined. This patch moves the function without modification. This makes later diffs easier to read. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:22 +04:00
*/
if (delta > 0) {
if (gather_surplus_pages(h, delta) < 0)
hugetlb: move hugetlb_acct_memory() This is a patchset to give reliable behaviour to a process that successfully calls mmap(MAP_PRIVATE) on a hugetlbfs file. Currently, it is possible for the process to be killed due to a small hugepage pool size even if it calls mlock(). MAP_SHARED mappings on hugetlbfs reserve huge pages at mmap() time. This guarantees all future faults against the mapping will succeed. This allows local allocations at first use improving NUMA locality whilst retaining reliability. MAP_PRIVATE mappings do not reserve pages. This can result in an application being SIGKILLed later if a huge page is not available at fault time. This makes huge pages usage very ill-advised in some cases as the unexpected application failure cannot be detected and handled as it is immediately fatal. Although an application may force instantiation of the pages using mlock(), this may lead to poor memory placement and the process may still be killed when performing COW. This patchset introduces a reliability guarantee for the process which creates a private mapping, i.e. the process that calls mmap() on a hugetlbfs file successfully. The first patch of the set is purely mechanical code move to make later diffs easier to read. The second patch will guarantee faults up until the process calls fork(). After patch two, as long as the child keeps the mappings, the parent is no longer guaranteed to be reliable. Patch 3 guarantees that the parent will always successfully COW by unmapping the pages from the child in the event there are insufficient pages in the hugepage pool in allocate a new page, be it via a static or dynamic pool. Existing hugepage-aware applications are unlikely to be affected by this change. For much of hugetlbfs's history, pages were pre-faulted at mmap() time or mmap() failed which acts in a reserve-like manner. If the pool is sized correctly already so that parent and child can fault reliably, the application will not even notice the reserves. It's only when the pool is too small for the application to function perfectly reliably that the reserves come into play. Credit goes to Andy Whitcroft for cleaning up a number of mistakes during review before the patches were released. This patch: A later patch in this set needs to call hugetlb_acct_memory() before it is defined. This patch moves the function without modification. This makes later diffs easier to read. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:22 +04:00
goto out;
if (delta > allowed_mems_nr(h)) {
return_unused_surplus_pages(h, delta);
hugetlb: move hugetlb_acct_memory() This is a patchset to give reliable behaviour to a process that successfully calls mmap(MAP_PRIVATE) on a hugetlbfs file. Currently, it is possible for the process to be killed due to a small hugepage pool size even if it calls mlock(). MAP_SHARED mappings on hugetlbfs reserve huge pages at mmap() time. This guarantees all future faults against the mapping will succeed. This allows local allocations at first use improving NUMA locality whilst retaining reliability. MAP_PRIVATE mappings do not reserve pages. This can result in an application being SIGKILLed later if a huge page is not available at fault time. This makes huge pages usage very ill-advised in some cases as the unexpected application failure cannot be detected and handled as it is immediately fatal. Although an application may force instantiation of the pages using mlock(), this may lead to poor memory placement and the process may still be killed when performing COW. This patchset introduces a reliability guarantee for the process which creates a private mapping, i.e. the process that calls mmap() on a hugetlbfs file successfully. The first patch of the set is purely mechanical code move to make later diffs easier to read. The second patch will guarantee faults up until the process calls fork(). After patch two, as long as the child keeps the mappings, the parent is no longer guaranteed to be reliable. Patch 3 guarantees that the parent will always successfully COW by unmapping the pages from the child in the event there are insufficient pages in the hugepage pool in allocate a new page, be it via a static or dynamic pool. Existing hugepage-aware applications are unlikely to be affected by this change. For much of hugetlbfs's history, pages were pre-faulted at mmap() time or mmap() failed which acts in a reserve-like manner. If the pool is sized correctly already so that parent and child can fault reliably, the application will not even notice the reserves. It's only when the pool is too small for the application to function perfectly reliably that the reserves come into play. Credit goes to Andy Whitcroft for cleaning up a number of mistakes during review before the patches were released. This patch: A later patch in this set needs to call hugetlb_acct_memory() before it is defined. This patch moves the function without modification. This makes later diffs easier to read. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:22 +04:00
goto out;
}
}
ret = 0;
if (delta < 0)
return_unused_surplus_pages(h, (unsigned long) -delta);
hugetlb: move hugetlb_acct_memory() This is a patchset to give reliable behaviour to a process that successfully calls mmap(MAP_PRIVATE) on a hugetlbfs file. Currently, it is possible for the process to be killed due to a small hugepage pool size even if it calls mlock(). MAP_SHARED mappings on hugetlbfs reserve huge pages at mmap() time. This guarantees all future faults against the mapping will succeed. This allows local allocations at first use improving NUMA locality whilst retaining reliability. MAP_PRIVATE mappings do not reserve pages. This can result in an application being SIGKILLed later if a huge page is not available at fault time. This makes huge pages usage very ill-advised in some cases as the unexpected application failure cannot be detected and handled as it is immediately fatal. Although an application may force instantiation of the pages using mlock(), this may lead to poor memory placement and the process may still be killed when performing COW. This patchset introduces a reliability guarantee for the process which creates a private mapping, i.e. the process that calls mmap() on a hugetlbfs file successfully. The first patch of the set is purely mechanical code move to make later diffs easier to read. The second patch will guarantee faults up until the process calls fork(). After patch two, as long as the child keeps the mappings, the parent is no longer guaranteed to be reliable. Patch 3 guarantees that the parent will always successfully COW by unmapping the pages from the child in the event there are insufficient pages in the hugepage pool in allocate a new page, be it via a static or dynamic pool. Existing hugepage-aware applications are unlikely to be affected by this change. For much of hugetlbfs's history, pages were pre-faulted at mmap() time or mmap() failed which acts in a reserve-like manner. If the pool is sized correctly already so that parent and child can fault reliably, the application will not even notice the reserves. It's only when the pool is too small for the application to function perfectly reliably that the reserves come into play. Credit goes to Andy Whitcroft for cleaning up a number of mistakes during review before the patches were released. This patch: A later patch in this set needs to call hugetlb_acct_memory() before it is defined. This patch moves the function without modification. This makes later diffs easier to read. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:22 +04:00
out:
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
hugetlb: move hugetlb_acct_memory() This is a patchset to give reliable behaviour to a process that successfully calls mmap(MAP_PRIVATE) on a hugetlbfs file. Currently, it is possible for the process to be killed due to a small hugepage pool size even if it calls mlock(). MAP_SHARED mappings on hugetlbfs reserve huge pages at mmap() time. This guarantees all future faults against the mapping will succeed. This allows local allocations at first use improving NUMA locality whilst retaining reliability. MAP_PRIVATE mappings do not reserve pages. This can result in an application being SIGKILLed later if a huge page is not available at fault time. This makes huge pages usage very ill-advised in some cases as the unexpected application failure cannot be detected and handled as it is immediately fatal. Although an application may force instantiation of the pages using mlock(), this may lead to poor memory placement and the process may still be killed when performing COW. This patchset introduces a reliability guarantee for the process which creates a private mapping, i.e. the process that calls mmap() on a hugetlbfs file successfully. The first patch of the set is purely mechanical code move to make later diffs easier to read. The second patch will guarantee faults up until the process calls fork(). After patch two, as long as the child keeps the mappings, the parent is no longer guaranteed to be reliable. Patch 3 guarantees that the parent will always successfully COW by unmapping the pages from the child in the event there are insufficient pages in the hugepage pool in allocate a new page, be it via a static or dynamic pool. Existing hugepage-aware applications are unlikely to be affected by this change. For much of hugetlbfs's history, pages were pre-faulted at mmap() time or mmap() failed which acts in a reserve-like manner. If the pool is sized correctly already so that parent and child can fault reliably, the application will not even notice the reserves. It's only when the pool is too small for the application to function perfectly reliably that the reserves come into play. Credit goes to Andy Whitcroft for cleaning up a number of mistakes during review before the patches were released. This patch: A later patch in this set needs to call hugetlb_acct_memory() before it is defined. This patch moves the function without modification. This makes later diffs easier to read. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:22 +04:00
return ret;
}
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
static void hugetlb_vm_op_open(struct vm_area_struct *vma)
{
struct resv_map *resv = vma_resv_map(vma);
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
/*
* This new VMA should share its siblings reservation map if present.
* The VMA will only ever have a valid reservation map pointer where
* it is being copied for another still existing VMA. As that VMA
* has a reference to the reservation map it cannot disappear until
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
* after this open call completes. It is therefore safe to take a
* new reference here without additional locking.
*/
hugetlb: fix hugetlb cgroup refcounting during vma split Guillaume Morin reported hitting the following WARNING followed by GPF or NULL pointer deference either in cgroups_destroy or in the kill_css path.: percpu ref (css_release) <= 0 (-1) after switching to atomic WARNING: CPU: 23 PID: 130 at lib/percpu-refcount.c:196 percpu_ref_switch_to_atomic_rcu+0x127/0x130 CPU: 23 PID: 130 Comm: ksoftirqd/23 Kdump: loaded Tainted: G O 5.10.60 #1 RIP: 0010:percpu_ref_switch_to_atomic_rcu+0x127/0x130 Call Trace: rcu_core+0x30f/0x530 rcu_core_si+0xe/0x10 __do_softirq+0x103/0x2a2 run_ksoftirqd+0x2b/0x40 smpboot_thread_fn+0x11a/0x170 kthread+0x10a/0x140 ret_from_fork+0x22/0x30 Upon further examination, it was discovered that the css structure was associated with hugetlb reservations. For private hugetlb mappings the vma points to a reserve map that contains a pointer to the css. At mmap time, reservations are set up and a reference to the css is taken. This reference is dropped in the vma close operation; hugetlb_vm_op_close. However, if a vma is split no additional reference to the css is taken yet hugetlb_vm_op_close will be called twice for the split vma resulting in an underflow. Fix by taking another reference in hugetlb_vm_op_open. Note that the reference is only taken for the owner of the reserve map. In the more common fork case, the pointer to the reserve map is cleared for non-owning vmas. Link: https://lkml.kernel.org/r/20210830215015.155224-1-mike.kravetz@oracle.com Fixes: e9fe92ae0cd2 ("hugetlb_cgroup: add reservation accounting for private mappings") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Guillaume Morin <guillaume@morinfr.org> Suggested-by: Guillaume Morin <guillaume@morinfr.org> Tested-by: Guillaume Morin <guillaume@morinfr.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:53 +03:00
if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
resv_map_dup_hugetlb_cgroup_uncharge_info(resv);
kref_get(&resv->refs);
hugetlb: fix hugetlb cgroup refcounting during vma split Guillaume Morin reported hitting the following WARNING followed by GPF or NULL pointer deference either in cgroups_destroy or in the kill_css path.: percpu ref (css_release) <= 0 (-1) after switching to atomic WARNING: CPU: 23 PID: 130 at lib/percpu-refcount.c:196 percpu_ref_switch_to_atomic_rcu+0x127/0x130 CPU: 23 PID: 130 Comm: ksoftirqd/23 Kdump: loaded Tainted: G O 5.10.60 #1 RIP: 0010:percpu_ref_switch_to_atomic_rcu+0x127/0x130 Call Trace: rcu_core+0x30f/0x530 rcu_core_si+0xe/0x10 __do_softirq+0x103/0x2a2 run_ksoftirqd+0x2b/0x40 smpboot_thread_fn+0x11a/0x170 kthread+0x10a/0x140 ret_from_fork+0x22/0x30 Upon further examination, it was discovered that the css structure was associated with hugetlb reservations. For private hugetlb mappings the vma points to a reserve map that contains a pointer to the css. At mmap time, reservations are set up and a reference to the css is taken. This reference is dropped in the vma close operation; hugetlb_vm_op_close. However, if a vma is split no additional reference to the css is taken yet hugetlb_vm_op_close will be called twice for the split vma resulting in an underflow. Fix by taking another reference in hugetlb_vm_op_open. Note that the reference is only taken for the owner of the reserve map. In the more common fork case, the pointer to the reserve map is cleared for non-owning vmas. Link: https://lkml.kernel.org/r/20210830215015.155224-1-mike.kravetz@oracle.com Fixes: e9fe92ae0cd2 ("hugetlb_cgroup: add reservation accounting for private mappings") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Guillaume Morin <guillaume@morinfr.org> Suggested-by: Guillaume Morin <guillaume@morinfr.org> Tested-by: Guillaume Morin <guillaume@morinfr.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 00:58:53 +03:00
}
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
}
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
static void hugetlb_vm_op_close(struct vm_area_struct *vma)
{
struct hstate *h = hstate_vma(vma);
struct resv_map *resv = vma_resv_map(vma);
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
struct hugepage_subpool *spool = subpool_vma(vma);
unsigned long reserve, start, end;
long gbl_reserve;
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER))
return;
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
start = vma_hugecache_offset(h, vma, vma->vm_start);
end = vma_hugecache_offset(h, vma, vma->vm_end);
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
reserve = (end - start) - region_count(resv, start, end);
hugetlb_cgroup: add reservation accounting for private mappings Normally the pointer to the cgroup to uncharge hangs off the struct page, and gets queried when it's time to free the page. With hugetlb_cgroup reservations, this is not possible. Because it's possible for a page to be reserved by one task and actually faulted in by another task. The best place to put the hugetlb_cgroup pointer to uncharge for reservations is in the resv_map. But, because the resv_map has different semantics for private and shared mappings, the code patch to charge/uncharge shared and private mappings is different. This patch implements charging and uncharging for private mappings. For private mappings, the counter to uncharge is in resv_map->reservation_counter. On initializing the resv_map this is set to NULL. On reservation of a region in private mapping, the tasks hugetlb_cgroup is charged and the hugetlb_cgroup is placed is resv_map->reservation_counter. On hugetlb_vm_op_close, we uncharge resv_map->reservation_counter. [akpm@linux-foundation.org: forward declare struct resv_map] Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Link: http://lkml.kernel.org/r/20200211213128.73302-3-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:21 +03:00
hugetlb_cgroup_uncharge_counter(resv, start, end);
if (reserve) {
/*
* Decrement reserve counts. The global reserve count may be
* adjusted if the subpool has a minimum size.
*/
gbl_reserve = hugepage_subpool_put_pages(spool, reserve);
hugetlb_acct_memory(h, -gbl_reserve);
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
}
hugetlb_cgroup: add reservation accounting for private mappings Normally the pointer to the cgroup to uncharge hangs off the struct page, and gets queried when it's time to free the page. With hugetlb_cgroup reservations, this is not possible. Because it's possible for a page to be reserved by one task and actually faulted in by another task. The best place to put the hugetlb_cgroup pointer to uncharge for reservations is in the resv_map. But, because the resv_map has different semantics for private and shared mappings, the code patch to charge/uncharge shared and private mappings is different. This patch implements charging and uncharging for private mappings. For private mappings, the counter to uncharge is in resv_map->reservation_counter. On initializing the resv_map this is set to NULL. On reservation of a region in private mapping, the tasks hugetlb_cgroup is charged and the hugetlb_cgroup is placed is resv_map->reservation_counter. On hugetlb_vm_op_close, we uncharge resv_map->reservation_counter. [akpm@linux-foundation.org: forward declare struct resv_map] Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Link: http://lkml.kernel.org/r/20200211213128.73302-3-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:21 +03:00
kref_put(&resv->refs, resv_map_release);
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
}
static int hugetlb_vm_op_split(struct vm_area_struct *vma, unsigned long addr)
{
if (addr & ~(huge_page_mask(hstate_vma(vma))))
return -EINVAL;
return 0;
}
static unsigned long hugetlb_vm_op_pagesize(struct vm_area_struct *vma)
{
return huge_page_size(hstate_vma(vma));
}
/*
* We cannot handle pagefaults against hugetlb pages at all. They cause
* handle_mm_fault() to try to instantiate regular-sized pages in the
* hugepage VMA. do_page_fault() is supposed to trap this, so BUG is we get
* this far.
*/
static vm_fault_t hugetlb_vm_op_fault(struct vm_fault *vmf)
{
BUG();
return 0;
}
ipc/shm.c add ->pagesize function to shm_vm_ops Commit 05ea88608d4e ("mm, hugetlbfs: introduce ->pagesize() to vm_operations_struct") adds a new ->pagesize() function to hugetlb_vm_ops, intended to cover all hugetlbfs backed files. With System V shared memory model, if "huge page" is specified, the "shared memory" is backed by hugetlbfs files, but the mappings initiated via shmget/shmat have their original vm_ops overwritten with shm_vm_ops, so we need to add a ->pagesize function to shm_vm_ops. Otherwise, vma_kernel_pagesize() returns PAGE_SIZE given a hugetlbfs backed vma, result in below BUG: fs/hugetlbfs/inode.c 443 if (unlikely(page_mapped(page))) { 444 BUG_ON(truncate_op); resulting in hugetlbfs: oracle (4592): Using mlock ulimits for SHM_HUGETLB is deprecated ------------[ cut here ]------------ kernel BUG at fs/hugetlbfs/inode.c:444! Modules linked in: nfsv3 rpcsec_gss_krb5 nfsv4 ... CPU: 35 PID: 5583 Comm: oracle_5583_sbt Not tainted 4.14.35-1829.el7uek.x86_64 #2 RIP: 0010:remove_inode_hugepages+0x3db/0x3e2 .... Call Trace: hugetlbfs_evict_inode+0x1e/0x3e evict+0xdb/0x1af iput+0x1a2/0x1f7 dentry_unlink_inode+0xc6/0xf0 __dentry_kill+0xd8/0x18d dput+0x1b5/0x1ed __fput+0x18b/0x216 ____fput+0xe/0x10 task_work_run+0x90/0xa7 exit_to_usermode_loop+0xdd/0x116 do_syscall_64+0x187/0x1ae entry_SYSCALL_64_after_hwframe+0x150/0x0 [jane.chu@oracle.com: relocate comment] Link: http://lkml.kernel.org/r/20180731044831.26036-1-jane.chu@oracle.com Link: http://lkml.kernel.org/r/20180727211727.5020-1-jane.chu@oracle.com Fixes: 05ea88608d4e13 ("mm, hugetlbfs: introduce ->pagesize() to vm_operations_struct") Signed-off-by: Jane Chu <jane.chu@oracle.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-03 01:36:05 +03:00
/*
* When a new function is introduced to vm_operations_struct and added
* to hugetlb_vm_ops, please consider adding the function to shm_vm_ops.
* This is because under System V memory model, mappings created via
* shmget/shmat with "huge page" specified are backed by hugetlbfs files,
* their original vm_ops are overwritten with shm_vm_ops.
*/
const struct vm_operations_struct hugetlb_vm_ops = {
.fault = hugetlb_vm_op_fault,
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
.open = hugetlb_vm_op_open,
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
.close = hugetlb_vm_op_close,
.may_split = hugetlb_vm_op_split,
.pagesize = hugetlb_vm_op_pagesize,
};
static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
int writable)
{
pte_t entry;
mm/hugetlb: change parameters of arch_make_huge_pte() Patch series "Subject: [PATCH v2 0/5] Implement huge VMAP and VMALLOC on powerpc 8xx", v2. This series implements huge VMAP and VMALLOC on powerpc 8xx. Powerpc 8xx has 4 page sizes: - 4k - 16k - 512k - 8M At the time being, vmalloc and vmap only support huge pages which are leaf at PMD level. Here the PMD level is 4M, it doesn't correspond to any supported page size. For now, implement use of 16k and 512k pages which is done at PTE level. Support of 8M pages will be implemented later, it requires use of hugepd tables. To allow this, the architecture provides two functions: - arch_vmap_pte_range_map_size() which tells vmap_pte_range() what page size to use. A stub returning PAGE_SIZE is provided when the architecture doesn't provide this function. - arch_vmap_pte_supported_shift() which tells __vmalloc_node_range() what page shift to use for a given area size. A stub returning PAGE_SHIFT is provided when the architecture doesn't provide this function. This patch (of 5): At the time being, arch_make_huge_pte() has the following prototype: pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, struct page *page, int writable); vma is used to get the pages shift or size. vma is also used on Sparc to get vm_flags. page is not used. writable is not used. In order to use this function without a vma, replace vma by shift and flags. Also remove the used parameters. Link: https://lkml.kernel.org/r/cover.1620795204.git.christophe.leroy@csgroup.eu Link: https://lkml.kernel.org/r/f4633ac6a7da2f22f31a04a89e0a7026bb78b15b.1620795204.git.christophe.leroy@csgroup.eu Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:00 +03:00
unsigned int shift = huge_page_shift(hstate_vma(vma));
if (writable) {
mm/hugetlb: add more arch-defined huge_pte functions Commit abf09bed3cce ("s390/mm: implement software dirty bits") introduced another difference in the pte layout vs. the pmd layout on s390, thoroughly breaking the s390 support for hugetlbfs. This requires replacing some more pte_xxx functions in mm/hugetlbfs.c with a huge_pte_xxx version. This patch introduces those huge_pte_xxx functions and their generic implementation in asm-generic/hugetlb.h, which will now be included on all architectures supporting hugetlbfs apart from s390. This change will be a no-op for those architectures. [akpm@linux-foundation.org: fix warning] Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> [for !s390 parts] Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 02:07:23 +04:00
entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page,
vma->vm_page_prot)));
} else {
mm/hugetlb: add more arch-defined huge_pte functions Commit abf09bed3cce ("s390/mm: implement software dirty bits") introduced another difference in the pte layout vs. the pmd layout on s390, thoroughly breaking the s390 support for hugetlbfs. This requires replacing some more pte_xxx functions in mm/hugetlbfs.c with a huge_pte_xxx version. This patch introduces those huge_pte_xxx functions and their generic implementation in asm-generic/hugetlb.h, which will now be included on all architectures supporting hugetlbfs apart from s390. This change will be a no-op for those architectures. [akpm@linux-foundation.org: fix warning] Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> [for !s390 parts] Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 02:07:23 +04:00
entry = huge_pte_wrprotect(mk_huge_pte(page,
vma->vm_page_prot));
}
entry = pte_mkyoung(entry);
mm/hugetlb: change parameters of arch_make_huge_pte() Patch series "Subject: [PATCH v2 0/5] Implement huge VMAP and VMALLOC on powerpc 8xx", v2. This series implements huge VMAP and VMALLOC on powerpc 8xx. Powerpc 8xx has 4 page sizes: - 4k - 16k - 512k - 8M At the time being, vmalloc and vmap only support huge pages which are leaf at PMD level. Here the PMD level is 4M, it doesn't correspond to any supported page size. For now, implement use of 16k and 512k pages which is done at PTE level. Support of 8M pages will be implemented later, it requires use of hugepd tables. To allow this, the architecture provides two functions: - arch_vmap_pte_range_map_size() which tells vmap_pte_range() what page size to use. A stub returning PAGE_SIZE is provided when the architecture doesn't provide this function. - arch_vmap_pte_supported_shift() which tells __vmalloc_node_range() what page shift to use for a given area size. A stub returning PAGE_SHIFT is provided when the architecture doesn't provide this function. This patch (of 5): At the time being, arch_make_huge_pte() has the following prototype: pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, struct page *page, int writable); vma is used to get the pages shift or size. vma is also used on Sparc to get vm_flags. page is not used. writable is not used. In order to use this function without a vma, replace vma by shift and flags. Also remove the used parameters. Link: https://lkml.kernel.org/r/cover.1620795204.git.christophe.leroy@csgroup.eu Link: https://lkml.kernel.org/r/f4633ac6a7da2f22f31a04a89e0a7026bb78b15b.1620795204.git.christophe.leroy@csgroup.eu Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:00 +03:00
entry = arch_make_huge_pte(entry, shift, vma->vm_flags);
return entry;
}
static void set_huge_ptep_writable(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep)
{
pte_t entry;
mm/hugetlb: add more arch-defined huge_pte functions Commit abf09bed3cce ("s390/mm: implement software dirty bits") introduced another difference in the pte layout vs. the pmd layout on s390, thoroughly breaking the s390 support for hugetlbfs. This requires replacing some more pte_xxx functions in mm/hugetlbfs.c with a huge_pte_xxx version. This patch introduces those huge_pte_xxx functions and their generic implementation in asm-generic/hugetlb.h, which will now be included on all architectures supporting hugetlbfs apart from s390. This change will be a no-op for those architectures. [akpm@linux-foundation.org: fix warning] Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> [for !s390 parts] Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 02:07:23 +04:00
entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep)));
if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
update_mmu_cache(vma, address, ptep);
}
bool is_hugetlb_entry_migration(pte_t pte)
{
swp_entry_t swp;
if (huge_pte_none(pte) || pte_present(pte))
return false;
swp = pte_to_swp_entry(pte);
if (is_migration_entry(swp))
return true;
else
return false;
}
static bool is_hugetlb_entry_hwpoisoned(pte_t pte)
{
swp_entry_t swp;
if (huge_pte_none(pte) || pte_present(pte))
return false;
swp = pte_to_swp_entry(pte);
if (is_hwpoison_entry(swp))
return true;
else
return false;
}
hugetlb: do early cow when page pinned on src mm This is the last missing piece of the COW-during-fork effort when there're pinned pages found. One can reference 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes", 2020-09-27) for more information, since we do similar things here rather than pte this time, but just for hugetlb. Note that after Jason's recent work on 57efa1fe5957 ("mm/gup: prevent gup_fast from racing with COW during fork", 2020-12-15) which is safer and easier to understand, we're safe now within the whole copy_page_range() against gup-fast, we don't need the wr-protect trick that proposed in 70e806e4e645 anymore. Link: https://lkml.kernel.org/r/20210217233547.93892-6-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Jason Gunthorpe <jgg@ziepe.ca> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Gal Pressman <galpress@amazon.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Cc: Wei Zhang <wzam@amazon.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:33 +03:00
static void
hugetlb_install_page(struct vm_area_struct *vma, pte_t *ptep, unsigned long addr,
struct page *new_page)
{
__SetPageUptodate(new_page);
hugepage_add_new_anon_rmap(new_page, vma, addr);
mm: change page type prior to adding page table entry Patch series "page table check", v3. Ensure that some memory corruptions are prevented by checking at the time of insertion of entries into user page tables that there is no illegal sharing. We have recently found a problem [1] that existed in kernel since 4.14. The problem was caused by broken page ref count and led to memory leaking from one process into another. The problem was accidentally detected by studying a dump of one process and noticing that one page contains memory that should not belong to this process. There are some other page->_refcount related problems that were recently fixed: [2], [3] which potentially could also lead to illegal sharing. In addition to hardening refcount [4] itself, this work is an attempt to prevent this class of memory corruption issues. It uses a simple state machine that is independent from regular MM logic to check for illegal sharing at time pages are inserted and removed from page tables. [1] https://lore.kernel.org/all/xr9335nxwc5y.fsf@gthelen2.svl.corp.google.com [2] https://lore.kernel.org/all/1582661774-30925-2-git-send-email-akaher@vmware.com [3] https://lore.kernel.org/all/20210622021423.154662-3-mike.kravetz@oracle.com [4] https://lore.kernel.org/all/20211221150140.988298-1-pasha.tatashin@soleen.com This patch (of 4): There are a few places where we first update the entry in the user page table, and later change the struct page to indicate that this is anonymous or file page. In most places, however, we first configure the page metadata and then insert entries into the page table. Page table check, will use the information from struct page to verify the type of entry is inserted. Change the order in all places to first update struct page, and later to update page table. This means that we first do calls that may change the type of page (anon or file): page_move_anon_rmap page_add_anon_rmap do_page_add_anon_rmap page_add_new_anon_rmap page_add_file_rmap hugepage_add_anon_rmap hugepage_add_new_anon_rmap And after that do calls that add entries to the page table: set_huge_pte_at set_pte_at Link: https://lkml.kernel.org/r/20211221154650.1047963-1-pasha.tatashin@soleen.com Link: https://lkml.kernel.org/r/20211221154650.1047963-2-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: David Rientjes <rientjes@google.com> Cc: Paul Turner <pjt@google.com> Cc: Wei Xu <weixugc@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Will Deacon <will@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-15 01:06:29 +03:00
set_huge_pte_at(vma->vm_mm, addr, ptep, make_huge_pte(vma, new_page, 1));
hugetlb: do early cow when page pinned on src mm This is the last missing piece of the COW-during-fork effort when there're pinned pages found. One can reference 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes", 2020-09-27) for more information, since we do similar things here rather than pte this time, but just for hugetlb. Note that after Jason's recent work on 57efa1fe5957 ("mm/gup: prevent gup_fast from racing with COW during fork", 2020-12-15) which is safer and easier to understand, we're safe now within the whole copy_page_range() against gup-fast, we don't need the wr-protect trick that proposed in 70e806e4e645 anymore. Link: https://lkml.kernel.org/r/20210217233547.93892-6-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Jason Gunthorpe <jgg@ziepe.ca> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Gal Pressman <galpress@amazon.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Cc: Wei Zhang <wzam@amazon.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:33 +03:00
hugetlb_count_add(pages_per_huge_page(hstate_vma(vma)), vma->vm_mm);
ClearHPageRestoreReserve(new_page);
SetHPageMigratable(new_page);
}
int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
struct vm_area_struct *vma)
{
hugetlbfs: fix kernel BUG at fs/hugetlbfs/inode.c:444! This bug has been experienced several times by the Oracle DB team. The BUG is in remove_inode_hugepages() as follows: /* * If page is mapped, it was faulted in after being * unmapped in caller. Unmap (again) now after taking * the fault mutex. The mutex will prevent faults * until we finish removing the page. * * This race can only happen in the hole punch case. * Getting here in a truncate operation is a bug. */ if (unlikely(page_mapped(page))) { BUG_ON(truncate_op); In this case, the elevated map count is not the result of a race. Rather it was incorrectly incremented as the result of a bug in the huge pmd sharing code. Consider the following: - Process A maps a hugetlbfs file of sufficient size and alignment (PUD_SIZE) that a pmd page could be shared. - Process B maps the same hugetlbfs file with the same size and alignment such that a pmd page is shared. - Process B then calls mprotect() to change protections for the mapping with the shared pmd. As a result, the pmd is 'unshared'. - Process B then calls mprotect() again to chage protections for the mapping back to their original value. pmd remains unshared. - Process B then forks and process C is created. During the fork process, we do dup_mm -> dup_mmap -> copy_page_range to copy page tables. Copying page tables for hugetlb mappings is done in the routine copy_hugetlb_page_range. In copy_hugetlb_page_range(), the destination pte is obtained by: dst_pte = huge_pte_alloc(dst, addr, sz); If pmd sharing is possible, the returned pointer will be to a pte in an existing page table. In the situation above, process C could share with either process A or process B. Since process A is first in the list, the returned pte is a pointer to a pte in process A's page table. However, the check for pmd sharing in copy_hugetlb_page_range is: /* If the pagetables are shared don't copy or take references */ if (dst_pte == src_pte) continue; Since process C is sharing with process A instead of process B, the above test fails. The code in copy_hugetlb_page_range which follows assumes dst_pte points to a huge_pte_none pte. It copies the pte entry from src_pte to dst_pte and increments this map count of the associated page. This is how we end up with an elevated map count. To solve, check the dst_pte entry for huge_pte_none. If !none, this implies PMD sharing so do not copy. Link: http://lkml.kernel.org/r/20181105212315.14125-1-mike.kravetz@oracle.com Fixes: c5c99429fa57 ("fix hugepages leak due to pagetable page sharing") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-11-17 02:08:04 +03:00
pte_t *src_pte, *dst_pte, entry, dst_entry;
struct page *ptepage;
unsigned long addr;
bool cow = is_cow_mapping(vma->vm_flags);
struct hstate *h = hstate_vma(vma);
unsigned long sz = huge_page_size(h);
hugetlb: do early cow when page pinned on src mm This is the last missing piece of the COW-during-fork effort when there're pinned pages found. One can reference 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes", 2020-09-27) for more information, since we do similar things here rather than pte this time, but just for hugetlb. Note that after Jason's recent work on 57efa1fe5957 ("mm/gup: prevent gup_fast from racing with COW during fork", 2020-12-15) which is safer and easier to understand, we're safe now within the whole copy_page_range() against gup-fast, we don't need the wr-protect trick that proposed in 70e806e4e645 anymore. Link: https://lkml.kernel.org/r/20210217233547.93892-6-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Jason Gunthorpe <jgg@ziepe.ca> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Gal Pressman <galpress@amazon.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Cc: Wei Zhang <wzam@amazon.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:33 +03:00
unsigned long npages = pages_per_huge_page(h);
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
struct address_space *mapping = vma->vm_file->f_mapping;
struct mmu_notifier_range range;
int ret = 0;
if (cow) {
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, src,
mm/mmu_notifier: contextual information for event triggering invalidation CPU page table update can happens for many reasons, not only as a result of a syscall (munmap(), mprotect(), mremap(), madvise(), ...) but also as a result of kernel activities (memory compression, reclaim, migration, ...). Users of mmu notifier API track changes to the CPU page table and take specific action for them. While current API only provide range of virtual address affected by the change, not why the changes is happening. This patchset do the initial mechanical convertion of all the places that calls mmu_notifier_range_init to also provide the default MMU_NOTIFY_UNMAP event as well as the vma if it is know (most invalidation happens against a given vma). Passing down the vma allows the users of mmu notifier to inspect the new vma page protection. The MMU_NOTIFY_UNMAP is always the safe default as users of mmu notifier should assume that every for the range is going away when that event happens. A latter patch do convert mm call path to use a more appropriate events for each call. This is done as 2 patches so that no call site is forgotten especialy as it uses this following coccinelle patch: %<---------------------------------------------------------------------- @@ identifier I1, I2, I3, I4; @@ static inline void mmu_notifier_range_init(struct mmu_notifier_range *I1, +enum mmu_notifier_event event, +unsigned flags, +struct vm_area_struct *vma, struct mm_struct *I2, unsigned long I3, unsigned long I4) { ... } @@ @@ -#define mmu_notifier_range_init(range, mm, start, end) +#define mmu_notifier_range_init(range, event, flags, vma, mm, start, end) @@ expression E1, E3, E4; identifier I1; @@ <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, I1, I1->vm_mm, E3, E4) ...> @@ expression E1, E2, E3, E4; identifier FN, VMA; @@ FN(..., struct vm_area_struct *VMA, ...) { <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, VMA, E2, E3, E4) ...> } @@ expression E1, E2, E3, E4; identifier FN, VMA; @@ FN(...) { struct vm_area_struct *VMA; <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, VMA, E2, E3, E4) ...> } @@ expression E1, E2, E3, E4; identifier FN; @@ FN(...) { <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, NULL, E2, E3, E4) ...> } ---------------------------------------------------------------------->% Applied with: spatch --all-includes --sp-file mmu-notifier.spatch fs/proc/task_mmu.c --in-place spatch --sp-file mmu-notifier.spatch --dir kernel/events/ --in-place spatch --sp-file mmu-notifier.spatch --dir mm --in-place Link: http://lkml.kernel.org/r/20190326164747.24405-6-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Cc: Christian König <christian.koenig@amd.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Peter Xu <peterx@redhat.com> Cc: Felix Kuehling <Felix.Kuehling@amd.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Ross Zwisler <zwisler@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krcmar <rkrcmar@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Christian Koenig <christian.koenig@amd.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 03:20:49 +03:00
vma->vm_start,
vma->vm_end);
mmu_notifier_invalidate_range_start(&range);
mm/hugetlb: take src_mm->write_protect_seq in copy_hugetlb_page_range() Let's do it just like copy_page_range(), taking the seqlock and making sure the mmap_lock is held in write mode. This allows for add a VM_BUG_ON to page_needs_cow_for_dma() and properly synchronizes concurrent fork() with GUP-fast of hugetlb pages, which will be relevant for further changes. Link: https://lkml.kernel.org/r/20220428083441.37290-3-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:42 +03:00
mmap_assert_write_locked(src);
raw_write_seqcount_begin(&src->write_protect_seq);
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
} else {
/*
* For shared mappings i_mmap_rwsem must be held to call
* huge_pte_alloc, otherwise the returned ptep could go
* away if part of a shared pmd and another thread calls
* huge_pmd_unshare.
*/
i_mmap_lock_read(mapping);
}
for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
spinlock_t *src_ptl, *dst_ptl;
mm/hugetlb: add size parameter to huge_pte_offset() A poisoned or migrated hugepage is stored as a swap entry in the page tables. On architectures that support hugepages consisting of contiguous page table entries (such as on arm64) this leads to ambiguity in determining the page table entry to return in huge_pte_offset() when a poisoned entry is encountered. Let's remove the ambiguity by adding a size parameter to convey additional information about the requested address. Also fixup the definition/usage of huge_pte_offset() throughout the tree. Link: http://lkml.kernel.org/r/20170522133604.11392-4-punit.agrawal@arm.com Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Acked-by: Steve Capper <steve.capper@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: James Hogan <james.hogan@imgtec.com> (odd fixer:METAG ARCHITECTURE) Cc: Ralf Baechle <ralf@linux-mips.org> (supporter:MIPS) Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Rich Felker <dalias@libc.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-07 01:39:42 +03:00
src_pte = huge_pte_offset(src, addr, sz);
if (!src_pte)
continue;
hugetlb: pass vma into huge_pte_alloc() and huge_pmd_share() Patch series "hugetlb: Disable huge pmd unshare for uffd-wp", v4. This series tries to disable huge pmd unshare of hugetlbfs backed memory for uffd-wp. Although uffd-wp of hugetlbfs is still during rfc stage, the idea of this series may be needed for multiple tasks (Axel's uffd minor fault series, and Mike's soft dirty series), so I picked it out from the larger series. This patch (of 4): It is a preparation work to be able to behave differently in the per architecture huge_pte_alloc() according to different VMA attributes. Pass it deeper into huge_pmd_share() so that we can avoid the find_vma() call. [peterx@redhat.com: build fix] Link: https://lkml.kernel.org/r/20210304164653.GB397383@xz-x1Link: https://lkml.kernel.org/r/20210218230633.15028-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210218230633.15028-2-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:33:00 +03:00
dst_pte = huge_pte_alloc(dst, vma, addr, sz);
if (!dst_pte) {
ret = -ENOMEM;
break;
}
fix hugepages leak due to pagetable page sharing The shared page table code for hugetlb memory on x86 and x86_64 is causing a leak. When a user of hugepages exits using this code the system leaks some of the hugepages. ------------------------------------------------------- Part of /proc/meminfo just before database startup: HugePages_Total: 5500 HugePages_Free: 5500 HugePages_Rsvd: 0 Hugepagesize: 2048 kB Just before shutdown: HugePages_Total: 5500 HugePages_Free: 4475 HugePages_Rsvd: 0 Hugepagesize: 2048 kB After shutdown: HugePages_Total: 5500 HugePages_Free: 4988 HugePages_Rsvd: 0 Hugepagesize: 2048 kB ---------------------------------------------------------- The problem occurs durring a fork, in copy_hugetlb_page_range(). It locates the dst_pte using huge_pte_alloc(). Since huge_pte_alloc() calls huge_pmd_share() it will share the pmd page if can, yet the main loop in copy_hugetlb_page_range() does a get_page() on every hugepage. This is a violation of the shared hugepmd pagetable protocol and creates additional referenced to the hugepages causing a leak when the unmap of the VMA occurs. We can skip the entire replication of the ptes when the hugepage pagetables are shared. The attached patch skips copying the ptes and the get_page() calls if the hugetlbpage pagetable is shared. [akpm@linux-foundation.org: coding-style cleanups] Signed-off-by: Larry Woodman <lwoodman@redhat.com> Signed-off-by: Adam Litke <agl@us.ibm.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Ken Chen <kenchen@google.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-01-24 16:49:25 +03:00
hugetlbfs: fix kernel BUG at fs/hugetlbfs/inode.c:444! This bug has been experienced several times by the Oracle DB team. The BUG is in remove_inode_hugepages() as follows: /* * If page is mapped, it was faulted in after being * unmapped in caller. Unmap (again) now after taking * the fault mutex. The mutex will prevent faults * until we finish removing the page. * * This race can only happen in the hole punch case. * Getting here in a truncate operation is a bug. */ if (unlikely(page_mapped(page))) { BUG_ON(truncate_op); In this case, the elevated map count is not the result of a race. Rather it was incorrectly incremented as the result of a bug in the huge pmd sharing code. Consider the following: - Process A maps a hugetlbfs file of sufficient size and alignment (PUD_SIZE) that a pmd page could be shared. - Process B maps the same hugetlbfs file with the same size and alignment such that a pmd page is shared. - Process B then calls mprotect() to change protections for the mapping with the shared pmd. As a result, the pmd is 'unshared'. - Process B then calls mprotect() again to chage protections for the mapping back to their original value. pmd remains unshared. - Process B then forks and process C is created. During the fork process, we do dup_mm -> dup_mmap -> copy_page_range to copy page tables. Copying page tables for hugetlb mappings is done in the routine copy_hugetlb_page_range. In copy_hugetlb_page_range(), the destination pte is obtained by: dst_pte = huge_pte_alloc(dst, addr, sz); If pmd sharing is possible, the returned pointer will be to a pte in an existing page table. In the situation above, process C could share with either process A or process B. Since process A is first in the list, the returned pte is a pointer to a pte in process A's page table. However, the check for pmd sharing in copy_hugetlb_page_range is: /* If the pagetables are shared don't copy or take references */ if (dst_pte == src_pte) continue; Since process C is sharing with process A instead of process B, the above test fails. The code in copy_hugetlb_page_range which follows assumes dst_pte points to a huge_pte_none pte. It copies the pte entry from src_pte to dst_pte and increments this map count of the associated page. This is how we end up with an elevated map count. To solve, check the dst_pte entry for huge_pte_none. If !none, this implies PMD sharing so do not copy. Link: http://lkml.kernel.org/r/20181105212315.14125-1-mike.kravetz@oracle.com Fixes: c5c99429fa57 ("fix hugepages leak due to pagetable page sharing") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-11-17 02:08:04 +03:00
/*
* If the pagetables are shared don't copy or take references.
* dst_pte == src_pte is the common case of src/dest sharing.
*
* However, src could have 'unshared' and dst shares with
* another vma. If dst_pte !none, this implies sharing.
* Check here before taking page table lock, and once again
* after taking the lock below.
*/
dst_entry = huge_ptep_get(dst_pte);
if ((dst_pte == src_pte) || !huge_pte_none(dst_entry))
fix hugepages leak due to pagetable page sharing The shared page table code for hugetlb memory on x86 and x86_64 is causing a leak. When a user of hugepages exits using this code the system leaks some of the hugepages. ------------------------------------------------------- Part of /proc/meminfo just before database startup: HugePages_Total: 5500 HugePages_Free: 5500 HugePages_Rsvd: 0 Hugepagesize: 2048 kB Just before shutdown: HugePages_Total: 5500 HugePages_Free: 4475 HugePages_Rsvd: 0 Hugepagesize: 2048 kB After shutdown: HugePages_Total: 5500 HugePages_Free: 4988 HugePages_Rsvd: 0 Hugepagesize: 2048 kB ---------------------------------------------------------- The problem occurs durring a fork, in copy_hugetlb_page_range(). It locates the dst_pte using huge_pte_alloc(). Since huge_pte_alloc() calls huge_pmd_share() it will share the pmd page if can, yet the main loop in copy_hugetlb_page_range() does a get_page() on every hugepage. This is a violation of the shared hugepmd pagetable protocol and creates additional referenced to the hugepages causing a leak when the unmap of the VMA occurs. We can skip the entire replication of the ptes when the hugepage pagetables are shared. The attached patch skips copying the ptes and the get_page() calls if the hugetlbpage pagetable is shared. [akpm@linux-foundation.org: coding-style cleanups] Signed-off-by: Larry Woodman <lwoodman@redhat.com> Signed-off-by: Adam Litke <agl@us.ibm.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Ken Chen <kenchen@google.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-01-24 16:49:25 +03:00
continue;
dst_ptl = huge_pte_lock(h, dst, dst_pte);
src_ptl = huge_pte_lockptr(h, src, src_pte);
spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
entry = huge_ptep_get(src_pte);
hugetlbfs: fix kernel BUG at fs/hugetlbfs/inode.c:444! This bug has been experienced several times by the Oracle DB team. The BUG is in remove_inode_hugepages() as follows: /* * If page is mapped, it was faulted in after being * unmapped in caller. Unmap (again) now after taking * the fault mutex. The mutex will prevent faults * until we finish removing the page. * * This race can only happen in the hole punch case. * Getting here in a truncate operation is a bug. */ if (unlikely(page_mapped(page))) { BUG_ON(truncate_op); In this case, the elevated map count is not the result of a race. Rather it was incorrectly incremented as the result of a bug in the huge pmd sharing code. Consider the following: - Process A maps a hugetlbfs file of sufficient size and alignment (PUD_SIZE) that a pmd page could be shared. - Process B maps the same hugetlbfs file with the same size and alignment such that a pmd page is shared. - Process B then calls mprotect() to change protections for the mapping with the shared pmd. As a result, the pmd is 'unshared'. - Process B then calls mprotect() again to chage protections for the mapping back to their original value. pmd remains unshared. - Process B then forks and process C is created. During the fork process, we do dup_mm -> dup_mmap -> copy_page_range to copy page tables. Copying page tables for hugetlb mappings is done in the routine copy_hugetlb_page_range. In copy_hugetlb_page_range(), the destination pte is obtained by: dst_pte = huge_pte_alloc(dst, addr, sz); If pmd sharing is possible, the returned pointer will be to a pte in an existing page table. In the situation above, process C could share with either process A or process B. Since process A is first in the list, the returned pte is a pointer to a pte in process A's page table. However, the check for pmd sharing in copy_hugetlb_page_range is: /* If the pagetables are shared don't copy or take references */ if (dst_pte == src_pte) continue; Since process C is sharing with process A instead of process B, the above test fails. The code in copy_hugetlb_page_range which follows assumes dst_pte points to a huge_pte_none pte. It copies the pte entry from src_pte to dst_pte and increments this map count of the associated page. This is how we end up with an elevated map count. To solve, check the dst_pte entry for huge_pte_none. If !none, this implies PMD sharing so do not copy. Link: http://lkml.kernel.org/r/20181105212315.14125-1-mike.kravetz@oracle.com Fixes: c5c99429fa57 ("fix hugepages leak due to pagetable page sharing") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-11-17 02:08:04 +03:00
dst_entry = huge_ptep_get(dst_pte);
hugetlb: do early cow when page pinned on src mm This is the last missing piece of the COW-during-fork effort when there're pinned pages found. One can reference 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes", 2020-09-27) for more information, since we do similar things here rather than pte this time, but just for hugetlb. Note that after Jason's recent work on 57efa1fe5957 ("mm/gup: prevent gup_fast from racing with COW during fork", 2020-12-15) which is safer and easier to understand, we're safe now within the whole copy_page_range() against gup-fast, we don't need the wr-protect trick that proposed in 70e806e4e645 anymore. Link: https://lkml.kernel.org/r/20210217233547.93892-6-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Jason Gunthorpe <jgg@ziepe.ca> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Gal Pressman <galpress@amazon.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Cc: Wei Zhang <wzam@amazon.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:33 +03:00
again:
hugetlbfs: fix kernel BUG at fs/hugetlbfs/inode.c:444! This bug has been experienced several times by the Oracle DB team. The BUG is in remove_inode_hugepages() as follows: /* * If page is mapped, it was faulted in after being * unmapped in caller. Unmap (again) now after taking * the fault mutex. The mutex will prevent faults * until we finish removing the page. * * This race can only happen in the hole punch case. * Getting here in a truncate operation is a bug. */ if (unlikely(page_mapped(page))) { BUG_ON(truncate_op); In this case, the elevated map count is not the result of a race. Rather it was incorrectly incremented as the result of a bug in the huge pmd sharing code. Consider the following: - Process A maps a hugetlbfs file of sufficient size and alignment (PUD_SIZE) that a pmd page could be shared. - Process B maps the same hugetlbfs file with the same size and alignment such that a pmd page is shared. - Process B then calls mprotect() to change protections for the mapping with the shared pmd. As a result, the pmd is 'unshared'. - Process B then calls mprotect() again to chage protections for the mapping back to their original value. pmd remains unshared. - Process B then forks and process C is created. During the fork process, we do dup_mm -> dup_mmap -> copy_page_range to copy page tables. Copying page tables for hugetlb mappings is done in the routine copy_hugetlb_page_range. In copy_hugetlb_page_range(), the destination pte is obtained by: dst_pte = huge_pte_alloc(dst, addr, sz); If pmd sharing is possible, the returned pointer will be to a pte in an existing page table. In the situation above, process C could share with either process A or process B. Since process A is first in the list, the returned pte is a pointer to a pte in process A's page table. However, the check for pmd sharing in copy_hugetlb_page_range is: /* If the pagetables are shared don't copy or take references */ if (dst_pte == src_pte) continue; Since process C is sharing with process A instead of process B, the above test fails. The code in copy_hugetlb_page_range which follows assumes dst_pte points to a huge_pte_none pte. It copies the pte entry from src_pte to dst_pte and increments this map count of the associated page. This is how we end up with an elevated map count. To solve, check the dst_pte entry for huge_pte_none. If !none, this implies PMD sharing so do not copy. Link: http://lkml.kernel.org/r/20181105212315.14125-1-mike.kravetz@oracle.com Fixes: c5c99429fa57 ("fix hugepages leak due to pagetable page sharing") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-11-17 02:08:04 +03:00
if (huge_pte_none(entry) || !huge_pte_none(dst_entry)) {
/*
* Skip if src entry none. Also, skip in the
* unlikely case dst entry !none as this implies
* sharing with another vma.
*/
;
} else if (unlikely(is_hugetlb_entry_migration(entry) ||
is_hugetlb_entry_hwpoisoned(entry))) {
swp_entry_t swp_entry = pte_to_swp_entry(entry);
mm: remember exclusively mapped anonymous pages with PG_anon_exclusive Let's mark exclusively mapped anonymous pages with PG_anon_exclusive as exclusive, and use that information to make GUP pins reliable and stay consistent with the page mapped into the page table even if the page table entry gets write-protected. With that information at hand, we can extend our COW logic to always reuse anonymous pages that are exclusive. For anonymous pages that might be shared, the existing logic applies. As already documented, PG_anon_exclusive is usually only expressive in combination with a page table entry. Especially PTE vs. PMD-mapped anonymous pages require more thought, some examples: due to mremap() we can easily have a single compound page PTE-mapped into multiple page tables exclusively in a single process -- multiple page table locks apply. Further, due to MADV_WIPEONFORK we might not necessarily write-protect all PTEs, and only some subpages might be pinned. Long story short: once PTE-mapped, we have to track information about exclusivity per sub-page, but until then, we can just track it for the compound page in the head page and not having to update a whole bunch of subpages all of the time for a simple PMD mapping of a THP. For simplicity, this commit mostly talks about "anonymous pages", while it's for THP actually "the part of an anonymous folio referenced via a page table entry". To not spill PG_anon_exclusive code all over the mm code-base, we let the anon rmap code to handle all PG_anon_exclusive logic it can easily handle. If a writable, present page table entry points at an anonymous (sub)page, that (sub)page must be PG_anon_exclusive. If GUP wants to take a reliably pin (FOLL_PIN) on an anonymous page references via a present page table entry, it must only pin if PG_anon_exclusive is set for the mapped (sub)page. This commit doesn't adjust GUP, so this is only implicitly handled for FOLL_WRITE, follow-up commits will teach GUP to also respect it for FOLL_PIN without FOLL_WRITE, to make all GUP pins of anonymous pages fully reliable. Whenever an anonymous page is to be shared (fork(), KSM), or when temporarily unmapping an anonymous page (swap, migration), the relevant PG_anon_exclusive bit has to be cleared to mark the anonymous page possibly shared. Clearing will fail if there are GUP pins on the page: * For fork(), this means having to copy the page and not being able to share it. fork() protects against concurrent GUP using the PT lock and the src_mm->write_protect_seq. * For KSM, this means sharing will fail. For swap this means, unmapping will fail, For migration this means, migration will fail early. All three cases protect against concurrent GUP using the PT lock and a proper clear/invalidate+flush of the relevant page table entry. This fixes memory corruptions reported for FOLL_PIN | FOLL_WRITE, when a pinned page gets mapped R/O and the successive write fault ends up replacing the page instead of reusing it. It improves the situation for O_DIRECT/vmsplice/... that still use FOLL_GET instead of FOLL_PIN, if fork() is *not* involved, however swapout and fork() are still problematic. Properly using FOLL_PIN instead of FOLL_GET for these GUP users will fix the issue for them. I. Details about basic handling I.1. Fresh anonymous pages page_add_new_anon_rmap() and hugepage_add_new_anon_rmap() will mark the given page exclusive via __page_set_anon_rmap(exclusive=1). As that is the mechanism fresh anonymous pages come into life (besides migration code where we copy the page->mapping), all fresh anonymous pages will start out as exclusive. I.2. COW reuse handling of anonymous pages When a COW handler stumbles over a (sub)page that's marked exclusive, it simply reuses it. Otherwise, the handler tries harder under page lock to detect if the (sub)page is exclusive and can be reused. If exclusive, page_move_anon_rmap() will mark the given (sub)page exclusive. Note that hugetlb code does not yet check for PageAnonExclusive(), as it still uses the old COW logic that is prone to the COW security issue because hugetlb code cannot really tolerate unnecessary/wrong COW as huge pages are a scarce resource. I.3. Migration handling try_to_migrate() has to try marking an exclusive anonymous page shared via page_try_share_anon_rmap(). If it fails because there are GUP pins on the page, unmap fails. migrate_vma_collect_pmd() and __split_huge_pmd_locked() are handled similarly. Writable migration entries implicitly point at shared anonymous pages. For readable migration entries that information is stored via a new "readable-exclusive" migration entry, specific to anonymous pages. When restoring a migration entry in remove_migration_pte(), information about exlusivity is detected via the migration entry type, and RMAP_EXCLUSIVE is set accordingly for page_add_anon_rmap()/hugepage_add_anon_rmap() to restore that information. I.4. Swapout handling try_to_unmap() has to try marking the mapped page possibly shared via page_try_share_anon_rmap(). If it fails because there are GUP pins on the page, unmap fails. For now, information about exclusivity is lost. In the future, we might want to remember that information in the swap entry in some cases, however, it requires more thought, care, and a way to store that information in swap entries. I.5. Swapin handling do_swap_page() will never stumble over exclusive anonymous pages in the swap cache, as try_to_migrate() prohibits that. do_swap_page() always has to detect manually if an anonymous page is exclusive and has to set RMAP_EXCLUSIVE for page_add_anon_rmap() accordingly. I.6. THP handling __split_huge_pmd_locked() has to move the information about exclusivity from the PMD to the PTEs. a) In case we have a readable-exclusive PMD migration entry, simply insert readable-exclusive PTE migration entries. b) In case we have a present PMD entry and we don't want to freeze ("convert to migration entries"), simply forward PG_anon_exclusive to all sub-pages, no need to temporarily clear the bit. c) In case we have a present PMD entry and want to freeze, handle it similar to try_to_migrate(): try marking the page shared first. In case we fail, we ignore the "freeze" instruction and simply split ordinarily. try_to_migrate() will properly fail because the THP is still mapped via PTEs. When splitting a compound anonymous folio (THP), the information about exclusivity is implicitly handled via the migration entries: no need to replicate PG_anon_exclusive manually. I.7. fork() handling fork() handling is relatively easy, because PG_anon_exclusive is only expressive for some page table entry types. a) Present anonymous pages page_try_dup_anon_rmap() will mark the given subpage shared -- which will fail if the page is pinned. If it failed, we have to copy (or PTE-map a PMD to handle it on the PTE level). Note that device exclusive entries are just a pointer at a PageAnon() page. fork() will first convert a device exclusive entry to a present page table and handle it just like present anonymous pages. b) Device private entry Device private entries point at PageAnon() pages that cannot be mapped directly and, therefore, cannot get pinned. page_try_dup_anon_rmap() will mark the given subpage shared, which cannot fail because they cannot get pinned. c) HW poison entries PG_anon_exclusive will remain untouched and is stale -- the page table entry is just a placeholder after all. d) Migration entries Writable and readable-exclusive entries are converted to readable entries: possibly shared. I.8. mprotect() handling mprotect() only has to properly handle the new readable-exclusive migration entry: When write-protecting a migration entry that points at an anonymous page, remember the information about exclusivity via the "readable-exclusive" migration entry type. II. Migration and GUP-fast Whenever replacing a present page table entry that maps an exclusive anonymous page by a migration entry, we have to mark the page possibly shared and synchronize against GUP-fast by a proper clear/invalidate+flush to make the following scenario impossible: 1. try_to_migrate() places a migration entry after checking for GUP pins and marks the page possibly shared. 2. GUP-fast pins the page due to lack of synchronization 3. fork() converts the "writable/readable-exclusive" migration entry into a readable migration entry 4. Migration fails due to the GUP pin (failing to freeze the refcount) 5. Migration entries are restored. PG_anon_exclusive is lost -> We have a pinned page that is not marked exclusive anymore. Note that we move information about exclusivity from the page to the migration entry as it otherwise highly overcomplicates fork() and PTE-mapping a THP. III. Swapout and GUP-fast Whenever replacing a present page table entry that maps an exclusive anonymous page by a swap entry, we have to mark the page possibly shared and synchronize against GUP-fast by a proper clear/invalidate+flush to make the following scenario impossible: 1. try_to_unmap() places a swap entry after checking for GUP pins and clears exclusivity information on the page. 2. GUP-fast pins the page due to lack of synchronization. -> We have a pinned page that is not marked exclusive anymore. If we'd ever store information about exclusivity in the swap entry, similar to migration handling, the same considerations as in II would apply. This is future work. Link: https://lkml.kernel.org/r/20220428083441.37290-13-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:44 +03:00
if (!is_readable_migration_entry(swp_entry) && cow) {
/*
* COW mappings require pages in both
* parent and child to be set to read.
*/
swp_entry = make_readable_migration_entry(
swp_offset(swp_entry));
entry = swp_entry_to_pte(swp_entry);
mm/hugetlb: introduce set_huge_swap_pte_at() helper set_huge_pte_at(), an architecture callback to populate hugepage ptes, does not provide the range of virtual memory that is targeted. This leads to ambiguity when dealing with swap entries on architectures that support hugepages consisting of contiguous ptes. Fix the problem by introducing an overridable helper that is called when populating the page tables with swap entries. The size of the targeted region is provided to the helper to help determine the number of entries to be updated. Provide a default implementation that maintains the current behaviour. [punit.agrawal@arm.com: v4] Link: http://lkml.kernel.org/r/20170524115409.31309-8-punit.agrawal@arm.com [punit.agrawal@arm.com: add an empty definition for set_huge_swap_pte_at()] Link: http://lkml.kernel.org/r/20170525171331.31469-1-punit.agrawal@arm.com Link: http://lkml.kernel.org/r/20170522133604.11392-6-punit.agrawal@arm.com Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Acked-by: Steve Capper <steve.capper@arm.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-07 01:39:50 +03:00
set_huge_swap_pte_at(src, addr, src_pte,
entry, sz);
}
mm/hugetlb: introduce set_huge_swap_pte_at() helper set_huge_pte_at(), an architecture callback to populate hugepage ptes, does not provide the range of virtual memory that is targeted. This leads to ambiguity when dealing with swap entries on architectures that support hugepages consisting of contiguous ptes. Fix the problem by introducing an overridable helper that is called when populating the page tables with swap entries. The size of the targeted region is provided to the helper to help determine the number of entries to be updated. Provide a default implementation that maintains the current behaviour. [punit.agrawal@arm.com: v4] Link: http://lkml.kernel.org/r/20170524115409.31309-8-punit.agrawal@arm.com [punit.agrawal@arm.com: add an empty definition for set_huge_swap_pte_at()] Link: http://lkml.kernel.org/r/20170525171331.31469-1-punit.agrawal@arm.com Link: http://lkml.kernel.org/r/20170522133604.11392-6-punit.agrawal@arm.com Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Acked-by: Steve Capper <steve.capper@arm.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-07 01:39:50 +03:00
set_huge_swap_pte_at(dst, addr, dst_pte, entry, sz);
} else {
hugetlb: do early cow when page pinned on src mm This is the last missing piece of the COW-during-fork effort when there're pinned pages found. One can reference 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes", 2020-09-27) for more information, since we do similar things here rather than pte this time, but just for hugetlb. Note that after Jason's recent work on 57efa1fe5957 ("mm/gup: prevent gup_fast from racing with COW during fork", 2020-12-15) which is safer and easier to understand, we're safe now within the whole copy_page_range() against gup-fast, we don't need the wr-protect trick that proposed in 70e806e4e645 anymore. Link: https://lkml.kernel.org/r/20210217233547.93892-6-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Jason Gunthorpe <jgg@ziepe.ca> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Gal Pressman <galpress@amazon.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Cc: Wei Zhang <wzam@amazon.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:33 +03:00
entry = huge_ptep_get(src_pte);
ptepage = pte_page(entry);
get_page(ptepage);
/*
mm/rmap: split page_dup_rmap() into page_dup_file_rmap() and page_try_dup_anon_rmap() ... and move the special check for pinned pages into page_try_dup_anon_rmap() to prepare for tracking exclusive anonymous pages via a new pageflag, clearing it only after making sure that there are no GUP pins on the anonymous page. We really only care about pins on anonymous pages, because they are prone to getting replaced in the COW handler once mapped R/O. For !anon pages in cow-mappings (!VM_SHARED && VM_MAYWRITE) we shouldn't really care about that, at least not that I could come up with an example. Let's drop the is_cow_mapping() check from page_needs_cow_for_dma(), as we know we're dealing with anonymous pages. Also, drop the handling of pinned pages from copy_huge_pud() and add a comment if ever supporting anonymous pages on the PUD level. This is a preparation for tracking exclusivity of anonymous pages in the rmap code, and disallowing marking a page shared (-> failing to duplicate) if there are GUP pins on a page. Link: https://lkml.kernel.org/r/20220428083441.37290-5-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:43 +03:00
* Failing to duplicate the anon rmap is a rare case
* where we see pinned hugetlb pages while they're
* prone to COW. We need to do the COW earlier during
* fork.
hugetlb: do early cow when page pinned on src mm This is the last missing piece of the COW-during-fork effort when there're pinned pages found. One can reference 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes", 2020-09-27) for more information, since we do similar things here rather than pte this time, but just for hugetlb. Note that after Jason's recent work on 57efa1fe5957 ("mm/gup: prevent gup_fast from racing with COW during fork", 2020-12-15) which is safer and easier to understand, we're safe now within the whole copy_page_range() against gup-fast, we don't need the wr-protect trick that proposed in 70e806e4e645 anymore. Link: https://lkml.kernel.org/r/20210217233547.93892-6-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Jason Gunthorpe <jgg@ziepe.ca> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Gal Pressman <galpress@amazon.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Cc: Wei Zhang <wzam@amazon.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:33 +03:00
*
* When pre-allocating the page or copying data, we
* need to be without the pgtable locks since we could
* sleep during the process.
*/
mm/rmap: split page_dup_rmap() into page_dup_file_rmap() and page_try_dup_anon_rmap() ... and move the special check for pinned pages into page_try_dup_anon_rmap() to prepare for tracking exclusive anonymous pages via a new pageflag, clearing it only after making sure that there are no GUP pins on the anonymous page. We really only care about pins on anonymous pages, because they are prone to getting replaced in the COW handler once mapped R/O. For !anon pages in cow-mappings (!VM_SHARED && VM_MAYWRITE) we shouldn't really care about that, at least not that I could come up with an example. Let's drop the is_cow_mapping() check from page_needs_cow_for_dma(), as we know we're dealing with anonymous pages. Also, drop the handling of pinned pages from copy_huge_pud() and add a comment if ever supporting anonymous pages on the PUD level. This is a preparation for tracking exclusivity of anonymous pages in the rmap code, and disallowing marking a page shared (-> failing to duplicate) if there are GUP pins on a page. Link: https://lkml.kernel.org/r/20220428083441.37290-5-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:43 +03:00
if (!PageAnon(ptepage)) {
page_dup_file_rmap(ptepage, true);
} else if (page_try_dup_anon_rmap(ptepage, true, vma)) {
hugetlb: do early cow when page pinned on src mm This is the last missing piece of the COW-during-fork effort when there're pinned pages found. One can reference 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes", 2020-09-27) for more information, since we do similar things here rather than pte this time, but just for hugetlb. Note that after Jason's recent work on 57efa1fe5957 ("mm/gup: prevent gup_fast from racing with COW during fork", 2020-12-15) which is safer and easier to understand, we're safe now within the whole copy_page_range() against gup-fast, we don't need the wr-protect trick that proposed in 70e806e4e645 anymore. Link: https://lkml.kernel.org/r/20210217233547.93892-6-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Jason Gunthorpe <jgg@ziepe.ca> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Gal Pressman <galpress@amazon.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Cc: Wei Zhang <wzam@amazon.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:33 +03:00
pte_t src_pte_old = entry;
struct page *new;
spin_unlock(src_ptl);
spin_unlock(dst_ptl);
/* Do not use reserve as it's private owned */
new = alloc_huge_page(vma, addr, 1);
if (IS_ERR(new)) {
put_page(ptepage);
ret = PTR_ERR(new);
break;
}
copy_user_huge_page(new, ptepage, addr, vma,
npages);
put_page(ptepage);
/* Install the new huge page if src pte stable */
dst_ptl = huge_pte_lock(h, dst, dst_pte);
src_ptl = huge_pte_lockptr(h, src, src_pte);
spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
entry = huge_ptep_get(src_pte);
if (!pte_same(src_pte_old, entry)) {
mm/hugetlb: expand restore_reserve_on_error functionality The routine restore_reserve_on_error is called to restore reservation information when an error occurs after page allocation. The routine alloc_huge_page modifies the mapping reserve map and potentially the reserve count during allocation. If code calling alloc_huge_page encounters an error after allocation and needs to free the page, the reservation information needs to be adjusted. Currently, restore_reserve_on_error only takes action on pages for which the reserve count was adjusted(HPageRestoreReserve flag). There is nothing wrong with these adjustments. However, alloc_huge_page ALWAYS modifies the reserve map during allocation even if the reserve count is not adjusted. This can cause issues as observed during development of this patch [1]. One specific series of operations causing an issue is: - Create a shared hugetlb mapping Reservations for all pages created by default - Fault in a page in the mapping Reservation exists so reservation count is decremented - Punch a hole in the file/mapping at index previously faulted Reservation and any associated pages will be removed - Allocate a page to fill the hole No reservation entry, so reserve count unmodified Reservation entry added to map by alloc_huge_page - Error after allocation and before instantiating the page Reservation entry remains in map - Allocate a page to fill the hole Reservation entry exists, so decrement reservation count This will cause a reservation count underflow as the reservation count was decremented twice for the same index. A user would observe a very large number for HugePages_Rsvd in /proc/meminfo. This would also likely cause subsequent allocations of hugetlb pages to fail as it would 'appear' that all pages are reserved. This sequence of operations is unlikely to happen, however they were easily reproduced and observed using hacked up code as described in [1]. Address the issue by having the routine restore_reserve_on_error take action on pages where HPageRestoreReserve is not set. In this case, we need to remove any reserve map entry created by alloc_huge_page. A new helper routine vma_del_reservation assists with this operation. There are three callers of alloc_huge_page which do not currently call restore_reserve_on error before freeing a page on error paths. Add those missing calls. [1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/ Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com Fixes: 96b96a96ddee ("mm/hugetlb: fix huge page reservation leak in private mapping error paths" Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:29 +03:00
restore_reserve_on_error(h, vma, addr,
new);
hugetlb: do early cow when page pinned on src mm This is the last missing piece of the COW-during-fork effort when there're pinned pages found. One can reference 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes", 2020-09-27) for more information, since we do similar things here rather than pte this time, but just for hugetlb. Note that after Jason's recent work on 57efa1fe5957 ("mm/gup: prevent gup_fast from racing with COW during fork", 2020-12-15) which is safer and easier to understand, we're safe now within the whole copy_page_range() against gup-fast, we don't need the wr-protect trick that proposed in 70e806e4e645 anymore. Link: https://lkml.kernel.org/r/20210217233547.93892-6-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Jason Gunthorpe <jgg@ziepe.ca> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Gal Pressman <galpress@amazon.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Cc: Wei Zhang <wzam@amazon.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:33 +03:00
put_page(new);
/* dst_entry won't change as in child */
goto again;
}
hugetlb_install_page(vma, dst_pte, addr, new);
spin_unlock(src_ptl);
spin_unlock(dst_ptl);
continue;
}
if (cow) {
mm/mmu_notifier: avoid double notification when it is useless This patch only affects users of mmu_notifier->invalidate_range callback which are device drivers related to ATS/PASID, CAPI, IOMMUv2, SVM ... and it is an optimization for those users. Everyone else is unaffected by it. When clearing a pte/pmd we are given a choice to notify the event under the page table lock (notify version of *_clear_flush helpers do call the mmu_notifier_invalidate_range). But that notification is not necessary in all cases. This patch removes almost all cases where it is useless to have a call to mmu_notifier_invalidate_range before mmu_notifier_invalidate_range_end. It also adds documentation in all those cases explaining why. Below is a more in depth analysis of why this is fine to do this: For secondary TLB (non CPU TLB) like IOMMU TLB or device TLB (when device use thing like ATS/PASID to get the IOMMU to walk the CPU page table to access a process virtual address space). There is only 2 cases when you need to notify those secondary TLB while holding page table lock when clearing a pte/pmd: A) page backing address is free before mmu_notifier_invalidate_range_end B) a page table entry is updated to point to a new page (COW, write fault on zero page, __replace_page(), ...) Case A is obvious you do not want to take the risk for the device to write to a page that might now be used by something completely different. Case B is more subtle. For correctness it requires the following sequence to happen: - take page table lock - clear page table entry and notify (pmd/pte_huge_clear_flush_notify()) - set page table entry to point to new page If clearing the page table entry is not followed by a notify before setting the new pte/pmd value then you can break memory model like C11 or C++11 for the device. Consider the following scenario (device use a feature similar to ATS/ PASID): Two address addrA and addrB such that |addrA - addrB| >= PAGE_SIZE we assume they are write protected for COW (other case of B apply too). [Time N] ----------------------------------------------------------------- CPU-thread-0 {try to write to addrA} CPU-thread-1 {try to write to addrB} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {read addrA and populate device TLB} DEV-thread-2 {read addrB and populate device TLB} [Time N+1] --------------------------------------------------------------- CPU-thread-0 {COW_step0: {mmu_notifier_invalidate_range_start(addrA)}} CPU-thread-1 {COW_step0: {mmu_notifier_invalidate_range_start(addrB)}} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+2] --------------------------------------------------------------- CPU-thread-0 {COW_step1: {update page table point to new page for addrA}} CPU-thread-1 {COW_step1: {update page table point to new page for addrB}} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+3] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {preempted} CPU-thread-2 {write to addrA which is a write to new page} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+3] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {preempted} CPU-thread-2 {} CPU-thread-3 {write to addrB which is a write to new page} DEV-thread-0 {} DEV-thread-2 {} [Time N+4] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {COW_step3: {mmu_notifier_invalidate_range_end(addrB)}} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+5] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {read addrA from old page} DEV-thread-2 {read addrB from new page} So here because at time N+2 the clear page table entry was not pair with a notification to invalidate the secondary TLB, the device see the new value for addrB before seing the new value for addrA. This break total memory ordering for the device. When changing a pte to write protect or to point to a new write protected page with same content (KSM) it is ok to delay invalidate_range callback to mmu_notifier_invalidate_range_end() outside the page table lock. This is true even if the thread doing page table update is preempted right after releasing page table lock before calling mmu_notifier_invalidate_range_end Thanks to Andrea for thinking of a problematic scenario for COW. [jglisse@redhat.com: v2] Link: http://lkml.kernel.org/r/20171017031003.7481-2-jglisse@redhat.com Link: http://lkml.kernel.org/r/20170901173011.10745-1-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Alistair Popple <alistair@popple.id.au> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Andrew Donnellan <andrew.donnellan@au1.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-16 04:34:07 +03:00
/*
* No need to notify as we are downgrading page
* table protection not changing it to point
* to a new page.
*
* See Documentation/vm/mmu_notifier.rst
mm/mmu_notifier: avoid double notification when it is useless This patch only affects users of mmu_notifier->invalidate_range callback which are device drivers related to ATS/PASID, CAPI, IOMMUv2, SVM ... and it is an optimization for those users. Everyone else is unaffected by it. When clearing a pte/pmd we are given a choice to notify the event under the page table lock (notify version of *_clear_flush helpers do call the mmu_notifier_invalidate_range). But that notification is not necessary in all cases. This patch removes almost all cases where it is useless to have a call to mmu_notifier_invalidate_range before mmu_notifier_invalidate_range_end. It also adds documentation in all those cases explaining why. Below is a more in depth analysis of why this is fine to do this: For secondary TLB (non CPU TLB) like IOMMU TLB or device TLB (when device use thing like ATS/PASID to get the IOMMU to walk the CPU page table to access a process virtual address space). There is only 2 cases when you need to notify those secondary TLB while holding page table lock when clearing a pte/pmd: A) page backing address is free before mmu_notifier_invalidate_range_end B) a page table entry is updated to point to a new page (COW, write fault on zero page, __replace_page(), ...) Case A is obvious you do not want to take the risk for the device to write to a page that might now be used by something completely different. Case B is more subtle. For correctness it requires the following sequence to happen: - take page table lock - clear page table entry and notify (pmd/pte_huge_clear_flush_notify()) - set page table entry to point to new page If clearing the page table entry is not followed by a notify before setting the new pte/pmd value then you can break memory model like C11 or C++11 for the device. Consider the following scenario (device use a feature similar to ATS/ PASID): Two address addrA and addrB such that |addrA - addrB| >= PAGE_SIZE we assume they are write protected for COW (other case of B apply too). [Time N] ----------------------------------------------------------------- CPU-thread-0 {try to write to addrA} CPU-thread-1 {try to write to addrB} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {read addrA and populate device TLB} DEV-thread-2 {read addrB and populate device TLB} [Time N+1] --------------------------------------------------------------- CPU-thread-0 {COW_step0: {mmu_notifier_invalidate_range_start(addrA)}} CPU-thread-1 {COW_step0: {mmu_notifier_invalidate_range_start(addrB)}} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+2] --------------------------------------------------------------- CPU-thread-0 {COW_step1: {update page table point to new page for addrA}} CPU-thread-1 {COW_step1: {update page table point to new page for addrB}} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+3] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {preempted} CPU-thread-2 {write to addrA which is a write to new page} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+3] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {preempted} CPU-thread-2 {} CPU-thread-3 {write to addrB which is a write to new page} DEV-thread-0 {} DEV-thread-2 {} [Time N+4] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {COW_step3: {mmu_notifier_invalidate_range_end(addrB)}} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+5] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {read addrA from old page} DEV-thread-2 {read addrB from new page} So here because at time N+2 the clear page table entry was not pair with a notification to invalidate the secondary TLB, the device see the new value for addrB before seing the new value for addrA. This break total memory ordering for the device. When changing a pte to write protect or to point to a new write protected page with same content (KSM) it is ok to delay invalidate_range callback to mmu_notifier_invalidate_range_end() outside the page table lock. This is true even if the thread doing page table update is preempted right after releasing page table lock before calling mmu_notifier_invalidate_range_end Thanks to Andrea for thinking of a problematic scenario for COW. [jglisse@redhat.com: v2] Link: http://lkml.kernel.org/r/20171017031003.7481-2-jglisse@redhat.com Link: http://lkml.kernel.org/r/20170901173011.10745-1-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Alistair Popple <alistair@popple.id.au> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Andrew Donnellan <andrew.donnellan@au1.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-16 04:34:07 +03:00
*/
huge_ptep_set_wrprotect(src, addr, src_pte);
entry = huge_pte_wrprotect(entry);
}
hugetlb: do early cow when page pinned on src mm This is the last missing piece of the COW-during-fork effort when there're pinned pages found. One can reference 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes", 2020-09-27) for more information, since we do similar things here rather than pte this time, but just for hugetlb. Note that after Jason's recent work on 57efa1fe5957 ("mm/gup: prevent gup_fast from racing with COW during fork", 2020-12-15) which is safer and easier to understand, we're safe now within the whole copy_page_range() against gup-fast, we don't need the wr-protect trick that proposed in 70e806e4e645 anymore. Link: https://lkml.kernel.org/r/20210217233547.93892-6-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Jason Gunthorpe <jgg@ziepe.ca> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Gal Pressman <galpress@amazon.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Cc: Wei Zhang <wzam@amazon.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:33 +03:00
set_huge_pte_at(dst, addr, dst_pte, entry);
hugetlb: do early cow when page pinned on src mm This is the last missing piece of the COW-during-fork effort when there're pinned pages found. One can reference 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes", 2020-09-27) for more information, since we do similar things here rather than pte this time, but just for hugetlb. Note that after Jason's recent work on 57efa1fe5957 ("mm/gup: prevent gup_fast from racing with COW during fork", 2020-12-15) which is safer and easier to understand, we're safe now within the whole copy_page_range() against gup-fast, we don't need the wr-protect trick that proposed in 70e806e4e645 anymore. Link: https://lkml.kernel.org/r/20210217233547.93892-6-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Jason Gunthorpe <jgg@ziepe.ca> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Gal Pressman <galpress@amazon.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Roland Scheidegger <sroland@vmware.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Cc: Wei Zhang <wzam@amazon.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-13 08:07:33 +03:00
hugetlb_count_add(npages, dst);
}
spin_unlock(src_ptl);
spin_unlock(dst_ptl);
}
mm/hugetlb: take src_mm->write_protect_seq in copy_hugetlb_page_range() Let's do it just like copy_page_range(), taking the seqlock and making sure the mmap_lock is held in write mode. This allows for add a VM_BUG_ON to page_needs_cow_for_dma() and properly synchronizes concurrent fork() with GUP-fast of hugetlb pages, which will be relevant for further changes. Link: https://lkml.kernel.org/r/20220428083441.37290-3-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:42 +03:00
if (cow) {
raw_write_seqcount_end(&src->write_protect_seq);
mmu_notifier_invalidate_range_end(&range);
mm/hugetlb: take src_mm->write_protect_seq in copy_hugetlb_page_range() Let's do it just like copy_page_range(), taking the seqlock and making sure the mmap_lock is held in write mode. This allows for add a VM_BUG_ON to page_needs_cow_for_dma() and properly synchronizes concurrent fork() with GUP-fast of hugetlb pages, which will be relevant for further changes. Link: https://lkml.kernel.org/r/20220428083441.37290-3-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:42 +03:00
} else {
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
i_mmap_unlock_read(mapping);
mm/hugetlb: take src_mm->write_protect_seq in copy_hugetlb_page_range() Let's do it just like copy_page_range(), taking the seqlock and making sure the mmap_lock is held in write mode. This allows for add a VM_BUG_ON to page_needs_cow_for_dma() and properly synchronizes concurrent fork() with GUP-fast of hugetlb pages, which will be relevant for further changes. Link: https://lkml.kernel.org/r/20220428083441.37290-3-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:42 +03:00
}
return ret;
}
static void move_huge_pte(struct vm_area_struct *vma, unsigned long old_addr,
mm/hugetlb: fix kernel crash with hugetlb mremap This fixes the below crash: kernel BUG at include/linux/mm.h:2373! cpu 0x5d: Vector: 700 (Program Check) at [c00000003c6e76e0] pc: c000000000581a54: pmd_to_page+0x54/0x80 lr: c00000000058d184: move_hugetlb_page_tables+0x4e4/0x5b0 sp: c00000003c6e7980 msr: 9000000000029033 current = 0xc00000003bd8d980 paca = 0xc000200fff610100 irqmask: 0x03 irq_happened: 0x01 pid = 9349, comm = hugepage-mremap kernel BUG at include/linux/mm.h:2373! move_hugetlb_page_tables+0x4e4/0x5b0 (link register) move_hugetlb_page_tables+0x22c/0x5b0 (unreliable) move_page_tables+0xdbc/0x1010 move_vma+0x254/0x5f0 sys_mremap+0x7c0/0x900 system_call_exception+0x160/0x2c0 the kernel can't use huge_pte_offset before it set the pte entry because a page table lookup check for huge PTE bit in the page table to differentiate between a huge pte entry and a pointer to pte page. A huge_pte_alloc won't mark the page table entry huge and hence kernel should not use huge_pte_offset after a huge_pte_alloc. Link: https://lkml.kernel.org/r/20220211063221.99293-1-aneesh.kumar@linux.ibm.com Fixes: 550a7d60bd5e ("mm, hugepages: add mremap() support for hugepage backed vma") Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-02-26 06:10:56 +03:00
unsigned long new_addr, pte_t *src_pte, pte_t *dst_pte)
{
struct hstate *h = hstate_vma(vma);
struct mm_struct *mm = vma->vm_mm;
spinlock_t *src_ptl, *dst_ptl;
mm/hugetlb: fix kernel crash with hugetlb mremap This fixes the below crash: kernel BUG at include/linux/mm.h:2373! cpu 0x5d: Vector: 700 (Program Check) at [c00000003c6e76e0] pc: c000000000581a54: pmd_to_page+0x54/0x80 lr: c00000000058d184: move_hugetlb_page_tables+0x4e4/0x5b0 sp: c00000003c6e7980 msr: 9000000000029033 current = 0xc00000003bd8d980 paca = 0xc000200fff610100 irqmask: 0x03 irq_happened: 0x01 pid = 9349, comm = hugepage-mremap kernel BUG at include/linux/mm.h:2373! move_hugetlb_page_tables+0x4e4/0x5b0 (link register) move_hugetlb_page_tables+0x22c/0x5b0 (unreliable) move_page_tables+0xdbc/0x1010 move_vma+0x254/0x5f0 sys_mremap+0x7c0/0x900 system_call_exception+0x160/0x2c0 the kernel can't use huge_pte_offset before it set the pte entry because a page table lookup check for huge PTE bit in the page table to differentiate between a huge pte entry and a pointer to pte page. A huge_pte_alloc won't mark the page table entry huge and hence kernel should not use huge_pte_offset after a huge_pte_alloc. Link: https://lkml.kernel.org/r/20220211063221.99293-1-aneesh.kumar@linux.ibm.com Fixes: 550a7d60bd5e ("mm, hugepages: add mremap() support for hugepage backed vma") Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-02-26 06:10:56 +03:00
pte_t pte;
dst_ptl = huge_pte_lock(h, mm, dst_pte);
src_ptl = huge_pte_lockptr(h, mm, src_pte);
/*
* We don't have to worry about the ordering of src and dst ptlocks
* because exclusive mmap_sem (or the i_mmap_lock) prevents deadlock.
*/
if (src_ptl != dst_ptl)
spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
pte = huge_ptep_get_and_clear(mm, old_addr, src_pte);
set_huge_pte_at(mm, new_addr, dst_pte, pte);
if (src_ptl != dst_ptl)
spin_unlock(src_ptl);
spin_unlock(dst_ptl);
}
int move_hugetlb_page_tables(struct vm_area_struct *vma,
struct vm_area_struct *new_vma,
unsigned long old_addr, unsigned long new_addr,
unsigned long len)
{
struct hstate *h = hstate_vma(vma);
struct address_space *mapping = vma->vm_file->f_mapping;
unsigned long sz = huge_page_size(h);
struct mm_struct *mm = vma->vm_mm;
unsigned long old_end = old_addr + len;
unsigned long old_addr_copy;
pte_t *src_pte, *dst_pte;
struct mmu_notifier_range range;
mm: hugetlb: considering PMD sharing when flushing cache/TLBs This patchset fixes some cache flushing issues if PMD sharing is possible for hugetlb pages, which were found by code inspection. Meanwhile Mike found the flush_cache_page() can not cover the whole size of a hugetlb page on some architectures [1], so I added a new patch 3 to fix this issue, since I found only try_to_unmap_one() and try_to_migrate_one() need to fix after some investigation. [1] https://lore.kernel.org/linux-mm/064da3bb-5b4b-7332-a722-c5a541128705@oracle.com/ This patch (of 3): When moving hugetlb page tables, the cache flushing is called in move_page_tables() without considering the shared PMDs, which may be cause cache issues on some architectures. Thus we should move the hugetlb cache flushing into move_hugetlb_page_tables() with considering the shared PMDs ranges, calculated by adjust_range_if_pmd_sharing_possible(). Meanwhile also expanding the TLBs flushing range in case of shared PMDs. Note this is discovered via code inspection, and did not meet a real problem in practice so far. Link: https://lkml.kernel.org/r/cover.1651056365.git.baolin.wang@linux.alibaba.com Link: https://lkml.kernel.org/r/0443c8cf20db554d3ff4b439b30e0ff26c0181dd.1651056365.git.baolin.wang@linux.alibaba.com Fixes: 550a7d60bd5e ("mm, hugepages: add mremap() support for hugepage backed vma") Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Cc: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:52 +03:00
bool shared_pmd = false;
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, old_addr,
old_end);
adjust_range_if_pmd_sharing_possible(vma, &range.start, &range.end);
mm: hugetlb: considering PMD sharing when flushing cache/TLBs This patchset fixes some cache flushing issues if PMD sharing is possible for hugetlb pages, which were found by code inspection. Meanwhile Mike found the flush_cache_page() can not cover the whole size of a hugetlb page on some architectures [1], so I added a new patch 3 to fix this issue, since I found only try_to_unmap_one() and try_to_migrate_one() need to fix after some investigation. [1] https://lore.kernel.org/linux-mm/064da3bb-5b4b-7332-a722-c5a541128705@oracle.com/ This patch (of 3): When moving hugetlb page tables, the cache flushing is called in move_page_tables() without considering the shared PMDs, which may be cause cache issues on some architectures. Thus we should move the hugetlb cache flushing into move_hugetlb_page_tables() with considering the shared PMDs ranges, calculated by adjust_range_if_pmd_sharing_possible(). Meanwhile also expanding the TLBs flushing range in case of shared PMDs. Note this is discovered via code inspection, and did not meet a real problem in practice so far. Link: https://lkml.kernel.org/r/cover.1651056365.git.baolin.wang@linux.alibaba.com Link: https://lkml.kernel.org/r/0443c8cf20db554d3ff4b439b30e0ff26c0181dd.1651056365.git.baolin.wang@linux.alibaba.com Fixes: 550a7d60bd5e ("mm, hugepages: add mremap() support for hugepage backed vma") Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Cc: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:52 +03:00
/*
* In case of shared PMDs, we should cover the maximum possible
* range.
*/
flush_cache_range(vma, range.start, range.end);
mmu_notifier_invalidate_range_start(&range);
/* Prevent race with file truncation */
i_mmap_lock_write(mapping);
for (; old_addr < old_end; old_addr += sz, new_addr += sz) {
src_pte = huge_pte_offset(mm, old_addr, sz);
if (!src_pte)
continue;
if (huge_pte_none(huge_ptep_get(src_pte)))
continue;
/* old_addr arg to huge_pmd_unshare() is a pointer and so the
* arg may be modified. Pass a copy instead to preserve the
* value in old_addr.
*/
old_addr_copy = old_addr;
mm: hugetlb: considering PMD sharing when flushing cache/TLBs This patchset fixes some cache flushing issues if PMD sharing is possible for hugetlb pages, which were found by code inspection. Meanwhile Mike found the flush_cache_page() can not cover the whole size of a hugetlb page on some architectures [1], so I added a new patch 3 to fix this issue, since I found only try_to_unmap_one() and try_to_migrate_one() need to fix after some investigation. [1] https://lore.kernel.org/linux-mm/064da3bb-5b4b-7332-a722-c5a541128705@oracle.com/ This patch (of 3): When moving hugetlb page tables, the cache flushing is called in move_page_tables() without considering the shared PMDs, which may be cause cache issues on some architectures. Thus we should move the hugetlb cache flushing into move_hugetlb_page_tables() with considering the shared PMDs ranges, calculated by adjust_range_if_pmd_sharing_possible(). Meanwhile also expanding the TLBs flushing range in case of shared PMDs. Note this is discovered via code inspection, and did not meet a real problem in practice so far. Link: https://lkml.kernel.org/r/cover.1651056365.git.baolin.wang@linux.alibaba.com Link: https://lkml.kernel.org/r/0443c8cf20db554d3ff4b439b30e0ff26c0181dd.1651056365.git.baolin.wang@linux.alibaba.com Fixes: 550a7d60bd5e ("mm, hugepages: add mremap() support for hugepage backed vma") Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Cc: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:52 +03:00
if (huge_pmd_unshare(mm, vma, &old_addr_copy, src_pte)) {
shared_pmd = true;
continue;
mm: hugetlb: considering PMD sharing when flushing cache/TLBs This patchset fixes some cache flushing issues if PMD sharing is possible for hugetlb pages, which were found by code inspection. Meanwhile Mike found the flush_cache_page() can not cover the whole size of a hugetlb page on some architectures [1], so I added a new patch 3 to fix this issue, since I found only try_to_unmap_one() and try_to_migrate_one() need to fix after some investigation. [1] https://lore.kernel.org/linux-mm/064da3bb-5b4b-7332-a722-c5a541128705@oracle.com/ This patch (of 3): When moving hugetlb page tables, the cache flushing is called in move_page_tables() without considering the shared PMDs, which may be cause cache issues on some architectures. Thus we should move the hugetlb cache flushing into move_hugetlb_page_tables() with considering the shared PMDs ranges, calculated by adjust_range_if_pmd_sharing_possible(). Meanwhile also expanding the TLBs flushing range in case of shared PMDs. Note this is discovered via code inspection, and did not meet a real problem in practice so far. Link: https://lkml.kernel.org/r/cover.1651056365.git.baolin.wang@linux.alibaba.com Link: https://lkml.kernel.org/r/0443c8cf20db554d3ff4b439b30e0ff26c0181dd.1651056365.git.baolin.wang@linux.alibaba.com Fixes: 550a7d60bd5e ("mm, hugepages: add mremap() support for hugepage backed vma") Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Cc: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:52 +03:00
}
dst_pte = huge_pte_alloc(mm, new_vma, new_addr, sz);
if (!dst_pte)
break;
mm/hugetlb: fix kernel crash with hugetlb mremap This fixes the below crash: kernel BUG at include/linux/mm.h:2373! cpu 0x5d: Vector: 700 (Program Check) at [c00000003c6e76e0] pc: c000000000581a54: pmd_to_page+0x54/0x80 lr: c00000000058d184: move_hugetlb_page_tables+0x4e4/0x5b0 sp: c00000003c6e7980 msr: 9000000000029033 current = 0xc00000003bd8d980 paca = 0xc000200fff610100 irqmask: 0x03 irq_happened: 0x01 pid = 9349, comm = hugepage-mremap kernel BUG at include/linux/mm.h:2373! move_hugetlb_page_tables+0x4e4/0x5b0 (link register) move_hugetlb_page_tables+0x22c/0x5b0 (unreliable) move_page_tables+0xdbc/0x1010 move_vma+0x254/0x5f0 sys_mremap+0x7c0/0x900 system_call_exception+0x160/0x2c0 the kernel can't use huge_pte_offset before it set the pte entry because a page table lookup check for huge PTE bit in the page table to differentiate between a huge pte entry and a pointer to pte page. A huge_pte_alloc won't mark the page table entry huge and hence kernel should not use huge_pte_offset after a huge_pte_alloc. Link: https://lkml.kernel.org/r/20220211063221.99293-1-aneesh.kumar@linux.ibm.com Fixes: 550a7d60bd5e ("mm, hugepages: add mremap() support for hugepage backed vma") Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-02-26 06:10:56 +03:00
move_huge_pte(vma, old_addr, new_addr, src_pte, dst_pte);
}
mm: hugetlb: considering PMD sharing when flushing cache/TLBs This patchset fixes some cache flushing issues if PMD sharing is possible for hugetlb pages, which were found by code inspection. Meanwhile Mike found the flush_cache_page() can not cover the whole size of a hugetlb page on some architectures [1], so I added a new patch 3 to fix this issue, since I found only try_to_unmap_one() and try_to_migrate_one() need to fix after some investigation. [1] https://lore.kernel.org/linux-mm/064da3bb-5b4b-7332-a722-c5a541128705@oracle.com/ This patch (of 3): When moving hugetlb page tables, the cache flushing is called in move_page_tables() without considering the shared PMDs, which may be cause cache issues on some architectures. Thus we should move the hugetlb cache flushing into move_hugetlb_page_tables() with considering the shared PMDs ranges, calculated by adjust_range_if_pmd_sharing_possible(). Meanwhile also expanding the TLBs flushing range in case of shared PMDs. Note this is discovered via code inspection, and did not meet a real problem in practice so far. Link: https://lkml.kernel.org/r/cover.1651056365.git.baolin.wang@linux.alibaba.com Link: https://lkml.kernel.org/r/0443c8cf20db554d3ff4b439b30e0ff26c0181dd.1651056365.git.baolin.wang@linux.alibaba.com Fixes: 550a7d60bd5e ("mm, hugepages: add mremap() support for hugepage backed vma") Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Cc: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:52 +03:00
if (shared_pmd)
flush_tlb_range(vma, range.start, range.end);
else
flush_tlb_range(vma, old_end - len, old_end);
mmu_notifier_invalidate_range_end(&range);
i_mmap_unlock_write(mapping);
return len + old_addr - old_end;
}
static void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
unsigned long start, unsigned long end,
struct page *ref_page)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long address;
pte_t *ptep;
pte_t pte;
spinlock_t *ptl;
struct page *page;
struct hstate *h = hstate_vma(vma);
unsigned long sz = huge_page_size(h);
struct mmu_notifier_range range;
bool force_flush = false;
WARN_ON(!is_vm_hugetlb_page(vma));
BUG_ON(start & ~huge_page_mask(h));
BUG_ON(end & ~huge_page_mask(h));
/*
* This is a hugetlb vma, all the pte entries should point
* to huge page.
*/
tlb_change_page_size(tlb, sz);
tlb_start_vma(tlb, vma);
/*
* If sharing possible, alert mmu notifiers of worst case.
*/
mm/mmu_notifier: contextual information for event triggering invalidation CPU page table update can happens for many reasons, not only as a result of a syscall (munmap(), mprotect(), mremap(), madvise(), ...) but also as a result of kernel activities (memory compression, reclaim, migration, ...). Users of mmu notifier API track changes to the CPU page table and take specific action for them. While current API only provide range of virtual address affected by the change, not why the changes is happening. This patchset do the initial mechanical convertion of all the places that calls mmu_notifier_range_init to also provide the default MMU_NOTIFY_UNMAP event as well as the vma if it is know (most invalidation happens against a given vma). Passing down the vma allows the users of mmu notifier to inspect the new vma page protection. The MMU_NOTIFY_UNMAP is always the safe default as users of mmu notifier should assume that every for the range is going away when that event happens. A latter patch do convert mm call path to use a more appropriate events for each call. This is done as 2 patches so that no call site is forgotten especialy as it uses this following coccinelle patch: %<---------------------------------------------------------------------- @@ identifier I1, I2, I3, I4; @@ static inline void mmu_notifier_range_init(struct mmu_notifier_range *I1, +enum mmu_notifier_event event, +unsigned flags, +struct vm_area_struct *vma, struct mm_struct *I2, unsigned long I3, unsigned long I4) { ... } @@ @@ -#define mmu_notifier_range_init(range, mm, start, end) +#define mmu_notifier_range_init(range, event, flags, vma, mm, start, end) @@ expression E1, E3, E4; identifier I1; @@ <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, I1, I1->vm_mm, E3, E4) ...> @@ expression E1, E2, E3, E4; identifier FN, VMA; @@ FN(..., struct vm_area_struct *VMA, ...) { <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, VMA, E2, E3, E4) ...> } @@ expression E1, E2, E3, E4; identifier FN, VMA; @@ FN(...) { struct vm_area_struct *VMA; <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, VMA, E2, E3, E4) ...> } @@ expression E1, E2, E3, E4; identifier FN; @@ FN(...) { <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, NULL, E2, E3, E4) ...> } ---------------------------------------------------------------------->% Applied with: spatch --all-includes --sp-file mmu-notifier.spatch fs/proc/task_mmu.c --in-place spatch --sp-file mmu-notifier.spatch --dir kernel/events/ --in-place spatch --sp-file mmu-notifier.spatch --dir mm --in-place Link: http://lkml.kernel.org/r/20190326164747.24405-6-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Cc: Christian König <christian.koenig@amd.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Peter Xu <peterx@redhat.com> Cc: Felix Kuehling <Felix.Kuehling@amd.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Ross Zwisler <zwisler@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krcmar <rkrcmar@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Christian Koenig <christian.koenig@amd.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 03:20:49 +03:00
mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, mm, start,
end);
adjust_range_if_pmd_sharing_possible(vma, &range.start, &range.end);
mmu_notifier_invalidate_range_start(&range);
address = start;
for (; address < end; address += sz) {
mm/hugetlb: add size parameter to huge_pte_offset() A poisoned or migrated hugepage is stored as a swap entry in the page tables. On architectures that support hugepages consisting of contiguous page table entries (such as on arm64) this leads to ambiguity in determining the page table entry to return in huge_pte_offset() when a poisoned entry is encountered. Let's remove the ambiguity by adding a size parameter to convey additional information about the requested address. Also fixup the definition/usage of huge_pte_offset() throughout the tree. Link: http://lkml.kernel.org/r/20170522133604.11392-4-punit.agrawal@arm.com Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Acked-by: Steve Capper <steve.capper@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: James Hogan <james.hogan@imgtec.com> (odd fixer:METAG ARCHITECTURE) Cc: Ralf Baechle <ralf@linux-mips.org> (supporter:MIPS) Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Rich Felker <dalias@libc.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-07 01:39:42 +03:00
ptep = huge_pte_offset(mm, address, sz);
if (!ptep)
continue;
ptl = huge_pte_lock(h, mm, ptep);
hugetlbfs: remove call to huge_pte_alloc without i_mmap_rwsem Commit c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") requires callers of huge_pte_alloc to hold i_mmap_rwsem in at least read mode. This is because the explicit locking in huge_pmd_share (called by huge_pte_alloc) was removed. When restructuring the code, the call to huge_pte_alloc in the else block at the beginning of hugetlb_fault was missed. Unfortunately, that else clause is exercised when there is no page table entry. This will likely lead to a call to huge_pmd_share. If huge_pmd_share thinks pmd sharing is possible, it will traverse the mapping tree (i_mmap) without holding i_mmap_rwsem. If someone else is modifying the tree, bad things such as addressing exceptions or worse could happen. Simply remove the else clause. It should have been removed previously. The code following the else will call huge_pte_alloc with the appropriate locking. To prevent this type of issue in the future, add routines to assert that i_mmap_rwsem is held, and call these routines in huge pmd sharing routines. Fixes: c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") Suggested-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A.Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/e670f327-5cf9-1959-96e4-6dc7cc30d3d5@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 04:31:38 +03:00
if (huge_pmd_unshare(mm, vma, &address, ptep)) {
spin_unlock(ptl);
tlb_flush_pmd_range(tlb, address & PUD_MASK, PUD_SIZE);
force_flush = true;
continue;
}
[PATCH] shared page table for hugetlb page Following up with the work on shared page table done by Dave McCracken. This set of patch target shared page table for hugetlb memory only. The shared page table is particular useful in the situation of large number of independent processes sharing large shared memory segments. In the normal page case, the amount of memory saved from process' page table is quite significant. For hugetlb, the saving on page table memory is not the primary objective (as hugetlb itself already cuts down page table overhead significantly), instead, the purpose of using shared page table on hugetlb is to allow faster TLB refill and smaller cache pollution upon TLB miss. With PT sharing, pte entries are shared among hundreds of processes, the cache consumption used by all the page table is smaller and in return, application gets much higher cache hit ratio. One other effect is that cache hit ratio with hardware page walker hitting on pte in cache will be higher and this helps to reduce tlb miss latency. These two effects contribute to higher application performance. Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Acked-by: Hugh Dickins <hugh@veritas.com> Cc: Dave McCracken <dmccr@us.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Adam Litke <agl@us.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 07:32:03 +03:00
pte = huge_ptep_get(ptep);
if (huge_pte_none(pte)) {
spin_unlock(ptl);
continue;
}
/*
* Migrating hugepage or HWPoisoned hugepage is already
* unmapped and its refcount is dropped, so just clear pte here.
*/
if (unlikely(!pte_present(pte))) {
2017-07-07 01:39:46 +03:00
huge_pte_clear(mm, address, ptep, sz);
spin_unlock(ptl);
continue;
}
page = pte_page(pte);
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
/*
* If a reference page is supplied, it is because a specific
* page is being unmapped, not a range. Ensure the page we
* are about to unmap is the actual page of interest.
*/
if (ref_page) {
if (page != ref_page) {
spin_unlock(ptl);
continue;
}
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
/*
* Mark the VMA as having unmapped its page so that
* future faults in this VMA will fail rather than
* looking like data was lost
*/
set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
}
pte = huge_ptep_get_and_clear(mm, address, ptep);
tlb_remove_huge_tlb_entry(h, tlb, ptep, address);
mm/hugetlb: add more arch-defined huge_pte functions Commit abf09bed3cce ("s390/mm: implement software dirty bits") introduced another difference in the pte layout vs. the pmd layout on s390, thoroughly breaking the s390 support for hugetlbfs. This requires replacing some more pte_xxx functions in mm/hugetlbfs.c with a huge_pte_xxx version. This patch introduces those huge_pte_xxx functions and their generic implementation in asm-generic/hugetlb.h, which will now be included on all architectures supporting hugetlbfs apart from s390. This change will be a no-op for those architectures. [akpm@linux-foundation.org: fix warning] Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> [for !s390 parts] Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 02:07:23 +04:00
if (huge_pte_dirty(pte))
set_page_dirty(page);
hugetlb_count_sub(pages_per_huge_page(h), mm);
mm/munlock: rmap call mlock_vma_page() munlock_vma_page() Add vma argument to mlock_vma_page() and munlock_vma_page(), make them inline functions which check (vma->vm_flags & VM_LOCKED) before calling mlock_page() and munlock_page() in mm/mlock.c. Add bool compound to mlock_vma_page() and munlock_vma_page(): this is because we have understandable difficulty in accounting pte maps of THPs, and if passed a PageHead page, mlock_page() and munlock_page() cannot tell whether it's a pmd map to be counted or a pte map to be ignored. Add vma arg to page_add_file_rmap() and page_remove_rmap(), like the others, and use that to call mlock_vma_page() at the end of the page adds, and munlock_vma_page() at the end of page_remove_rmap() (end or beginning? unimportant, but end was easier for assertions in testing). No page lock is required (although almost all adds happen to hold it): delete the "Serialize with page migration" BUG_ON(!PageLocked(page))s. Certainly page lock did serialize with page migration, but I'm having difficulty explaining why that was ever important. Mlock accounting on THPs has been hard to define, differed between anon and file, involved PageDoubleMap in some places and not others, required clear_page_mlock() at some points. Keep it simple now: just count the pmds and ignore the ptes, there is no reason for ptes to undo pmd mlocks. page_add_new_anon_rmap() callers unchanged: they have long been calling lru_cache_add_inactive_or_unevictable(), which does its own VM_LOCKED handling (it also checks for not VM_SPECIAL: I think that's overcautious, and inconsistent with other checks, that mmap_region() already prevents VM_LOCKED on VM_SPECIAL; but haven't quite convinced myself to change it). Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
2022-02-15 05:26:39 +03:00
page_remove_rmap(page, vma, true);
spin_unlock(ptl);
tlb_remove_page_size(tlb, page, huge_page_size(h));
/*
* Bail out after unmapping reference page if supplied
*/
if (ref_page)
break;
}
mmu_notifier_invalidate_range_end(&range);
tlb_end_vma(tlb, vma);
/*
* If we unshared PMDs, the TLB flush was not recorded in mmu_gather. We
* could defer the flush until now, since by holding i_mmap_rwsem we
* guaranteed that the last refernece would not be dropped. But we must
* do the flushing before we return, as otherwise i_mmap_rwsem will be
* dropped and the last reference to the shared PMDs page might be
* dropped as well.
*
* In theory we could defer the freeing of the PMD pages as well, but
* huge_pmd_unshare() relies on the exact page_count for the PMD page to
* detect sharing, so we cannot defer the release of the page either.
* Instead, do flush now.
*/
if (force_flush)
tlb_flush_mmu_tlbonly(tlb);
}
mm: hugetlbfs: close race during teardown of hugetlbfs shared page tables If a process creates a large hugetlbfs mapping that is eligible for page table sharing and forks heavily with children some of whom fault and others which destroy the mapping then it is possible for page tables to get corrupted. Some teardowns of the mapping encounter a "bad pmd" and output a message to the kernel log. The final teardown will trigger a BUG_ON in mm/filemap.c. This was reproduced in 3.4 but is known to have existed for a long time and goes back at least as far as 2.6.37. It was probably was introduced in 2.6.20 by [39dde65c: shared page table for hugetlb page]. The messages look like this; [ ..........] Lots of bad pmd messages followed by this [ 127.164256] mm/memory.c:391: bad pmd ffff880412e04fe8(80000003de4000e7). [ 127.164257] mm/memory.c:391: bad pmd ffff880412e04ff0(80000003de6000e7). [ 127.164258] mm/memory.c:391: bad pmd ffff880412e04ff8(80000003de0000e7). [ 127.186778] ------------[ cut here ]------------ [ 127.186781] kernel BUG at mm/filemap.c:134! [ 127.186782] invalid opcode: 0000 [#1] SMP [ 127.186783] CPU 7 [ 127.186784] Modules linked in: af_packet cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf ext3 jbd dm_mod coretemp crc32c_intel usb_storage ghash_clmulni_intel aesni_intel i2c_i801 r8169 mii uas sr_mod cdrom sg iTCO_wdt iTCO_vendor_support shpchp serio_raw cryptd aes_x86_64 e1000e pci_hotplug dcdbas aes_generic container microcode ext4 mbcache jbd2 crc16 sd_mod crc_t10dif i915 drm_kms_helper drm i2c_algo_bit ehci_hcd ahci libahci usbcore rtc_cmos usb_common button i2c_core intel_agp video intel_gtt fan processor thermal thermal_sys hwmon ata_generic pata_atiixp libata scsi_mod [ 127.186801] [ 127.186802] Pid: 9017, comm: hugetlbfs-test Not tainted 3.4.0-autobuild #53 Dell Inc. OptiPlex 990/06D7TR [ 127.186804] RIP: 0010:[<ffffffff810ed6ce>] [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160 [ 127.186809] RSP: 0000:ffff8804144b5c08 EFLAGS: 00010002 [ 127.186810] RAX: 0000000000000001 RBX: ffffea000a5c9000 RCX: 00000000ffffffc0 [ 127.186811] RDX: 0000000000000000 RSI: 0000000000000009 RDI: ffff88042dfdad00 [ 127.186812] RBP: ffff8804144b5c18 R08: 0000000000000009 R09: 0000000000000003 [ 127.186813] R10: 0000000000000000 R11: 000000000000002d R12: ffff880412ff83d8 [ 127.186814] R13: ffff880412ff83d8 R14: 0000000000000000 R15: ffff880412ff83d8 [ 127.186815] FS: 00007fe18ed2c700(0000) GS:ffff88042dce0000(0000) knlGS:0000000000000000 [ 127.186816] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 127.186817] CR2: 00007fe340000503 CR3: 0000000417a14000 CR4: 00000000000407e0 [ 127.186818] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 127.186819] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 127.186820] Process hugetlbfs-test (pid: 9017, threadinfo ffff8804144b4000, task ffff880417f803c0) [ 127.186821] Stack: [ 127.186822] ffffea000a5c9000 0000000000000000 ffff8804144b5c48 ffffffff810ed83b [ 127.186824] ffff8804144b5c48 000000000000138a 0000000000001387 ffff8804144b5c98 [ 127.186825] ffff8804144b5d48 ffffffff811bc925 ffff8804144b5cb8 0000000000000000 [ 127.186827] Call Trace: [ 127.186829] [<ffffffff810ed83b>] delete_from_page_cache+0x3b/0x80 [ 127.186832] [<ffffffff811bc925>] truncate_hugepages+0x115/0x220 [ 127.186834] [<ffffffff811bca43>] hugetlbfs_evict_inode+0x13/0x30 [ 127.186837] [<ffffffff811655c7>] evict+0xa7/0x1b0 [ 127.186839] [<ffffffff811657a3>] iput_final+0xd3/0x1f0 [ 127.186840] [<ffffffff811658f9>] iput+0x39/0x50 [ 127.186842] [<ffffffff81162708>] d_kill+0xf8/0x130 [ 127.186843] [<ffffffff81162812>] dput+0xd2/0x1a0 [ 127.186845] [<ffffffff8114e2d0>] __fput+0x170/0x230 [ 127.186848] [<ffffffff81236e0e>] ? rb_erase+0xce/0x150 [ 127.186849] [<ffffffff8114e3ad>] fput+0x1d/0x30 [ 127.186851] [<ffffffff81117db7>] remove_vma+0x37/0x80 [ 127.186853] [<ffffffff81119182>] do_munmap+0x2d2/0x360 [ 127.186855] [<ffffffff811cc639>] sys_shmdt+0xc9/0x170 [ 127.186857] [<ffffffff81410a39>] system_call_fastpath+0x16/0x1b [ 127.186858] Code: 0f 1f 44 00 00 48 8b 43 08 48 8b 00 48 8b 40 28 8b b0 40 03 00 00 85 f6 0f 88 df fe ff ff 48 89 df e8 e7 cb 05 00 e9 d2 fe ff ff <0f> 0b 55 83 e2 fd 48 89 e5 48 83 ec 30 48 89 5d d8 4c 89 65 e0 [ 127.186868] RIP [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160 [ 127.186870] RSP <ffff8804144b5c08> [ 127.186871] ---[ end trace 7cbac5d1db69f426 ]--- The bug is a race and not always easy to reproduce. To reproduce it I was doing the following on a single socket I7-based machine with 16G of RAM. $ hugeadm --pool-pages-max DEFAULT:13G $ echo $((18*1048576*1024)) > /proc/sys/kernel/shmmax $ echo $((18*1048576*1024)) > /proc/sys/kernel/shmall $ for i in `seq 1 9000`; do ./hugetlbfs-test; done On my particular machine, it usually triggers within 10 minutes but enabling debug options can change the timing such that it never hits. Once the bug is triggered, the machine is in trouble and needs to be rebooted. The machine will respond but processes accessing proc like "ps aux" will hang due to the BUG_ON. shutdown will also hang and needs a hard reset or a sysrq-b. The basic problem is a race between page table sharing and teardown. For the most part page table sharing depends on i_mmap_mutex. In some cases, it is also taking the mm->page_table_lock for the PTE updates but with shared page tables, it is the i_mmap_mutex that is more important. Unfortunately it appears to be also insufficient. Consider the following situation Process A Process B --------- --------- hugetlb_fault shmdt LockWrite(mmap_sem) do_munmap unmap_region unmap_vmas unmap_single_vma unmap_hugepage_range Lock(i_mmap_mutex) Lock(mm->page_table_lock) huge_pmd_unshare/unmap tables <--- (1) Unlock(mm->page_table_lock) Unlock(i_mmap_mutex) huge_pte_alloc ... Lock(i_mmap_mutex) ... vma_prio_walk, find svma, spte ... Lock(mm->page_table_lock) ... share spte ... Unlock(mm->page_table_lock) ... Unlock(i_mmap_mutex) ... hugetlb_no_page <--- (2) free_pgtables unlink_file_vma hugetlb_free_pgd_range remove_vma_list In this scenario, it is possible for Process A to share page tables with Process B that is trying to tear them down. The i_mmap_mutex on its own does not prevent Process A walking Process B's page tables. At (1) above, the page tables are not shared yet so it unmaps the PMDs. Process A sets up page table sharing and at (2) faults a new entry. Process B then trips up on it in free_pgtables. This patch fixes the problem by adding a new function __unmap_hugepage_range_final that is only called when the VMA is about to be destroyed. This function clears VM_MAYSHARE during unmap_hugepage_range() under the i_mmap_mutex. This makes the VMA ineligible for sharing and avoids the race. Superficially this looks like it would then be vunerable to truncate and madvise issues but hugetlbfs has its own truncate handlers so does not use unmap_mapping_range() and does not support madvise(DONTNEED). This should be treated as a -stable candidate if it is merged. Test program is as follows. The test case was mostly written by Michal Hocko with a few minor changes to reproduce this bug. ==== CUT HERE ==== static size_t huge_page_size = (2UL << 20); static size_t nr_huge_page_A = 512; static size_t nr_huge_page_B = 5632; unsigned int get_random(unsigned int max) { struct timeval tv; gettimeofday(&tv, NULL); srandom(tv.tv_usec); return random() % max; } static void play(void *addr, size_t size) { unsigned char *start = addr, *end = start + size, *a; start += get_random(size/2); /* we could itterate on huge pages but let's give it more time. */ for (a = start; a < end; a += 4096) *a = 0; } int main(int argc, char **argv) { key_t key = IPC_PRIVATE; size_t sizeA = nr_huge_page_A * huge_page_size; size_t sizeB = nr_huge_page_B * huge_page_size; int shmidA, shmidB; void *addrA = NULL, *addrB = NULL; int nr_children = 300, n = 0; if ((shmidA = shmget(key, sizeA, IPC_CREAT|SHM_HUGETLB|0660)) == -1) { perror("shmget:"); return 1; } if ((addrA = shmat(shmidA, addrA, SHM_R|SHM_W)) == (void *)-1UL) { perror("shmat"); return 1; } if ((shmidB = shmget(key, sizeB, IPC_CREAT|SHM_HUGETLB|0660)) == -1) { perror("shmget:"); return 1; } if ((addrB = shmat(shmidB, addrB, SHM_R|SHM_W)) == (void *)-1UL) { perror("shmat"); return 1; } fork_child: switch(fork()) { case 0: switch (n%3) { case 0: play(addrA, sizeA); break; case 1: play(addrB, sizeB); break; case 2: break; } break; case -1: perror("fork:"); break; default: if (++n < nr_children) goto fork_child; play(addrA, sizeA); break; } shmdt(addrA); shmdt(addrB); do { wait(NULL); } while (--n > 0); shmctl(shmidA, IPC_RMID, NULL); shmctl(shmidB, IPC_RMID, NULL); return 0; } [akpm@linux-foundation.org: name the declaration's args, fix CONFIG_HUGETLBFS=n build] Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-08-01 03:46:20 +04:00
void __unmap_hugepage_range_final(struct mmu_gather *tlb,
struct vm_area_struct *vma, unsigned long start,
unsigned long end, struct page *ref_page)
{
__unmap_hugepage_range(tlb, vma, start, end, ref_page);
/*
* Clear this flag so that x86's huge_pmd_share page_table_shareable
* test will fail on a vma being torn down, and not grab a page table
* on its way out. We're lucky that the flag has such an appropriate
* name, and can in fact be safely cleared here. We could clear it
* before the __unmap_hugepage_range above, but all that's necessary
* is to clear it before releasing the i_mmap_rwsem. This works
mm: hugetlbfs: close race during teardown of hugetlbfs shared page tables If a process creates a large hugetlbfs mapping that is eligible for page table sharing and forks heavily with children some of whom fault and others which destroy the mapping then it is possible for page tables to get corrupted. Some teardowns of the mapping encounter a "bad pmd" and output a message to the kernel log. The final teardown will trigger a BUG_ON in mm/filemap.c. This was reproduced in 3.4 but is known to have existed for a long time and goes back at least as far as 2.6.37. It was probably was introduced in 2.6.20 by [39dde65c: shared page table for hugetlb page]. The messages look like this; [ ..........] Lots of bad pmd messages followed by this [ 127.164256] mm/memory.c:391: bad pmd ffff880412e04fe8(80000003de4000e7). [ 127.164257] mm/memory.c:391: bad pmd ffff880412e04ff0(80000003de6000e7). [ 127.164258] mm/memory.c:391: bad pmd ffff880412e04ff8(80000003de0000e7). [ 127.186778] ------------[ cut here ]------------ [ 127.186781] kernel BUG at mm/filemap.c:134! [ 127.186782] invalid opcode: 0000 [#1] SMP [ 127.186783] CPU 7 [ 127.186784] Modules linked in: af_packet cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf ext3 jbd dm_mod coretemp crc32c_intel usb_storage ghash_clmulni_intel aesni_intel i2c_i801 r8169 mii uas sr_mod cdrom sg iTCO_wdt iTCO_vendor_support shpchp serio_raw cryptd aes_x86_64 e1000e pci_hotplug dcdbas aes_generic container microcode ext4 mbcache jbd2 crc16 sd_mod crc_t10dif i915 drm_kms_helper drm i2c_algo_bit ehci_hcd ahci libahci usbcore rtc_cmos usb_common button i2c_core intel_agp video intel_gtt fan processor thermal thermal_sys hwmon ata_generic pata_atiixp libata scsi_mod [ 127.186801] [ 127.186802] Pid: 9017, comm: hugetlbfs-test Not tainted 3.4.0-autobuild #53 Dell Inc. OptiPlex 990/06D7TR [ 127.186804] RIP: 0010:[<ffffffff810ed6ce>] [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160 [ 127.186809] RSP: 0000:ffff8804144b5c08 EFLAGS: 00010002 [ 127.186810] RAX: 0000000000000001 RBX: ffffea000a5c9000 RCX: 00000000ffffffc0 [ 127.186811] RDX: 0000000000000000 RSI: 0000000000000009 RDI: ffff88042dfdad00 [ 127.186812] RBP: ffff8804144b5c18 R08: 0000000000000009 R09: 0000000000000003 [ 127.186813] R10: 0000000000000000 R11: 000000000000002d R12: ffff880412ff83d8 [ 127.186814] R13: ffff880412ff83d8 R14: 0000000000000000 R15: ffff880412ff83d8 [ 127.186815] FS: 00007fe18ed2c700(0000) GS:ffff88042dce0000(0000) knlGS:0000000000000000 [ 127.186816] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 127.186817] CR2: 00007fe340000503 CR3: 0000000417a14000 CR4: 00000000000407e0 [ 127.186818] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 127.186819] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 127.186820] Process hugetlbfs-test (pid: 9017, threadinfo ffff8804144b4000, task ffff880417f803c0) [ 127.186821] Stack: [ 127.186822] ffffea000a5c9000 0000000000000000 ffff8804144b5c48 ffffffff810ed83b [ 127.186824] ffff8804144b5c48 000000000000138a 0000000000001387 ffff8804144b5c98 [ 127.186825] ffff8804144b5d48 ffffffff811bc925 ffff8804144b5cb8 0000000000000000 [ 127.186827] Call Trace: [ 127.186829] [<ffffffff810ed83b>] delete_from_page_cache+0x3b/0x80 [ 127.186832] [<ffffffff811bc925>] truncate_hugepages+0x115/0x220 [ 127.186834] [<ffffffff811bca43>] hugetlbfs_evict_inode+0x13/0x30 [ 127.186837] [<ffffffff811655c7>] evict+0xa7/0x1b0 [ 127.186839] [<ffffffff811657a3>] iput_final+0xd3/0x1f0 [ 127.186840] [<ffffffff811658f9>] iput+0x39/0x50 [ 127.186842] [<ffffffff81162708>] d_kill+0xf8/0x130 [ 127.186843] [<ffffffff81162812>] dput+0xd2/0x1a0 [ 127.186845] [<ffffffff8114e2d0>] __fput+0x170/0x230 [ 127.186848] [<ffffffff81236e0e>] ? rb_erase+0xce/0x150 [ 127.186849] [<ffffffff8114e3ad>] fput+0x1d/0x30 [ 127.186851] [<ffffffff81117db7>] remove_vma+0x37/0x80 [ 127.186853] [<ffffffff81119182>] do_munmap+0x2d2/0x360 [ 127.186855] [<ffffffff811cc639>] sys_shmdt+0xc9/0x170 [ 127.186857] [<ffffffff81410a39>] system_call_fastpath+0x16/0x1b [ 127.186858] Code: 0f 1f 44 00 00 48 8b 43 08 48 8b 00 48 8b 40 28 8b b0 40 03 00 00 85 f6 0f 88 df fe ff ff 48 89 df e8 e7 cb 05 00 e9 d2 fe ff ff <0f> 0b 55 83 e2 fd 48 89 e5 48 83 ec 30 48 89 5d d8 4c 89 65 e0 [ 127.186868] RIP [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160 [ 127.186870] RSP <ffff8804144b5c08> [ 127.186871] ---[ end trace 7cbac5d1db69f426 ]--- The bug is a race and not always easy to reproduce. To reproduce it I was doing the following on a single socket I7-based machine with 16G of RAM. $ hugeadm --pool-pages-max DEFAULT:13G $ echo $((18*1048576*1024)) > /proc/sys/kernel/shmmax $ echo $((18*1048576*1024)) > /proc/sys/kernel/shmall $ for i in `seq 1 9000`; do ./hugetlbfs-test; done On my particular machine, it usually triggers within 10 minutes but enabling debug options can change the timing such that it never hits. Once the bug is triggered, the machine is in trouble and needs to be rebooted. The machine will respond but processes accessing proc like "ps aux" will hang due to the BUG_ON. shutdown will also hang and needs a hard reset or a sysrq-b. The basic problem is a race between page table sharing and teardown. For the most part page table sharing depends on i_mmap_mutex. In some cases, it is also taking the mm->page_table_lock for the PTE updates but with shared page tables, it is the i_mmap_mutex that is more important. Unfortunately it appears to be also insufficient. Consider the following situation Process A Process B --------- --------- hugetlb_fault shmdt LockWrite(mmap_sem) do_munmap unmap_region unmap_vmas unmap_single_vma unmap_hugepage_range Lock(i_mmap_mutex) Lock(mm->page_table_lock) huge_pmd_unshare/unmap tables <--- (1) Unlock(mm->page_table_lock) Unlock(i_mmap_mutex) huge_pte_alloc ... Lock(i_mmap_mutex) ... vma_prio_walk, find svma, spte ... Lock(mm->page_table_lock) ... share spte ... Unlock(mm->page_table_lock) ... Unlock(i_mmap_mutex) ... hugetlb_no_page <--- (2) free_pgtables unlink_file_vma hugetlb_free_pgd_range remove_vma_list In this scenario, it is possible for Process A to share page tables with Process B that is trying to tear them down. The i_mmap_mutex on its own does not prevent Process A walking Process B's page tables. At (1) above, the page tables are not shared yet so it unmaps the PMDs. Process A sets up page table sharing and at (2) faults a new entry. Process B then trips up on it in free_pgtables. This patch fixes the problem by adding a new function __unmap_hugepage_range_final that is only called when the VMA is about to be destroyed. This function clears VM_MAYSHARE during unmap_hugepage_range() under the i_mmap_mutex. This makes the VMA ineligible for sharing and avoids the race. Superficially this looks like it would then be vunerable to truncate and madvise issues but hugetlbfs has its own truncate handlers so does not use unmap_mapping_range() and does not support madvise(DONTNEED). This should be treated as a -stable candidate if it is merged. Test program is as follows. The test case was mostly written by Michal Hocko with a few minor changes to reproduce this bug. ==== CUT HERE ==== static size_t huge_page_size = (2UL << 20); static size_t nr_huge_page_A = 512; static size_t nr_huge_page_B = 5632; unsigned int get_random(unsigned int max) { struct timeval tv; gettimeofday(&tv, NULL); srandom(tv.tv_usec); return random() % max; } static void play(void *addr, size_t size) { unsigned char *start = addr, *end = start + size, *a; start += get_random(size/2); /* we could itterate on huge pages but let's give it more time. */ for (a = start; a < end; a += 4096) *a = 0; } int main(int argc, char **argv) { key_t key = IPC_PRIVATE; size_t sizeA = nr_huge_page_A * huge_page_size; size_t sizeB = nr_huge_page_B * huge_page_size; int shmidA, shmidB; void *addrA = NULL, *addrB = NULL; int nr_children = 300, n = 0; if ((shmidA = shmget(key, sizeA, IPC_CREAT|SHM_HUGETLB|0660)) == -1) { perror("shmget:"); return 1; } if ((addrA = shmat(shmidA, addrA, SHM_R|SHM_W)) == (void *)-1UL) { perror("shmat"); return 1; } if ((shmidB = shmget(key, sizeB, IPC_CREAT|SHM_HUGETLB|0660)) == -1) { perror("shmget:"); return 1; } if ((addrB = shmat(shmidB, addrB, SHM_R|SHM_W)) == (void *)-1UL) { perror("shmat"); return 1; } fork_child: switch(fork()) { case 0: switch (n%3) { case 0: play(addrA, sizeA); break; case 1: play(addrB, sizeB); break; case 2: break; } break; case -1: perror("fork:"); break; default: if (++n < nr_children) goto fork_child; play(addrA, sizeA); break; } shmdt(addrA); shmdt(addrB); do { wait(NULL); } while (--n > 0); shmctl(shmidA, IPC_RMID, NULL); shmctl(shmidB, IPC_RMID, NULL); return 0; } [akpm@linux-foundation.org: name the declaration's args, fix CONFIG_HUGETLBFS=n build] Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-08-01 03:46:20 +04:00
* because in the context this is called, the VMA is about to be
* destroyed and the i_mmap_rwsem is held.
mm: hugetlbfs: close race during teardown of hugetlbfs shared page tables If a process creates a large hugetlbfs mapping that is eligible for page table sharing and forks heavily with children some of whom fault and others which destroy the mapping then it is possible for page tables to get corrupted. Some teardowns of the mapping encounter a "bad pmd" and output a message to the kernel log. The final teardown will trigger a BUG_ON in mm/filemap.c. This was reproduced in 3.4 but is known to have existed for a long time and goes back at least as far as 2.6.37. It was probably was introduced in 2.6.20 by [39dde65c: shared page table for hugetlb page]. The messages look like this; [ ..........] Lots of bad pmd messages followed by this [ 127.164256] mm/memory.c:391: bad pmd ffff880412e04fe8(80000003de4000e7). [ 127.164257] mm/memory.c:391: bad pmd ffff880412e04ff0(80000003de6000e7). [ 127.164258] mm/memory.c:391: bad pmd ffff880412e04ff8(80000003de0000e7). [ 127.186778] ------------[ cut here ]------------ [ 127.186781] kernel BUG at mm/filemap.c:134! [ 127.186782] invalid opcode: 0000 [#1] SMP [ 127.186783] CPU 7 [ 127.186784] Modules linked in: af_packet cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf ext3 jbd dm_mod coretemp crc32c_intel usb_storage ghash_clmulni_intel aesni_intel i2c_i801 r8169 mii uas sr_mod cdrom sg iTCO_wdt iTCO_vendor_support shpchp serio_raw cryptd aes_x86_64 e1000e pci_hotplug dcdbas aes_generic container microcode ext4 mbcache jbd2 crc16 sd_mod crc_t10dif i915 drm_kms_helper drm i2c_algo_bit ehci_hcd ahci libahci usbcore rtc_cmos usb_common button i2c_core intel_agp video intel_gtt fan processor thermal thermal_sys hwmon ata_generic pata_atiixp libata scsi_mod [ 127.186801] [ 127.186802] Pid: 9017, comm: hugetlbfs-test Not tainted 3.4.0-autobuild #53 Dell Inc. OptiPlex 990/06D7TR [ 127.186804] RIP: 0010:[<ffffffff810ed6ce>] [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160 [ 127.186809] RSP: 0000:ffff8804144b5c08 EFLAGS: 00010002 [ 127.186810] RAX: 0000000000000001 RBX: ffffea000a5c9000 RCX: 00000000ffffffc0 [ 127.186811] RDX: 0000000000000000 RSI: 0000000000000009 RDI: ffff88042dfdad00 [ 127.186812] RBP: ffff8804144b5c18 R08: 0000000000000009 R09: 0000000000000003 [ 127.186813] R10: 0000000000000000 R11: 000000000000002d R12: ffff880412ff83d8 [ 127.186814] R13: ffff880412ff83d8 R14: 0000000000000000 R15: ffff880412ff83d8 [ 127.186815] FS: 00007fe18ed2c700(0000) GS:ffff88042dce0000(0000) knlGS:0000000000000000 [ 127.186816] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 127.186817] CR2: 00007fe340000503 CR3: 0000000417a14000 CR4: 00000000000407e0 [ 127.186818] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 127.186819] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 127.186820] Process hugetlbfs-test (pid: 9017, threadinfo ffff8804144b4000, task ffff880417f803c0) [ 127.186821] Stack: [ 127.186822] ffffea000a5c9000 0000000000000000 ffff8804144b5c48 ffffffff810ed83b [ 127.186824] ffff8804144b5c48 000000000000138a 0000000000001387 ffff8804144b5c98 [ 127.186825] ffff8804144b5d48 ffffffff811bc925 ffff8804144b5cb8 0000000000000000 [ 127.186827] Call Trace: [ 127.186829] [<ffffffff810ed83b>] delete_from_page_cache+0x3b/0x80 [ 127.186832] [<ffffffff811bc925>] truncate_hugepages+0x115/0x220 [ 127.186834] [<ffffffff811bca43>] hugetlbfs_evict_inode+0x13/0x30 [ 127.186837] [<ffffffff811655c7>] evict+0xa7/0x1b0 [ 127.186839] [<ffffffff811657a3>] iput_final+0xd3/0x1f0 [ 127.186840] [<ffffffff811658f9>] iput+0x39/0x50 [ 127.186842] [<ffffffff81162708>] d_kill+0xf8/0x130 [ 127.186843] [<ffffffff81162812>] dput+0xd2/0x1a0 [ 127.186845] [<ffffffff8114e2d0>] __fput+0x170/0x230 [ 127.186848] [<ffffffff81236e0e>] ? rb_erase+0xce/0x150 [ 127.186849] [<ffffffff8114e3ad>] fput+0x1d/0x30 [ 127.186851] [<ffffffff81117db7>] remove_vma+0x37/0x80 [ 127.186853] [<ffffffff81119182>] do_munmap+0x2d2/0x360 [ 127.186855] [<ffffffff811cc639>] sys_shmdt+0xc9/0x170 [ 127.186857] [<ffffffff81410a39>] system_call_fastpath+0x16/0x1b [ 127.186858] Code: 0f 1f 44 00 00 48 8b 43 08 48 8b 00 48 8b 40 28 8b b0 40 03 00 00 85 f6 0f 88 df fe ff ff 48 89 df e8 e7 cb 05 00 e9 d2 fe ff ff <0f> 0b 55 83 e2 fd 48 89 e5 48 83 ec 30 48 89 5d d8 4c 89 65 e0 [ 127.186868] RIP [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160 [ 127.186870] RSP <ffff8804144b5c08> [ 127.186871] ---[ end trace 7cbac5d1db69f426 ]--- The bug is a race and not always easy to reproduce. To reproduce it I was doing the following on a single socket I7-based machine with 16G of RAM. $ hugeadm --pool-pages-max DEFAULT:13G $ echo $((18*1048576*1024)) > /proc/sys/kernel/shmmax $ echo $((18*1048576*1024)) > /proc/sys/kernel/shmall $ for i in `seq 1 9000`; do ./hugetlbfs-test; done On my particular machine, it usually triggers within 10 minutes but enabling debug options can change the timing such that it never hits. Once the bug is triggered, the machine is in trouble and needs to be rebooted. The machine will respond but processes accessing proc like "ps aux" will hang due to the BUG_ON. shutdown will also hang and needs a hard reset or a sysrq-b. The basic problem is a race between page table sharing and teardown. For the most part page table sharing depends on i_mmap_mutex. In some cases, it is also taking the mm->page_table_lock for the PTE updates but with shared page tables, it is the i_mmap_mutex that is more important. Unfortunately it appears to be also insufficient. Consider the following situation Process A Process B --------- --------- hugetlb_fault shmdt LockWrite(mmap_sem) do_munmap unmap_region unmap_vmas unmap_single_vma unmap_hugepage_range Lock(i_mmap_mutex) Lock(mm->page_table_lock) huge_pmd_unshare/unmap tables <--- (1) Unlock(mm->page_table_lock) Unlock(i_mmap_mutex) huge_pte_alloc ... Lock(i_mmap_mutex) ... vma_prio_walk, find svma, spte ... Lock(mm->page_table_lock) ... share spte ... Unlock(mm->page_table_lock) ... Unlock(i_mmap_mutex) ... hugetlb_no_page <--- (2) free_pgtables unlink_file_vma hugetlb_free_pgd_range remove_vma_list In this scenario, it is possible for Process A to share page tables with Process B that is trying to tear them down. The i_mmap_mutex on its own does not prevent Process A walking Process B's page tables. At (1) above, the page tables are not shared yet so it unmaps the PMDs. Process A sets up page table sharing and at (2) faults a new entry. Process B then trips up on it in free_pgtables. This patch fixes the problem by adding a new function __unmap_hugepage_range_final that is only called when the VMA is about to be destroyed. This function clears VM_MAYSHARE during unmap_hugepage_range() under the i_mmap_mutex. This makes the VMA ineligible for sharing and avoids the race. Superficially this looks like it would then be vunerable to truncate and madvise issues but hugetlbfs has its own truncate handlers so does not use unmap_mapping_range() and does not support madvise(DONTNEED). This should be treated as a -stable candidate if it is merged. Test program is as follows. The test case was mostly written by Michal Hocko with a few minor changes to reproduce this bug. ==== CUT HERE ==== static size_t huge_page_size = (2UL << 20); static size_t nr_huge_page_A = 512; static size_t nr_huge_page_B = 5632; unsigned int get_random(unsigned int max) { struct timeval tv; gettimeofday(&tv, NULL); srandom(tv.tv_usec); return random() % max; } static void play(void *addr, size_t size) { unsigned char *start = addr, *end = start + size, *a; start += get_random(size/2); /* we could itterate on huge pages but let's give it more time. */ for (a = start; a < end; a += 4096) *a = 0; } int main(int argc, char **argv) { key_t key = IPC_PRIVATE; size_t sizeA = nr_huge_page_A * huge_page_size; size_t sizeB = nr_huge_page_B * huge_page_size; int shmidA, shmidB; void *addrA = NULL, *addrB = NULL; int nr_children = 300, n = 0; if ((shmidA = shmget(key, sizeA, IPC_CREAT|SHM_HUGETLB|0660)) == -1) { perror("shmget:"); return 1; } if ((addrA = shmat(shmidA, addrA, SHM_R|SHM_W)) == (void *)-1UL) { perror("shmat"); return 1; } if ((shmidB = shmget(key, sizeB, IPC_CREAT|SHM_HUGETLB|0660)) == -1) { perror("shmget:"); return 1; } if ((addrB = shmat(shmidB, addrB, SHM_R|SHM_W)) == (void *)-1UL) { perror("shmat"); return 1; } fork_child: switch(fork()) { case 0: switch (n%3) { case 0: play(addrA, sizeA); break; case 1: play(addrB, sizeB); break; case 2: break; } break; case -1: perror("fork:"); break; default: if (++n < nr_children) goto fork_child; play(addrA, sizeA); break; } shmdt(addrA); shmdt(addrB); do { wait(NULL); } while (--n > 0); shmctl(shmidA, IPC_RMID, NULL); shmctl(shmidB, IPC_RMID, NULL); return 0; } [akpm@linux-foundation.org: name the declaration's args, fix CONFIG_HUGETLBFS=n build] Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-08-01 03:46:20 +04:00
*/
vma->vm_flags &= ~VM_MAYSHARE;
}
void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
unsigned long end, struct page *ref_page)
{
struct mmu_gather tlb;
tlb_gather_mmu(&tlb, vma->vm_mm);
__unmap_hugepage_range(&tlb, vma, start, end, ref_page);
tlb_finish_mmu(&tlb);
}
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
/*
* This is called when the original mapper is failing to COW a MAP_PRIVATE
* mapping it owns the reserve page for. The intention is to unmap the page
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
* from other VMAs and let the children be SIGKILLed if they are faulting the
* same region.
*/
static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
struct page *page, unsigned long address)
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
{
struct hstate *h = hstate_vma(vma);
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
struct vm_area_struct *iter_vma;
struct address_space *mapping;
pgoff_t pgoff;
/*
* vm_pgoff is in PAGE_SIZE units, hence the different calculation
* from page cache lookup which is in HPAGE_SIZE units.
*/
address = address & huge_page_mask(h);
pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
vma->vm_pgoff;
mapping = vma->vm_file->f_mapping;
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
/*
* Take the mapping lock for the duration of the table walk. As
* this mapping should be shared between all the VMAs,
* __unmap_hugepage_range() is called as the lock is already held
*/
i_mmap_lock_write(mapping);
vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) {
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
/* Do not unmap the current VMA */
if (iter_vma == vma)
continue;
mm: hugetlbfs: skip shared VMAs when unmapping private pages to satisfy a fault SunDong reported the following on https://bugzilla.kernel.org/show_bug.cgi?id=103841 I think I find a linux bug, I have the test cases is constructed. I can stable recurring problems in fedora22(4.0.4) kernel version, arch for x86_64. I construct transparent huge page, when the parent and child process with MAP_SHARE, MAP_PRIVATE way to access the same huge page area, it has the opportunity to lead to huge page copy on write failure, and then it will munmap the child corresponding mmap area, but then the child mmap area with VM_MAYSHARE attributes, child process munmap this area can trigger VM_BUG_ON in set_vma_resv_flags functions (vma - > vm_flags & VM_MAYSHARE). There were a number of problems with the report (e.g. it's hugetlbfs that triggers this, not transparent huge pages) but it was fundamentally correct in that a VM_BUG_ON in set_vma_resv_flags() can be triggered that looks like this vma ffff8804651fd0d0 start 00007fc474e00000 end 00007fc475e00000 next ffff8804651fd018 prev ffff8804651fd188 mm ffff88046b1b1800 prot 8000000000000027 anon_vma (null) vm_ops ffffffff8182a7a0 pgoff 0 file ffff88106bdb9800 private_data (null) flags: 0x84400fb(read|write|shared|mayread|maywrite|mayexec|mayshare|dontexpand|hugetlb) ------------ kernel BUG at mm/hugetlb.c:462! SMP Modules linked in: xt_pkttype xt_LOG xt_limit [..] CPU: 38 PID: 26839 Comm: map Not tainted 4.0.4-default #1 Hardware name: Dell Inc. PowerEdge R810/0TT6JF, BIOS 2.7.4 04/26/2012 set_vma_resv_flags+0x2d/0x30 The VM_BUG_ON is correct because private and shared mappings have different reservation accounting but the warning clearly shows that the VMA is shared. When a private COW fails to allocate a new page then only the process that created the VMA gets the page -- all the children unmap the page. If the children access that data in the future then they get killed. The problem is that the same file is mapped shared and private. During the COW, the allocation fails, the VMAs are traversed to unmap the other private pages but a shared VMA is found and the bug is triggered. This patch identifies such VMAs and skips them. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reported-by: SunDong <sund_sky@126.com> Reviewed-by: Michal Hocko <mhocko@suse.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: David Rientjes <rientjes@google.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-10-02 01:36:57 +03:00
/*
* Shared VMAs have their own reserves and do not affect
* MAP_PRIVATE accounting but it is possible that a shared
* VMA is using the same page so check and skip such VMAs.
*/
if (iter_vma->vm_flags & VM_MAYSHARE)
continue;
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
/*
* Unmap the page from other VMAs without their own reserves.
* They get marked to be SIGKILLed if they fault in these
* areas. This is because a future no-page fault on this VMA
* could insert a zeroed page instead of the data existing
* from the time of fork. This would look like data corruption
*/
if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
unmap_hugepage_range(iter_vma, address,
address + huge_page_size(h), page);
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
}
i_mmap_unlock_write(mapping);
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
}
hugetlb, rmap: add reverse mapping for hugepage This patch adds reverse mapping feature for hugepage by introducing mapcount for shared/private-mapped hugepage and anon_vma for private-mapped hugepage. While hugepage is not currently swappable, reverse mapping can be useful for memory error handler. Without this patch, memory error handler cannot identify processes using the bad hugepage nor unmap it from them. That is: - for shared hugepage: we can collect processes using a hugepage through pagecache, but can not unmap the hugepage because of the lack of mapcount. - for privately mapped hugepage: we can neither collect processes nor unmap the hugepage. This patch solves these problems. This patch include the bug fix given by commit 23be7468e8, so reverts it. Dependency: "hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h" ChangeLog since May 24. - create hugetlb_inline.h and move is_vm_hugetlb_index() in it. - move functions setting up anon_vma for hugepage into mm/rmap.c. ChangeLog since May 13. - rebased to 2.6.34 - fix logic error (in case that private mapping and shared mapping coexist) - move is_vm_hugetlb_page() into include/linux/mm.h to use this function from linear_page_index() - define and use linear_hugepage_index() instead of compound_order() - use page_move_anon_rmap() in hugetlb_cow() - copy exclusive switch of __set_page_anon_rmap() into hugepage counterpart. - revert commit 24be7468 completely Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Acked-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andi Kleen <ak@linux.intel.com>
2010-05-28 04:29:16 +04:00
/*
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
* hugetlb_wp() should be called with page lock of the original hugepage held.
* Called with hugetlb_fault_mutex_table held and pte_page locked so we
* cannot race with other handlers or page migration.
* Keep the pte_same checks anyway to make transition from the mutex easier.
hugetlb, rmap: add reverse mapping for hugepage This patch adds reverse mapping feature for hugepage by introducing mapcount for shared/private-mapped hugepage and anon_vma for private-mapped hugepage. While hugepage is not currently swappable, reverse mapping can be useful for memory error handler. Without this patch, memory error handler cannot identify processes using the bad hugepage nor unmap it from them. That is: - for shared hugepage: we can collect processes using a hugepage through pagecache, but can not unmap the hugepage because of the lack of mapcount. - for privately mapped hugepage: we can neither collect processes nor unmap the hugepage. This patch solves these problems. This patch include the bug fix given by commit 23be7468e8, so reverts it. Dependency: "hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h" ChangeLog since May 24. - create hugetlb_inline.h and move is_vm_hugetlb_index() in it. - move functions setting up anon_vma for hugepage into mm/rmap.c. ChangeLog since May 13. - rebased to 2.6.34 - fix logic error (in case that private mapping and shared mapping coexist) - move is_vm_hugetlb_page() into include/linux/mm.h to use this function from linear_page_index() - define and use linear_hugepage_index() instead of compound_order() - use page_move_anon_rmap() in hugetlb_cow() - copy exclusive switch of __set_page_anon_rmap() into hugepage counterpart. - revert commit 24be7468 completely Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Acked-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andi Kleen <ak@linux.intel.com>
2010-05-28 04:29:16 +04:00
*/
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, pte_t *ptep, unsigned int flags,
mm/hugetlb.c: use the right pte val for compare in hugetlb_cow We cannot use the pte value used in set_pte_at for pte_same comparison, because archs like ppc64, filter/add new pte flag in set_pte_at. Instead fetch the pte value inside hugetlb_cow. We are comparing pte value to make sure the pte didn't change since we dropped the page table lock. hugetlb_cow get called with page table lock held, and we can take a copy of the pte value before we drop the page table lock. With hugetlbfs, we optimize the MAP_PRIVATE write fault path with no previous mapping (huge_pte_none entries), by forcing a cow in the fault path. This avoid take an addition fault to covert a read-only mapping to read/write. Here we were comparing a recently instantiated pte (via set_pte_at) to the pte values from linux page table. As explained above on ppc64 such pte_same check returned wrong result, resulting in us taking an additional fault on ppc64. Fixes: 6a119eae942c ("powerpc/mm: Add a _PAGE_PTE bit") Link: http://lkml.kernel.org/r/20161018154245.18023-1-aneesh.kumar@linux.vnet.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Reported-by: Jan Stancek <jstancek@redhat.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Scott Wood <scottwood@freescale.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-13 03:41:56 +03:00
struct page *pagecache_page, spinlock_t *ptl)
{
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
const bool unshare = flags & FAULT_FLAG_UNSHARE;
mm/hugetlb.c: use the right pte val for compare in hugetlb_cow We cannot use the pte value used in set_pte_at for pte_same comparison, because archs like ppc64, filter/add new pte flag in set_pte_at. Instead fetch the pte value inside hugetlb_cow. We are comparing pte value to make sure the pte didn't change since we dropped the page table lock. hugetlb_cow get called with page table lock held, and we can take a copy of the pte value before we drop the page table lock. With hugetlbfs, we optimize the MAP_PRIVATE write fault path with no previous mapping (huge_pte_none entries), by forcing a cow in the fault path. This avoid take an addition fault to covert a read-only mapping to read/write. Here we were comparing a recently instantiated pte (via set_pte_at) to the pte values from linux page table. As explained above on ppc64 such pte_same check returned wrong result, resulting in us taking an additional fault on ppc64. Fixes: 6a119eae942c ("powerpc/mm: Add a _PAGE_PTE bit") Link: http://lkml.kernel.org/r/20161018154245.18023-1-aneesh.kumar@linux.vnet.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Reported-by: Jan Stancek <jstancek@redhat.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Scott Wood <scottwood@freescale.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-13 03:41:56 +03:00
pte_t pte;
struct hstate *h = hstate_vma(vma);
struct page *old_page, *new_page;
int outside_reserve = 0;
vm_fault_t ret = 0;
unsigned long haddr = address & huge_page_mask(h);
struct mmu_notifier_range range;
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
VM_BUG_ON(unshare && (flags & FOLL_WRITE));
VM_BUG_ON(!unshare && !(flags & FOLL_WRITE));
mm/hugetlb.c: use the right pte val for compare in hugetlb_cow We cannot use the pte value used in set_pte_at for pte_same comparison, because archs like ppc64, filter/add new pte flag in set_pte_at. Instead fetch the pte value inside hugetlb_cow. We are comparing pte value to make sure the pte didn't change since we dropped the page table lock. hugetlb_cow get called with page table lock held, and we can take a copy of the pte value before we drop the page table lock. With hugetlbfs, we optimize the MAP_PRIVATE write fault path with no previous mapping (huge_pte_none entries), by forcing a cow in the fault path. This avoid take an addition fault to covert a read-only mapping to read/write. Here we were comparing a recently instantiated pte (via set_pte_at) to the pte values from linux page table. As explained above on ppc64 such pte_same check returned wrong result, resulting in us taking an additional fault on ppc64. Fixes: 6a119eae942c ("powerpc/mm: Add a _PAGE_PTE bit") Link: http://lkml.kernel.org/r/20161018154245.18023-1-aneesh.kumar@linux.vnet.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Reported-by: Jan Stancek <jstancek@redhat.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Scott Wood <scottwood@freescale.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-13 03:41:56 +03:00
pte = huge_ptep_get(ptep);
old_page = pte_page(pte);
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
retry_avoidcopy:
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
/*
* If no-one else is actually using this page, we're the exclusive
* owner and can reuse this page.
*/
mm, hugetlb: do not use a page in page cache for cow optimization Currently, we use a page with mapped count 1 in page cache for cow optimization. If we find this condition, we don't allocate a new page and copy contents. Instead, we map this page directly. This may introduce a problem that writting to private mapping overwrite hugetlb file directly. You can find this situation with following code. size = 20 * MB; flag = MAP_SHARED; p = mmap(NULL, size, PROT_READ|PROT_WRITE, flag, fd, 0); if (p == MAP_FAILED) { fprintf(stderr, "mmap() failed: %s\n", strerror(errno)); return -1; } p[0] = 's'; fprintf(stdout, "BEFORE STEAL PRIVATE WRITE: %c\n", p[0]); munmap(p, size); flag = MAP_PRIVATE; p = mmap(NULL, size, PROT_READ|PROT_WRITE, flag, fd, 0); if (p == MAP_FAILED) { fprintf(stderr, "mmap() failed: %s\n", strerror(errno)); } p[0] = 'c'; munmap(p, size); flag = MAP_SHARED; p = mmap(NULL, size, PROT_READ|PROT_WRITE, flag, fd, 0); if (p == MAP_FAILED) { fprintf(stderr, "mmap() failed: %s\n", strerror(errno)); return -1; } fprintf(stdout, "AFTER STEAL PRIVATE WRITE: %c\n", p[0]); munmap(p, size); We can see that "AFTER STEAL PRIVATE WRITE: c", not "AFTER STEAL PRIVATE WRITE: s". If we turn off this optimization to a page in page cache, the problem is disappeared. So, I change the trigger condition of optimization. If this page is not AnonPage, we don't do optimization. This makes this optimization turning off for a page cache. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <dhillf@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:21:04 +04:00
if (page_mapcount(old_page) == 1 && PageAnon(old_page)) {
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
if (!PageAnonExclusive(old_page))
page_move_anon_rmap(old_page, vma);
if (likely(!unshare))
set_huge_ptep_writable(vma, haddr, ptep);
mm: fault feedback #2 This patch completes Linus's wish that the fault return codes be made into bit flags, which I agree makes everything nicer. This requires requires all handle_mm_fault callers to be modified (possibly the modifications should go further and do things like fault accounting in handle_mm_fault -- however that would be for another patch). [akpm@linux-foundation.org: fix alpha build] [akpm@linux-foundation.org: fix s390 build] [akpm@linux-foundation.org: fix sparc build] [akpm@linux-foundation.org: fix sparc64 build] [akpm@linux-foundation.org: fix ia64 build] Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ian Molton <spyro@f2s.com> Cc: Bryan Wu <bryan.wu@analog.com> Cc: Mikael Starvik <starvik@axis.com> Cc: David Howells <dhowells@redhat.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Hirokazu Takata <takata@linux-m32r.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Greg Ungerer <gerg@uclinux.org> Cc: Matthew Wilcox <willy@debian.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp> Cc: Richard Curnow <rc@rc0.org.uk> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp> Cc: Chris Zankel <chris@zankel.net> Acked-by: Kyle McMartin <kyle@mcmartin.ca> Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com> Acked-by: Ralf Baechle <ralf@linux-mips.org> Acked-by: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> [ Still apparently needs some ARM and PPC loving - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 12:47:05 +04:00
return 0;
}
mm: remember exclusively mapped anonymous pages with PG_anon_exclusive Let's mark exclusively mapped anonymous pages with PG_anon_exclusive as exclusive, and use that information to make GUP pins reliable and stay consistent with the page mapped into the page table even if the page table entry gets write-protected. With that information at hand, we can extend our COW logic to always reuse anonymous pages that are exclusive. For anonymous pages that might be shared, the existing logic applies. As already documented, PG_anon_exclusive is usually only expressive in combination with a page table entry. Especially PTE vs. PMD-mapped anonymous pages require more thought, some examples: due to mremap() we can easily have a single compound page PTE-mapped into multiple page tables exclusively in a single process -- multiple page table locks apply. Further, due to MADV_WIPEONFORK we might not necessarily write-protect all PTEs, and only some subpages might be pinned. Long story short: once PTE-mapped, we have to track information about exclusivity per sub-page, but until then, we can just track it for the compound page in the head page and not having to update a whole bunch of subpages all of the time for a simple PMD mapping of a THP. For simplicity, this commit mostly talks about "anonymous pages", while it's for THP actually "the part of an anonymous folio referenced via a page table entry". To not spill PG_anon_exclusive code all over the mm code-base, we let the anon rmap code to handle all PG_anon_exclusive logic it can easily handle. If a writable, present page table entry points at an anonymous (sub)page, that (sub)page must be PG_anon_exclusive. If GUP wants to take a reliably pin (FOLL_PIN) on an anonymous page references via a present page table entry, it must only pin if PG_anon_exclusive is set for the mapped (sub)page. This commit doesn't adjust GUP, so this is only implicitly handled for FOLL_WRITE, follow-up commits will teach GUP to also respect it for FOLL_PIN without FOLL_WRITE, to make all GUP pins of anonymous pages fully reliable. Whenever an anonymous page is to be shared (fork(), KSM), or when temporarily unmapping an anonymous page (swap, migration), the relevant PG_anon_exclusive bit has to be cleared to mark the anonymous page possibly shared. Clearing will fail if there are GUP pins on the page: * For fork(), this means having to copy the page and not being able to share it. fork() protects against concurrent GUP using the PT lock and the src_mm->write_protect_seq. * For KSM, this means sharing will fail. For swap this means, unmapping will fail, For migration this means, migration will fail early. All three cases protect against concurrent GUP using the PT lock and a proper clear/invalidate+flush of the relevant page table entry. This fixes memory corruptions reported for FOLL_PIN | FOLL_WRITE, when a pinned page gets mapped R/O and the successive write fault ends up replacing the page instead of reusing it. It improves the situation for O_DIRECT/vmsplice/... that still use FOLL_GET instead of FOLL_PIN, if fork() is *not* involved, however swapout and fork() are still problematic. Properly using FOLL_PIN instead of FOLL_GET for these GUP users will fix the issue for them. I. Details about basic handling I.1. Fresh anonymous pages page_add_new_anon_rmap() and hugepage_add_new_anon_rmap() will mark the given page exclusive via __page_set_anon_rmap(exclusive=1). As that is the mechanism fresh anonymous pages come into life (besides migration code where we copy the page->mapping), all fresh anonymous pages will start out as exclusive. I.2. COW reuse handling of anonymous pages When a COW handler stumbles over a (sub)page that's marked exclusive, it simply reuses it. Otherwise, the handler tries harder under page lock to detect if the (sub)page is exclusive and can be reused. If exclusive, page_move_anon_rmap() will mark the given (sub)page exclusive. Note that hugetlb code does not yet check for PageAnonExclusive(), as it still uses the old COW logic that is prone to the COW security issue because hugetlb code cannot really tolerate unnecessary/wrong COW as huge pages are a scarce resource. I.3. Migration handling try_to_migrate() has to try marking an exclusive anonymous page shared via page_try_share_anon_rmap(). If it fails because there are GUP pins on the page, unmap fails. migrate_vma_collect_pmd() and __split_huge_pmd_locked() are handled similarly. Writable migration entries implicitly point at shared anonymous pages. For readable migration entries that information is stored via a new "readable-exclusive" migration entry, specific to anonymous pages. When restoring a migration entry in remove_migration_pte(), information about exlusivity is detected via the migration entry type, and RMAP_EXCLUSIVE is set accordingly for page_add_anon_rmap()/hugepage_add_anon_rmap() to restore that information. I.4. Swapout handling try_to_unmap() has to try marking the mapped page possibly shared via page_try_share_anon_rmap(). If it fails because there are GUP pins on the page, unmap fails. For now, information about exclusivity is lost. In the future, we might want to remember that information in the swap entry in some cases, however, it requires more thought, care, and a way to store that information in swap entries. I.5. Swapin handling do_swap_page() will never stumble over exclusive anonymous pages in the swap cache, as try_to_migrate() prohibits that. do_swap_page() always has to detect manually if an anonymous page is exclusive and has to set RMAP_EXCLUSIVE for page_add_anon_rmap() accordingly. I.6. THP handling __split_huge_pmd_locked() has to move the information about exclusivity from the PMD to the PTEs. a) In case we have a readable-exclusive PMD migration entry, simply insert readable-exclusive PTE migration entries. b) In case we have a present PMD entry and we don't want to freeze ("convert to migration entries"), simply forward PG_anon_exclusive to all sub-pages, no need to temporarily clear the bit. c) In case we have a present PMD entry and want to freeze, handle it similar to try_to_migrate(): try marking the page shared first. In case we fail, we ignore the "freeze" instruction and simply split ordinarily. try_to_migrate() will properly fail because the THP is still mapped via PTEs. When splitting a compound anonymous folio (THP), the information about exclusivity is implicitly handled via the migration entries: no need to replicate PG_anon_exclusive manually. I.7. fork() handling fork() handling is relatively easy, because PG_anon_exclusive is only expressive for some page table entry types. a) Present anonymous pages page_try_dup_anon_rmap() will mark the given subpage shared -- which will fail if the page is pinned. If it failed, we have to copy (or PTE-map a PMD to handle it on the PTE level). Note that device exclusive entries are just a pointer at a PageAnon() page. fork() will first convert a device exclusive entry to a present page table and handle it just like present anonymous pages. b) Device private entry Device private entries point at PageAnon() pages that cannot be mapped directly and, therefore, cannot get pinned. page_try_dup_anon_rmap() will mark the given subpage shared, which cannot fail because they cannot get pinned. c) HW poison entries PG_anon_exclusive will remain untouched and is stale -- the page table entry is just a placeholder after all. d) Migration entries Writable and readable-exclusive entries are converted to readable entries: possibly shared. I.8. mprotect() handling mprotect() only has to properly handle the new readable-exclusive migration entry: When write-protecting a migration entry that points at an anonymous page, remember the information about exclusivity via the "readable-exclusive" migration entry type. II. Migration and GUP-fast Whenever replacing a present page table entry that maps an exclusive anonymous page by a migration entry, we have to mark the page possibly shared and synchronize against GUP-fast by a proper clear/invalidate+flush to make the following scenario impossible: 1. try_to_migrate() places a migration entry after checking for GUP pins and marks the page possibly shared. 2. GUP-fast pins the page due to lack of synchronization 3. fork() converts the "writable/readable-exclusive" migration entry into a readable migration entry 4. Migration fails due to the GUP pin (failing to freeze the refcount) 5. Migration entries are restored. PG_anon_exclusive is lost -> We have a pinned page that is not marked exclusive anymore. Note that we move information about exclusivity from the page to the migration entry as it otherwise highly overcomplicates fork() and PTE-mapping a THP. III. Swapout and GUP-fast Whenever replacing a present page table entry that maps an exclusive anonymous page by a swap entry, we have to mark the page possibly shared and synchronize against GUP-fast by a proper clear/invalidate+flush to make the following scenario impossible: 1. try_to_unmap() places a swap entry after checking for GUP pins and clears exclusivity information on the page. 2. GUP-fast pins the page due to lack of synchronization. -> We have a pinned page that is not marked exclusive anymore. If we'd ever store information about exclusivity in the swap entry, similar to migration handling, the same considerations as in II would apply. This is future work. Link: https://lkml.kernel.org/r/20220428083441.37290-13-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:44 +03:00
VM_BUG_ON_PAGE(PageAnon(old_page) && PageAnonExclusive(old_page),
old_page);
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
/*
* If the process that created a MAP_PRIVATE mapping is about to
* perform a COW due to a shared page count, attempt to satisfy
* the allocation without using the existing reserves. The pagecache
* page is used to determine if the reserve at this address was
* consumed or not. If reserves were used, a partial faulted mapping
* at the time of fork() could consume its reserves on COW instead
* of the full address range.
*/
if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
old_page != pagecache_page)
outside_reserve = 1;
mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago with promise that one day it will be possible to implement page cache with bigger chunks than PAGE_SIZE. This promise never materialized. And unlikely will. We have many places where PAGE_CACHE_SIZE assumed to be equal to PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* or PAGE_* constant should be used in a particular case, especially on the border between fs and mm. Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much breakage to be doable. Let's stop pretending that pages in page cache are special. They are not. The changes are pretty straight-forward: - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; - page_cache_get() -> get_page(); - page_cache_release() -> put_page(); This patch contains automated changes generated with coccinelle using script below. For some reason, coccinelle doesn't patch header files. I've called spatch for them manually. The only adjustment after coccinelle is revert of changes to PAGE_CAHCE_ALIGN definition: we are going to drop it later. There are few places in the code where coccinelle didn't reach. I'll fix them manually in a separate patch. Comments and documentation also will be addressed with the separate patch. virtual patch @@ expression E; @@ - E << (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ expression E; @@ - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ @@ - PAGE_CACHE_SHIFT + PAGE_SHIFT @@ @@ - PAGE_CACHE_SIZE + PAGE_SIZE @@ @@ - PAGE_CACHE_MASK + PAGE_MASK @@ expression E; @@ - PAGE_CACHE_ALIGN(E) + PAGE_ALIGN(E) @@ expression E; @@ - page_cache_get(E) + get_page(E) @@ expression E; @@ - page_cache_release(E) + put_page(E) Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-01 15:29:47 +03:00
get_page(old_page);
hugetlb: prevent deadlock in __unmap_hugepage_range() when alloc_huge_page() fails hugetlb_fault() takes the mm->page_table_lock spinlock then calls hugetlb_cow(). If the alloc_huge_page() in hugetlb_cow() fails due to an insufficient huge page pool it calls unmap_ref_private() with the mm->page_table_lock held. unmap_ref_private() then calls unmap_hugepage_range() which tries to acquire the mm->page_table_lock. [<ffffffff810928c3>] print_circular_bug_tail+0x80/0x9f [<ffffffff8109280b>] ? check_noncircular+0xb0/0xe8 [<ffffffff810935e0>] __lock_acquire+0x956/0xc0e [<ffffffff81093986>] lock_acquire+0xee/0x12e [<ffffffff8111a7a6>] ? unmap_hugepage_range+0x3e/0x84 [<ffffffff8111a7a6>] ? unmap_hugepage_range+0x3e/0x84 [<ffffffff814c348d>] _spin_lock+0x40/0x89 [<ffffffff8111a7a6>] ? unmap_hugepage_range+0x3e/0x84 [<ffffffff8111afee>] ? alloc_huge_page+0x218/0x318 [<ffffffff8111a7a6>] unmap_hugepage_range+0x3e/0x84 [<ffffffff8111b2d0>] hugetlb_cow+0x1e2/0x3f4 [<ffffffff8111b935>] ? hugetlb_fault+0x453/0x4f6 [<ffffffff8111b962>] hugetlb_fault+0x480/0x4f6 [<ffffffff8111baee>] follow_hugetlb_page+0x116/0x2d9 [<ffffffff814c31a7>] ? _spin_unlock_irq+0x3a/0x5c [<ffffffff81107b4d>] __get_user_pages+0x2a3/0x427 [<ffffffff81107d0f>] get_user_pages+0x3e/0x54 [<ffffffff81040b8b>] get_user_pages_fast+0x170/0x1b5 [<ffffffff81160352>] dio_get_page+0x64/0x14a [<ffffffff8116112a>] __blockdev_direct_IO+0x4b7/0xb31 [<ffffffff8115ef91>] blkdev_direct_IO+0x58/0x6e [<ffffffff8115e0a4>] ? blkdev_get_blocks+0x0/0xb8 [<ffffffff810ed2c5>] generic_file_aio_read+0xdd/0x528 [<ffffffff81219da3>] ? avc_has_perm+0x66/0x8c [<ffffffff81132842>] do_sync_read+0xf5/0x146 [<ffffffff8107da00>] ? autoremove_wake_function+0x0/0x5a [<ffffffff81211857>] ? security_file_permission+0x24/0x3a [<ffffffff81132fd8>] vfs_read+0xb5/0x126 [<ffffffff81133f6b>] ? fget_light+0x5e/0xf8 [<ffffffff81133131>] sys_read+0x54/0x8c [<ffffffff81011e42>] system_call_fastpath+0x16/0x1b This can be fixed by dropping the mm->page_table_lock around the call to unmap_ref_private() if alloc_huge_page() fails, its dropped right below in the normal path anyway. However, earlier in the that function, it's also possible to call into the page allocator with the same spinlock held. What this patch does is drop the spinlock before the page allocator is potentially entered. The check for page allocation failure can be made without the page_table_lock as well as the copy of the huge page. Even if the PTE changed while the spinlock was held, the consequence is that a huge page is copied unnecessarily. This resolves both the double taking of the lock and sleeping with the spinlock held. [mel@csn.ul.ie: Cover also the case where process can sleep with spinlock] Signed-off-by: Larry Woodman <lwooman@redhat.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:59:37 +03:00
/*
* Drop page table lock as buddy allocator may be called. It will
* be acquired again before returning to the caller, as expected.
*/
spin_unlock(ptl);
mm, hugetlbfs: rename address to haddr in hugetlb_cow() To take better advantage of general huge page copying optimization, the target subpage address will be passed to hugetlb_cow(), then copy_user_huge_page(). So we will use both target subpage address and huge page size aligned address in hugetlb_cow(). To distinguish between them, "haddr" is used for huge page size aligned address to be consistent with Transparent Huge Page naming convention. Now, only huge page size aligned address is used in hugetlb_cow(), so the "address" is renamed to "haddr" in hugetlb_cow() in this patch. Next patch will use target subpage address in hugetlb_cow() too. The patch is just code cleanup without any functionality changes. Link: http://lkml.kernel.org/r/20180524005851.4079-4-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Suggested-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-18 01:45:53 +03:00
new_page = alloc_huge_page(vma, haddr, outside_reserve);
if (IS_ERR(new_page)) {
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
/*
* If a process owning a MAP_PRIVATE mapping fails to COW,
* it is due to references held by a child and an insufficient
* huge page pool. To guarantee the original mappers
* reliability, unmap the page from child processes. The child
* may get SIGKILLed if it later faults.
*/
if (outside_reserve) {
mm/hugetlb: fix deadlock in hugetlb_cow error path syzbot reported the deadlock here [1]. The issue is in hugetlb cow error handling when there are not enough huge pages for the faulting task which took the original reservation. It is possible that other (child) tasks could have consumed pages associated with the reservation. In this case, we want the task which took the original reservation to succeed. So, we unmap any associated pages in children so that they can be used by the faulting task that owns the reservation. The unmapping code needs to hold i_mmap_rwsem in write mode. However, due to commit c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") we are already holding i_mmap_rwsem in read mode when hugetlb_cow is called. Technically, i_mmap_rwsem does not need to be held in read mode for COW mappings as they can not share pmd's. Modifying the fault code to not take i_mmap_rwsem in read mode for COW (and other non-sharable) mappings is too involved for a stable fix. Instead, we simply drop the hugetlb_fault_mutex and i_mmap_rwsem before unmapping. This is OK as it is technically not needed. They are reacquired after unmapping as expected by calling code. Since this is done in an uncommon error path, the overhead of dropping and reacquiring mutexes is acceptable. While making changes, remove redundant BUG_ON after unmap_ref_private. [1] https://lkml.kernel.org/r/000000000000b73ccc05b5cf8558@google.com Link: https://lkml.kernel.org/r/4c5781b8-3b00-761e-c0c7-c5edebb6ec1a@oracle.com Fixes: c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: syzbot+5eee4145df3c15e96625@syzkaller.appspotmail.com Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-30 02:14:25 +03:00
struct address_space *mapping = vma->vm_file->f_mapping;
pgoff_t idx;
u32 hash;
mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago with promise that one day it will be possible to implement page cache with bigger chunks than PAGE_SIZE. This promise never materialized. And unlikely will. We have many places where PAGE_CACHE_SIZE assumed to be equal to PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* or PAGE_* constant should be used in a particular case, especially on the border between fs and mm. Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much breakage to be doable. Let's stop pretending that pages in page cache are special. They are not. The changes are pretty straight-forward: - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; - page_cache_get() -> get_page(); - page_cache_release() -> put_page(); This patch contains automated changes generated with coccinelle using script below. For some reason, coccinelle doesn't patch header files. I've called spatch for them manually. The only adjustment after coccinelle is revert of changes to PAGE_CAHCE_ALIGN definition: we are going to drop it later. There are few places in the code where coccinelle didn't reach. I'll fix them manually in a separate patch. Comments and documentation also will be addressed with the separate patch. virtual patch @@ expression E; @@ - E << (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ expression E; @@ - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ @@ - PAGE_CACHE_SHIFT + PAGE_SHIFT @@ @@ - PAGE_CACHE_SIZE + PAGE_SIZE @@ @@ - PAGE_CACHE_MASK + PAGE_MASK @@ expression E; @@ - PAGE_CACHE_ALIGN(E) + PAGE_ALIGN(E) @@ expression E; @@ - page_cache_get(E) + get_page(E) @@ expression E; @@ - page_cache_release(E) + put_page(E) Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-01 15:29:47 +03:00
put_page(old_page);
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
BUG_ON(huge_pte_none(pte));
mm/hugetlb: fix deadlock in hugetlb_cow error path syzbot reported the deadlock here [1]. The issue is in hugetlb cow error handling when there are not enough huge pages for the faulting task which took the original reservation. It is possible that other (child) tasks could have consumed pages associated with the reservation. In this case, we want the task which took the original reservation to succeed. So, we unmap any associated pages in children so that they can be used by the faulting task that owns the reservation. The unmapping code needs to hold i_mmap_rwsem in write mode. However, due to commit c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") we are already holding i_mmap_rwsem in read mode when hugetlb_cow is called. Technically, i_mmap_rwsem does not need to be held in read mode for COW mappings as they can not share pmd's. Modifying the fault code to not take i_mmap_rwsem in read mode for COW (and other non-sharable) mappings is too involved for a stable fix. Instead, we simply drop the hugetlb_fault_mutex and i_mmap_rwsem before unmapping. This is OK as it is technically not needed. They are reacquired after unmapping as expected by calling code. Since this is done in an uncommon error path, the overhead of dropping and reacquiring mutexes is acceptable. While making changes, remove redundant BUG_ON after unmap_ref_private. [1] https://lkml.kernel.org/r/000000000000b73ccc05b5cf8558@google.com Link: https://lkml.kernel.org/r/4c5781b8-3b00-761e-c0c7-c5edebb6ec1a@oracle.com Fixes: c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: syzbot+5eee4145df3c15e96625@syzkaller.appspotmail.com Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-30 02:14:25 +03:00
/*
* Drop hugetlb_fault_mutex and i_mmap_rwsem before
* unmapping. unmapping needs to hold i_mmap_rwsem
* in write mode. Dropping i_mmap_rwsem in read mode
* here is OK as COW mappings do not interact with
* PMD sharing.
*
* Reacquire both after unmap operation.
*/
idx = vma_hugecache_offset(h, vma, haddr);
hash = hugetlb_fault_mutex_hash(mapping, idx);
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
i_mmap_unlock_read(mapping);
mm, hugetlbfs: rename address to haddr in hugetlb_cow() To take better advantage of general huge page copying optimization, the target subpage address will be passed to hugetlb_cow(), then copy_user_huge_page(). So we will use both target subpage address and huge page size aligned address in hugetlb_cow(). To distinguish between them, "haddr" is used for huge page size aligned address to be consistent with Transparent Huge Page naming convention. Now, only huge page size aligned address is used in hugetlb_cow(), so the "address" is renamed to "haddr" in hugetlb_cow() in this patch. Next patch will use target subpage address in hugetlb_cow() too. The patch is just code cleanup without any functionality changes. Link: http://lkml.kernel.org/r/20180524005851.4079-4-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Suggested-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-18 01:45:53 +03:00
unmap_ref_private(mm, vma, old_page, haddr);
mm/hugetlb: fix deadlock in hugetlb_cow error path syzbot reported the deadlock here [1]. The issue is in hugetlb cow error handling when there are not enough huge pages for the faulting task which took the original reservation. It is possible that other (child) tasks could have consumed pages associated with the reservation. In this case, we want the task which took the original reservation to succeed. So, we unmap any associated pages in children so that they can be used by the faulting task that owns the reservation. The unmapping code needs to hold i_mmap_rwsem in write mode. However, due to commit c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") we are already holding i_mmap_rwsem in read mode when hugetlb_cow is called. Technically, i_mmap_rwsem does not need to be held in read mode for COW mappings as they can not share pmd's. Modifying the fault code to not take i_mmap_rwsem in read mode for COW (and other non-sharable) mappings is too involved for a stable fix. Instead, we simply drop the hugetlb_fault_mutex and i_mmap_rwsem before unmapping. This is OK as it is technically not needed. They are reacquired after unmapping as expected by calling code. Since this is done in an uncommon error path, the overhead of dropping and reacquiring mutexes is acceptable. While making changes, remove redundant BUG_ON after unmap_ref_private. [1] https://lkml.kernel.org/r/000000000000b73ccc05b5cf8558@google.com Link: https://lkml.kernel.org/r/4c5781b8-3b00-761e-c0c7-c5edebb6ec1a@oracle.com Fixes: c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: syzbot+5eee4145df3c15e96625@syzkaller.appspotmail.com Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-30 02:14:25 +03:00
i_mmap_lock_read(mapping);
mutex_lock(&hugetlb_fault_mutex_table[hash]);
spin_lock(ptl);
mm, hugetlbfs: rename address to haddr in hugetlb_cow() To take better advantage of general huge page copying optimization, the target subpage address will be passed to hugetlb_cow(), then copy_user_huge_page(). So we will use both target subpage address and huge page size aligned address in hugetlb_cow(). To distinguish between them, "haddr" is used for huge page size aligned address to be consistent with Transparent Huge Page naming convention. Now, only huge page size aligned address is used in hugetlb_cow(), so the "address" is renamed to "haddr" in hugetlb_cow() in this patch. Next patch will use target subpage address in hugetlb_cow() too. The patch is just code cleanup without any functionality changes. Link: http://lkml.kernel.org/r/20180524005851.4079-4-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Suggested-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-18 01:45:53 +03:00
ptep = huge_pte_offset(mm, haddr, huge_page_size(h));
if (likely(ptep &&
pte_same(huge_ptep_get(ptep), pte)))
goto retry_avoidcopy;
/*
* race occurs while re-acquiring page table
* lock, and our job is done.
*/
return 0;
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
}
ret = vmf_error(PTR_ERR(new_page));
goto out_release_old;
}
hugetlb, rmap: add reverse mapping for hugepage This patch adds reverse mapping feature for hugepage by introducing mapcount for shared/private-mapped hugepage and anon_vma for private-mapped hugepage. While hugepage is not currently swappable, reverse mapping can be useful for memory error handler. Without this patch, memory error handler cannot identify processes using the bad hugepage nor unmap it from them. That is: - for shared hugepage: we can collect processes using a hugepage through pagecache, but can not unmap the hugepage because of the lack of mapcount. - for privately mapped hugepage: we can neither collect processes nor unmap the hugepage. This patch solves these problems. This patch include the bug fix given by commit 23be7468e8, so reverts it. Dependency: "hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h" ChangeLog since May 24. - create hugetlb_inline.h and move is_vm_hugetlb_index() in it. - move functions setting up anon_vma for hugepage into mm/rmap.c. ChangeLog since May 13. - rebased to 2.6.34 - fix logic error (in case that private mapping and shared mapping coexist) - move is_vm_hugetlb_page() into include/linux/mm.h to use this function from linear_page_index() - define and use linear_hugepage_index() instead of compound_order() - use page_move_anon_rmap() in hugetlb_cow() - copy exclusive switch of __set_page_anon_rmap() into hugepage counterpart. - revert commit 24be7468 completely Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Acked-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andi Kleen <ak@linux.intel.com>
2010-05-28 04:29:16 +04:00
/*
* When the original hugepage is shared one, it does not have
* anon_vma prepared.
*/
if (unlikely(anon_vma_prepare(vma))) {
ret = VM_FAULT_OOM;
goto out_release_all;
}
hugetlb, rmap: add reverse mapping for hugepage This patch adds reverse mapping feature for hugepage by introducing mapcount for shared/private-mapped hugepage and anon_vma for private-mapped hugepage. While hugepage is not currently swappable, reverse mapping can be useful for memory error handler. Without this patch, memory error handler cannot identify processes using the bad hugepage nor unmap it from them. That is: - for shared hugepage: we can collect processes using a hugepage through pagecache, but can not unmap the hugepage because of the lack of mapcount. - for privately mapped hugepage: we can neither collect processes nor unmap the hugepage. This patch solves these problems. This patch include the bug fix given by commit 23be7468e8, so reverts it. Dependency: "hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h" ChangeLog since May 24. - create hugetlb_inline.h and move is_vm_hugetlb_index() in it. - move functions setting up anon_vma for hugepage into mm/rmap.c. ChangeLog since May 13. - rebased to 2.6.34 - fix logic error (in case that private mapping and shared mapping coexist) - move is_vm_hugetlb_page() into include/linux/mm.h to use this function from linear_page_index() - define and use linear_hugepage_index() instead of compound_order() - use page_move_anon_rmap() in hugetlb_cow() - copy exclusive switch of __set_page_anon_rmap() into hugepage counterpart. - revert commit 24be7468 completely Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Acked-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andi Kleen <ak@linux.intel.com>
2010-05-28 04:29:16 +04:00
copy_user_huge_page(new_page, old_page, address, vma,
pages_per_huge_page(h));
mm: fix PageUptodate data race After running SetPageUptodate, preceeding stores to the page contents to actually bring it uptodate may not be ordered with the store to set the page uptodate. Therefore, another CPU which checks PageUptodate is true, then reads the page contents can get stale data. Fix this by having an smp_wmb before SetPageUptodate, and smp_rmb after PageUptodate. Many places that test PageUptodate, do so with the page locked, and this would be enough to ensure memory ordering in those places if SetPageUptodate were only called while the page is locked. Unfortunately that is not always the case for some filesystems, but it could be an idea for the future. Also bring the handling of anonymous page uptodateness in line with that of file backed page management, by marking anon pages as uptodate when they _are_ uptodate, rather than when our implementation requires that they be marked as such. Doing allows us to get rid of the smp_wmb's in the page copying functions, which were especially added for anonymous pages for an analogous memory ordering problem. Both file and anonymous pages are handled with the same barriers. FAQ: Q. Why not do this in flush_dcache_page? A. Firstly, flush_dcache_page handles only one side (the smb side) of the ordering protocol; we'd still need smp_rmb somewhere. Secondly, hiding away memory barriers in a completely unrelated function is nasty; at least in the PageUptodate macros, they are located together with (half) the operations involved in the ordering. Thirdly, the smp_wmb is only required when first bringing the page uptodate, wheras flush_dcache_page should be called each time it is written to through the kernel mapping. It is logically the wrong place to put it. Q. Why does this increase my text size / reduce my performance / etc. A. Because it is adding the necessary instructions to eliminate the data-race. Q. Can it be improved? A. Yes, eg. if you were to create a rule that all SetPageUptodate operations run under the page lock, we could avoid the smp_rmb places where PageUptodate is queried under the page lock. Requires audit of all filesystems and at least some would need reworking. That's great you're interested, I'm eagerly awaiting your patches. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 09:29:34 +03:00
__SetPageUptodate(new_page);
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, haddr,
mm/mmu_notifier: contextual information for event triggering invalidation CPU page table update can happens for many reasons, not only as a result of a syscall (munmap(), mprotect(), mremap(), madvise(), ...) but also as a result of kernel activities (memory compression, reclaim, migration, ...). Users of mmu notifier API track changes to the CPU page table and take specific action for them. While current API only provide range of virtual address affected by the change, not why the changes is happening. This patchset do the initial mechanical convertion of all the places that calls mmu_notifier_range_init to also provide the default MMU_NOTIFY_UNMAP event as well as the vma if it is know (most invalidation happens against a given vma). Passing down the vma allows the users of mmu notifier to inspect the new vma page protection. The MMU_NOTIFY_UNMAP is always the safe default as users of mmu notifier should assume that every for the range is going away when that event happens. A latter patch do convert mm call path to use a more appropriate events for each call. This is done as 2 patches so that no call site is forgotten especialy as it uses this following coccinelle patch: %<---------------------------------------------------------------------- @@ identifier I1, I2, I3, I4; @@ static inline void mmu_notifier_range_init(struct mmu_notifier_range *I1, +enum mmu_notifier_event event, +unsigned flags, +struct vm_area_struct *vma, struct mm_struct *I2, unsigned long I3, unsigned long I4) { ... } @@ @@ -#define mmu_notifier_range_init(range, mm, start, end) +#define mmu_notifier_range_init(range, event, flags, vma, mm, start, end) @@ expression E1, E3, E4; identifier I1; @@ <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, I1, I1->vm_mm, E3, E4) ...> @@ expression E1, E2, E3, E4; identifier FN, VMA; @@ FN(..., struct vm_area_struct *VMA, ...) { <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, VMA, E2, E3, E4) ...> } @@ expression E1, E2, E3, E4; identifier FN, VMA; @@ FN(...) { struct vm_area_struct *VMA; <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, VMA, E2, E3, E4) ...> } @@ expression E1, E2, E3, E4; identifier FN; @@ FN(...) { <... mmu_notifier_range_init(E1, +MMU_NOTIFY_UNMAP, 0, NULL, E2, E3, E4) ...> } ---------------------------------------------------------------------->% Applied with: spatch --all-includes --sp-file mmu-notifier.spatch fs/proc/task_mmu.c --in-place spatch --sp-file mmu-notifier.spatch --dir kernel/events/ --in-place spatch --sp-file mmu-notifier.spatch --dir mm --in-place Link: http://lkml.kernel.org/r/20190326164747.24405-6-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Cc: Christian König <christian.koenig@amd.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Peter Xu <peterx@redhat.com> Cc: Felix Kuehling <Felix.Kuehling@amd.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Ross Zwisler <zwisler@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krcmar <rkrcmar@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Christian Koenig <christian.koenig@amd.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 03:20:49 +03:00
haddr + huge_page_size(h));
mmu_notifier_invalidate_range_start(&range);
hugetlb: prevent deadlock in __unmap_hugepage_range() when alloc_huge_page() fails hugetlb_fault() takes the mm->page_table_lock spinlock then calls hugetlb_cow(). If the alloc_huge_page() in hugetlb_cow() fails due to an insufficient huge page pool it calls unmap_ref_private() with the mm->page_table_lock held. unmap_ref_private() then calls unmap_hugepage_range() which tries to acquire the mm->page_table_lock. [<ffffffff810928c3>] print_circular_bug_tail+0x80/0x9f [<ffffffff8109280b>] ? check_noncircular+0xb0/0xe8 [<ffffffff810935e0>] __lock_acquire+0x956/0xc0e [<ffffffff81093986>] lock_acquire+0xee/0x12e [<ffffffff8111a7a6>] ? unmap_hugepage_range+0x3e/0x84 [<ffffffff8111a7a6>] ? unmap_hugepage_range+0x3e/0x84 [<ffffffff814c348d>] _spin_lock+0x40/0x89 [<ffffffff8111a7a6>] ? unmap_hugepage_range+0x3e/0x84 [<ffffffff8111afee>] ? alloc_huge_page+0x218/0x318 [<ffffffff8111a7a6>] unmap_hugepage_range+0x3e/0x84 [<ffffffff8111b2d0>] hugetlb_cow+0x1e2/0x3f4 [<ffffffff8111b935>] ? hugetlb_fault+0x453/0x4f6 [<ffffffff8111b962>] hugetlb_fault+0x480/0x4f6 [<ffffffff8111baee>] follow_hugetlb_page+0x116/0x2d9 [<ffffffff814c31a7>] ? _spin_unlock_irq+0x3a/0x5c [<ffffffff81107b4d>] __get_user_pages+0x2a3/0x427 [<ffffffff81107d0f>] get_user_pages+0x3e/0x54 [<ffffffff81040b8b>] get_user_pages_fast+0x170/0x1b5 [<ffffffff81160352>] dio_get_page+0x64/0x14a [<ffffffff8116112a>] __blockdev_direct_IO+0x4b7/0xb31 [<ffffffff8115ef91>] blkdev_direct_IO+0x58/0x6e [<ffffffff8115e0a4>] ? blkdev_get_blocks+0x0/0xb8 [<ffffffff810ed2c5>] generic_file_aio_read+0xdd/0x528 [<ffffffff81219da3>] ? avc_has_perm+0x66/0x8c [<ffffffff81132842>] do_sync_read+0xf5/0x146 [<ffffffff8107da00>] ? autoremove_wake_function+0x0/0x5a [<ffffffff81211857>] ? security_file_permission+0x24/0x3a [<ffffffff81132fd8>] vfs_read+0xb5/0x126 [<ffffffff81133f6b>] ? fget_light+0x5e/0xf8 [<ffffffff81133131>] sys_read+0x54/0x8c [<ffffffff81011e42>] system_call_fastpath+0x16/0x1b This can be fixed by dropping the mm->page_table_lock around the call to unmap_ref_private() if alloc_huge_page() fails, its dropped right below in the normal path anyway. However, earlier in the that function, it's also possible to call into the page allocator with the same spinlock held. What this patch does is drop the spinlock before the page allocator is potentially entered. The check for page allocation failure can be made without the page_table_lock as well as the copy of the huge page. Even if the PTE changed while the spinlock was held, the consequence is that a huge page is copied unnecessarily. This resolves both the double taking of the lock and sleeping with the spinlock held. [mel@csn.ul.ie: Cover also the case where process can sleep with spinlock] Signed-off-by: Larry Woodman <lwooman@redhat.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:59:37 +03:00
/*
* Retake the page table lock to check for racing updates
hugetlb: prevent deadlock in __unmap_hugepage_range() when alloc_huge_page() fails hugetlb_fault() takes the mm->page_table_lock spinlock then calls hugetlb_cow(). If the alloc_huge_page() in hugetlb_cow() fails due to an insufficient huge page pool it calls unmap_ref_private() with the mm->page_table_lock held. unmap_ref_private() then calls unmap_hugepage_range() which tries to acquire the mm->page_table_lock. [<ffffffff810928c3>] print_circular_bug_tail+0x80/0x9f [<ffffffff8109280b>] ? check_noncircular+0xb0/0xe8 [<ffffffff810935e0>] __lock_acquire+0x956/0xc0e [<ffffffff81093986>] lock_acquire+0xee/0x12e [<ffffffff8111a7a6>] ? unmap_hugepage_range+0x3e/0x84 [<ffffffff8111a7a6>] ? unmap_hugepage_range+0x3e/0x84 [<ffffffff814c348d>] _spin_lock+0x40/0x89 [<ffffffff8111a7a6>] ? unmap_hugepage_range+0x3e/0x84 [<ffffffff8111afee>] ? alloc_huge_page+0x218/0x318 [<ffffffff8111a7a6>] unmap_hugepage_range+0x3e/0x84 [<ffffffff8111b2d0>] hugetlb_cow+0x1e2/0x3f4 [<ffffffff8111b935>] ? hugetlb_fault+0x453/0x4f6 [<ffffffff8111b962>] hugetlb_fault+0x480/0x4f6 [<ffffffff8111baee>] follow_hugetlb_page+0x116/0x2d9 [<ffffffff814c31a7>] ? _spin_unlock_irq+0x3a/0x5c [<ffffffff81107b4d>] __get_user_pages+0x2a3/0x427 [<ffffffff81107d0f>] get_user_pages+0x3e/0x54 [<ffffffff81040b8b>] get_user_pages_fast+0x170/0x1b5 [<ffffffff81160352>] dio_get_page+0x64/0x14a [<ffffffff8116112a>] __blockdev_direct_IO+0x4b7/0xb31 [<ffffffff8115ef91>] blkdev_direct_IO+0x58/0x6e [<ffffffff8115e0a4>] ? blkdev_get_blocks+0x0/0xb8 [<ffffffff810ed2c5>] generic_file_aio_read+0xdd/0x528 [<ffffffff81219da3>] ? avc_has_perm+0x66/0x8c [<ffffffff81132842>] do_sync_read+0xf5/0x146 [<ffffffff8107da00>] ? autoremove_wake_function+0x0/0x5a [<ffffffff81211857>] ? security_file_permission+0x24/0x3a [<ffffffff81132fd8>] vfs_read+0xb5/0x126 [<ffffffff81133f6b>] ? fget_light+0x5e/0xf8 [<ffffffff81133131>] sys_read+0x54/0x8c [<ffffffff81011e42>] system_call_fastpath+0x16/0x1b This can be fixed by dropping the mm->page_table_lock around the call to unmap_ref_private() if alloc_huge_page() fails, its dropped right below in the normal path anyway. However, earlier in the that function, it's also possible to call into the page allocator with the same spinlock held. What this patch does is drop the spinlock before the page allocator is potentially entered. The check for page allocation failure can be made without the page_table_lock as well as the copy of the huge page. Even if the PTE changed while the spinlock was held, the consequence is that a huge page is copied unnecessarily. This resolves both the double taking of the lock and sleeping with the spinlock held. [mel@csn.ul.ie: Cover also the case where process can sleep with spinlock] Signed-off-by: Larry Woodman <lwooman@redhat.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 04:59:37 +03:00
* before the page tables are altered
*/
spin_lock(ptl);
mm, hugetlbfs: rename address to haddr in hugetlb_cow() To take better advantage of general huge page copying optimization, the target subpage address will be passed to hugetlb_cow(), then copy_user_huge_page(). So we will use both target subpage address and huge page size aligned address in hugetlb_cow(). To distinguish between them, "haddr" is used for huge page size aligned address to be consistent with Transparent Huge Page naming convention. Now, only huge page size aligned address is used in hugetlb_cow(), so the "address" is renamed to "haddr" in hugetlb_cow() in this patch. Next patch will use target subpage address in hugetlb_cow() too. The patch is just code cleanup without any functionality changes. Link: http://lkml.kernel.org/r/20180524005851.4079-4-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Suggested-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-18 01:45:53 +03:00
ptep = huge_pte_offset(mm, haddr, huge_page_size(h));
if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
hugetlb: use page.private for hugetlb specific page flags Patch series "create hugetlb flags to consolidate state", v3. While discussing a series of hugetlb fixes in [1], it became evident that the hugetlb specific page state information is stored in a somewhat haphazard manner. Code dealing with state information would be easier to read, understand and maintain if this information was stored in a consistent manner. This series uses page.private of the hugetlb head page for storing a set of hugetlb specific page flags. Routines are priovided for test, set and clear of the flags. [1] https://lore.kernel.org/r/20210106084739.63318-1-songmuchun@bytedance.com This patch (of 4): As hugetlbfs evolved, state information about hugetlb pages was added. One 'convenient' way of doing this was to use available fields in tail pages. Over time, it has become difficult to know the meaning or contents of fields simply by looking at a small bit of code. Sometimes, the naming is just confusing. For example: The PagePrivate flag indicates a huge page reservation was consumed and needs to be restored if an error is encountered and the page is freed before it is instantiated. The page.private field contains the pointer to a subpool if the page is associated with one. In an effort to make the code more readable, use page.private to contain hugetlb specific page flags. These flags will have test, set and clear functions similar to those used for 'normal' page flags. More importantly, an enum of flag values will be created with names that actually reflect their purpose. In this patch, - Create infrastructure for hugetlb specific page flag functions - Move subpool pointer to page[1].private to make way for flags Create routines with meaningful names to modify subpool field - Use new HPageRestoreReserve flag instead of PagePrivate Conversion of other state information will happen in subsequent patches. Link: https://lkml.kernel.org/r/20210122195231.324857-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210122195231.324857-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:51 +03:00
ClearHPageRestoreReserve(new_page);
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
/* Break COW or unshare */
mm, hugetlbfs: rename address to haddr in hugetlb_cow() To take better advantage of general huge page copying optimization, the target subpage address will be passed to hugetlb_cow(), then copy_user_huge_page(). So we will use both target subpage address and huge page size aligned address in hugetlb_cow(). To distinguish between them, "haddr" is used for huge page size aligned address to be consistent with Transparent Huge Page naming convention. Now, only huge page size aligned address is used in hugetlb_cow(), so the "address" is renamed to "haddr" in hugetlb_cow() in this patch. Next patch will use target subpage address in hugetlb_cow() too. The patch is just code cleanup without any functionality changes. Link: http://lkml.kernel.org/r/20180524005851.4079-4-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Suggested-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-18 01:45:53 +03:00
huge_ptep_clear_flush(vma, haddr, ptep);
mmu_notifier_invalidate_range(mm, range.start, range.end);
mm/munlock: rmap call mlock_vma_page() munlock_vma_page() Add vma argument to mlock_vma_page() and munlock_vma_page(), make them inline functions which check (vma->vm_flags & VM_LOCKED) before calling mlock_page() and munlock_page() in mm/mlock.c. Add bool compound to mlock_vma_page() and munlock_vma_page(): this is because we have understandable difficulty in accounting pte maps of THPs, and if passed a PageHead page, mlock_page() and munlock_page() cannot tell whether it's a pmd map to be counted or a pte map to be ignored. Add vma arg to page_add_file_rmap() and page_remove_rmap(), like the others, and use that to call mlock_vma_page() at the end of the page adds, and munlock_vma_page() at the end of page_remove_rmap() (end or beginning? unimportant, but end was easier for assertions in testing). No page lock is required (although almost all adds happen to hold it): delete the "Serialize with page migration" BUG_ON(!PageLocked(page))s. Certainly page lock did serialize with page migration, but I'm having difficulty explaining why that was ever important. Mlock accounting on THPs has been hard to define, differed between anon and file, involved PageDoubleMap in some places and not others, required clear_page_mlock() at some points. Keep it simple now: just count the pmds and ignore the ptes, there is no reason for ptes to undo pmd mlocks. page_add_new_anon_rmap() callers unchanged: they have long been calling lru_cache_add_inactive_or_unevictable(), which does its own VM_LOCKED handling (it also checks for not VM_SPECIAL: I think that's overcautious, and inconsistent with other checks, that mmap_region() already prevents VM_LOCKED on VM_SPECIAL; but haven't quite convinced myself to change it). Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
2022-02-15 05:26:39 +03:00
page_remove_rmap(old_page, vma, true);
mm, hugetlbfs: rename address to haddr in hugetlb_cow() To take better advantage of general huge page copying optimization, the target subpage address will be passed to hugetlb_cow(), then copy_user_huge_page(). So we will use both target subpage address and huge page size aligned address in hugetlb_cow(). To distinguish between them, "haddr" is used for huge page size aligned address to be consistent with Transparent Huge Page naming convention. Now, only huge page size aligned address is used in hugetlb_cow(), so the "address" is renamed to "haddr" in hugetlb_cow() in this patch. Next patch will use target subpage address in hugetlb_cow() too. The patch is just code cleanup without any functionality changes. Link: http://lkml.kernel.org/r/20180524005851.4079-4-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Suggested-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-18 01:45:53 +03:00
hugepage_add_new_anon_rmap(new_page, vma, haddr);
mm: change page type prior to adding page table entry Patch series "page table check", v3. Ensure that some memory corruptions are prevented by checking at the time of insertion of entries into user page tables that there is no illegal sharing. We have recently found a problem [1] that existed in kernel since 4.14. The problem was caused by broken page ref count and led to memory leaking from one process into another. The problem was accidentally detected by studying a dump of one process and noticing that one page contains memory that should not belong to this process. There are some other page->_refcount related problems that were recently fixed: [2], [3] which potentially could also lead to illegal sharing. In addition to hardening refcount [4] itself, this work is an attempt to prevent this class of memory corruption issues. It uses a simple state machine that is independent from regular MM logic to check for illegal sharing at time pages are inserted and removed from page tables. [1] https://lore.kernel.org/all/xr9335nxwc5y.fsf@gthelen2.svl.corp.google.com [2] https://lore.kernel.org/all/1582661774-30925-2-git-send-email-akaher@vmware.com [3] https://lore.kernel.org/all/20210622021423.154662-3-mike.kravetz@oracle.com [4] https://lore.kernel.org/all/20211221150140.988298-1-pasha.tatashin@soleen.com This patch (of 4): There are a few places where we first update the entry in the user page table, and later change the struct page to indicate that this is anonymous or file page. In most places, however, we first configure the page metadata and then insert entries into the page table. Page table check, will use the information from struct page to verify the type of entry is inserted. Change the order in all places to first update struct page, and later to update page table. This means that we first do calls that may change the type of page (anon or file): page_move_anon_rmap page_add_anon_rmap do_page_add_anon_rmap page_add_new_anon_rmap page_add_file_rmap hugepage_add_anon_rmap hugepage_add_new_anon_rmap And after that do calls that add entries to the page table: set_huge_pte_at set_pte_at Link: https://lkml.kernel.org/r/20211221154650.1047963-1-pasha.tatashin@soleen.com Link: https://lkml.kernel.org/r/20211221154650.1047963-2-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: David Rientjes <rientjes@google.com> Cc: Paul Turner <pjt@google.com> Cc: Wei Xu <weixugc@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Will Deacon <will@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-15 01:06:29 +03:00
set_huge_pte_at(mm, haddr, ptep,
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
make_huge_pte(vma, new_page, !unshare));
hugetlb: convert page_huge_active() HPageMigratable flag Use the new hugetlb page specific flag HPageMigratable to replace the page_huge_active interfaces. By it's name, page_huge_active implied that a huge page was on the active list. However, that is not really what code checking the flag wanted to know. It really wanted to determine if the huge page could be migrated. This happens when the page is actually added to the page cache and/or task page table. This is the reasoning behind the name change. The VM_BUG_ON_PAGE() calls in the *_huge_active() interfaces are not really necessary as we KNOW the page is a hugetlb page. Therefore, they are removed. The routine page_huge_active checked for PageHeadHuge before testing the active bit. This is unnecessary in the case where we hold a reference or lock and know it is a hugetlb head page. page_huge_active is also called without holding a reference or lock (scan_movable_pages), and can race with code freeing the page. The extra check in page_huge_active shortened the race window, but did not prevent the race. Offline code calling scan_movable_pages already deals with these races, so removing the check is acceptable. Add comment to racy code. [songmuchun@bytedance.com: remove set_page_huge_active() declaration from include/linux/hugetlb.h] Link: https://lkml.kernel.org/r/CAMZfGtUda+KoAZscU0718TN61cSFwp4zy=y2oZ=+6Z2TAZZwng@mail.gmail.com Link: https://lkml.kernel.org/r/20210122195231.324857-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:56 +03:00
SetHPageMigratable(new_page);
/* Make the old page be freed below */
new_page = old_page;
}
spin_unlock(ptl);
mmu_notifier_invalidate_range_end(&range);
out_release_all:
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
/*
* No restore in case of successful pagetable update (Break COW or
* unshare)
*/
hugetlb: don't pass page cache pages to restore_reserve_on_error syzbot hit kernel BUG at fs/hugetlbfs/inode.c:532 as described in [1]. This BUG triggers if the HPageRestoreReserve flag is set on a page in the page cache. It should never be set, as the routine huge_add_to_page_cache explicitly clears the flag after adding a page to the cache. The only code other than huge page allocation which sets the flag is restore_reserve_on_error. It will potentially set the flag in rare out of memory conditions. syzbot was injecting errors to cause memory allocation errors which exercised this specific path. The code in restore_reserve_on_error is doing the right thing. However, there are instances where pages in the page cache were being passed to restore_reserve_on_error. This is incorrect, as once a page goes into the cache reservation information will not be modified for the page until it is removed from the cache. Error paths do not remove pages from the cache, so even in the case of error, the page will remain in the cache and no reservation adjustment is needed. Modify routines that potentially call restore_reserve_on_error with a page cache page to no longer do so. Note on fixes tag: Prior to commit 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") the routine would not process page cache pages because the HPageRestoreReserve flag is not set on such pages. Therefore, this issue could not be trigggered. The code added by commit 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") is needed and correct. It exposed incorrect calls to restore_reserve_on_error which is the root cause addressed by this commit. [1] https://lore.kernel.org/linux-mm/00000000000050776d05c9b7c7f0@google.com/ Link: https://lkml.kernel.org/r/20210818213304.37038-1-mike.kravetz@oracle.com Fixes: 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: <syzbot+67654e51e54455f1c585@syzkaller.appspotmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-08-20 05:04:33 +03:00
if (new_page != old_page)
restore_reserve_on_error(h, vma, haddr, new_page);
mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago with promise that one day it will be possible to implement page cache with bigger chunks than PAGE_SIZE. This promise never materialized. And unlikely will. We have many places where PAGE_CACHE_SIZE assumed to be equal to PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* or PAGE_* constant should be used in a particular case, especially on the border between fs and mm. Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much breakage to be doable. Let's stop pretending that pages in page cache are special. They are not. The changes are pretty straight-forward: - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; - page_cache_get() -> get_page(); - page_cache_release() -> put_page(); This patch contains automated changes generated with coccinelle using script below. For some reason, coccinelle doesn't patch header files. I've called spatch for them manually. The only adjustment after coccinelle is revert of changes to PAGE_CAHCE_ALIGN definition: we are going to drop it later. There are few places in the code where coccinelle didn't reach. I'll fix them manually in a separate patch. Comments and documentation also will be addressed with the separate patch. virtual patch @@ expression E; @@ - E << (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ expression E; @@ - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ @@ - PAGE_CACHE_SHIFT + PAGE_SHIFT @@ @@ - PAGE_CACHE_SIZE + PAGE_SIZE @@ @@ - PAGE_CACHE_MASK + PAGE_MASK @@ expression E; @@ - PAGE_CACHE_ALIGN(E) + PAGE_ALIGN(E) @@ expression E; @@ - page_cache_get(E) + get_page(E) @@ expression E; @@ - page_cache_release(E) + put_page(E) Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-01 15:29:47 +03:00
put_page(new_page);
out_release_old:
mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago with promise that one day it will be possible to implement page cache with bigger chunks than PAGE_SIZE. This promise never materialized. And unlikely will. We have many places where PAGE_CACHE_SIZE assumed to be equal to PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* or PAGE_* constant should be used in a particular case, especially on the border between fs and mm. Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much breakage to be doable. Let's stop pretending that pages in page cache are special. They are not. The changes are pretty straight-forward: - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; - page_cache_get() -> get_page(); - page_cache_release() -> put_page(); This patch contains automated changes generated with coccinelle using script below. For some reason, coccinelle doesn't patch header files. I've called spatch for them manually. The only adjustment after coccinelle is revert of changes to PAGE_CAHCE_ALIGN definition: we are going to drop it later. There are few places in the code where coccinelle didn't reach. I'll fix them manually in a separate patch. Comments and documentation also will be addressed with the separate patch. virtual patch @@ expression E; @@ - E << (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ expression E; @@ - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ @@ - PAGE_CACHE_SHIFT + PAGE_SHIFT @@ @@ - PAGE_CACHE_SIZE + PAGE_SIZE @@ @@ - PAGE_CACHE_MASK + PAGE_MASK @@ expression E; @@ - PAGE_CACHE_ALIGN(E) + PAGE_ALIGN(E) @@ expression E; @@ - page_cache_get(E) + get_page(E) @@ expression E; @@ - page_cache_release(E) + put_page(E) Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-01 15:29:47 +03:00
put_page(old_page);
spin_lock(ptl); /* Caller expects lock to be held */
return ret;
}
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
/* Return the pagecache page at a given address within a VMA */
static struct page *hugetlbfs_pagecache_page(struct hstate *h,
struct vm_area_struct *vma, unsigned long address)
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
{
struct address_space *mapping;
pgoff_t idx;
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
mapping = vma->vm_file->f_mapping;
idx = vma_hugecache_offset(h, vma, address);
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
return find_lock_page(mapping, idx);
}
/*
* Return whether there is a pagecache page to back given address within VMA.
* Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
*/
static bool hugetlbfs_pagecache_present(struct hstate *h,
struct vm_area_struct *vma, unsigned long address)
{
struct address_space *mapping;
pgoff_t idx;
struct page *page;
mapping = vma->vm_file->f_mapping;
idx = vma_hugecache_offset(h, vma, address);
page = find_get_page(mapping, idx);
if (page)
put_page(page);
return page != NULL;
}
int huge_add_to_page_cache(struct page *page, struct address_space *mapping,
pgoff_t idx)
{
struct inode *inode = mapping->host;
struct hstate *h = hstate_inode(inode);
int err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
if (err)
return err;
hugetlb: use page.private for hugetlb specific page flags Patch series "create hugetlb flags to consolidate state", v3. While discussing a series of hugetlb fixes in [1], it became evident that the hugetlb specific page state information is stored in a somewhat haphazard manner. Code dealing with state information would be easier to read, understand and maintain if this information was stored in a consistent manner. This series uses page.private of the hugetlb head page for storing a set of hugetlb specific page flags. Routines are priovided for test, set and clear of the flags. [1] https://lore.kernel.org/r/20210106084739.63318-1-songmuchun@bytedance.com This patch (of 4): As hugetlbfs evolved, state information about hugetlb pages was added. One 'convenient' way of doing this was to use available fields in tail pages. Over time, it has become difficult to know the meaning or contents of fields simply by looking at a small bit of code. Sometimes, the naming is just confusing. For example: The PagePrivate flag indicates a huge page reservation was consumed and needs to be restored if an error is encountered and the page is freed before it is instantiated. The page.private field contains the pointer to a subpool if the page is associated with one. In an effort to make the code more readable, use page.private to contain hugetlb specific page flags. These flags will have test, set and clear functions similar to those used for 'normal' page flags. More importantly, an enum of flag values will be created with names that actually reflect their purpose. In this patch, - Create infrastructure for hugetlb specific page flag functions - Move subpool pointer to page[1].private to make way for flags Create routines with meaningful names to modify subpool field - Use new HPageRestoreReserve flag instead of PagePrivate Conversion of other state information will happen in subsequent patches. Link: https://lkml.kernel.org/r/20210122195231.324857-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210122195231.324857-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:51 +03:00
ClearHPageRestoreReserve(page);
hugetlbfs: dirty pages as they are added to pagecache Some test systems were experiencing negative huge page reserve counts and incorrect file block counts. This was traced to /proc/sys/vm/drop_caches removing clean pages from hugetlbfs file pagecaches. When non-hugetlbfs explicit code removes the pages, the appropriate accounting is not performed. This can be recreated as follows: fallocate -l 2M /dev/hugepages/foo echo 1 > /proc/sys/vm/drop_caches fallocate -l 2M /dev/hugepages/foo grep -i huge /proc/meminfo AnonHugePages: 0 kB ShmemHugePages: 0 kB HugePages_Total: 2048 HugePages_Free: 2047 HugePages_Rsvd: 18446744073709551615 HugePages_Surp: 0 Hugepagesize: 2048 kB Hugetlb: 4194304 kB ls -lsh /dev/hugepages/foo 4.0M -rw-r--r--. 1 root root 2.0M Oct 17 20:05 /dev/hugepages/foo To address this issue, dirty pages as they are added to pagecache. This can easily be reproduced with fallocate as shown above. Read faulted pages will eventually end up being marked dirty. But there is a window where they are clean and could be impacted by code such as drop_caches. So, just dirty them all as they are added to the pagecache. Link: http://lkml.kernel.org/r/b5be45b8-5afe-56cd-9482-28384699a049@oracle.com Fixes: 6bda666a03f0 ("hugepages: fold find_or_alloc_pages into huge_no_page()") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Mihcla Hocko <mhocko@suse.com> Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-27 01:10:58 +03:00
/*
* set page dirty so that it will not be removed from cache/file
* by non-hugetlbfs specific code paths.
*/
set_page_dirty(page);
spin_lock(&inode->i_lock);
inode->i_blocks += blocks_per_huge_page(h);
spin_unlock(&inode->i_lock);
return 0;
}
userfaultfd: add minor fault registration mode Patch series "userfaultfd: add minor fault handling", v9. Overview ======== This series adds a new userfaultfd feature, UFFD_FEATURE_MINOR_HUGETLBFS. When enabled (via the UFFDIO_API ioctl), this feature means that any hugetlbfs VMAs registered with UFFDIO_REGISTER_MODE_MISSING will *also* get events for "minor" faults. By "minor" fault, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s) (shared memory). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. We also add a new ioctl to resolve such faults: UFFDIO_CONTINUE. The idea is, userspace resolves the fault by either a) doing nothing if the contents are already correct, or b) updating the underlying contents using the second, non-UFFD mapping (via memcpy/memset or similar, or something fancier like RDMA, or etc...). In either case, userspace issues UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Use Case ======== Consider the use case of VM live migration (e.g. under QEMU/KVM): 1. While a VM is still running, we copy the contents of its memory to a target machine. The pages are populated on the target by writing to the non-UFFD mapping, using the setup described above. The VM is still running (and therefore its memory is likely changing), so this may be repeated several times, until we decide the target is "up to date enough". 2. We pause the VM on the source, and start executing on the target machine. During this gap, the VM's user(s) will *see* a pause, so it is desirable to minimize this window. 3. Between the last time any page was copied from the source to the target, and when the VM was paused, the contents of that page may have changed - and therefore the copy we have on the target machine is out of date. Although we can keep track of which pages are out of date, for VMs with large amounts of memory, it is "slow" to transfer this information to the target machine. We want to resume execution before such a transfer would complete. 4. So, the guest begins executing on the target machine. The first time it touches its memory (via the UFFD-registered mapping), userspace wants to intercept this fault. Userspace checks whether or not the page is up to date, and if not, copies the updated page from the source machine, via the non-UFFD mapping. Finally, whether a copy was performed or not, userspace issues a UFFDIO_CONTINUE ioctl to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". We don't have to do all of the final updates on-demand. The userfaultfd manager can, in the background, also copy over updated pages once it receives the map of which pages are up-to-date or not. Interaction with Existing APIs ============================== Because this is a feature, a registered VMA could potentially receive both missing and minor faults. I spent some time thinking through how the existing API interacts with the new feature: UFFDIO_CONTINUE cannot be used to resolve non-minor faults, as it does not allocate a new page. If UFFDIO_CONTINUE is used on a non-minor fault: - For non-shared memory or shmem, -EINVAL is returned. - For hugetlb, -EFAULT is returned. UFFDIO_COPY and UFFDIO_ZEROPAGE cannot be used to resolve minor faults. Without modifications, the existing codepath assumes a new page needs to be allocated. This is okay, since userspace must have a second non-UFFD-registered mapping anyway, thus there isn't much reason to want to use these in any case (just memcpy or memset or similar). - If UFFDIO_COPY is used on a minor fault, -EEXIST is returned. - If UFFDIO_ZEROPAGE is used on a minor fault, -EEXIST is returned (or -EINVAL in the case of hugetlb, as UFFDIO_ZEROPAGE is unsupported in any case). - UFFDIO_WRITEPROTECT simply doesn't work with shared memory, and returns -ENOENT in that case (regardless of the kind of fault). Future Work =========== This series only supports hugetlbfs. I have a second series in flight to support shmem as well, extending the functionality. This series is more mature than the shmem support at this point, and the functionality works fully on hugetlbfs, so this series can be merged first and then shmem support will follow. This patch (of 6): This feature allows userspace to intercept "minor" faults. By "minor" faults, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. This commit adds the new registration mode, and sets the relevant flag on the VMAs being registered. In the hugetlb fault path, if we find that we have huge_pte_none(), but find_lock_page() does indeed find an existing page, then we have a "minor" fault, and if the VMA has the userfaultfd registration flag, we call into userfaultfd to handle it. This is implemented as a new registration mode, instead of an API feature. This is because the alternative implementation has significant drawbacks [1]. However, doing it this was requires we allocate a VM_* flag for the new registration mode. On 32-bit systems, there are no unused bits, so this feature is only supported on architectures with CONFIG_ARCH_USES_HIGH_VMA_FLAGS. When attempting to register a VMA in MINOR mode on 32-bit architectures, we return -EINVAL. [1] https://lore.kernel.org/patchwork/patch/1380226/ [peterx@redhat.com: fix minor fault page leak] Link: https://lkml.kernel.org/r/20210322175132.36659-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210301222728.176417-1-axelrasmussen@google.com Link: https://lkml.kernel.org/r/20210301222728.176417-2-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Steven Price <steven.price@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:36 +03:00
static inline vm_fault_t hugetlb_handle_userfault(struct vm_area_struct *vma,
struct address_space *mapping,
pgoff_t idx,
unsigned int flags,
unsigned long haddr,
userfaultfd: provide unmasked address on page-fault Userfaultfd is supposed to provide the full address (i.e., unmasked) of the faulting access back to userspace. However, that is not the case for quite some time. Even running "userfaultfd_demo" from the userfaultfd man page provides the wrong output (and contradicts the man page). Notice that "UFFD_EVENT_PAGEFAULT event" shows the masked address (7fc5e30b3000) and not the first read address (0x7fc5e30b300f). Address returned by mmap() = 0x7fc5e30b3000 fault_handler_thread(): poll() returns: nready = 1; POLLIN = 1; POLLERR = 0 UFFD_EVENT_PAGEFAULT event: flags = 0; address = 7fc5e30b3000 (uffdio_copy.copy returned 4096) Read address 0x7fc5e30b300f in main(): A Read address 0x7fc5e30b340f in main(): A Read address 0x7fc5e30b380f in main(): A Read address 0x7fc5e30b3c0f in main(): A The exact address is useful for various reasons and specifically for prefetching decisions. If it is known that the memory is populated by certain objects whose size is not page-aligned, then based on the faulting address, the uffd-monitor can decide whether to prefetch and prefault the adjacent page. This bug has been for quite some time in the kernel: since commit 1a29d85eb0f1 ("mm: use vmf->address instead of of vmf->virtual_address") vmf->virtual_address"), which dates back to 2016. A concern has been raised that existing userspace application might rely on the old/wrong behavior in which the address is masked. Therefore, it was suggested to provide the masked address unless the user explicitly asks for the exact address. Add a new userfaultfd feature UFFD_FEATURE_EXACT_ADDRESS to direct userfaultfd to provide the exact address. Add a new "real_address" field to vmf to hold the unmasked address. Provide the address to userspace accordingly. Initialize real_address in various code-paths to be consistent with address, even when it is not used, to be on the safe side. [namit@vmware.com: initialize real_address on all code paths, per Jan] Link: https://lkml.kernel.org/r/20220226022655.350562-1-namit@vmware.com [akpm@linux-foundation.org: fix typo in comment, per Jan] Link: https://lkml.kernel.org/r/20220218041003.3508-1-namit@vmware.com Signed-off-by: Nadav Amit <namit@vmware.com> Acked-by: Peter Xu <peterx@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-03-23 00:45:32 +03:00
unsigned long addr,
userfaultfd: add minor fault registration mode Patch series "userfaultfd: add minor fault handling", v9. Overview ======== This series adds a new userfaultfd feature, UFFD_FEATURE_MINOR_HUGETLBFS. When enabled (via the UFFDIO_API ioctl), this feature means that any hugetlbfs VMAs registered with UFFDIO_REGISTER_MODE_MISSING will *also* get events for "minor" faults. By "minor" fault, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s) (shared memory). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. We also add a new ioctl to resolve such faults: UFFDIO_CONTINUE. The idea is, userspace resolves the fault by either a) doing nothing if the contents are already correct, or b) updating the underlying contents using the second, non-UFFD mapping (via memcpy/memset or similar, or something fancier like RDMA, or etc...). In either case, userspace issues UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Use Case ======== Consider the use case of VM live migration (e.g. under QEMU/KVM): 1. While a VM is still running, we copy the contents of its memory to a target machine. The pages are populated on the target by writing to the non-UFFD mapping, using the setup described above. The VM is still running (and therefore its memory is likely changing), so this may be repeated several times, until we decide the target is "up to date enough". 2. We pause the VM on the source, and start executing on the target machine. During this gap, the VM's user(s) will *see* a pause, so it is desirable to minimize this window. 3. Between the last time any page was copied from the source to the target, and when the VM was paused, the contents of that page may have changed - and therefore the copy we have on the target machine is out of date. Although we can keep track of which pages are out of date, for VMs with large amounts of memory, it is "slow" to transfer this information to the target machine. We want to resume execution before such a transfer would complete. 4. So, the guest begins executing on the target machine. The first time it touches its memory (via the UFFD-registered mapping), userspace wants to intercept this fault. Userspace checks whether or not the page is up to date, and if not, copies the updated page from the source machine, via the non-UFFD mapping. Finally, whether a copy was performed or not, userspace issues a UFFDIO_CONTINUE ioctl to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". We don't have to do all of the final updates on-demand. The userfaultfd manager can, in the background, also copy over updated pages once it receives the map of which pages are up-to-date or not. Interaction with Existing APIs ============================== Because this is a feature, a registered VMA could potentially receive both missing and minor faults. I spent some time thinking through how the existing API interacts with the new feature: UFFDIO_CONTINUE cannot be used to resolve non-minor faults, as it does not allocate a new page. If UFFDIO_CONTINUE is used on a non-minor fault: - For non-shared memory or shmem, -EINVAL is returned. - For hugetlb, -EFAULT is returned. UFFDIO_COPY and UFFDIO_ZEROPAGE cannot be used to resolve minor faults. Without modifications, the existing codepath assumes a new page needs to be allocated. This is okay, since userspace must have a second non-UFFD-registered mapping anyway, thus there isn't much reason to want to use these in any case (just memcpy or memset or similar). - If UFFDIO_COPY is used on a minor fault, -EEXIST is returned. - If UFFDIO_ZEROPAGE is used on a minor fault, -EEXIST is returned (or -EINVAL in the case of hugetlb, as UFFDIO_ZEROPAGE is unsupported in any case). - UFFDIO_WRITEPROTECT simply doesn't work with shared memory, and returns -ENOENT in that case (regardless of the kind of fault). Future Work =========== This series only supports hugetlbfs. I have a second series in flight to support shmem as well, extending the functionality. This series is more mature than the shmem support at this point, and the functionality works fully on hugetlbfs, so this series can be merged first and then shmem support will follow. This patch (of 6): This feature allows userspace to intercept "minor" faults. By "minor" faults, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. This commit adds the new registration mode, and sets the relevant flag on the VMAs being registered. In the hugetlb fault path, if we find that we have huge_pte_none(), but find_lock_page() does indeed find an existing page, then we have a "minor" fault, and if the VMA has the userfaultfd registration flag, we call into userfaultfd to handle it. This is implemented as a new registration mode, instead of an API feature. This is because the alternative implementation has significant drawbacks [1]. However, doing it this was requires we allocate a VM_* flag for the new registration mode. On 32-bit systems, there are no unused bits, so this feature is only supported on architectures with CONFIG_ARCH_USES_HIGH_VMA_FLAGS. When attempting to register a VMA in MINOR mode on 32-bit architectures, we return -EINVAL. [1] https://lore.kernel.org/patchwork/patch/1380226/ [peterx@redhat.com: fix minor fault page leak] Link: https://lkml.kernel.org/r/20210322175132.36659-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210301222728.176417-1-axelrasmussen@google.com Link: https://lkml.kernel.org/r/20210301222728.176417-2-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Steven Price <steven.price@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:36 +03:00
unsigned long reason)
{
vm_fault_t ret;
u32 hash;
struct vm_fault vmf = {
.vma = vma,
.address = haddr,
userfaultfd: provide unmasked address on page-fault Userfaultfd is supposed to provide the full address (i.e., unmasked) of the faulting access back to userspace. However, that is not the case for quite some time. Even running "userfaultfd_demo" from the userfaultfd man page provides the wrong output (and contradicts the man page). Notice that "UFFD_EVENT_PAGEFAULT event" shows the masked address (7fc5e30b3000) and not the first read address (0x7fc5e30b300f). Address returned by mmap() = 0x7fc5e30b3000 fault_handler_thread(): poll() returns: nready = 1; POLLIN = 1; POLLERR = 0 UFFD_EVENT_PAGEFAULT event: flags = 0; address = 7fc5e30b3000 (uffdio_copy.copy returned 4096) Read address 0x7fc5e30b300f in main(): A Read address 0x7fc5e30b340f in main(): A Read address 0x7fc5e30b380f in main(): A Read address 0x7fc5e30b3c0f in main(): A The exact address is useful for various reasons and specifically for prefetching decisions. If it is known that the memory is populated by certain objects whose size is not page-aligned, then based on the faulting address, the uffd-monitor can decide whether to prefetch and prefault the adjacent page. This bug has been for quite some time in the kernel: since commit 1a29d85eb0f1 ("mm: use vmf->address instead of of vmf->virtual_address") vmf->virtual_address"), which dates back to 2016. A concern has been raised that existing userspace application might rely on the old/wrong behavior in which the address is masked. Therefore, it was suggested to provide the masked address unless the user explicitly asks for the exact address. Add a new userfaultfd feature UFFD_FEATURE_EXACT_ADDRESS to direct userfaultfd to provide the exact address. Add a new "real_address" field to vmf to hold the unmasked address. Provide the address to userspace accordingly. Initialize real_address in various code-paths to be consistent with address, even when it is not used, to be on the safe side. [namit@vmware.com: initialize real_address on all code paths, per Jan] Link: https://lkml.kernel.org/r/20220226022655.350562-1-namit@vmware.com [akpm@linux-foundation.org: fix typo in comment, per Jan] Link: https://lkml.kernel.org/r/20220218041003.3508-1-namit@vmware.com Signed-off-by: Nadav Amit <namit@vmware.com> Acked-by: Peter Xu <peterx@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-03-23 00:45:32 +03:00
.real_address = addr,
userfaultfd: add minor fault registration mode Patch series "userfaultfd: add minor fault handling", v9. Overview ======== This series adds a new userfaultfd feature, UFFD_FEATURE_MINOR_HUGETLBFS. When enabled (via the UFFDIO_API ioctl), this feature means that any hugetlbfs VMAs registered with UFFDIO_REGISTER_MODE_MISSING will *also* get events for "minor" faults. By "minor" fault, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s) (shared memory). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. We also add a new ioctl to resolve such faults: UFFDIO_CONTINUE. The idea is, userspace resolves the fault by either a) doing nothing if the contents are already correct, or b) updating the underlying contents using the second, non-UFFD mapping (via memcpy/memset or similar, or something fancier like RDMA, or etc...). In either case, userspace issues UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Use Case ======== Consider the use case of VM live migration (e.g. under QEMU/KVM): 1. While a VM is still running, we copy the contents of its memory to a target machine. The pages are populated on the target by writing to the non-UFFD mapping, using the setup described above. The VM is still running (and therefore its memory is likely changing), so this may be repeated several times, until we decide the target is "up to date enough". 2. We pause the VM on the source, and start executing on the target machine. During this gap, the VM's user(s) will *see* a pause, so it is desirable to minimize this window. 3. Between the last time any page was copied from the source to the target, and when the VM was paused, the contents of that page may have changed - and therefore the copy we have on the target machine is out of date. Although we can keep track of which pages are out of date, for VMs with large amounts of memory, it is "slow" to transfer this information to the target machine. We want to resume execution before such a transfer would complete. 4. So, the guest begins executing on the target machine. The first time it touches its memory (via the UFFD-registered mapping), userspace wants to intercept this fault. Userspace checks whether or not the page is up to date, and if not, copies the updated page from the source machine, via the non-UFFD mapping. Finally, whether a copy was performed or not, userspace issues a UFFDIO_CONTINUE ioctl to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". We don't have to do all of the final updates on-demand. The userfaultfd manager can, in the background, also copy over updated pages once it receives the map of which pages are up-to-date or not. Interaction with Existing APIs ============================== Because this is a feature, a registered VMA could potentially receive both missing and minor faults. I spent some time thinking through how the existing API interacts with the new feature: UFFDIO_CONTINUE cannot be used to resolve non-minor faults, as it does not allocate a new page. If UFFDIO_CONTINUE is used on a non-minor fault: - For non-shared memory or shmem, -EINVAL is returned. - For hugetlb, -EFAULT is returned. UFFDIO_COPY and UFFDIO_ZEROPAGE cannot be used to resolve minor faults. Without modifications, the existing codepath assumes a new page needs to be allocated. This is okay, since userspace must have a second non-UFFD-registered mapping anyway, thus there isn't much reason to want to use these in any case (just memcpy or memset or similar). - If UFFDIO_COPY is used on a minor fault, -EEXIST is returned. - If UFFDIO_ZEROPAGE is used on a minor fault, -EEXIST is returned (or -EINVAL in the case of hugetlb, as UFFDIO_ZEROPAGE is unsupported in any case). - UFFDIO_WRITEPROTECT simply doesn't work with shared memory, and returns -ENOENT in that case (regardless of the kind of fault). Future Work =========== This series only supports hugetlbfs. I have a second series in flight to support shmem as well, extending the functionality. This series is more mature than the shmem support at this point, and the functionality works fully on hugetlbfs, so this series can be merged first and then shmem support will follow. This patch (of 6): This feature allows userspace to intercept "minor" faults. By "minor" faults, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. This commit adds the new registration mode, and sets the relevant flag on the VMAs being registered. In the hugetlb fault path, if we find that we have huge_pte_none(), but find_lock_page() does indeed find an existing page, then we have a "minor" fault, and if the VMA has the userfaultfd registration flag, we call into userfaultfd to handle it. This is implemented as a new registration mode, instead of an API feature. This is because the alternative implementation has significant drawbacks [1]. However, doing it this was requires we allocate a VM_* flag for the new registration mode. On 32-bit systems, there are no unused bits, so this feature is only supported on architectures with CONFIG_ARCH_USES_HIGH_VMA_FLAGS. When attempting to register a VMA in MINOR mode on 32-bit architectures, we return -EINVAL. [1] https://lore.kernel.org/patchwork/patch/1380226/ [peterx@redhat.com: fix minor fault page leak] Link: https://lkml.kernel.org/r/20210322175132.36659-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210301222728.176417-1-axelrasmussen@google.com Link: https://lkml.kernel.org/r/20210301222728.176417-2-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Steven Price <steven.price@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:36 +03:00
.flags = flags,
/*
* Hard to debug if it ends up being
* used by a callee that assumes
* something about the other
* uninitialized fields... same as in
* memory.c
*/
};
/*
* hugetlb_fault_mutex and i_mmap_rwsem must be
* dropped before handling userfault. Reacquire
* after handling fault to make calling code simpler.
*/
hash = hugetlb_fault_mutex_hash(mapping, idx);
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
i_mmap_unlock_read(mapping);
ret = handle_userfault(&vmf, reason);
i_mmap_lock_read(mapping);
mutex_lock(&hugetlb_fault_mutex_table[hash]);
return ret;
}
static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
struct vm_area_struct *vma,
struct address_space *mapping, pgoff_t idx,
unsigned long address, pte_t *ptep, unsigned int flags)
{
struct hstate *h = hstate_vma(vma);
vm_fault_t ret = VM_FAULT_SIGBUS;
int anon_rmap = 0;
unsigned long size;
struct page *page;
pte_t new_pte;
spinlock_t *ptl;
mm, hugetlbfs: pass fault address to no page handler This is to take better advantage of general huge page clearing optimization (commit c79b57e462b5: "mm: hugetlb: clear target sub-page last when clearing huge page") for hugetlbfs. In the general optimization patch, the sub-page to access will be cleared last to avoid the cache lines of to access sub-page to be evicted when clearing other sub-pages. This works better if we have the address of the sub-page to access, that is, the fault address inside the huge page. So the hugetlbfs no page fault handler is changed to pass that information. This will benefit workloads which don't access the begin of the hugetlbfs huge page after the page fault under heavy cache contention for shared last level cache. The patch is a generic optimization which should benefit quite some workloads, not for a specific use case. To demonstrate the performance benefit of the patch, we tested it with vm-scalability run on hugetlbfs. With this patch, the throughput increases ~28.1% in vm-scalability anon-w-seq test case with 88 processes on a 2 socket Xeon E5 2699 v4 system (44 cores, 88 threads). The test case creates 88 processes, each process mmaps a big anonymous memory area with MAP_HUGETLB and writes to it from the end to the begin. For each process, other processes could be seen as other workload which generates heavy cache pressure. At the same time, the cache miss rate reduced from ~36.3% to ~25.6%, the IPC (instruction per cycle) increased from 0.3 to 0.37, and the time spent in user space is reduced ~19.3%. Link: http://lkml.kernel.org/r/20180517083539.9242-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-08 03:08:08 +03:00
unsigned long haddr = address & huge_page_mask(h);
hugetlb: don't pass page cache pages to restore_reserve_on_error syzbot hit kernel BUG at fs/hugetlbfs/inode.c:532 as described in [1]. This BUG triggers if the HPageRestoreReserve flag is set on a page in the page cache. It should never be set, as the routine huge_add_to_page_cache explicitly clears the flag after adding a page to the cache. The only code other than huge page allocation which sets the flag is restore_reserve_on_error. It will potentially set the flag in rare out of memory conditions. syzbot was injecting errors to cause memory allocation errors which exercised this specific path. The code in restore_reserve_on_error is doing the right thing. However, there are instances where pages in the page cache were being passed to restore_reserve_on_error. This is incorrect, as once a page goes into the cache reservation information will not be modified for the page until it is removed from the cache. Error paths do not remove pages from the cache, so even in the case of error, the page will remain in the cache and no reservation adjustment is needed. Modify routines that potentially call restore_reserve_on_error with a page cache page to no longer do so. Note on fixes tag: Prior to commit 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") the routine would not process page cache pages because the HPageRestoreReserve flag is not set on such pages. Therefore, this issue could not be trigggered. The code added by commit 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") is needed and correct. It exposed incorrect calls to restore_reserve_on_error which is the root cause addressed by this commit. [1] https://lore.kernel.org/linux-mm/00000000000050776d05c9b7c7f0@google.com/ Link: https://lkml.kernel.org/r/20210818213304.37038-1-mike.kravetz@oracle.com Fixes: 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: <syzbot+67654e51e54455f1c585@syzkaller.appspotmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-08-20 05:04:33 +03:00
bool new_page, new_pagecache_page = false;
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
/*
* Currently, we are forced to kill the process in the event the
* original mapper has unmapped pages from the child due to a failed
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
* COW/unsharing. Warn that such a situation has occurred as it may not
* be obvious.
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
*/
if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
mm/hugetlb: hugetlb_no_page: rate-limit warning message The warning message "killed due to inadequate hugepage pool" simply indicates that SIGBUS was sent, not that the process was forcibly killed. If the process has a signal handler installed does not fix the problem, this message can rapidly spam the kernel log. On my amd64 dev machine that does not have hugepages configured, I can reproduce the repeated warnings easily by setting vm.nr_hugepages=2 (i.e., 4 megabytes of huge pages) and running something that sets a signal handler and forks, like #include <sys/mman.h> #include <signal.h> #include <stdlib.h> #include <unistd.h> sig_atomic_t counter = 10; void handler(int signal) { if (counter-- == 0) exit(0); } int main(void) { int status; char *addr = mmap(NULL, 4 * 1048576, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0); if (addr == MAP_FAILED) {perror("mmap"); return 1;} *addr = 'x'; switch (fork()) { case -1: perror("fork"); return 1; case 0: signal(SIGBUS, handler); *addr = 'x'; break; default: *addr = 'x'; wait(&status); if (WIFSIGNALED(status)) { psignal(WTERMSIG(status), "child"); } break; } } Signed-off-by: Geoffrey Thomas <geofft@ldpreload.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-10 01:08:04 +03:00
pr_warn_ratelimited("PID %d killed due to inadequate hugepage pool\n",
current->pid);
hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:25 +04:00
return ret;
}
/*
hugetlbfs: Use i_mmap_rwsem to address page fault/truncate race hugetlbfs page faults can race with truncate and hole punch operations. Current code in the page fault path attempts to handle this by 'backing out' operations if we encounter the race. One obvious omission in the current code is removing a page newly added to the page cache. This is pretty straight forward to address, but there is a more subtle and difficult issue of backing out hugetlb reservations. To handle this correctly, the 'reservation state' before page allocation needs to be noted so that it can be properly backed out. There are four distinct possibilities for reservation state: shared/reserved, shared/no-resv, private/reserved and private/no-resv. Backing out a reservation may require memory allocation which could fail so that needs to be taken into account as well. Instead of writing the required complicated code for this rare occurrence, just eliminate the race. i_mmap_rwsem is now held in read mode for the duration of page fault processing. Hold i_mmap_rwsem in write mode when modifying i_size. In this way, truncation can not proceed when page faults are being processed. In addition, i_size will not change during fault processing so a single check can be made to ensure faults are not beyond (proposed) end of file. Faults can still race with hole punch, but that race is handled by existing code and the use of hugetlb_fault_mutex. With this modification, checks for races with truncation in the page fault path can be simplified and removed. remove_inode_hugepages no longer needs to take hugetlb_fault_mutex in the case of truncation. Comments are expanded to explain reasoning behind locking. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Hugh Dickins <hughd@google.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-3-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:08 +03:00
* We can not race with truncation due to holding i_mmap_rwsem.
* i_size is modified when holding i_mmap_rwsem, so check here
* once for faults beyond end of file.
*/
hugetlbfs: Use i_mmap_rwsem to address page fault/truncate race hugetlbfs page faults can race with truncate and hole punch operations. Current code in the page fault path attempts to handle this by 'backing out' operations if we encounter the race. One obvious omission in the current code is removing a page newly added to the page cache. This is pretty straight forward to address, but there is a more subtle and difficult issue of backing out hugetlb reservations. To handle this correctly, the 'reservation state' before page allocation needs to be noted so that it can be properly backed out. There are four distinct possibilities for reservation state: shared/reserved, shared/no-resv, private/reserved and private/no-resv. Backing out a reservation may require memory allocation which could fail so that needs to be taken into account as well. Instead of writing the required complicated code for this rare occurrence, just eliminate the race. i_mmap_rwsem is now held in read mode for the duration of page fault processing. Hold i_mmap_rwsem in write mode when modifying i_size. In this way, truncation can not proceed when page faults are being processed. In addition, i_size will not change during fault processing so a single check can be made to ensure faults are not beyond (proposed) end of file. Faults can still race with hole punch, but that race is handled by existing code and the use of hugetlb_fault_mutex. With this modification, checks for races with truncation in the page fault path can be simplified and removed. remove_inode_hugepages no longer needs to take hugetlb_fault_mutex in the case of truncation. Comments are expanded to explain reasoning behind locking. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Hugh Dickins <hughd@google.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-3-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:08 +03:00
size = i_size_read(mapping->host) >> huge_page_shift(h);
if (idx >= size)
goto out;
retry:
hugetlb: don't pass page cache pages to restore_reserve_on_error syzbot hit kernel BUG at fs/hugetlbfs/inode.c:532 as described in [1]. This BUG triggers if the HPageRestoreReserve flag is set on a page in the page cache. It should never be set, as the routine huge_add_to_page_cache explicitly clears the flag after adding a page to the cache. The only code other than huge page allocation which sets the flag is restore_reserve_on_error. It will potentially set the flag in rare out of memory conditions. syzbot was injecting errors to cause memory allocation errors which exercised this specific path. The code in restore_reserve_on_error is doing the right thing. However, there are instances where pages in the page cache were being passed to restore_reserve_on_error. This is incorrect, as once a page goes into the cache reservation information will not be modified for the page until it is removed from the cache. Error paths do not remove pages from the cache, so even in the case of error, the page will remain in the cache and no reservation adjustment is needed. Modify routines that potentially call restore_reserve_on_error with a page cache page to no longer do so. Note on fixes tag: Prior to commit 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") the routine would not process page cache pages because the HPageRestoreReserve flag is not set on such pages. Therefore, this issue could not be trigggered. The code added by commit 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") is needed and correct. It exposed incorrect calls to restore_reserve_on_error which is the root cause addressed by this commit. [1] https://lore.kernel.org/linux-mm/00000000000050776d05c9b7c7f0@google.com/ Link: https://lkml.kernel.org/r/20210818213304.37038-1-mike.kravetz@oracle.com Fixes: 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: <syzbot+67654e51e54455f1c585@syzkaller.appspotmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-08-20 05:04:33 +03:00
new_page = false;
page = find_lock_page(mapping, idx);
if (!page) {
userfaultfd: add minor fault registration mode Patch series "userfaultfd: add minor fault handling", v9. Overview ======== This series adds a new userfaultfd feature, UFFD_FEATURE_MINOR_HUGETLBFS. When enabled (via the UFFDIO_API ioctl), this feature means that any hugetlbfs VMAs registered with UFFDIO_REGISTER_MODE_MISSING will *also* get events for "minor" faults. By "minor" fault, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s) (shared memory). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. We also add a new ioctl to resolve such faults: UFFDIO_CONTINUE. The idea is, userspace resolves the fault by either a) doing nothing if the contents are already correct, or b) updating the underlying contents using the second, non-UFFD mapping (via memcpy/memset or similar, or something fancier like RDMA, or etc...). In either case, userspace issues UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Use Case ======== Consider the use case of VM live migration (e.g. under QEMU/KVM): 1. While a VM is still running, we copy the contents of its memory to a target machine. The pages are populated on the target by writing to the non-UFFD mapping, using the setup described above. The VM is still running (and therefore its memory is likely changing), so this may be repeated several times, until we decide the target is "up to date enough". 2. We pause the VM on the source, and start executing on the target machine. During this gap, the VM's user(s) will *see* a pause, so it is desirable to minimize this window. 3. Between the last time any page was copied from the source to the target, and when the VM was paused, the contents of that page may have changed - and therefore the copy we have on the target machine is out of date. Although we can keep track of which pages are out of date, for VMs with large amounts of memory, it is "slow" to transfer this information to the target machine. We want to resume execution before such a transfer would complete. 4. So, the guest begins executing on the target machine. The first time it touches its memory (via the UFFD-registered mapping), userspace wants to intercept this fault. Userspace checks whether or not the page is up to date, and if not, copies the updated page from the source machine, via the non-UFFD mapping. Finally, whether a copy was performed or not, userspace issues a UFFDIO_CONTINUE ioctl to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". We don't have to do all of the final updates on-demand. The userfaultfd manager can, in the background, also copy over updated pages once it receives the map of which pages are up-to-date or not. Interaction with Existing APIs ============================== Because this is a feature, a registered VMA could potentially receive both missing and minor faults. I spent some time thinking through how the existing API interacts with the new feature: UFFDIO_CONTINUE cannot be used to resolve non-minor faults, as it does not allocate a new page. If UFFDIO_CONTINUE is used on a non-minor fault: - For non-shared memory or shmem, -EINVAL is returned. - For hugetlb, -EFAULT is returned. UFFDIO_COPY and UFFDIO_ZEROPAGE cannot be used to resolve minor faults. Without modifications, the existing codepath assumes a new page needs to be allocated. This is okay, since userspace must have a second non-UFFD-registered mapping anyway, thus there isn't much reason to want to use these in any case (just memcpy or memset or similar). - If UFFDIO_COPY is used on a minor fault, -EEXIST is returned. - If UFFDIO_ZEROPAGE is used on a minor fault, -EEXIST is returned (or -EINVAL in the case of hugetlb, as UFFDIO_ZEROPAGE is unsupported in any case). - UFFDIO_WRITEPROTECT simply doesn't work with shared memory, and returns -ENOENT in that case (regardless of the kind of fault). Future Work =========== This series only supports hugetlbfs. I have a second series in flight to support shmem as well, extending the functionality. This series is more mature than the shmem support at this point, and the functionality works fully on hugetlbfs, so this series can be merged first and then shmem support will follow. This patch (of 6): This feature allows userspace to intercept "minor" faults. By "minor" faults, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. This commit adds the new registration mode, and sets the relevant flag on the VMAs being registered. In the hugetlb fault path, if we find that we have huge_pte_none(), but find_lock_page() does indeed find an existing page, then we have a "minor" fault, and if the VMA has the userfaultfd registration flag, we call into userfaultfd to handle it. This is implemented as a new registration mode, instead of an API feature. This is because the alternative implementation has significant drawbacks [1]. However, doing it this was requires we allocate a VM_* flag for the new registration mode. On 32-bit systems, there are no unused bits, so this feature is only supported on architectures with CONFIG_ARCH_USES_HIGH_VMA_FLAGS. When attempting to register a VMA in MINOR mode on 32-bit architectures, we return -EINVAL. [1] https://lore.kernel.org/patchwork/patch/1380226/ [peterx@redhat.com: fix minor fault page leak] Link: https://lkml.kernel.org/r/20210322175132.36659-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210301222728.176417-1-axelrasmussen@google.com Link: https://lkml.kernel.org/r/20210301222728.176417-2-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Steven Price <steven.price@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:36 +03:00
/* Check for page in userfault range */
if (userfaultfd_missing(vma)) {
userfaultfd: add minor fault registration mode Patch series "userfaultfd: add minor fault handling", v9. Overview ======== This series adds a new userfaultfd feature, UFFD_FEATURE_MINOR_HUGETLBFS. When enabled (via the UFFDIO_API ioctl), this feature means that any hugetlbfs VMAs registered with UFFDIO_REGISTER_MODE_MISSING will *also* get events for "minor" faults. By "minor" fault, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s) (shared memory). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. We also add a new ioctl to resolve such faults: UFFDIO_CONTINUE. The idea is, userspace resolves the fault by either a) doing nothing if the contents are already correct, or b) updating the underlying contents using the second, non-UFFD mapping (via memcpy/memset or similar, or something fancier like RDMA, or etc...). In either case, userspace issues UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Use Case ======== Consider the use case of VM live migration (e.g. under QEMU/KVM): 1. While a VM is still running, we copy the contents of its memory to a target machine. The pages are populated on the target by writing to the non-UFFD mapping, using the setup described above. The VM is still running (and therefore its memory is likely changing), so this may be repeated several times, until we decide the target is "up to date enough". 2. We pause the VM on the source, and start executing on the target machine. During this gap, the VM's user(s) will *see* a pause, so it is desirable to minimize this window. 3. Between the last time any page was copied from the source to the target, and when the VM was paused, the contents of that page may have changed - and therefore the copy we have on the target machine is out of date. Although we can keep track of which pages are out of date, for VMs with large amounts of memory, it is "slow" to transfer this information to the target machine. We want to resume execution before such a transfer would complete. 4. So, the guest begins executing on the target machine. The first time it touches its memory (via the UFFD-registered mapping), userspace wants to intercept this fault. Userspace checks whether or not the page is up to date, and if not, copies the updated page from the source machine, via the non-UFFD mapping. Finally, whether a copy was performed or not, userspace issues a UFFDIO_CONTINUE ioctl to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". We don't have to do all of the final updates on-demand. The userfaultfd manager can, in the background, also copy over updated pages once it receives the map of which pages are up-to-date or not. Interaction with Existing APIs ============================== Because this is a feature, a registered VMA could potentially receive both missing and minor faults. I spent some time thinking through how the existing API interacts with the new feature: UFFDIO_CONTINUE cannot be used to resolve non-minor faults, as it does not allocate a new page. If UFFDIO_CONTINUE is used on a non-minor fault: - For non-shared memory or shmem, -EINVAL is returned. - For hugetlb, -EFAULT is returned. UFFDIO_COPY and UFFDIO_ZEROPAGE cannot be used to resolve minor faults. Without modifications, the existing codepath assumes a new page needs to be allocated. This is okay, since userspace must have a second non-UFFD-registered mapping anyway, thus there isn't much reason to want to use these in any case (just memcpy or memset or similar). - If UFFDIO_COPY is used on a minor fault, -EEXIST is returned. - If UFFDIO_ZEROPAGE is used on a minor fault, -EEXIST is returned (or -EINVAL in the case of hugetlb, as UFFDIO_ZEROPAGE is unsupported in any case). - UFFDIO_WRITEPROTECT simply doesn't work with shared memory, and returns -ENOENT in that case (regardless of the kind of fault). Future Work =========== This series only supports hugetlbfs. I have a second series in flight to support shmem as well, extending the functionality. This series is more mature than the shmem support at this point, and the functionality works fully on hugetlbfs, so this series can be merged first and then shmem support will follow. This patch (of 6): This feature allows userspace to intercept "minor" faults. By "minor" faults, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. This commit adds the new registration mode, and sets the relevant flag on the VMAs being registered. In the hugetlb fault path, if we find that we have huge_pte_none(), but find_lock_page() does indeed find an existing page, then we have a "minor" fault, and if the VMA has the userfaultfd registration flag, we call into userfaultfd to handle it. This is implemented as a new registration mode, instead of an API feature. This is because the alternative implementation has significant drawbacks [1]. However, doing it this was requires we allocate a VM_* flag for the new registration mode. On 32-bit systems, there are no unused bits, so this feature is only supported on architectures with CONFIG_ARCH_USES_HIGH_VMA_FLAGS. When attempting to register a VMA in MINOR mode on 32-bit architectures, we return -EINVAL. [1] https://lore.kernel.org/patchwork/patch/1380226/ [peterx@redhat.com: fix minor fault page leak] Link: https://lkml.kernel.org/r/20210322175132.36659-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210301222728.176417-1-axelrasmussen@google.com Link: https://lkml.kernel.org/r/20210301222728.176417-2-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Steven Price <steven.price@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:36 +03:00
ret = hugetlb_handle_userfault(vma, mapping, idx,
userfaultfd: provide unmasked address on page-fault Userfaultfd is supposed to provide the full address (i.e., unmasked) of the faulting access back to userspace. However, that is not the case for quite some time. Even running "userfaultfd_demo" from the userfaultfd man page provides the wrong output (and contradicts the man page). Notice that "UFFD_EVENT_PAGEFAULT event" shows the masked address (7fc5e30b3000) and not the first read address (0x7fc5e30b300f). Address returned by mmap() = 0x7fc5e30b3000 fault_handler_thread(): poll() returns: nready = 1; POLLIN = 1; POLLERR = 0 UFFD_EVENT_PAGEFAULT event: flags = 0; address = 7fc5e30b3000 (uffdio_copy.copy returned 4096) Read address 0x7fc5e30b300f in main(): A Read address 0x7fc5e30b340f in main(): A Read address 0x7fc5e30b380f in main(): A Read address 0x7fc5e30b3c0f in main(): A The exact address is useful for various reasons and specifically for prefetching decisions. If it is known that the memory is populated by certain objects whose size is not page-aligned, then based on the faulting address, the uffd-monitor can decide whether to prefetch and prefault the adjacent page. This bug has been for quite some time in the kernel: since commit 1a29d85eb0f1 ("mm: use vmf->address instead of of vmf->virtual_address") vmf->virtual_address"), which dates back to 2016. A concern has been raised that existing userspace application might rely on the old/wrong behavior in which the address is masked. Therefore, it was suggested to provide the masked address unless the user explicitly asks for the exact address. Add a new userfaultfd feature UFFD_FEATURE_EXACT_ADDRESS to direct userfaultfd to provide the exact address. Add a new "real_address" field to vmf to hold the unmasked address. Provide the address to userspace accordingly. Initialize real_address in various code-paths to be consistent with address, even when it is not used, to be on the safe side. [namit@vmware.com: initialize real_address on all code paths, per Jan] Link: https://lkml.kernel.org/r/20220226022655.350562-1-namit@vmware.com [akpm@linux-foundation.org: fix typo in comment, per Jan] Link: https://lkml.kernel.org/r/20220218041003.3508-1-namit@vmware.com Signed-off-by: Nadav Amit <namit@vmware.com> Acked-by: Peter Xu <peterx@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-03-23 00:45:32 +03:00
flags, haddr, address,
userfaultfd: add minor fault registration mode Patch series "userfaultfd: add minor fault handling", v9. Overview ======== This series adds a new userfaultfd feature, UFFD_FEATURE_MINOR_HUGETLBFS. When enabled (via the UFFDIO_API ioctl), this feature means that any hugetlbfs VMAs registered with UFFDIO_REGISTER_MODE_MISSING will *also* get events for "minor" faults. By "minor" fault, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s) (shared memory). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. We also add a new ioctl to resolve such faults: UFFDIO_CONTINUE. The idea is, userspace resolves the fault by either a) doing nothing if the contents are already correct, or b) updating the underlying contents using the second, non-UFFD mapping (via memcpy/memset or similar, or something fancier like RDMA, or etc...). In either case, userspace issues UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Use Case ======== Consider the use case of VM live migration (e.g. under QEMU/KVM): 1. While a VM is still running, we copy the contents of its memory to a target machine. The pages are populated on the target by writing to the non-UFFD mapping, using the setup described above. The VM is still running (and therefore its memory is likely changing), so this may be repeated several times, until we decide the target is "up to date enough". 2. We pause the VM on the source, and start executing on the target machine. During this gap, the VM's user(s) will *see* a pause, so it is desirable to minimize this window. 3. Between the last time any page was copied from the source to the target, and when the VM was paused, the contents of that page may have changed - and therefore the copy we have on the target machine is out of date. Although we can keep track of which pages are out of date, for VMs with large amounts of memory, it is "slow" to transfer this information to the target machine. We want to resume execution before such a transfer would complete. 4. So, the guest begins executing on the target machine. The first time it touches its memory (via the UFFD-registered mapping), userspace wants to intercept this fault. Userspace checks whether or not the page is up to date, and if not, copies the updated page from the source machine, via the non-UFFD mapping. Finally, whether a copy was performed or not, userspace issues a UFFDIO_CONTINUE ioctl to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". We don't have to do all of the final updates on-demand. The userfaultfd manager can, in the background, also copy over updated pages once it receives the map of which pages are up-to-date or not. Interaction with Existing APIs ============================== Because this is a feature, a registered VMA could potentially receive both missing and minor faults. I spent some time thinking through how the existing API interacts with the new feature: UFFDIO_CONTINUE cannot be used to resolve non-minor faults, as it does not allocate a new page. If UFFDIO_CONTINUE is used on a non-minor fault: - For non-shared memory or shmem, -EINVAL is returned. - For hugetlb, -EFAULT is returned. UFFDIO_COPY and UFFDIO_ZEROPAGE cannot be used to resolve minor faults. Without modifications, the existing codepath assumes a new page needs to be allocated. This is okay, since userspace must have a second non-UFFD-registered mapping anyway, thus there isn't much reason to want to use these in any case (just memcpy or memset or similar). - If UFFDIO_COPY is used on a minor fault, -EEXIST is returned. - If UFFDIO_ZEROPAGE is used on a minor fault, -EEXIST is returned (or -EINVAL in the case of hugetlb, as UFFDIO_ZEROPAGE is unsupported in any case). - UFFDIO_WRITEPROTECT simply doesn't work with shared memory, and returns -ENOENT in that case (regardless of the kind of fault). Future Work =========== This series only supports hugetlbfs. I have a second series in flight to support shmem as well, extending the functionality. This series is more mature than the shmem support at this point, and the functionality works fully on hugetlbfs, so this series can be merged first and then shmem support will follow. This patch (of 6): This feature allows userspace to intercept "minor" faults. By "minor" faults, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. This commit adds the new registration mode, and sets the relevant flag on the VMAs being registered. In the hugetlb fault path, if we find that we have huge_pte_none(), but find_lock_page() does indeed find an existing page, then we have a "minor" fault, and if the VMA has the userfaultfd registration flag, we call into userfaultfd to handle it. This is implemented as a new registration mode, instead of an API feature. This is because the alternative implementation has significant drawbacks [1]. However, doing it this was requires we allocate a VM_* flag for the new registration mode. On 32-bit systems, there are no unused bits, so this feature is only supported on architectures with CONFIG_ARCH_USES_HIGH_VMA_FLAGS. When attempting to register a VMA in MINOR mode on 32-bit architectures, we return -EINVAL. [1] https://lore.kernel.org/patchwork/patch/1380226/ [peterx@redhat.com: fix minor fault page leak] Link: https://lkml.kernel.org/r/20210322175132.36659-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210301222728.176417-1-axelrasmussen@google.com Link: https://lkml.kernel.org/r/20210301222728.176417-2-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Steven Price <steven.price@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:36 +03:00
VM_UFFD_MISSING);
goto out;
}
mm, hugetlbfs: pass fault address to no page handler This is to take better advantage of general huge page clearing optimization (commit c79b57e462b5: "mm: hugetlb: clear target sub-page last when clearing huge page") for hugetlbfs. In the general optimization patch, the sub-page to access will be cleared last to avoid the cache lines of to access sub-page to be evicted when clearing other sub-pages. This works better if we have the address of the sub-page to access, that is, the fault address inside the huge page. So the hugetlbfs no page fault handler is changed to pass that information. This will benefit workloads which don't access the begin of the hugetlbfs huge page after the page fault under heavy cache contention for shared last level cache. The patch is a generic optimization which should benefit quite some workloads, not for a specific use case. To demonstrate the performance benefit of the patch, we tested it with vm-scalability run on hugetlbfs. With this patch, the throughput increases ~28.1% in vm-scalability anon-w-seq test case with 88 processes on a 2 socket Xeon E5 2699 v4 system (44 cores, 88 threads). The test case creates 88 processes, each process mmaps a big anonymous memory area with MAP_HUGETLB and writes to it from the end to the begin. For each process, other processes could be seen as other workload which generates heavy cache pressure. At the same time, the cache miss rate reduced from ~36.3% to ~25.6%, the IPC (instruction per cycle) increased from 0.3 to 0.37, and the time spent in user space is reduced ~19.3%. Link: http://lkml.kernel.org/r/20180517083539.9242-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-08 03:08:08 +03:00
page = alloc_huge_page(vma, haddr, 0);
if (IS_ERR(page)) {
hugetlbfs: fix hugetlb page migration/fault race causing SIGBUS Li Wang discovered that LTP/move_page12 V2 sometimes triggers SIGBUS in the kernel-v5.2.3 testing. This is caused by a race between hugetlb page migration and page fault. If a hugetlb page can not be allocated to satisfy a page fault, the task is sent SIGBUS. This is normal hugetlbfs behavior. A hugetlb fault mutex exists to prevent two tasks from trying to instantiate the same page. This protects against the situation where there is only one hugetlb page, and both tasks would try to allocate. Without the mutex, one would fail and SIGBUS even though the other fault would be successful. There is a similar race between hugetlb page migration and fault. Migration code will allocate a page for the target of the migration. It will then unmap the original page from all page tables. It does this unmap by first clearing the pte and then writing a migration entry. The page table lock is held for the duration of this clear and write operation. However, the beginnings of the hugetlb page fault code optimistically checks the pte without taking the page table lock. If clear (as it can be during the migration unmap operation), a hugetlb page allocation is attempted to satisfy the fault. Note that the page which will eventually satisfy this fault was already allocated by the migration code. However, the allocation within the fault path could fail which would result in the task incorrectly being sent SIGBUS. Ideally, we could take the hugetlb fault mutex in the migration code when modifying the page tables. However, locks must be taken in the order of hugetlb fault mutex, page lock, page table lock. This would require significant rework of the migration code. Instead, the issue is addressed in the hugetlb fault code. After failing to allocate a huge page, take the page table lock and check for huge_pte_none before returning an error. This is the same check that must be made further in the code even if page allocation is successful. Link: http://lkml.kernel.org/r/20190808000533.7701-1-mike.kravetz@oracle.com Fixes: 290408d4a250 ("hugetlb: hugepage migration core") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Li Wang <liwang@redhat.com> Tested-by: Li Wang <liwang@redhat.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Cyril Hrubis <chrubis@suse.cz> Cc: Xishi Qiu <xishi.qiuxishi@alibaba-inc.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-14 01:38:00 +03:00
/*
* Returning error will result in faulting task being
* sent SIGBUS. The hugetlb fault mutex prevents two
* tasks from racing to fault in the same page which
* could result in false unable to allocate errors.
* Page migration does not take the fault mutex, but
* does a clear then write of pte's under page table
* lock. Page fault code could race with migration,
* notice the clear pte and try to allocate a page
* here. Before returning error, get ptl and make
* sure there really is no pte entry.
*/
ptl = huge_pte_lock(h, mm, ptep);
ret = 0;
if (huge_pte_none(huge_ptep_get(ptep)))
ret = vmf_error(PTR_ERR(page));
hugetlbfs: fix hugetlb page migration/fault race causing SIGBUS Li Wang discovered that LTP/move_page12 V2 sometimes triggers SIGBUS in the kernel-v5.2.3 testing. This is caused by a race between hugetlb page migration and page fault. If a hugetlb page can not be allocated to satisfy a page fault, the task is sent SIGBUS. This is normal hugetlbfs behavior. A hugetlb fault mutex exists to prevent two tasks from trying to instantiate the same page. This protects against the situation where there is only one hugetlb page, and both tasks would try to allocate. Without the mutex, one would fail and SIGBUS even though the other fault would be successful. There is a similar race between hugetlb page migration and fault. Migration code will allocate a page for the target of the migration. It will then unmap the original page from all page tables. It does this unmap by first clearing the pte and then writing a migration entry. The page table lock is held for the duration of this clear and write operation. However, the beginnings of the hugetlb page fault code optimistically checks the pte without taking the page table lock. If clear (as it can be during the migration unmap operation), a hugetlb page allocation is attempted to satisfy the fault. Note that the page which will eventually satisfy this fault was already allocated by the migration code. However, the allocation within the fault path could fail which would result in the task incorrectly being sent SIGBUS. Ideally, we could take the hugetlb fault mutex in the migration code when modifying the page tables. However, locks must be taken in the order of hugetlb fault mutex, page lock, page table lock. This would require significant rework of the migration code. Instead, the issue is addressed in the hugetlb fault code. After failing to allocate a huge page, take the page table lock and check for huge_pte_none before returning an error. This is the same check that must be made further in the code even if page allocation is successful. Link: http://lkml.kernel.org/r/20190808000533.7701-1-mike.kravetz@oracle.com Fixes: 290408d4a250 ("hugetlb: hugepage migration core") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Li Wang <liwang@redhat.com> Tested-by: Li Wang <liwang@redhat.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Cyril Hrubis <chrubis@suse.cz> Cc: Xishi Qiu <xishi.qiuxishi@alibaba-inc.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-14 01:38:00 +03:00
spin_unlock(ptl);
goto out;
}
clear_huge_page(page, address, pages_per_huge_page(h));
mm: fix PageUptodate data race After running SetPageUptodate, preceeding stores to the page contents to actually bring it uptodate may not be ordered with the store to set the page uptodate. Therefore, another CPU which checks PageUptodate is true, then reads the page contents can get stale data. Fix this by having an smp_wmb before SetPageUptodate, and smp_rmb after PageUptodate. Many places that test PageUptodate, do so with the page locked, and this would be enough to ensure memory ordering in those places if SetPageUptodate were only called while the page is locked. Unfortunately that is not always the case for some filesystems, but it could be an idea for the future. Also bring the handling of anonymous page uptodateness in line with that of file backed page management, by marking anon pages as uptodate when they _are_ uptodate, rather than when our implementation requires that they be marked as such. Doing allows us to get rid of the smp_wmb's in the page copying functions, which were especially added for anonymous pages for an analogous memory ordering problem. Both file and anonymous pages are handled with the same barriers. FAQ: Q. Why not do this in flush_dcache_page? A. Firstly, flush_dcache_page handles only one side (the smb side) of the ordering protocol; we'd still need smp_rmb somewhere. Secondly, hiding away memory barriers in a completely unrelated function is nasty; at least in the PageUptodate macros, they are located together with (half) the operations involved in the ordering. Thirdly, the smp_wmb is only required when first bringing the page uptodate, wheras flush_dcache_page should be called each time it is written to through the kernel mapping. It is logically the wrong place to put it. Q. Why does this increase my text size / reduce my performance / etc. A. Because it is adding the necessary instructions to eliminate the data-race. Q. Can it be improved? A. Yes, eg. if you were to create a rule that all SetPageUptodate operations run under the page lock, we could avoid the smp_rmb places where PageUptodate is queried under the page lock. Requires audit of all filesystems and at least some would need reworking. That's great you're interested, I'm eagerly awaiting your patches. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 09:29:34 +03:00
__SetPageUptodate(page);
hugetlbfs: fix races and page leaks during migration hugetlb pages should only be migrated if they are 'active'. The routines set/clear_page_huge_active() modify the active state of hugetlb pages. When a new hugetlb page is allocated at fault time, set_page_huge_active is called before the page is locked. Therefore, another thread could race and migrate the page while it is being added to page table by the fault code. This race is somewhat hard to trigger, but can be seen by strategically adding udelay to simulate worst case scheduling behavior. Depending on 'how' the code races, various BUG()s could be triggered. To address this issue, simply delay the set_page_huge_active call until after the page is successfully added to the page table. Hugetlb pages can also be leaked at migration time if the pages are associated with a file in an explicitly mounted hugetlbfs filesystem. For example, consider a two node system with 4GB worth of huge pages available. A program mmaps a 2G file in a hugetlbfs filesystem. It then migrates the pages associated with the file from one node to another. When the program exits, huge page counts are as follows: node0 1024 free_hugepages 1024 nr_hugepages node1 0 free_hugepages 1024 nr_hugepages Filesystem Size Used Avail Use% Mounted on nodev 4.0G 2.0G 2.0G 50% /var/opt/hugepool That is as expected. 2G of huge pages are taken from the free_hugepages counts, and 2G is the size of the file in the explicitly mounted filesystem. If the file is then removed, the counts become: node0 1024 free_hugepages 1024 nr_hugepages node1 1024 free_hugepages 1024 nr_hugepages Filesystem Size Used Avail Use% Mounted on nodev 4.0G 2.0G 2.0G 50% /var/opt/hugepool Note that the filesystem still shows 2G of pages used, while there actually are no huge pages in use. The only way to 'fix' the filesystem accounting is to unmount the filesystem If a hugetlb page is associated with an explicitly mounted filesystem, this information in contained in the page_private field. At migration time, this information is not preserved. To fix, simply transfer page_private from old to new page at migration time if necessary. There is a related race with removing a huge page from a file and migration. When a huge page is removed from the pagecache, the page_mapping() field is cleared, yet page_private remains set until the page is actually freed by free_huge_page(). A page could be migrated while in this state. However, since page_mapping() is not set the hugetlbfs specific routine to transfer page_private is not called and we leak the page count in the filesystem. To fix that, check for this condition before migrating a huge page. If the condition is detected, return EBUSY for the page. Link: http://lkml.kernel.org/r/74510272-7319-7372-9ea6-ec914734c179@oracle.com Link: http://lkml.kernel.org/r/20190212221400.3512-1-mike.kravetz@oracle.com Fixes: bcc54222309c ("mm: hugetlb: introduce page_huge_active") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: <stable@vger.kernel.org> [mike.kravetz@oracle.com: v2] Link: http://lkml.kernel.org/r/7534d322-d782-8ac6-1c8d-a8dc380eb3ab@oracle.com [mike.kravetz@oracle.com: update comment and changelog] Link: http://lkml.kernel.org/r/420bcfd6-158b-38e4-98da-26d0cd85bd01@oracle.com Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-01 03:22:02 +03:00
new_page = true;
mm: account for MAP_SHARED mappings using VM_MAYSHARE and not VM_SHARED in hugetlbfs Addresses http://bugzilla.kernel.org/show_bug.cgi?id=13302 hugetlbfs reserves huge pages but does not fault them at mmap() time to ensure that future faults succeed. The reservation behaviour differs depending on whether the mapping was mapped MAP_SHARED or MAP_PRIVATE. For MAP_SHARED mappings, hugepages are reserved when mmap() is first called and are tracked based on information associated with the inode. Other processes mapping MAP_SHARED use the same reservation. MAP_PRIVATE track the reservations based on the VMA created as part of the mmap() operation. Each process mapping MAP_PRIVATE must make its own reservation. hugetlbfs currently checks if a VMA is MAP_SHARED with the VM_SHARED flag and not VM_MAYSHARE. For file-backed mappings, such as hugetlbfs, VM_SHARED is set only if the mapping is MAP_SHARED and the file was opened read-write. If a shared memory mapping was mapped shared-read-write for populating of data and mapped shared-read-only by other processes, then hugetlbfs would account for the mapping as if it was MAP_PRIVATE. This causes processes to fail to map the file MAP_SHARED even though it should succeed as the reservation is there. This patch alters mm/hugetlb.c and replaces VM_SHARED with VM_MAYSHARE when the intent of the code was to check whether the VMA was mapped MAP_SHARED or MAP_PRIVATE. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Ingo Molnar <mingo@elte.hu> Cc: <stable@kernel.org> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: <starlight@binnacle.cx> Cc: Eric B Munson <ebmunson@us.ibm.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-05-29 01:34:40 +04:00
if (vma->vm_flags & VM_MAYSHARE) {
int err = huge_add_to_page_cache(page, mapping, idx);
if (err) {
put_page(page);
if (err == -EEXIST)
goto retry;
goto out;
}
hugetlb: don't pass page cache pages to restore_reserve_on_error syzbot hit kernel BUG at fs/hugetlbfs/inode.c:532 as described in [1]. This BUG triggers if the HPageRestoreReserve flag is set on a page in the page cache. It should never be set, as the routine huge_add_to_page_cache explicitly clears the flag after adding a page to the cache. The only code other than huge page allocation which sets the flag is restore_reserve_on_error. It will potentially set the flag in rare out of memory conditions. syzbot was injecting errors to cause memory allocation errors which exercised this specific path. The code in restore_reserve_on_error is doing the right thing. However, there are instances where pages in the page cache were being passed to restore_reserve_on_error. This is incorrect, as once a page goes into the cache reservation information will not be modified for the page until it is removed from the cache. Error paths do not remove pages from the cache, so even in the case of error, the page will remain in the cache and no reservation adjustment is needed. Modify routines that potentially call restore_reserve_on_error with a page cache page to no longer do so. Note on fixes tag: Prior to commit 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") the routine would not process page cache pages because the HPageRestoreReserve flag is not set on such pages. Therefore, this issue could not be trigggered. The code added by commit 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") is needed and correct. It exposed incorrect calls to restore_reserve_on_error which is the root cause addressed by this commit. [1] https://lore.kernel.org/linux-mm/00000000000050776d05c9b7c7f0@google.com/ Link: https://lkml.kernel.org/r/20210818213304.37038-1-mike.kravetz@oracle.com Fixes: 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: <syzbot+67654e51e54455f1c585@syzkaller.appspotmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-08-20 05:04:33 +03:00
new_pagecache_page = true;
} else {
lock_page(page);
hugetlb, rmap: add reverse mapping for hugepage This patch adds reverse mapping feature for hugepage by introducing mapcount for shared/private-mapped hugepage and anon_vma for private-mapped hugepage. While hugepage is not currently swappable, reverse mapping can be useful for memory error handler. Without this patch, memory error handler cannot identify processes using the bad hugepage nor unmap it from them. That is: - for shared hugepage: we can collect processes using a hugepage through pagecache, but can not unmap the hugepage because of the lack of mapcount. - for privately mapped hugepage: we can neither collect processes nor unmap the hugepage. This patch solves these problems. This patch include the bug fix given by commit 23be7468e8, so reverts it. Dependency: "hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h" ChangeLog since May 24. - create hugetlb_inline.h and move is_vm_hugetlb_index() in it. - move functions setting up anon_vma for hugepage into mm/rmap.c. ChangeLog since May 13. - rebased to 2.6.34 - fix logic error (in case that private mapping and shared mapping coexist) - move is_vm_hugetlb_page() into include/linux/mm.h to use this function from linear_page_index() - define and use linear_hugepage_index() instead of compound_order() - use page_move_anon_rmap() in hugetlb_cow() - copy exclusive switch of __set_page_anon_rmap() into hugepage counterpart. - revert commit 24be7468 completely Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Acked-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andi Kleen <ak@linux.intel.com>
2010-05-28 04:29:16 +04:00
if (unlikely(anon_vma_prepare(vma))) {
ret = VM_FAULT_OOM;
goto backout_unlocked;
}
anon_rmap = 1;
}
hugetlb, rmap: add reverse mapping for hugepage This patch adds reverse mapping feature for hugepage by introducing mapcount for shared/private-mapped hugepage and anon_vma for private-mapped hugepage. While hugepage is not currently swappable, reverse mapping can be useful for memory error handler. Without this patch, memory error handler cannot identify processes using the bad hugepage nor unmap it from them. That is: - for shared hugepage: we can collect processes using a hugepage through pagecache, but can not unmap the hugepage because of the lack of mapcount. - for privately mapped hugepage: we can neither collect processes nor unmap the hugepage. This patch solves these problems. This patch include the bug fix given by commit 23be7468e8, so reverts it. Dependency: "hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h" ChangeLog since May 24. - create hugetlb_inline.h and move is_vm_hugetlb_index() in it. - move functions setting up anon_vma for hugepage into mm/rmap.c. ChangeLog since May 13. - rebased to 2.6.34 - fix logic error (in case that private mapping and shared mapping coexist) - move is_vm_hugetlb_page() into include/linux/mm.h to use this function from linear_page_index() - define and use linear_hugepage_index() instead of compound_order() - use page_move_anon_rmap() in hugetlb_cow() - copy exclusive switch of __set_page_anon_rmap() into hugepage counterpart. - revert commit 24be7468 completely Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Acked-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andi Kleen <ak@linux.intel.com>
2010-05-28 04:29:16 +04:00
} else {
/*
* If memory error occurs between mmap() and fault, some process
* don't have hwpoisoned swap entry for errored virtual address.
* So we need to block hugepage fault by PG_hwpoison bit check.
*/
if (unlikely(PageHWPoison(page))) {
ret = VM_FAULT_HWPOISON_LARGE |
VM_FAULT_SET_HINDEX(hstate_index(h));
goto backout_unlocked;
}
userfaultfd: add minor fault registration mode Patch series "userfaultfd: add minor fault handling", v9. Overview ======== This series adds a new userfaultfd feature, UFFD_FEATURE_MINOR_HUGETLBFS. When enabled (via the UFFDIO_API ioctl), this feature means that any hugetlbfs VMAs registered with UFFDIO_REGISTER_MODE_MISSING will *also* get events for "minor" faults. By "minor" fault, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s) (shared memory). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. We also add a new ioctl to resolve such faults: UFFDIO_CONTINUE. The idea is, userspace resolves the fault by either a) doing nothing if the contents are already correct, or b) updating the underlying contents using the second, non-UFFD mapping (via memcpy/memset or similar, or something fancier like RDMA, or etc...). In either case, userspace issues UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Use Case ======== Consider the use case of VM live migration (e.g. under QEMU/KVM): 1. While a VM is still running, we copy the contents of its memory to a target machine. The pages are populated on the target by writing to the non-UFFD mapping, using the setup described above. The VM is still running (and therefore its memory is likely changing), so this may be repeated several times, until we decide the target is "up to date enough". 2. We pause the VM on the source, and start executing on the target machine. During this gap, the VM's user(s) will *see* a pause, so it is desirable to minimize this window. 3. Between the last time any page was copied from the source to the target, and when the VM was paused, the contents of that page may have changed - and therefore the copy we have on the target machine is out of date. Although we can keep track of which pages are out of date, for VMs with large amounts of memory, it is "slow" to transfer this information to the target machine. We want to resume execution before such a transfer would complete. 4. So, the guest begins executing on the target machine. The first time it touches its memory (via the UFFD-registered mapping), userspace wants to intercept this fault. Userspace checks whether or not the page is up to date, and if not, copies the updated page from the source machine, via the non-UFFD mapping. Finally, whether a copy was performed or not, userspace issues a UFFDIO_CONTINUE ioctl to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". We don't have to do all of the final updates on-demand. The userfaultfd manager can, in the background, also copy over updated pages once it receives the map of which pages are up-to-date or not. Interaction with Existing APIs ============================== Because this is a feature, a registered VMA could potentially receive both missing and minor faults. I spent some time thinking through how the existing API interacts with the new feature: UFFDIO_CONTINUE cannot be used to resolve non-minor faults, as it does not allocate a new page. If UFFDIO_CONTINUE is used on a non-minor fault: - For non-shared memory or shmem, -EINVAL is returned. - For hugetlb, -EFAULT is returned. UFFDIO_COPY and UFFDIO_ZEROPAGE cannot be used to resolve minor faults. Without modifications, the existing codepath assumes a new page needs to be allocated. This is okay, since userspace must have a second non-UFFD-registered mapping anyway, thus there isn't much reason to want to use these in any case (just memcpy or memset or similar). - If UFFDIO_COPY is used on a minor fault, -EEXIST is returned. - If UFFDIO_ZEROPAGE is used on a minor fault, -EEXIST is returned (or -EINVAL in the case of hugetlb, as UFFDIO_ZEROPAGE is unsupported in any case). - UFFDIO_WRITEPROTECT simply doesn't work with shared memory, and returns -ENOENT in that case (regardless of the kind of fault). Future Work =========== This series only supports hugetlbfs. I have a second series in flight to support shmem as well, extending the functionality. This series is more mature than the shmem support at this point, and the functionality works fully on hugetlbfs, so this series can be merged first and then shmem support will follow. This patch (of 6): This feature allows userspace to intercept "minor" faults. By "minor" faults, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. This commit adds the new registration mode, and sets the relevant flag on the VMAs being registered. In the hugetlb fault path, if we find that we have huge_pte_none(), but find_lock_page() does indeed find an existing page, then we have a "minor" fault, and if the VMA has the userfaultfd registration flag, we call into userfaultfd to handle it. This is implemented as a new registration mode, instead of an API feature. This is because the alternative implementation has significant drawbacks [1]. However, doing it this was requires we allocate a VM_* flag for the new registration mode. On 32-bit systems, there are no unused bits, so this feature is only supported on architectures with CONFIG_ARCH_USES_HIGH_VMA_FLAGS. When attempting to register a VMA in MINOR mode on 32-bit architectures, we return -EINVAL. [1] https://lore.kernel.org/patchwork/patch/1380226/ [peterx@redhat.com: fix minor fault page leak] Link: https://lkml.kernel.org/r/20210322175132.36659-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210301222728.176417-1-axelrasmussen@google.com Link: https://lkml.kernel.org/r/20210301222728.176417-2-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Steven Price <steven.price@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:36 +03:00
/* Check for page in userfault range. */
if (userfaultfd_minor(vma)) {
unlock_page(page);
put_page(page);
ret = hugetlb_handle_userfault(vma, mapping, idx,
userfaultfd: provide unmasked address on page-fault Userfaultfd is supposed to provide the full address (i.e., unmasked) of the faulting access back to userspace. However, that is not the case for quite some time. Even running "userfaultfd_demo" from the userfaultfd man page provides the wrong output (and contradicts the man page). Notice that "UFFD_EVENT_PAGEFAULT event" shows the masked address (7fc5e30b3000) and not the first read address (0x7fc5e30b300f). Address returned by mmap() = 0x7fc5e30b3000 fault_handler_thread(): poll() returns: nready = 1; POLLIN = 1; POLLERR = 0 UFFD_EVENT_PAGEFAULT event: flags = 0; address = 7fc5e30b3000 (uffdio_copy.copy returned 4096) Read address 0x7fc5e30b300f in main(): A Read address 0x7fc5e30b340f in main(): A Read address 0x7fc5e30b380f in main(): A Read address 0x7fc5e30b3c0f in main(): A The exact address is useful for various reasons and specifically for prefetching decisions. If it is known that the memory is populated by certain objects whose size is not page-aligned, then based on the faulting address, the uffd-monitor can decide whether to prefetch and prefault the adjacent page. This bug has been for quite some time in the kernel: since commit 1a29d85eb0f1 ("mm: use vmf->address instead of of vmf->virtual_address") vmf->virtual_address"), which dates back to 2016. A concern has been raised that existing userspace application might rely on the old/wrong behavior in which the address is masked. Therefore, it was suggested to provide the masked address unless the user explicitly asks for the exact address. Add a new userfaultfd feature UFFD_FEATURE_EXACT_ADDRESS to direct userfaultfd to provide the exact address. Add a new "real_address" field to vmf to hold the unmasked address. Provide the address to userspace accordingly. Initialize real_address in various code-paths to be consistent with address, even when it is not used, to be on the safe side. [namit@vmware.com: initialize real_address on all code paths, per Jan] Link: https://lkml.kernel.org/r/20220226022655.350562-1-namit@vmware.com [akpm@linux-foundation.org: fix typo in comment, per Jan] Link: https://lkml.kernel.org/r/20220218041003.3508-1-namit@vmware.com Signed-off-by: Nadav Amit <namit@vmware.com> Acked-by: Peter Xu <peterx@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-03-23 00:45:32 +03:00
flags, haddr, address,
userfaultfd: add minor fault registration mode Patch series "userfaultfd: add minor fault handling", v9. Overview ======== This series adds a new userfaultfd feature, UFFD_FEATURE_MINOR_HUGETLBFS. When enabled (via the UFFDIO_API ioctl), this feature means that any hugetlbfs VMAs registered with UFFDIO_REGISTER_MODE_MISSING will *also* get events for "minor" faults. By "minor" fault, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s) (shared memory). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. We also add a new ioctl to resolve such faults: UFFDIO_CONTINUE. The idea is, userspace resolves the fault by either a) doing nothing if the contents are already correct, or b) updating the underlying contents using the second, non-UFFD mapping (via memcpy/memset or similar, or something fancier like RDMA, or etc...). In either case, userspace issues UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Use Case ======== Consider the use case of VM live migration (e.g. under QEMU/KVM): 1. While a VM is still running, we copy the contents of its memory to a target machine. The pages are populated on the target by writing to the non-UFFD mapping, using the setup described above. The VM is still running (and therefore its memory is likely changing), so this may be repeated several times, until we decide the target is "up to date enough". 2. We pause the VM on the source, and start executing on the target machine. During this gap, the VM's user(s) will *see* a pause, so it is desirable to minimize this window. 3. Between the last time any page was copied from the source to the target, and when the VM was paused, the contents of that page may have changed - and therefore the copy we have on the target machine is out of date. Although we can keep track of which pages are out of date, for VMs with large amounts of memory, it is "slow" to transfer this information to the target machine. We want to resume execution before such a transfer would complete. 4. So, the guest begins executing on the target machine. The first time it touches its memory (via the UFFD-registered mapping), userspace wants to intercept this fault. Userspace checks whether or not the page is up to date, and if not, copies the updated page from the source machine, via the non-UFFD mapping. Finally, whether a copy was performed or not, userspace issues a UFFDIO_CONTINUE ioctl to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". We don't have to do all of the final updates on-demand. The userfaultfd manager can, in the background, also copy over updated pages once it receives the map of which pages are up-to-date or not. Interaction with Existing APIs ============================== Because this is a feature, a registered VMA could potentially receive both missing and minor faults. I spent some time thinking through how the existing API interacts with the new feature: UFFDIO_CONTINUE cannot be used to resolve non-minor faults, as it does not allocate a new page. If UFFDIO_CONTINUE is used on a non-minor fault: - For non-shared memory or shmem, -EINVAL is returned. - For hugetlb, -EFAULT is returned. UFFDIO_COPY and UFFDIO_ZEROPAGE cannot be used to resolve minor faults. Without modifications, the existing codepath assumes a new page needs to be allocated. This is okay, since userspace must have a second non-UFFD-registered mapping anyway, thus there isn't much reason to want to use these in any case (just memcpy or memset or similar). - If UFFDIO_COPY is used on a minor fault, -EEXIST is returned. - If UFFDIO_ZEROPAGE is used on a minor fault, -EEXIST is returned (or -EINVAL in the case of hugetlb, as UFFDIO_ZEROPAGE is unsupported in any case). - UFFDIO_WRITEPROTECT simply doesn't work with shared memory, and returns -ENOENT in that case (regardless of the kind of fault). Future Work =========== This series only supports hugetlbfs. I have a second series in flight to support shmem as well, extending the functionality. This series is more mature than the shmem support at this point, and the functionality works fully on hugetlbfs, so this series can be merged first and then shmem support will follow. This patch (of 6): This feature allows userspace to intercept "minor" faults. By "minor" faults, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. This commit adds the new registration mode, and sets the relevant flag on the VMAs being registered. In the hugetlb fault path, if we find that we have huge_pte_none(), but find_lock_page() does indeed find an existing page, then we have a "minor" fault, and if the VMA has the userfaultfd registration flag, we call into userfaultfd to handle it. This is implemented as a new registration mode, instead of an API feature. This is because the alternative implementation has significant drawbacks [1]. However, doing it this was requires we allocate a VM_* flag for the new registration mode. On 32-bit systems, there are no unused bits, so this feature is only supported on architectures with CONFIG_ARCH_USES_HIGH_VMA_FLAGS. When attempting to register a VMA in MINOR mode on 32-bit architectures, we return -EINVAL. [1] https://lore.kernel.org/patchwork/patch/1380226/ [peterx@redhat.com: fix minor fault page leak] Link: https://lkml.kernel.org/r/20210322175132.36659-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210301222728.176417-1-axelrasmussen@google.com Link: https://lkml.kernel.org/r/20210301222728.176417-2-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Steven Price <steven.price@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:36 +03:00
VM_UFFD_MINOR);
goto out;
}
}
/*
* If we are going to COW a private mapping later, we examine the
* pending reservations for this page now. This will ensure that
* any allocations necessary to record that reservation occur outside
* the spinlock.
*/
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
mm, hugetlbfs: pass fault address to no page handler This is to take better advantage of general huge page clearing optimization (commit c79b57e462b5: "mm: hugetlb: clear target sub-page last when clearing huge page") for hugetlbfs. In the general optimization patch, the sub-page to access will be cleared last to avoid the cache lines of to access sub-page to be evicted when clearing other sub-pages. This works better if we have the address of the sub-page to access, that is, the fault address inside the huge page. So the hugetlbfs no page fault handler is changed to pass that information. This will benefit workloads which don't access the begin of the hugetlbfs huge page after the page fault under heavy cache contention for shared last level cache. The patch is a generic optimization which should benefit quite some workloads, not for a specific use case. To demonstrate the performance benefit of the patch, we tested it with vm-scalability run on hugetlbfs. With this patch, the throughput increases ~28.1% in vm-scalability anon-w-seq test case with 88 processes on a 2 socket Xeon E5 2699 v4 system (44 cores, 88 threads). The test case creates 88 processes, each process mmaps a big anonymous memory area with MAP_HUGETLB and writes to it from the end to the begin. For each process, other processes could be seen as other workload which generates heavy cache pressure. At the same time, the cache miss rate reduced from ~36.3% to ~25.6%, the IPC (instruction per cycle) increased from 0.3 to 0.37, and the time spent in user space is reduced ~19.3%. Link: http://lkml.kernel.org/r/20180517083539.9242-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-08 03:08:08 +03:00
if (vma_needs_reservation(h, vma, haddr) < 0) {
ret = VM_FAULT_OOM;
goto backout_unlocked;
}
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
/* Just decrements count, does not deallocate */
mm, hugetlbfs: pass fault address to no page handler This is to take better advantage of general huge page clearing optimization (commit c79b57e462b5: "mm: hugetlb: clear target sub-page last when clearing huge page") for hugetlbfs. In the general optimization patch, the sub-page to access will be cleared last to avoid the cache lines of to access sub-page to be evicted when clearing other sub-pages. This works better if we have the address of the sub-page to access, that is, the fault address inside the huge page. So the hugetlbfs no page fault handler is changed to pass that information. This will benefit workloads which don't access the begin of the hugetlbfs huge page after the page fault under heavy cache contention for shared last level cache. The patch is a generic optimization which should benefit quite some workloads, not for a specific use case. To demonstrate the performance benefit of the patch, we tested it with vm-scalability run on hugetlbfs. With this patch, the throughput increases ~28.1% in vm-scalability anon-w-seq test case with 88 processes on a 2 socket Xeon E5 2699 v4 system (44 cores, 88 threads). The test case creates 88 processes, each process mmaps a big anonymous memory area with MAP_HUGETLB and writes to it from the end to the begin. For each process, other processes could be seen as other workload which generates heavy cache pressure. At the same time, the cache miss rate reduced from ~36.3% to ~25.6%, the IPC (instruction per cycle) increased from 0.3 to 0.37, and the time spent in user space is reduced ~19.3%. Link: http://lkml.kernel.org/r/20180517083539.9242-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-08 03:08:08 +03:00
vma_end_reservation(h, vma, haddr);
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
}
ptl = huge_pte_lock(h, mm, ptep);
mm: fault feedback #2 This patch completes Linus's wish that the fault return codes be made into bit flags, which I agree makes everything nicer. This requires requires all handle_mm_fault callers to be modified (possibly the modifications should go further and do things like fault accounting in handle_mm_fault -- however that would be for another patch). [akpm@linux-foundation.org: fix alpha build] [akpm@linux-foundation.org: fix s390 build] [akpm@linux-foundation.org: fix sparc build] [akpm@linux-foundation.org: fix sparc64 build] [akpm@linux-foundation.org: fix ia64 build] Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ian Molton <spyro@f2s.com> Cc: Bryan Wu <bryan.wu@analog.com> Cc: Mikael Starvik <starvik@axis.com> Cc: David Howells <dhowells@redhat.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Hirokazu Takata <takata@linux-m32r.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Greg Ungerer <gerg@uclinux.org> Cc: Matthew Wilcox <willy@debian.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp> Cc: Richard Curnow <rc@rc0.org.uk> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp> Cc: Chris Zankel <chris@zankel.net> Acked-by: Kyle McMartin <kyle@mcmartin.ca> Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com> Acked-by: Ralf Baechle <ralf@linux-mips.org> Acked-by: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> [ Still apparently needs some ARM and PPC loving - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 12:47:05 +04:00
ret = 0;
if (!huge_pte_none(huge_ptep_get(ptep)))
goto backout;
if (anon_rmap) {
hugetlb: use page.private for hugetlb specific page flags Patch series "create hugetlb flags to consolidate state", v3. While discussing a series of hugetlb fixes in [1], it became evident that the hugetlb specific page state information is stored in a somewhat haphazard manner. Code dealing with state information would be easier to read, understand and maintain if this information was stored in a consistent manner. This series uses page.private of the hugetlb head page for storing a set of hugetlb specific page flags. Routines are priovided for test, set and clear of the flags. [1] https://lore.kernel.org/r/20210106084739.63318-1-songmuchun@bytedance.com This patch (of 4): As hugetlbfs evolved, state information about hugetlb pages was added. One 'convenient' way of doing this was to use available fields in tail pages. Over time, it has become difficult to know the meaning or contents of fields simply by looking at a small bit of code. Sometimes, the naming is just confusing. For example: The PagePrivate flag indicates a huge page reservation was consumed and needs to be restored if an error is encountered and the page is freed before it is instantiated. The page.private field contains the pointer to a subpool if the page is associated with one. In an effort to make the code more readable, use page.private to contain hugetlb specific page flags. These flags will have test, set and clear functions similar to those used for 'normal' page flags. More importantly, an enum of flag values will be created with names that actually reflect their purpose. In this patch, - Create infrastructure for hugetlb specific page flag functions - Move subpool pointer to page[1].private to make way for flags Create routines with meaningful names to modify subpool field - Use new HPageRestoreReserve flag instead of PagePrivate Conversion of other state information will happen in subsequent patches. Link: https://lkml.kernel.org/r/20210122195231.324857-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210122195231.324857-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:51 +03:00
ClearHPageRestoreReserve(page);
mm, hugetlbfs: pass fault address to no page handler This is to take better advantage of general huge page clearing optimization (commit c79b57e462b5: "mm: hugetlb: clear target sub-page last when clearing huge page") for hugetlbfs. In the general optimization patch, the sub-page to access will be cleared last to avoid the cache lines of to access sub-page to be evicted when clearing other sub-pages. This works better if we have the address of the sub-page to access, that is, the fault address inside the huge page. So the hugetlbfs no page fault handler is changed to pass that information. This will benefit workloads which don't access the begin of the hugetlbfs huge page after the page fault under heavy cache contention for shared last level cache. The patch is a generic optimization which should benefit quite some workloads, not for a specific use case. To demonstrate the performance benefit of the patch, we tested it with vm-scalability run on hugetlbfs. With this patch, the throughput increases ~28.1% in vm-scalability anon-w-seq test case with 88 processes on a 2 socket Xeon E5 2699 v4 system (44 cores, 88 threads). The test case creates 88 processes, each process mmaps a big anonymous memory area with MAP_HUGETLB and writes to it from the end to the begin. For each process, other processes could be seen as other workload which generates heavy cache pressure. At the same time, the cache miss rate reduced from ~36.3% to ~25.6%, the IPC (instruction per cycle) increased from 0.3 to 0.37, and the time spent in user space is reduced ~19.3%. Link: http://lkml.kernel.org/r/20180517083539.9242-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-08 03:08:08 +03:00
hugepage_add_new_anon_rmap(page, vma, haddr);
} else
mm/rmap: split page_dup_rmap() into page_dup_file_rmap() and page_try_dup_anon_rmap() ... and move the special check for pinned pages into page_try_dup_anon_rmap() to prepare for tracking exclusive anonymous pages via a new pageflag, clearing it only after making sure that there are no GUP pins on the anonymous page. We really only care about pins on anonymous pages, because they are prone to getting replaced in the COW handler once mapped R/O. For !anon pages in cow-mappings (!VM_SHARED && VM_MAYWRITE) we shouldn't really care about that, at least not that I could come up with an example. Let's drop the is_cow_mapping() check from page_needs_cow_for_dma(), as we know we're dealing with anonymous pages. Also, drop the handling of pinned pages from copy_huge_pud() and add a comment if ever supporting anonymous pages on the PUD level. This is a preparation for tracking exclusivity of anonymous pages in the rmap code, and disallowing marking a page shared (-> failing to duplicate) if there are GUP pins on a page. Link: https://lkml.kernel.org/r/20220428083441.37290-5-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:43 +03:00
page_dup_file_rmap(page, true);
new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
&& (vma->vm_flags & VM_SHARED)));
mm, hugetlbfs: pass fault address to no page handler This is to take better advantage of general huge page clearing optimization (commit c79b57e462b5: "mm: hugetlb: clear target sub-page last when clearing huge page") for hugetlbfs. In the general optimization patch, the sub-page to access will be cleared last to avoid the cache lines of to access sub-page to be evicted when clearing other sub-pages. This works better if we have the address of the sub-page to access, that is, the fault address inside the huge page. So the hugetlbfs no page fault handler is changed to pass that information. This will benefit workloads which don't access the begin of the hugetlbfs huge page after the page fault under heavy cache contention for shared last level cache. The patch is a generic optimization which should benefit quite some workloads, not for a specific use case. To demonstrate the performance benefit of the patch, we tested it with vm-scalability run on hugetlbfs. With this patch, the throughput increases ~28.1% in vm-scalability anon-w-seq test case with 88 processes on a 2 socket Xeon E5 2699 v4 system (44 cores, 88 threads). The test case creates 88 processes, each process mmaps a big anonymous memory area with MAP_HUGETLB and writes to it from the end to the begin. For each process, other processes could be seen as other workload which generates heavy cache pressure. At the same time, the cache miss rate reduced from ~36.3% to ~25.6%, the IPC (instruction per cycle) increased from 0.3 to 0.37, and the time spent in user space is reduced ~19.3%. Link: http://lkml.kernel.org/r/20180517083539.9242-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-08 03:08:08 +03:00
set_huge_pte_at(mm, haddr, ptep, new_pte);
hugetlb_count_add(pages_per_huge_page(h), mm);
if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
/* Optimization, do the COW without a second fault */
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
ret = hugetlb_wp(mm, vma, address, ptep, flags, page, ptl);
}
spin_unlock(ptl);
hugetlbfs: fix races and page leaks during migration hugetlb pages should only be migrated if they are 'active'. The routines set/clear_page_huge_active() modify the active state of hugetlb pages. When a new hugetlb page is allocated at fault time, set_page_huge_active is called before the page is locked. Therefore, another thread could race and migrate the page while it is being added to page table by the fault code. This race is somewhat hard to trigger, but can be seen by strategically adding udelay to simulate worst case scheduling behavior. Depending on 'how' the code races, various BUG()s could be triggered. To address this issue, simply delay the set_page_huge_active call until after the page is successfully added to the page table. Hugetlb pages can also be leaked at migration time if the pages are associated with a file in an explicitly mounted hugetlbfs filesystem. For example, consider a two node system with 4GB worth of huge pages available. A program mmaps a 2G file in a hugetlbfs filesystem. It then migrates the pages associated with the file from one node to another. When the program exits, huge page counts are as follows: node0 1024 free_hugepages 1024 nr_hugepages node1 0 free_hugepages 1024 nr_hugepages Filesystem Size Used Avail Use% Mounted on nodev 4.0G 2.0G 2.0G 50% /var/opt/hugepool That is as expected. 2G of huge pages are taken from the free_hugepages counts, and 2G is the size of the file in the explicitly mounted filesystem. If the file is then removed, the counts become: node0 1024 free_hugepages 1024 nr_hugepages node1 1024 free_hugepages 1024 nr_hugepages Filesystem Size Used Avail Use% Mounted on nodev 4.0G 2.0G 2.0G 50% /var/opt/hugepool Note that the filesystem still shows 2G of pages used, while there actually are no huge pages in use. The only way to 'fix' the filesystem accounting is to unmount the filesystem If a hugetlb page is associated with an explicitly mounted filesystem, this information in contained in the page_private field. At migration time, this information is not preserved. To fix, simply transfer page_private from old to new page at migration time if necessary. There is a related race with removing a huge page from a file and migration. When a huge page is removed from the pagecache, the page_mapping() field is cleared, yet page_private remains set until the page is actually freed by free_huge_page(). A page could be migrated while in this state. However, since page_mapping() is not set the hugetlbfs specific routine to transfer page_private is not called and we leak the page count in the filesystem. To fix that, check for this condition before migrating a huge page. If the condition is detected, return EBUSY for the page. Link: http://lkml.kernel.org/r/74510272-7319-7372-9ea6-ec914734c179@oracle.com Link: http://lkml.kernel.org/r/20190212221400.3512-1-mike.kravetz@oracle.com Fixes: bcc54222309c ("mm: hugetlb: introduce page_huge_active") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: <stable@vger.kernel.org> [mike.kravetz@oracle.com: v2] Link: http://lkml.kernel.org/r/7534d322-d782-8ac6-1c8d-a8dc380eb3ab@oracle.com [mike.kravetz@oracle.com: update comment and changelog] Link: http://lkml.kernel.org/r/420bcfd6-158b-38e4-98da-26d0cd85bd01@oracle.com Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-01 03:22:02 +03:00
/*
hugetlb: convert page_huge_active() HPageMigratable flag Use the new hugetlb page specific flag HPageMigratable to replace the page_huge_active interfaces. By it's name, page_huge_active implied that a huge page was on the active list. However, that is not really what code checking the flag wanted to know. It really wanted to determine if the huge page could be migrated. This happens when the page is actually added to the page cache and/or task page table. This is the reasoning behind the name change. The VM_BUG_ON_PAGE() calls in the *_huge_active() interfaces are not really necessary as we KNOW the page is a hugetlb page. Therefore, they are removed. The routine page_huge_active checked for PageHeadHuge before testing the active bit. This is unnecessary in the case where we hold a reference or lock and know it is a hugetlb head page. page_huge_active is also called without holding a reference or lock (scan_movable_pages), and can race with code freeing the page. The extra check in page_huge_active shortened the race window, but did not prevent the race. Offline code calling scan_movable_pages already deals with these races, so removing the check is acceptable. Add comment to racy code. [songmuchun@bytedance.com: remove set_page_huge_active() declaration from include/linux/hugetlb.h] Link: https://lkml.kernel.org/r/CAMZfGtUda+KoAZscU0718TN61cSFwp4zy=y2oZ=+6Z2TAZZwng@mail.gmail.com Link: https://lkml.kernel.org/r/20210122195231.324857-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:56 +03:00
* Only set HPageMigratable in newly allocated pages. Existing pages
* found in the pagecache may not have HPageMigratableset if they have
* been isolated for migration.
hugetlbfs: fix races and page leaks during migration hugetlb pages should only be migrated if they are 'active'. The routines set/clear_page_huge_active() modify the active state of hugetlb pages. When a new hugetlb page is allocated at fault time, set_page_huge_active is called before the page is locked. Therefore, another thread could race and migrate the page while it is being added to page table by the fault code. This race is somewhat hard to trigger, but can be seen by strategically adding udelay to simulate worst case scheduling behavior. Depending on 'how' the code races, various BUG()s could be triggered. To address this issue, simply delay the set_page_huge_active call until after the page is successfully added to the page table. Hugetlb pages can also be leaked at migration time if the pages are associated with a file in an explicitly mounted hugetlbfs filesystem. For example, consider a two node system with 4GB worth of huge pages available. A program mmaps a 2G file in a hugetlbfs filesystem. It then migrates the pages associated with the file from one node to another. When the program exits, huge page counts are as follows: node0 1024 free_hugepages 1024 nr_hugepages node1 0 free_hugepages 1024 nr_hugepages Filesystem Size Used Avail Use% Mounted on nodev 4.0G 2.0G 2.0G 50% /var/opt/hugepool That is as expected. 2G of huge pages are taken from the free_hugepages counts, and 2G is the size of the file in the explicitly mounted filesystem. If the file is then removed, the counts become: node0 1024 free_hugepages 1024 nr_hugepages node1 1024 free_hugepages 1024 nr_hugepages Filesystem Size Used Avail Use% Mounted on nodev 4.0G 2.0G 2.0G 50% /var/opt/hugepool Note that the filesystem still shows 2G of pages used, while there actually are no huge pages in use. The only way to 'fix' the filesystem accounting is to unmount the filesystem If a hugetlb page is associated with an explicitly mounted filesystem, this information in contained in the page_private field. At migration time, this information is not preserved. To fix, simply transfer page_private from old to new page at migration time if necessary. There is a related race with removing a huge page from a file and migration. When a huge page is removed from the pagecache, the page_mapping() field is cleared, yet page_private remains set until the page is actually freed by free_huge_page(). A page could be migrated while in this state. However, since page_mapping() is not set the hugetlbfs specific routine to transfer page_private is not called and we leak the page count in the filesystem. To fix that, check for this condition before migrating a huge page. If the condition is detected, return EBUSY for the page. Link: http://lkml.kernel.org/r/74510272-7319-7372-9ea6-ec914734c179@oracle.com Link: http://lkml.kernel.org/r/20190212221400.3512-1-mike.kravetz@oracle.com Fixes: bcc54222309c ("mm: hugetlb: introduce page_huge_active") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: <stable@vger.kernel.org> [mike.kravetz@oracle.com: v2] Link: http://lkml.kernel.org/r/7534d322-d782-8ac6-1c8d-a8dc380eb3ab@oracle.com [mike.kravetz@oracle.com: update comment and changelog] Link: http://lkml.kernel.org/r/420bcfd6-158b-38e4-98da-26d0cd85bd01@oracle.com Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-01 03:22:02 +03:00
*/
if (new_page)
hugetlb: convert page_huge_active() HPageMigratable flag Use the new hugetlb page specific flag HPageMigratable to replace the page_huge_active interfaces. By it's name, page_huge_active implied that a huge page was on the active list. However, that is not really what code checking the flag wanted to know. It really wanted to determine if the huge page could be migrated. This happens when the page is actually added to the page cache and/or task page table. This is the reasoning behind the name change. The VM_BUG_ON_PAGE() calls in the *_huge_active() interfaces are not really necessary as we KNOW the page is a hugetlb page. Therefore, they are removed. The routine page_huge_active checked for PageHeadHuge before testing the active bit. This is unnecessary in the case where we hold a reference or lock and know it is a hugetlb head page. page_huge_active is also called without holding a reference or lock (scan_movable_pages), and can race with code freeing the page. The extra check in page_huge_active shortened the race window, but did not prevent the race. Offline code calling scan_movable_pages already deals with these races, so removing the check is acceptable. Add comment to racy code. [songmuchun@bytedance.com: remove set_page_huge_active() declaration from include/linux/hugetlb.h] Link: https://lkml.kernel.org/r/CAMZfGtUda+KoAZscU0718TN61cSFwp4zy=y2oZ=+6Z2TAZZwng@mail.gmail.com Link: https://lkml.kernel.org/r/20210122195231.324857-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:56 +03:00
SetHPageMigratable(page);
hugetlbfs: fix races and page leaks during migration hugetlb pages should only be migrated if they are 'active'. The routines set/clear_page_huge_active() modify the active state of hugetlb pages. When a new hugetlb page is allocated at fault time, set_page_huge_active is called before the page is locked. Therefore, another thread could race and migrate the page while it is being added to page table by the fault code. This race is somewhat hard to trigger, but can be seen by strategically adding udelay to simulate worst case scheduling behavior. Depending on 'how' the code races, various BUG()s could be triggered. To address this issue, simply delay the set_page_huge_active call until after the page is successfully added to the page table. Hugetlb pages can also be leaked at migration time if the pages are associated with a file in an explicitly mounted hugetlbfs filesystem. For example, consider a two node system with 4GB worth of huge pages available. A program mmaps a 2G file in a hugetlbfs filesystem. It then migrates the pages associated with the file from one node to another. When the program exits, huge page counts are as follows: node0 1024 free_hugepages 1024 nr_hugepages node1 0 free_hugepages 1024 nr_hugepages Filesystem Size Used Avail Use% Mounted on nodev 4.0G 2.0G 2.0G 50% /var/opt/hugepool That is as expected. 2G of huge pages are taken from the free_hugepages counts, and 2G is the size of the file in the explicitly mounted filesystem. If the file is then removed, the counts become: node0 1024 free_hugepages 1024 nr_hugepages node1 1024 free_hugepages 1024 nr_hugepages Filesystem Size Used Avail Use% Mounted on nodev 4.0G 2.0G 2.0G 50% /var/opt/hugepool Note that the filesystem still shows 2G of pages used, while there actually are no huge pages in use. The only way to 'fix' the filesystem accounting is to unmount the filesystem If a hugetlb page is associated with an explicitly mounted filesystem, this information in contained in the page_private field. At migration time, this information is not preserved. To fix, simply transfer page_private from old to new page at migration time if necessary. There is a related race with removing a huge page from a file and migration. When a huge page is removed from the pagecache, the page_mapping() field is cleared, yet page_private remains set until the page is actually freed by free_huge_page(). A page could be migrated while in this state. However, since page_mapping() is not set the hugetlbfs specific routine to transfer page_private is not called and we leak the page count in the filesystem. To fix that, check for this condition before migrating a huge page. If the condition is detected, return EBUSY for the page. Link: http://lkml.kernel.org/r/74510272-7319-7372-9ea6-ec914734c179@oracle.com Link: http://lkml.kernel.org/r/20190212221400.3512-1-mike.kravetz@oracle.com Fixes: bcc54222309c ("mm: hugetlb: introduce page_huge_active") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: <stable@vger.kernel.org> [mike.kravetz@oracle.com: v2] Link: http://lkml.kernel.org/r/7534d322-d782-8ac6-1c8d-a8dc380eb3ab@oracle.com [mike.kravetz@oracle.com: update comment and changelog] Link: http://lkml.kernel.org/r/420bcfd6-158b-38e4-98da-26d0cd85bd01@oracle.com Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-01 03:22:02 +03:00
unlock_page(page);
out:
return ret;
backout:
spin_unlock(ptl);
backout_unlocked:
unlock_page(page);
hugetlb: don't pass page cache pages to restore_reserve_on_error syzbot hit kernel BUG at fs/hugetlbfs/inode.c:532 as described in [1]. This BUG triggers if the HPageRestoreReserve flag is set on a page in the page cache. It should never be set, as the routine huge_add_to_page_cache explicitly clears the flag after adding a page to the cache. The only code other than huge page allocation which sets the flag is restore_reserve_on_error. It will potentially set the flag in rare out of memory conditions. syzbot was injecting errors to cause memory allocation errors which exercised this specific path. The code in restore_reserve_on_error is doing the right thing. However, there are instances where pages in the page cache were being passed to restore_reserve_on_error. This is incorrect, as once a page goes into the cache reservation information will not be modified for the page until it is removed from the cache. Error paths do not remove pages from the cache, so even in the case of error, the page will remain in the cache and no reservation adjustment is needed. Modify routines that potentially call restore_reserve_on_error with a page cache page to no longer do so. Note on fixes tag: Prior to commit 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") the routine would not process page cache pages because the HPageRestoreReserve flag is not set on such pages. Therefore, this issue could not be trigggered. The code added by commit 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") is needed and correct. It exposed incorrect calls to restore_reserve_on_error which is the root cause addressed by this commit. [1] https://lore.kernel.org/linux-mm/00000000000050776d05c9b7c7f0@google.com/ Link: https://lkml.kernel.org/r/20210818213304.37038-1-mike.kravetz@oracle.com Fixes: 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: <syzbot+67654e51e54455f1c585@syzkaller.appspotmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-08-20 05:04:33 +03:00
/* restore reserve for newly allocated pages not in page cache */
if (new_page && !new_pagecache_page)
restore_reserve_on_error(h, vma, haddr, page);
put_page(page);
goto out;
}
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
#ifdef CONFIG_SMP
u32 hugetlb_fault_mutex_hash(struct address_space *mapping, pgoff_t idx)
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
{
unsigned long key[2];
u32 hash;
hugetlb: use same fault hash key for shared and private mappings hugetlb uses a fault mutex hash table to prevent page faults of the same pages concurrently. The key for shared and private mappings is different. Shared keys off address_space and file index. Private keys off mm and virtual address. Consider a private mappings of a populated hugetlbfs file. A fault will map the page from the file and if needed do a COW to map a writable page. Hugetlbfs hole punch uses the fault mutex to prevent mappings of file pages. It uses the address_space file index key. However, private mappings will use a different key and could race with this code to map the file page. This causes problems (BUG) for the page cache remove code as it expects the page to be unmapped. A sample stack is: page dumped because: VM_BUG_ON_PAGE(page_mapped(page)) kernel BUG at mm/filemap.c:169! ... RIP: 0010:unaccount_page_cache_page+0x1b8/0x200 ... Call Trace: __delete_from_page_cache+0x39/0x220 delete_from_page_cache+0x45/0x70 remove_inode_hugepages+0x13c/0x380 ? __add_to_page_cache_locked+0x162/0x380 hugetlbfs_fallocate+0x403/0x540 ? _cond_resched+0x15/0x30 ? __inode_security_revalidate+0x5d/0x70 ? selinux_file_permission+0x100/0x130 vfs_fallocate+0x13f/0x270 ksys_fallocate+0x3c/0x80 __x64_sys_fallocate+0x1a/0x20 do_syscall_64+0x5b/0x180 entry_SYSCALL_64_after_hwframe+0x44/0xa9 There seems to be another potential COW issue/race with this approach of different private and shared keys as noted in commit 8382d914ebf7 ("mm, hugetlb: improve page-fault scalability"). Since every hugetlb mapping (even anon and private) is actually a file mapping, just use the address_space index key for all mappings. This results in potentially more hash collisions. However, this should not be the common case. Link: http://lkml.kernel.org/r/20190328234704.27083-3-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20190412165235.t4sscoujczfhuiyt@linux-r8p5 Fixes: b5cec28d36f5 ("hugetlbfs: truncate_hugepages() takes a range of pages") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reviewed-by: Davidlohr Bueso <dbueso@suse.de> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 03:19:41 +03:00
key[0] = (unsigned long) mapping;
key[1] = idx;
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
hash = jhash2((u32 *)&key, sizeof(key)/(sizeof(u32)), 0);
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
return hash & (num_fault_mutexes - 1);
}
#else
/*
* For uniprocessor systems we always use a single mutex, so just
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
* return 0 and avoid the hashing overhead.
*/
u32 hugetlb_fault_mutex_hash(struct address_space *mapping, pgoff_t idx)
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
{
return 0;
}
#endif
vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, unsigned int flags)
{
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
pte_t *ptep, entry;
spinlock_t *ptl;
vm_fault_t ret;
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
u32 hash;
pgoff_t idx;
hugetlb, rmap: add reverse mapping for hugepage This patch adds reverse mapping feature for hugepage by introducing mapcount for shared/private-mapped hugepage and anon_vma for private-mapped hugepage. While hugepage is not currently swappable, reverse mapping can be useful for memory error handler. Without this patch, memory error handler cannot identify processes using the bad hugepage nor unmap it from them. That is: - for shared hugepage: we can collect processes using a hugepage through pagecache, but can not unmap the hugepage because of the lack of mapcount. - for privately mapped hugepage: we can neither collect processes nor unmap the hugepage. This patch solves these problems. This patch include the bug fix given by commit 23be7468e8, so reverts it. Dependency: "hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h" ChangeLog since May 24. - create hugetlb_inline.h and move is_vm_hugetlb_index() in it. - move functions setting up anon_vma for hugepage into mm/rmap.c. ChangeLog since May 13. - rebased to 2.6.34 - fix logic error (in case that private mapping and shared mapping coexist) - move is_vm_hugetlb_page() into include/linux/mm.h to use this function from linear_page_index() - define and use linear_hugepage_index() instead of compound_order() - use page_move_anon_rmap() in hugetlb_cow() - copy exclusive switch of __set_page_anon_rmap() into hugepage counterpart. - revert commit 24be7468 completely Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Acked-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andi Kleen <ak@linux.intel.com>
2010-05-28 04:29:16 +04:00
struct page *page = NULL;
struct page *pagecache_page = NULL;
struct hstate *h = hstate_vma(vma);
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
struct address_space *mapping;
int need_wait_lock = 0;
mm, hugetlbfs: pass fault address to no page handler This is to take better advantage of general huge page clearing optimization (commit c79b57e462b5: "mm: hugetlb: clear target sub-page last when clearing huge page") for hugetlbfs. In the general optimization patch, the sub-page to access will be cleared last to avoid the cache lines of to access sub-page to be evicted when clearing other sub-pages. This works better if we have the address of the sub-page to access, that is, the fault address inside the huge page. So the hugetlbfs no page fault handler is changed to pass that information. This will benefit workloads which don't access the begin of the hugetlbfs huge page after the page fault under heavy cache contention for shared last level cache. The patch is a generic optimization which should benefit quite some workloads, not for a specific use case. To demonstrate the performance benefit of the patch, we tested it with vm-scalability run on hugetlbfs. With this patch, the throughput increases ~28.1% in vm-scalability anon-w-seq test case with 88 processes on a 2 socket Xeon E5 2699 v4 system (44 cores, 88 threads). The test case creates 88 processes, each process mmaps a big anonymous memory area with MAP_HUGETLB and writes to it from the end to the begin. For each process, other processes could be seen as other workload which generates heavy cache pressure. At the same time, the cache miss rate reduced from ~36.3% to ~25.6%, the IPC (instruction per cycle) increased from 0.3 to 0.37, and the time spent in user space is reduced ~19.3%. Link: http://lkml.kernel.org/r/20180517083539.9242-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-08 03:08:08 +03:00
unsigned long haddr = address & huge_page_mask(h);
mm, hugetlbfs: pass fault address to no page handler This is to take better advantage of general huge page clearing optimization (commit c79b57e462b5: "mm: hugetlb: clear target sub-page last when clearing huge page") for hugetlbfs. In the general optimization patch, the sub-page to access will be cleared last to avoid the cache lines of to access sub-page to be evicted when clearing other sub-pages. This works better if we have the address of the sub-page to access, that is, the fault address inside the huge page. So the hugetlbfs no page fault handler is changed to pass that information. This will benefit workloads which don't access the begin of the hugetlbfs huge page after the page fault under heavy cache contention for shared last level cache. The patch is a generic optimization which should benefit quite some workloads, not for a specific use case. To demonstrate the performance benefit of the patch, we tested it with vm-scalability run on hugetlbfs. With this patch, the throughput increases ~28.1% in vm-scalability anon-w-seq test case with 88 processes on a 2 socket Xeon E5 2699 v4 system (44 cores, 88 threads). The test case creates 88 processes, each process mmaps a big anonymous memory area with MAP_HUGETLB and writes to it from the end to the begin. For each process, other processes could be seen as other workload which generates heavy cache pressure. At the same time, the cache miss rate reduced from ~36.3% to ~25.6%, the IPC (instruction per cycle) increased from 0.3 to 0.37, and the time spent in user space is reduced ~19.3%. Link: http://lkml.kernel.org/r/20180517083539.9242-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-08 03:08:08 +03:00
ptep = huge_pte_offset(mm, haddr, huge_page_size(h));
if (ptep) {
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
/*
* Since we hold no locks, ptep could be stale. That is
* OK as we are only making decisions based on content and
* not actually modifying content here.
*/
entry = huge_ptep_get(ptep);
if (unlikely(is_hugetlb_entry_migration(entry))) {
migration_entry_wait_huge(vma, mm, ptep);
return 0;
} else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
return VM_FAULT_HWPOISON_LARGE |
VM_FAULT_SET_HINDEX(hstate_index(h));
}
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
/*
* Acquire i_mmap_rwsem before calling huge_pte_alloc and hold
hugetlbfs: Use i_mmap_rwsem to address page fault/truncate race hugetlbfs page faults can race with truncate and hole punch operations. Current code in the page fault path attempts to handle this by 'backing out' operations if we encounter the race. One obvious omission in the current code is removing a page newly added to the page cache. This is pretty straight forward to address, but there is a more subtle and difficult issue of backing out hugetlb reservations. To handle this correctly, the 'reservation state' before page allocation needs to be noted so that it can be properly backed out. There are four distinct possibilities for reservation state: shared/reserved, shared/no-resv, private/reserved and private/no-resv. Backing out a reservation may require memory allocation which could fail so that needs to be taken into account as well. Instead of writing the required complicated code for this rare occurrence, just eliminate the race. i_mmap_rwsem is now held in read mode for the duration of page fault processing. Hold i_mmap_rwsem in write mode when modifying i_size. In this way, truncation can not proceed when page faults are being processed. In addition, i_size will not change during fault processing so a single check can be made to ensure faults are not beyond (proposed) end of file. Faults can still race with hole punch, but that race is handled by existing code and the use of hugetlb_fault_mutex. With this modification, checks for races with truncation in the page fault path can be simplified and removed. remove_inode_hugepages no longer needs to take hugetlb_fault_mutex in the case of truncation. Comments are expanded to explain reasoning behind locking. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Hugh Dickins <hughd@google.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-3-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:08 +03:00
* until finished with ptep. This serves two purposes:
* 1) It prevents huge_pmd_unshare from being called elsewhere
* and making the ptep no longer valid.
* 2) It synchronizes us with i_size modifications during truncation.
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
*
* ptep could have already be assigned via huge_pte_offset. That
* is OK, as huge_pte_alloc will return the same value unless
* something has changed.
*/
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
mapping = vma->vm_file->f_mapping;
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
i_mmap_lock_read(mapping);
hugetlb: pass vma into huge_pte_alloc() and huge_pmd_share() Patch series "hugetlb: Disable huge pmd unshare for uffd-wp", v4. This series tries to disable huge pmd unshare of hugetlbfs backed memory for uffd-wp. Although uffd-wp of hugetlbfs is still during rfc stage, the idea of this series may be needed for multiple tasks (Axel's uffd minor fault series, and Mike's soft dirty series), so I picked it out from the larger series. This patch (of 4): It is a preparation work to be able to behave differently in the per architecture huge_pte_alloc() according to different VMA attributes. Pass it deeper into huge_pmd_share() so that we can avoid the find_vma() call. [peterx@redhat.com: build fix] Link: https://lkml.kernel.org/r/20210304164653.GB397383@xz-x1Link: https://lkml.kernel.org/r/20210218230633.15028-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210218230633.15028-2-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:33:00 +03:00
ptep = huge_pte_alloc(mm, vma, haddr, huge_page_size(h));
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
if (!ptep) {
i_mmap_unlock_read(mapping);
return VM_FAULT_OOM;
}
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
[PATCH] hugepage: serialize hugepage allocation and instantiation Currently, no lock or mutex is held between allocating a hugepage and inserting it into the pagetables / page cache. When we do go to insert the page into pagetables or page cache, we recheck and may free the newly allocated hugepage. However, since the number of hugepages in the system is strictly limited, and it's usualy to want to use all of them, this can still lead to spurious allocation failures. For example, suppose two processes are both mapping (MAP_SHARED) the same hugepage file, large enough to consume the entire available hugepage pool. If they race instantiating the last page in the mapping, they will both attempt to allocate the last available hugepage. One will fail, of course, returning OOM from the fault and thus causing the process to be killed, despite the fact that the entire mapping can, in fact, be instantiated. The patch fixes this race by the simple method of adding a (sleeping) mutex to serialize the hugepage fault path between allocation and insertion into pagetables and/or page cache. It would be possible to avoid the serialization by catching the allocation failures, waiting on some condition, then rechecking to see if someone else has instantiated the page for us. Given the likely frequency of hugepage instantiations, it seems very doubtful it's worth the extra complexity. This patch causes no regression on the libhugetlbfs testsuite, and one test, which can trigger this race now passes where it previously failed. Actually, the test still sometimes fails, though less often and only as a shmat() failure, rather processes getting OOM killed by the VM. The dodgy heuristic tests in fs/hugetlbfs/inode.c for whether there's enough hugepage space aren't protected by the new mutex, and would be ugly to do so, so there's still a race there. Another patch to replace those tests with something saner for this reason as well as others coming... Signed-off-by: David Gibson <dwg@au1.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 11:08:53 +03:00
/*
* Serialize hugepage allocation and instantiation, so that we don't
* get spurious allocation failures if two CPUs race to instantiate
* the same page in the page cache.
*/
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
idx = vma_hugecache_offset(h, vma, haddr);
hash = hugetlb_fault_mutex_hash(mapping, idx);
mutex_lock(&hugetlb_fault_mutex_table[hash]);
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
entry = huge_ptep_get(ptep);
if (huge_pte_none(entry)) {
mm, hugetlb: improve page-fault scalability The kernel can currently only handle a single hugetlb page fault at a time. This is due to a single mutex that serializes the entire path. This lock protects from spurious OOM errors under conditions of low availability of free hugepages. This problem is specific to hugepages, because it is normal to want to use every single hugepage in the system - with normal pages we simply assume there will always be a few spare pages which can be used temporarily until the race is resolved. Address this problem by using a table of mutexes, allowing a better chance of parallelization, where each hugepage is individually serialized. The hash key is selected depending on the mapping type. For shared ones it consists of the address space and file offset being faulted; while for private ones the mm and virtual address are used. The size of the table is selected based on a compromise of collisions and memory footprint of a series of database workloads. Large database workloads that make heavy use of hugepages can be particularly exposed to this issue, causing start-up times to be painfully slow. This patch reduces the startup time of a 10 Gb Oracle DB (with ~5000 faults) from 37.5 secs to 25.7 secs. Larger workloads will naturally benefit even more. NOTE: The only downside to this patch, detected by Joonsoo Kim, is that a small race is possible in private mappings: A child process (with its own mm, after cow) can instantiate a page that is already being handled by the parent in a cow fault. When low on pages, can trigger spurious OOMs. I have not been able to think of a efficient way of handling this... but do we really care about such a tiny window? We already maintain another theoretical race with normal pages. If not, one possible way to is to maintain the single hash for private mappings -- any workloads that *really* suffer from this scaling problem should already use shared mappings. [akpm@linux-foundation.org: remove stray + characters, go BUG if hugetlb_init() kmalloc fails] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-04 01:47:31 +04:00
ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, flags);
goto out_mutex;
[PATCH] hugepage: serialize hugepage allocation and instantiation Currently, no lock or mutex is held between allocating a hugepage and inserting it into the pagetables / page cache. When we do go to insert the page into pagetables or page cache, we recheck and may free the newly allocated hugepage. However, since the number of hugepages in the system is strictly limited, and it's usualy to want to use all of them, this can still lead to spurious allocation failures. For example, suppose two processes are both mapping (MAP_SHARED) the same hugepage file, large enough to consume the entire available hugepage pool. If they race instantiating the last page in the mapping, they will both attempt to allocate the last available hugepage. One will fail, of course, returning OOM from the fault and thus causing the process to be killed, despite the fact that the entire mapping can, in fact, be instantiated. The patch fixes this race by the simple method of adding a (sleeping) mutex to serialize the hugepage fault path between allocation and insertion into pagetables and/or page cache. It would be possible to avoid the serialization by catching the allocation failures, waiting on some condition, then rechecking to see if someone else has instantiated the page for us. Given the likely frequency of hugepage instantiations, it seems very doubtful it's worth the extra complexity. This patch causes no regression on the libhugetlbfs testsuite, and one test, which can trigger this race now passes where it previously failed. Actually, the test still sometimes fails, though less often and only as a shmat() failure, rather processes getting OOM killed by the VM. The dodgy heuristic tests in fs/hugetlbfs/inode.c for whether there's enough hugepage space aren't protected by the new mutex, and would be ugly to do so, so there's still a race there. Another patch to replace those tests with something saner for this reason as well as others coming... Signed-off-by: David Gibson <dwg@au1.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 11:08:53 +03:00
}
mm: fault feedback #2 This patch completes Linus's wish that the fault return codes be made into bit flags, which I agree makes everything nicer. This requires requires all handle_mm_fault callers to be modified (possibly the modifications should go further and do things like fault accounting in handle_mm_fault -- however that would be for another patch). [akpm@linux-foundation.org: fix alpha build] [akpm@linux-foundation.org: fix s390 build] [akpm@linux-foundation.org: fix sparc build] [akpm@linux-foundation.org: fix sparc64 build] [akpm@linux-foundation.org: fix ia64 build] Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ian Molton <spyro@f2s.com> Cc: Bryan Wu <bryan.wu@analog.com> Cc: Mikael Starvik <starvik@axis.com> Cc: David Howells <dhowells@redhat.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Hirokazu Takata <takata@linux-m32r.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Greg Ungerer <gerg@uclinux.org> Cc: Matthew Wilcox <willy@debian.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp> Cc: Richard Curnow <rc@rc0.org.uk> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp> Cc: Chris Zankel <chris@zankel.net> Acked-by: Kyle McMartin <kyle@mcmartin.ca> Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com> Acked-by: Ralf Baechle <ralf@linux-mips.org> Acked-by: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> [ Still apparently needs some ARM and PPC loving - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 12:47:05 +04:00
ret = 0;
/*
* entry could be a migration/hwpoison entry at this point, so this
* check prevents the kernel from going below assuming that we have
* an active hugepage in pagecache. This goto expects the 2nd page
* fault, and is_hugetlb_entry_(migration|hwpoisoned) check will
* properly handle it.
*/
if (!pte_present(entry))
goto out_mutex;
/*
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
* If we are going to COW/unshare the mapping later, we examine the
* pending reservations for this page now. This will ensure that any
* allocations necessary to record that reservation occur outside the
* spinlock. For private mappings, we also lookup the pagecache
* page now as it is used to determine if a reservation has been
* consumed.
*/
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) &&
!huge_pte_write(entry)) {
mm, hugetlbfs: pass fault address to no page handler This is to take better advantage of general huge page clearing optimization (commit c79b57e462b5: "mm: hugetlb: clear target sub-page last when clearing huge page") for hugetlbfs. In the general optimization patch, the sub-page to access will be cleared last to avoid the cache lines of to access sub-page to be evicted when clearing other sub-pages. This works better if we have the address of the sub-page to access, that is, the fault address inside the huge page. So the hugetlbfs no page fault handler is changed to pass that information. This will benefit workloads which don't access the begin of the hugetlbfs huge page after the page fault under heavy cache contention for shared last level cache. The patch is a generic optimization which should benefit quite some workloads, not for a specific use case. To demonstrate the performance benefit of the patch, we tested it with vm-scalability run on hugetlbfs. With this patch, the throughput increases ~28.1% in vm-scalability anon-w-seq test case with 88 processes on a 2 socket Xeon E5 2699 v4 system (44 cores, 88 threads). The test case creates 88 processes, each process mmaps a big anonymous memory area with MAP_HUGETLB and writes to it from the end to the begin. For each process, other processes could be seen as other workload which generates heavy cache pressure. At the same time, the cache miss rate reduced from ~36.3% to ~25.6%, the IPC (instruction per cycle) increased from 0.3 to 0.37, and the time spent in user space is reduced ~19.3%. Link: http://lkml.kernel.org/r/20180517083539.9242-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-08 03:08:08 +03:00
if (vma_needs_reservation(h, vma, haddr) < 0) {
ret = VM_FAULT_OOM;
goto out_mutex;
}
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
/* Just decrements count, does not deallocate */
mm, hugetlbfs: pass fault address to no page handler This is to take better advantage of general huge page clearing optimization (commit c79b57e462b5: "mm: hugetlb: clear target sub-page last when clearing huge page") for hugetlbfs. In the general optimization patch, the sub-page to access will be cleared last to avoid the cache lines of to access sub-page to be evicted when clearing other sub-pages. This works better if we have the address of the sub-page to access, that is, the fault address inside the huge page. So the hugetlbfs no page fault handler is changed to pass that information. This will benefit workloads which don't access the begin of the hugetlbfs huge page after the page fault under heavy cache contention for shared last level cache. The patch is a generic optimization which should benefit quite some workloads, not for a specific use case. To demonstrate the performance benefit of the patch, we tested it with vm-scalability run on hugetlbfs. With this patch, the throughput increases ~28.1% in vm-scalability anon-w-seq test case with 88 processes on a 2 socket Xeon E5 2699 v4 system (44 cores, 88 threads). The test case creates 88 processes, each process mmaps a big anonymous memory area with MAP_HUGETLB and writes to it from the end to the begin. For each process, other processes could be seen as other workload which generates heavy cache pressure. At the same time, the cache miss rate reduced from ~36.3% to ~25.6%, the IPC (instruction per cycle) increased from 0.3 to 0.37, and the time spent in user space is reduced ~19.3%. Link: http://lkml.kernel.org/r/20180517083539.9242-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-08 03:08:08 +03:00
vma_end_reservation(h, vma, haddr);
mm: account for MAP_SHARED mappings using VM_MAYSHARE and not VM_SHARED in hugetlbfs Addresses http://bugzilla.kernel.org/show_bug.cgi?id=13302 hugetlbfs reserves huge pages but does not fault them at mmap() time to ensure that future faults succeed. The reservation behaviour differs depending on whether the mapping was mapped MAP_SHARED or MAP_PRIVATE. For MAP_SHARED mappings, hugepages are reserved when mmap() is first called and are tracked based on information associated with the inode. Other processes mapping MAP_SHARED use the same reservation. MAP_PRIVATE track the reservations based on the VMA created as part of the mmap() operation. Each process mapping MAP_PRIVATE must make its own reservation. hugetlbfs currently checks if a VMA is MAP_SHARED with the VM_SHARED flag and not VM_MAYSHARE. For file-backed mappings, such as hugetlbfs, VM_SHARED is set only if the mapping is MAP_SHARED and the file was opened read-write. If a shared memory mapping was mapped shared-read-write for populating of data and mapped shared-read-only by other processes, then hugetlbfs would account for the mapping as if it was MAP_PRIVATE. This causes processes to fail to map the file MAP_SHARED even though it should succeed as the reservation is there. This patch alters mm/hugetlb.c and replaces VM_SHARED with VM_MAYSHARE when the intent of the code was to check whether the VMA was mapped MAP_SHARED or MAP_PRIVATE. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Ingo Molnar <mingo@elte.hu> Cc: <stable@kernel.org> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: <starlight@binnacle.cx> Cc: Eric B Munson <ebmunson@us.ibm.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-05-29 01:34:40 +04:00
if (!(vma->vm_flags & VM_MAYSHARE))
pagecache_page = hugetlbfs_pagecache_page(h,
mm, hugetlbfs: pass fault address to no page handler This is to take better advantage of general huge page clearing optimization (commit c79b57e462b5: "mm: hugetlb: clear target sub-page last when clearing huge page") for hugetlbfs. In the general optimization patch, the sub-page to access will be cleared last to avoid the cache lines of to access sub-page to be evicted when clearing other sub-pages. This works better if we have the address of the sub-page to access, that is, the fault address inside the huge page. So the hugetlbfs no page fault handler is changed to pass that information. This will benefit workloads which don't access the begin of the hugetlbfs huge page after the page fault under heavy cache contention for shared last level cache. The patch is a generic optimization which should benefit quite some workloads, not for a specific use case. To demonstrate the performance benefit of the patch, we tested it with vm-scalability run on hugetlbfs. With this patch, the throughput increases ~28.1% in vm-scalability anon-w-seq test case with 88 processes on a 2 socket Xeon E5 2699 v4 system (44 cores, 88 threads). The test case creates 88 processes, each process mmaps a big anonymous memory area with MAP_HUGETLB and writes to it from the end to the begin. For each process, other processes could be seen as other workload which generates heavy cache pressure. At the same time, the cache miss rate reduced from ~36.3% to ~25.6%, the IPC (instruction per cycle) increased from 0.3 to 0.37, and the time spent in user space is reduced ~19.3%. Link: http://lkml.kernel.org/r/20180517083539.9242-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-08 03:08:08 +03:00
vma, haddr);
}
ptl = huge_pte_lock(h, mm, ptep);
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
/* Check for a racing update before calling hugetlb_wp() */
if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
goto out_ptl;
/* Handle userfault-wp first, before trying to lock more pages */
if (userfaultfd_wp(vma) && huge_pte_uffd_wp(huge_ptep_get(ptep)) &&
(flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) {
struct vm_fault vmf = {
.vma = vma,
.address = haddr,
.real_address = address,
.flags = flags,
};
spin_unlock(ptl);
if (pagecache_page) {
unlock_page(pagecache_page);
put_page(pagecache_page);
}
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
i_mmap_unlock_read(mapping);
return handle_userfault(&vmf, VM_UFFD_WP);
}
/*
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
* hugetlb_wp() requires page locks of pte_page(entry) and
* pagecache_page, so here we need take the former one
* when page != pagecache_page or !pagecache_page.
*/
page = pte_page(entry);
if (page != pagecache_page)
if (!trylock_page(page)) {
need_wait_lock = 1;
goto out_ptl;
}
get_page(page);
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
if (flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) {
mm/hugetlb: add more arch-defined huge_pte functions Commit abf09bed3cce ("s390/mm: implement software dirty bits") introduced another difference in the pte layout vs. the pmd layout on s390, thoroughly breaking the s390 support for hugetlbfs. This requires replacing some more pte_xxx functions in mm/hugetlbfs.c with a huge_pte_xxx version. This patch introduces those huge_pte_xxx functions and their generic implementation in asm-generic/hugetlb.h, which will now be included on all architectures supporting hugetlbfs apart from s390. This change will be a no-op for those architectures. [akpm@linux-foundation.org: fix warning] Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> [for !s390 parts] Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 02:07:23 +04:00
if (!huge_pte_write(entry)) {
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
ret = hugetlb_wp(mm, vma, address, ptep, flags,
pagecache_page, ptl);
goto out_put_page;
mm: support GUP-triggered unsharing of anonymous pages Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. We want to implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. To implement 3), we need a way for GUP to trigger unsharing: FAULT_FLAG_UNSHARE. FAULT_FLAG_UNSHARE is only applicable to R/O mapped anonymous pages and resembles COW logic during a write fault. However, in contrast to a write fault, GUP-triggered unsharing will, for example, still maintain the write protection. Let's implement FAULT_FLAG_UNSHARE by hooking into the existing write fault handlers for all applicable anonymous page types: ordinary pages, THP and hugetlb. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that has been marked exclusive in the meantime by someone else, there is nothing to do. * If FAULT_FLAG_UNSHARE finds a R/O-mapped anonymous page that's not marked exclusive, it will try detecting if the process is the exclusive owner. If exclusive, it can be set exclusive similar to reuse logic during write faults via page_move_anon_rmap() and there is nothing else to do; otherwise, we either have to copy and map a fresh, anonymous exclusive page R/O (ordinary pages, hugetlb), or split the THP. This commit is heavily based on patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-16-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
} else if (likely(flags & FAULT_FLAG_WRITE)) {
entry = huge_pte_mkdirty(entry);
}
}
entry = pte_mkyoung(entry);
mm, hugetlbfs: pass fault address to no page handler This is to take better advantage of general huge page clearing optimization (commit c79b57e462b5: "mm: hugetlb: clear target sub-page last when clearing huge page") for hugetlbfs. In the general optimization patch, the sub-page to access will be cleared last to avoid the cache lines of to access sub-page to be evicted when clearing other sub-pages. This works better if we have the address of the sub-page to access, that is, the fault address inside the huge page. So the hugetlbfs no page fault handler is changed to pass that information. This will benefit workloads which don't access the begin of the hugetlbfs huge page after the page fault under heavy cache contention for shared last level cache. The patch is a generic optimization which should benefit quite some workloads, not for a specific use case. To demonstrate the performance benefit of the patch, we tested it with vm-scalability run on hugetlbfs. With this patch, the throughput increases ~28.1% in vm-scalability anon-w-seq test case with 88 processes on a 2 socket Xeon E5 2699 v4 system (44 cores, 88 threads). The test case creates 88 processes, each process mmaps a big anonymous memory area with MAP_HUGETLB and writes to it from the end to the begin. For each process, other processes could be seen as other workload which generates heavy cache pressure. At the same time, the cache miss rate reduced from ~36.3% to ~25.6%, the IPC (instruction per cycle) increased from 0.3 to 0.37, and the time spent in user space is reduced ~19.3%. Link: http://lkml.kernel.org/r/20180517083539.9242-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-08 03:08:08 +03:00
if (huge_ptep_set_access_flags(vma, haddr, ptep, entry,
flags & FAULT_FLAG_WRITE))
mm, hugetlbfs: pass fault address to no page handler This is to take better advantage of general huge page clearing optimization (commit c79b57e462b5: "mm: hugetlb: clear target sub-page last when clearing huge page") for hugetlbfs. In the general optimization patch, the sub-page to access will be cleared last to avoid the cache lines of to access sub-page to be evicted when clearing other sub-pages. This works better if we have the address of the sub-page to access, that is, the fault address inside the huge page. So the hugetlbfs no page fault handler is changed to pass that information. This will benefit workloads which don't access the begin of the hugetlbfs huge page after the page fault under heavy cache contention for shared last level cache. The patch is a generic optimization which should benefit quite some workloads, not for a specific use case. To demonstrate the performance benefit of the patch, we tested it with vm-scalability run on hugetlbfs. With this patch, the throughput increases ~28.1% in vm-scalability anon-w-seq test case with 88 processes on a 2 socket Xeon E5 2699 v4 system (44 cores, 88 threads). The test case creates 88 processes, each process mmaps a big anonymous memory area with MAP_HUGETLB and writes to it from the end to the begin. For each process, other processes could be seen as other workload which generates heavy cache pressure. At the same time, the cache miss rate reduced from ~36.3% to ~25.6%, the IPC (instruction per cycle) increased from 0.3 to 0.37, and the time spent in user space is reduced ~19.3%. Link: http://lkml.kernel.org/r/20180517083539.9242-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-08 03:08:08 +03:00
update_mmu_cache(vma, haddr, ptep);
out_put_page:
if (page != pagecache_page)
unlock_page(page);
put_page(page);
out_ptl:
spin_unlock(ptl);
if (pagecache_page) {
unlock_page(pagecache_page);
put_page(pagecache_page);
}
out_mutex:
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
i_mmap_unlock_read(mapping);
/*
* Generally it's safe to hold refcount during waiting page lock. But
* here we just wait to defer the next page fault to avoid busy loop and
* the page is not used after unlocked before returning from the current
* page fault. So we are safe from accessing freed page, even if we wait
* here without taking refcount.
*/
if (need_wait_lock)
wait_on_page_locked(page);
return ret;
}
userfaultfd: hugetlbfs: only compile UFFD helpers if config enabled For background, mm/userfaultfd.c provides a general mcopy_atomic implementation. But some types of memory (i.e., hugetlb and shmem) need a slightly different implementation, so they provide their own helpers for this. In other words, userfaultfd is the only caller of these functions. This patch achieves two things: 1. Don't spend time compiling code which will end up never being referenced anyway (a small build time optimization). 2. In patches later in this series, we extend the signature of these helpers with UFFD-specific state (a mode enumeration). Once this happens, we *have to* either not compile the helpers, or unconditionally define the UFFD-only state (which seems messier to me). This includes the declarations in the headers, as otherwise they'd yield warnings about implicitly defining the type of those arguments. Link: https://lkml.kernel.org/r/20210301222728.176417-4-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:45 +03:00
#ifdef CONFIG_USERFAULTFD
/*
* Used by userfaultfd UFFDIO_COPY. Based on mcopy_atomic_pte with
* modifications for huge pages.
*/
int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
pte_t *dst_pte,
struct vm_area_struct *dst_vma,
unsigned long dst_addr,
unsigned long src_addr,
userfaultfd: add UFFDIO_CONTINUE ioctl This ioctl is how userspace ought to resolve "minor" userfaults. The idea is, userspace is notified that a minor fault has occurred. It might change the contents of the page using its second non-UFFD mapping, or not. Then, it calls UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Note that it doesn't make much sense to use UFFDIO_{COPY,ZEROPAGE} for MINOR registered VMAs. ZEROPAGE maps the VMA to the zero page; but in the minor fault case, we already have some pre-existing underlying page. Likewise, UFFDIO_COPY isn't useful if we have a second non-UFFD mapping. We'd just use memcpy() or similar instead. It turns out hugetlb_mcopy_atomic_pte() already does very close to what we want, if an existing page is provided via `struct page **pagep`. We already special-case the behavior a bit for the UFFDIO_ZEROPAGE case, so just extend that design: add an enum for the three modes of operation, and make the small adjustments needed for the MCOPY_ATOMIC_CONTINUE case. (Basically, look up the existing page, and avoid adding the existing page to the page cache or calling set_page_huge_active() on it.) Link: https://lkml.kernel.org/r/20210301222728.176417-5-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:49 +03:00
enum mcopy_atomic_mode mode,
struct page **pagep)
{
userfaultfd: add UFFDIO_CONTINUE ioctl This ioctl is how userspace ought to resolve "minor" userfaults. The idea is, userspace is notified that a minor fault has occurred. It might change the contents of the page using its second non-UFFD mapping, or not. Then, it calls UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Note that it doesn't make much sense to use UFFDIO_{COPY,ZEROPAGE} for MINOR registered VMAs. ZEROPAGE maps the VMA to the zero page; but in the minor fault case, we already have some pre-existing underlying page. Likewise, UFFDIO_COPY isn't useful if we have a second non-UFFD mapping. We'd just use memcpy() or similar instead. It turns out hugetlb_mcopy_atomic_pte() already does very close to what we want, if an existing page is provided via `struct page **pagep`. We already special-case the behavior a bit for the UFFDIO_ZEROPAGE case, so just extend that design: add an enum for the three modes of operation, and make the small adjustments needed for the MCOPY_ATOMIC_CONTINUE case. (Basically, look up the existing page, and avoid adding the existing page to the page cache or calling set_page_huge_active() on it.) Link: https://lkml.kernel.org/r/20210301222728.176417-5-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:49 +03:00
bool is_continue = (mode == MCOPY_ATOMIC_CONTINUE);
mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY On UFFDIO_COPY, if we fail to copy the page contents while holding the hugetlb_fault_mutex, we will drop the mutex and return to the caller after allocating a page that consumed a reservation. In this case there may be a fault that double consumes the reservation. To handle this, we free the allocated page, fix the reservations, and allocate a temporary hugetlb page and return that to the caller. When the caller does the copy outside of the lock, we again check the cache, and allocate a page consuming the reservation, and copy over the contents. Test: Hacked the code locally such that resv_huge_pages underflows produce a warning and the copy_huge_page_from_user() always fails, then: ./tools/testing/selftests/vm/userfaultfd hugetlb_shared 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success ./tools/testing/selftests/vm/userfaultfd hugetlb 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success Both tests succeed and produce no warnings. After the test runs number of free/resv hugepages is correct. [yuehaibing@huawei.com: remove set but not used variable 'vm_alloc_shared'] Link: https://lkml.kernel.org/r/20210601141610.28332-1-yuehaibing@huawei.com [almasrymina@google.com: fix allocation error check and copy func name] Link: https://lkml.kernel.org/r/20210605010626.1459873-1-almasrymina@google.com Link: https://lkml.kernel.org/r/20210528005029.88088-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: YueHaibing <yuehaibing@huawei.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:19 +03:00
struct hstate *h = hstate_vma(dst_vma);
struct address_space *mapping = dst_vma->vm_file->f_mapping;
pgoff_t idx = vma_hugecache_offset(h, dst_vma, dst_addr);
unsigned long size;
int vm_shared = dst_vma->vm_flags & VM_SHARED;
pte_t _dst_pte;
spinlock_t *ptl;
mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY On UFFDIO_COPY, if we fail to copy the page contents while holding the hugetlb_fault_mutex, we will drop the mutex and return to the caller after allocating a page that consumed a reservation. In this case there may be a fault that double consumes the reservation. To handle this, we free the allocated page, fix the reservations, and allocate a temporary hugetlb page and return that to the caller. When the caller does the copy outside of the lock, we again check the cache, and allocate a page consuming the reservation, and copy over the contents. Test: Hacked the code locally such that resv_huge_pages underflows produce a warning and the copy_huge_page_from_user() always fails, then: ./tools/testing/selftests/vm/userfaultfd hugetlb_shared 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success ./tools/testing/selftests/vm/userfaultfd hugetlb 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success Both tests succeed and produce no warnings. After the test runs number of free/resv hugepages is correct. [yuehaibing@huawei.com: remove set but not used variable 'vm_alloc_shared'] Link: https://lkml.kernel.org/r/20210601141610.28332-1-yuehaibing@huawei.com [almasrymina@google.com: fix allocation error check and copy func name] Link: https://lkml.kernel.org/r/20210605010626.1459873-1-almasrymina@google.com Link: https://lkml.kernel.org/r/20210528005029.88088-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: YueHaibing <yuehaibing@huawei.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:19 +03:00
int ret = -ENOMEM;
struct page *page;
userfaultfd: add UFFDIO_CONTINUE ioctl This ioctl is how userspace ought to resolve "minor" userfaults. The idea is, userspace is notified that a minor fault has occurred. It might change the contents of the page using its second non-UFFD mapping, or not. Then, it calls UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Note that it doesn't make much sense to use UFFDIO_{COPY,ZEROPAGE} for MINOR registered VMAs. ZEROPAGE maps the VMA to the zero page; but in the minor fault case, we already have some pre-existing underlying page. Likewise, UFFDIO_COPY isn't useful if we have a second non-UFFD mapping. We'd just use memcpy() or similar instead. It turns out hugetlb_mcopy_atomic_pte() already does very close to what we want, if an existing page is provided via `struct page **pagep`. We already special-case the behavior a bit for the UFFDIO_ZEROPAGE case, so just extend that design: add an enum for the three modes of operation, and make the small adjustments needed for the MCOPY_ATOMIC_CONTINUE case. (Basically, look up the existing page, and avoid adding the existing page to the page cache or calling set_page_huge_active() on it.) Link: https://lkml.kernel.org/r/20210301222728.176417-5-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:49 +03:00
int writable;
bool page_in_pagecache = false;
userfaultfd: add UFFDIO_CONTINUE ioctl This ioctl is how userspace ought to resolve "minor" userfaults. The idea is, userspace is notified that a minor fault has occurred. It might change the contents of the page using its second non-UFFD mapping, or not. Then, it calls UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Note that it doesn't make much sense to use UFFDIO_{COPY,ZEROPAGE} for MINOR registered VMAs. ZEROPAGE maps the VMA to the zero page; but in the minor fault case, we already have some pre-existing underlying page. Likewise, UFFDIO_COPY isn't useful if we have a second non-UFFD mapping. We'd just use memcpy() or similar instead. It turns out hugetlb_mcopy_atomic_pte() already does very close to what we want, if an existing page is provided via `struct page **pagep`. We already special-case the behavior a bit for the UFFDIO_ZEROPAGE case, so just extend that design: add an enum for the three modes of operation, and make the small adjustments needed for the MCOPY_ATOMIC_CONTINUE case. (Basically, look up the existing page, and avoid adding the existing page to the page cache or calling set_page_huge_active() on it.) Link: https://lkml.kernel.org/r/20210301222728.176417-5-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:49 +03:00
if (is_continue) {
ret = -EFAULT;
page = find_lock_page(mapping, idx);
if (!page)
goto out;
page_in_pagecache = true;
userfaultfd: add UFFDIO_CONTINUE ioctl This ioctl is how userspace ought to resolve "minor" userfaults. The idea is, userspace is notified that a minor fault has occurred. It might change the contents of the page using its second non-UFFD mapping, or not. Then, it calls UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Note that it doesn't make much sense to use UFFDIO_{COPY,ZEROPAGE} for MINOR registered VMAs. ZEROPAGE maps the VMA to the zero page; but in the minor fault case, we already have some pre-existing underlying page. Likewise, UFFDIO_COPY isn't useful if we have a second non-UFFD mapping. We'd just use memcpy() or similar instead. It turns out hugetlb_mcopy_atomic_pte() already does very close to what we want, if an existing page is provided via `struct page **pagep`. We already special-case the behavior a bit for the UFFDIO_ZEROPAGE case, so just extend that design: add an enum for the three modes of operation, and make the small adjustments needed for the MCOPY_ATOMIC_CONTINUE case. (Basically, look up the existing page, and avoid adding the existing page to the page cache or calling set_page_huge_active() on it.) Link: https://lkml.kernel.org/r/20210301222728.176417-5-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:49 +03:00
} else if (!*pagep) {
mm, hugetlb: fix simple resv_huge_pages underflow on UFFDIO_COPY The userfaultfd hugetlb tests cause a resv_huge_pages underflow. This happens when hugetlb_mcopy_atomic_pte() is called with !is_continue on an index for which we already have a page in the cache. When this happens, we allocate a second page, double consuming the reservation, and then fail to insert the page into the cache and return -EEXIST. To fix this, we first check if there is a page in the cache which already consumed the reservation, and return -EEXIST immediately if so. There is still a rare condition where we fail to copy the page contents AND race with a call for hugetlb_no_page() for this index and again we will underflow resv_huge_pages. That is fixed in a more complicated patch not targeted for -stable. Test: Hacked the code locally such that resv_huge_pages underflows produce a warning, then: ./tools/testing/selftests/vm/userfaultfd hugetlb_shared 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success ./tools/testing/selftests/vm/userfaultfd hugetlb 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success Both tests succeed and produce no warnings. After the test runs number of free/resv hugepages is correct. [mike.kravetz@oracle.com: changelog fixes] Link: https://lkml.kernel.org/r/20210528004649.85298-1-almasrymina@google.com Fixes: 8fb5debc5fcd ("userfaultfd: hugetlbfs: add hugetlb_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Mina Almasry <almasrymina@google.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-05 06:01:36 +03:00
/* If a page already exists, then it's UFFDIO_COPY for
* a non-missing case. Return -EEXIST.
*/
if (vm_shared &&
hugetlbfs_pagecache_present(h, dst_vma, dst_addr)) {
ret = -EEXIST;
goto out;
}
page = alloc_huge_page(dst_vma, dst_addr, 0);
mm, hugetlb: fix simple resv_huge_pages underflow on UFFDIO_COPY The userfaultfd hugetlb tests cause a resv_huge_pages underflow. This happens when hugetlb_mcopy_atomic_pte() is called with !is_continue on an index for which we already have a page in the cache. When this happens, we allocate a second page, double consuming the reservation, and then fail to insert the page into the cache and return -EEXIST. To fix this, we first check if there is a page in the cache which already consumed the reservation, and return -EEXIST immediately if so. There is still a rare condition where we fail to copy the page contents AND race with a call for hugetlb_no_page() for this index and again we will underflow resv_huge_pages. That is fixed in a more complicated patch not targeted for -stable. Test: Hacked the code locally such that resv_huge_pages underflows produce a warning, then: ./tools/testing/selftests/vm/userfaultfd hugetlb_shared 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success ./tools/testing/selftests/vm/userfaultfd hugetlb 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success Both tests succeed and produce no warnings. After the test runs number of free/resv hugepages is correct. [mike.kravetz@oracle.com: changelog fixes] Link: https://lkml.kernel.org/r/20210528004649.85298-1-almasrymina@google.com Fixes: 8fb5debc5fcd ("userfaultfd: hugetlbfs: add hugetlb_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Mina Almasry <almasrymina@google.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-05 06:01:36 +03:00
if (IS_ERR(page)) {
ret = -ENOMEM;
goto out;
mm, hugetlb: fix simple resv_huge_pages underflow on UFFDIO_COPY The userfaultfd hugetlb tests cause a resv_huge_pages underflow. This happens when hugetlb_mcopy_atomic_pte() is called with !is_continue on an index for which we already have a page in the cache. When this happens, we allocate a second page, double consuming the reservation, and then fail to insert the page into the cache and return -EEXIST. To fix this, we first check if there is a page in the cache which already consumed the reservation, and return -EEXIST immediately if so. There is still a rare condition where we fail to copy the page contents AND race with a call for hugetlb_no_page() for this index and again we will underflow resv_huge_pages. That is fixed in a more complicated patch not targeted for -stable. Test: Hacked the code locally such that resv_huge_pages underflows produce a warning, then: ./tools/testing/selftests/vm/userfaultfd hugetlb_shared 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success ./tools/testing/selftests/vm/userfaultfd hugetlb 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success Both tests succeed and produce no warnings. After the test runs number of free/resv hugepages is correct. [mike.kravetz@oracle.com: changelog fixes] Link: https://lkml.kernel.org/r/20210528004649.85298-1-almasrymina@google.com Fixes: 8fb5debc5fcd ("userfaultfd: hugetlbfs: add hugetlb_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Mina Almasry <almasrymina@google.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-05 06:01:36 +03:00
}
ret = copy_huge_page_from_user(page,
(const void __user *) src_addr,
pages_per_huge_page(h), false);
/* fallback to copy_from_user outside mmap_lock */
if (unlikely(ret)) {
userfaultfd: use ENOENT instead of EFAULT if the atomic copy user fails Patch series "userfaultfd shmem updates". Jann found two bugs in the userfaultfd shmem MAP_SHARED backend: the lack of the VM_MAYWRITE check and the lack of i_size checks. Then looking into the above we also fixed the MAP_PRIVATE case. Hugh by source review also found a data loss source if UFFDIO_COPY is used on shmem MAP_SHARED PROT_READ mappings (the production usages incidentally run with PROT_READ|PROT_WRITE, so the data loss couldn't happen in those production usages like with QEMU). The whole patchset is marked for stable. We verified QEMU postcopy live migration with guest running on shmem MAP_PRIVATE run as well as before after the fix of shmem MAP_PRIVATE. Regardless if it's shmem or hugetlbfs or MAP_PRIVATE or MAP_SHARED, QEMU unconditionally invokes a punch hole if the guest mapping is filebacked and a MADV_DONTNEED too (needed to get rid of the MAP_PRIVATE COWs and for the anon backend). This patch (of 5): We internally used EFAULT to communicate with the caller, switch to ENOENT, so EFAULT can be used as a non internal retval. Link: http://lkml.kernel.org/r/20181126173452.26955-2-aarcange@redhat.com Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Hugh Dickins <hughd@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Jann Horn <jannh@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: <stable@vger.kernel.org> Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01 01:09:25 +03:00
ret = -ENOENT;
mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY On UFFDIO_COPY, if we fail to copy the page contents while holding the hugetlb_fault_mutex, we will drop the mutex and return to the caller after allocating a page that consumed a reservation. In this case there may be a fault that double consumes the reservation. To handle this, we free the allocated page, fix the reservations, and allocate a temporary hugetlb page and return that to the caller. When the caller does the copy outside of the lock, we again check the cache, and allocate a page consuming the reservation, and copy over the contents. Test: Hacked the code locally such that resv_huge_pages underflows produce a warning and the copy_huge_page_from_user() always fails, then: ./tools/testing/selftests/vm/userfaultfd hugetlb_shared 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success ./tools/testing/selftests/vm/userfaultfd hugetlb 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success Both tests succeed and produce no warnings. After the test runs number of free/resv hugepages is correct. [yuehaibing@huawei.com: remove set but not used variable 'vm_alloc_shared'] Link: https://lkml.kernel.org/r/20210601141610.28332-1-yuehaibing@huawei.com [almasrymina@google.com: fix allocation error check and copy func name] Link: https://lkml.kernel.org/r/20210605010626.1459873-1-almasrymina@google.com Link: https://lkml.kernel.org/r/20210528005029.88088-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: YueHaibing <yuehaibing@huawei.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:19 +03:00
/* Free the allocated page which may have
* consumed a reservation.
*/
restore_reserve_on_error(h, dst_vma, dst_addr, page);
put_page(page);
/* Allocate a temporary page to hold the copied
* contents.
*/
page = alloc_huge_page_vma(h, dst_vma, dst_addr);
if (!page) {
ret = -ENOMEM;
goto out;
}
*pagep = page;
mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY On UFFDIO_COPY, if we fail to copy the page contents while holding the hugetlb_fault_mutex, we will drop the mutex and return to the caller after allocating a page that consumed a reservation. In this case there may be a fault that double consumes the reservation. To handle this, we free the allocated page, fix the reservations, and allocate a temporary hugetlb page and return that to the caller. When the caller does the copy outside of the lock, we again check the cache, and allocate a page consuming the reservation, and copy over the contents. Test: Hacked the code locally such that resv_huge_pages underflows produce a warning and the copy_huge_page_from_user() always fails, then: ./tools/testing/selftests/vm/userfaultfd hugetlb_shared 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success ./tools/testing/selftests/vm/userfaultfd hugetlb 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success Both tests succeed and produce no warnings. After the test runs number of free/resv hugepages is correct. [yuehaibing@huawei.com: remove set but not used variable 'vm_alloc_shared'] Link: https://lkml.kernel.org/r/20210601141610.28332-1-yuehaibing@huawei.com [almasrymina@google.com: fix allocation error check and copy func name] Link: https://lkml.kernel.org/r/20210605010626.1459873-1-almasrymina@google.com Link: https://lkml.kernel.org/r/20210528005029.88088-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: YueHaibing <yuehaibing@huawei.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:19 +03:00
/* Set the outparam pagep and return to the caller to
* copy the contents outside the lock. Don't free the
* page.
*/
goto out;
}
} else {
mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY On UFFDIO_COPY, if we fail to copy the page contents while holding the hugetlb_fault_mutex, we will drop the mutex and return to the caller after allocating a page that consumed a reservation. In this case there may be a fault that double consumes the reservation. To handle this, we free the allocated page, fix the reservations, and allocate a temporary hugetlb page and return that to the caller. When the caller does the copy outside of the lock, we again check the cache, and allocate a page consuming the reservation, and copy over the contents. Test: Hacked the code locally such that resv_huge_pages underflows produce a warning and the copy_huge_page_from_user() always fails, then: ./tools/testing/selftests/vm/userfaultfd hugetlb_shared 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success ./tools/testing/selftests/vm/userfaultfd hugetlb 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success Both tests succeed and produce no warnings. After the test runs number of free/resv hugepages is correct. [yuehaibing@huawei.com: remove set but not used variable 'vm_alloc_shared'] Link: https://lkml.kernel.org/r/20210601141610.28332-1-yuehaibing@huawei.com [almasrymina@google.com: fix allocation error check and copy func name] Link: https://lkml.kernel.org/r/20210605010626.1459873-1-almasrymina@google.com Link: https://lkml.kernel.org/r/20210528005029.88088-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: YueHaibing <yuehaibing@huawei.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:19 +03:00
if (vm_shared &&
hugetlbfs_pagecache_present(h, dst_vma, dst_addr)) {
put_page(*pagep);
ret = -EEXIST;
*pagep = NULL;
goto out;
}
page = alloc_huge_page(dst_vma, dst_addr, 0);
if (IS_ERR(page)) {
ret = -ENOMEM;
*pagep = NULL;
goto out;
}
copy_user_huge_page(page, *pagep, dst_addr, dst_vma,
pages_per_huge_page(h));
mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY On UFFDIO_COPY, if we fail to copy the page contents while holding the hugetlb_fault_mutex, we will drop the mutex and return to the caller after allocating a page that consumed a reservation. In this case there may be a fault that double consumes the reservation. To handle this, we free the allocated page, fix the reservations, and allocate a temporary hugetlb page and return that to the caller. When the caller does the copy outside of the lock, we again check the cache, and allocate a page consuming the reservation, and copy over the contents. Test: Hacked the code locally such that resv_huge_pages underflows produce a warning and the copy_huge_page_from_user() always fails, then: ./tools/testing/selftests/vm/userfaultfd hugetlb_shared 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success ./tools/testing/selftests/vm/userfaultfd hugetlb 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success Both tests succeed and produce no warnings. After the test runs number of free/resv hugepages is correct. [yuehaibing@huawei.com: remove set but not used variable 'vm_alloc_shared'] Link: https://lkml.kernel.org/r/20210601141610.28332-1-yuehaibing@huawei.com [almasrymina@google.com: fix allocation error check and copy func name] Link: https://lkml.kernel.org/r/20210605010626.1459873-1-almasrymina@google.com Link: https://lkml.kernel.org/r/20210528005029.88088-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: YueHaibing <yuehaibing@huawei.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:19 +03:00
put_page(*pagep);
*pagep = NULL;
}
/*
* The memory barrier inside __SetPageUptodate makes sure that
* preceding stores to the page contents become visible before
* the set_pte_at() write.
*/
__SetPageUptodate(page);
userfaultfd: add UFFDIO_CONTINUE ioctl This ioctl is how userspace ought to resolve "minor" userfaults. The idea is, userspace is notified that a minor fault has occurred. It might change the contents of the page using its second non-UFFD mapping, or not. Then, it calls UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Note that it doesn't make much sense to use UFFDIO_{COPY,ZEROPAGE} for MINOR registered VMAs. ZEROPAGE maps the VMA to the zero page; but in the minor fault case, we already have some pre-existing underlying page. Likewise, UFFDIO_COPY isn't useful if we have a second non-UFFD mapping. We'd just use memcpy() or similar instead. It turns out hugetlb_mcopy_atomic_pte() already does very close to what we want, if an existing page is provided via `struct page **pagep`. We already special-case the behavior a bit for the UFFDIO_ZEROPAGE case, so just extend that design: add an enum for the three modes of operation, and make the small adjustments needed for the MCOPY_ATOMIC_CONTINUE case. (Basically, look up the existing page, and avoid adding the existing page to the page cache or calling set_page_huge_active() on it.) Link: https://lkml.kernel.org/r/20210301222728.176417-5-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:49 +03:00
/* Add shared, newly allocated pages to the page cache. */
if (vm_shared && !is_continue) {
size = i_size_read(mapping->host) >> huge_page_shift(h);
ret = -EFAULT;
if (idx >= size)
goto out_release_nounlock;
/*
* Serialization between remove_inode_hugepages() and
* huge_add_to_page_cache() below happens through the
* hugetlb_fault_mutex_table that here must be hold by
* the caller.
*/
ret = huge_add_to_page_cache(page, mapping, idx);
if (ret)
goto out_release_nounlock;
page_in_pagecache = true;
}
ptl = huge_pte_lockptr(h, dst_mm, dst_pte);
spin_lock(ptl);
/*
* Recheck the i_size after holding PT lock to make sure not
* to leave any page mapped (as page_mapped()) beyond the end
* of the i_size (remove_inode_hugepages() is strict about
* enforcing that). If we bail out here, we'll also leave a
* page in the radix tree in the vm_shared case beyond the end
* of the i_size, but remove_inode_hugepages() will take care
* of it as soon as we drop the hugetlb_fault_mutex_table.
*/
size = i_size_read(mapping->host) >> huge_page_shift(h);
ret = -EFAULT;
if (idx >= size)
goto out_release_unlock;
ret = -EEXIST;
if (!huge_pte_none(huge_ptep_get(dst_pte)))
goto out_release_unlock;
if (vm_shared) {
mm/rmap: split page_dup_rmap() into page_dup_file_rmap() and page_try_dup_anon_rmap() ... and move the special check for pinned pages into page_try_dup_anon_rmap() to prepare for tracking exclusive anonymous pages via a new pageflag, clearing it only after making sure that there are no GUP pins on the anonymous page. We really only care about pins on anonymous pages, because they are prone to getting replaced in the COW handler once mapped R/O. For !anon pages in cow-mappings (!VM_SHARED && VM_MAYWRITE) we shouldn't really care about that, at least not that I could come up with an example. Let's drop the is_cow_mapping() check from page_needs_cow_for_dma(), as we know we're dealing with anonymous pages. Also, drop the handling of pinned pages from copy_huge_pud() and add a comment if ever supporting anonymous pages on the PUD level. This is a preparation for tracking exclusivity of anonymous pages in the rmap code, and disallowing marking a page shared (-> failing to duplicate) if there are GUP pins on a page. Link: https://lkml.kernel.org/r/20220428083441.37290-5-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:43 +03:00
page_dup_file_rmap(page, true);
} else {
hugetlb: use page.private for hugetlb specific page flags Patch series "create hugetlb flags to consolidate state", v3. While discussing a series of hugetlb fixes in [1], it became evident that the hugetlb specific page state information is stored in a somewhat haphazard manner. Code dealing with state information would be easier to read, understand and maintain if this information was stored in a consistent manner. This series uses page.private of the hugetlb head page for storing a set of hugetlb specific page flags. Routines are priovided for test, set and clear of the flags. [1] https://lore.kernel.org/r/20210106084739.63318-1-songmuchun@bytedance.com This patch (of 4): As hugetlbfs evolved, state information about hugetlb pages was added. One 'convenient' way of doing this was to use available fields in tail pages. Over time, it has become difficult to know the meaning or contents of fields simply by looking at a small bit of code. Sometimes, the naming is just confusing. For example: The PagePrivate flag indicates a huge page reservation was consumed and needs to be restored if an error is encountered and the page is freed before it is instantiated. The page.private field contains the pointer to a subpool if the page is associated with one. In an effort to make the code more readable, use page.private to contain hugetlb specific page flags. These flags will have test, set and clear functions similar to those used for 'normal' page flags. More importantly, an enum of flag values will be created with names that actually reflect their purpose. In this patch, - Create infrastructure for hugetlb specific page flag functions - Move subpool pointer to page[1].private to make way for flags Create routines with meaningful names to modify subpool field - Use new HPageRestoreReserve flag instead of PagePrivate Conversion of other state information will happen in subsequent patches. Link: https://lkml.kernel.org/r/20210122195231.324857-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20210122195231.324857-2-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:51 +03:00
ClearHPageRestoreReserve(page);
hugepage_add_new_anon_rmap(page, dst_vma, dst_addr);
}
userfaultfd: add UFFDIO_CONTINUE ioctl This ioctl is how userspace ought to resolve "minor" userfaults. The idea is, userspace is notified that a minor fault has occurred. It might change the contents of the page using its second non-UFFD mapping, or not. Then, it calls UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Note that it doesn't make much sense to use UFFDIO_{COPY,ZEROPAGE} for MINOR registered VMAs. ZEROPAGE maps the VMA to the zero page; but in the minor fault case, we already have some pre-existing underlying page. Likewise, UFFDIO_COPY isn't useful if we have a second non-UFFD mapping. We'd just use memcpy() or similar instead. It turns out hugetlb_mcopy_atomic_pte() already does very close to what we want, if an existing page is provided via `struct page **pagep`. We already special-case the behavior a bit for the UFFDIO_ZEROPAGE case, so just extend that design: add an enum for the three modes of operation, and make the small adjustments needed for the MCOPY_ATOMIC_CONTINUE case. (Basically, look up the existing page, and avoid adding the existing page to the page cache or calling set_page_huge_active() on it.) Link: https://lkml.kernel.org/r/20210301222728.176417-5-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:49 +03:00
/* For CONTINUE on a non-shared VMA, don't set VM_WRITE for CoW. */
if (is_continue && !vm_shared)
writable = 0;
else
writable = dst_vma->vm_flags & VM_WRITE;
_dst_pte = make_huge_pte(dst_vma, page, writable);
if (writable)
_dst_pte = huge_pte_mkdirty(_dst_pte);
_dst_pte = pte_mkyoung(_dst_pte);
set_huge_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
(void)huge_ptep_set_access_flags(dst_vma, dst_addr, dst_pte, _dst_pte,
dst_vma->vm_flags & VM_WRITE);
hugetlb_count_add(pages_per_huge_page(h), dst_mm);
/* No need to invalidate - it was non-present before */
update_mmu_cache(dst_vma, dst_addr, dst_pte);
spin_unlock(ptl);
userfaultfd: add UFFDIO_CONTINUE ioctl This ioctl is how userspace ought to resolve "minor" userfaults. The idea is, userspace is notified that a minor fault has occurred. It might change the contents of the page using its second non-UFFD mapping, or not. Then, it calls UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Note that it doesn't make much sense to use UFFDIO_{COPY,ZEROPAGE} for MINOR registered VMAs. ZEROPAGE maps the VMA to the zero page; but in the minor fault case, we already have some pre-existing underlying page. Likewise, UFFDIO_COPY isn't useful if we have a second non-UFFD mapping. We'd just use memcpy() or similar instead. It turns out hugetlb_mcopy_atomic_pte() already does very close to what we want, if an existing page is provided via `struct page **pagep`. We already special-case the behavior a bit for the UFFDIO_ZEROPAGE case, so just extend that design: add an enum for the three modes of operation, and make the small adjustments needed for the MCOPY_ATOMIC_CONTINUE case. (Basically, look up the existing page, and avoid adding the existing page to the page cache or calling set_page_huge_active() on it.) Link: https://lkml.kernel.org/r/20210301222728.176417-5-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:49 +03:00
if (!is_continue)
SetHPageMigratable(page);
if (vm_shared || is_continue)
unlock_page(page);
ret = 0;
out:
return ret;
out_release_unlock:
spin_unlock(ptl);
userfaultfd: add UFFDIO_CONTINUE ioctl This ioctl is how userspace ought to resolve "minor" userfaults. The idea is, userspace is notified that a minor fault has occurred. It might change the contents of the page using its second non-UFFD mapping, or not. Then, it calls UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Note that it doesn't make much sense to use UFFDIO_{COPY,ZEROPAGE} for MINOR registered VMAs. ZEROPAGE maps the VMA to the zero page; but in the minor fault case, we already have some pre-existing underlying page. Likewise, UFFDIO_COPY isn't useful if we have a second non-UFFD mapping. We'd just use memcpy() or similar instead. It turns out hugetlb_mcopy_atomic_pte() already does very close to what we want, if an existing page is provided via `struct page **pagep`. We already special-case the behavior a bit for the UFFDIO_ZEROPAGE case, so just extend that design: add an enum for the three modes of operation, and make the small adjustments needed for the MCOPY_ATOMIC_CONTINUE case. (Basically, look up the existing page, and avoid adding the existing page to the page cache or calling set_page_huge_active() on it.) Link: https://lkml.kernel.org/r/20210301222728.176417-5-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:49 +03:00
if (vm_shared || is_continue)
unlock_page(page);
out_release_nounlock:
if (!page_in_pagecache)
hugetlb: don't pass page cache pages to restore_reserve_on_error syzbot hit kernel BUG at fs/hugetlbfs/inode.c:532 as described in [1]. This BUG triggers if the HPageRestoreReserve flag is set on a page in the page cache. It should never be set, as the routine huge_add_to_page_cache explicitly clears the flag after adding a page to the cache. The only code other than huge page allocation which sets the flag is restore_reserve_on_error. It will potentially set the flag in rare out of memory conditions. syzbot was injecting errors to cause memory allocation errors which exercised this specific path. The code in restore_reserve_on_error is doing the right thing. However, there are instances where pages in the page cache were being passed to restore_reserve_on_error. This is incorrect, as once a page goes into the cache reservation information will not be modified for the page until it is removed from the cache. Error paths do not remove pages from the cache, so even in the case of error, the page will remain in the cache and no reservation adjustment is needed. Modify routines that potentially call restore_reserve_on_error with a page cache page to no longer do so. Note on fixes tag: Prior to commit 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") the routine would not process page cache pages because the HPageRestoreReserve flag is not set on such pages. Therefore, this issue could not be trigggered. The code added by commit 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") is needed and correct. It exposed incorrect calls to restore_reserve_on_error which is the root cause addressed by this commit. [1] https://lore.kernel.org/linux-mm/00000000000050776d05c9b7c7f0@google.com/ Link: https://lkml.kernel.org/r/20210818213304.37038-1-mike.kravetz@oracle.com Fixes: 846be08578ed ("mm/hugetlb: expand restore_reserve_on_error functionality") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: <syzbot+67654e51e54455f1c585@syzkaller.appspotmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-08-20 05:04:33 +03:00
restore_reserve_on_error(h, dst_vma, dst_addr, page);
put_page(page);
goto out;
}
userfaultfd: hugetlbfs: only compile UFFD helpers if config enabled For background, mm/userfaultfd.c provides a general mcopy_atomic implementation. But some types of memory (i.e., hugetlb and shmem) need a slightly different implementation, so they provide their own helpers for this. In other words, userfaultfd is the only caller of these functions. This patch achieves two things: 1. Don't spend time compiling code which will end up never being referenced anyway (a small build time optimization). 2. In patches later in this series, we extend the signature of these helpers with UFFD-specific state (a mode enumeration). Once this happens, we *have to* either not compile the helpers, or unconditionally define the UFFD-only state (which seems messier to me). This includes the declarations in the headers, as otherwise they'd yield warnings about implicitly defining the type of those arguments. Link: https://lkml.kernel.org/r/20210301222728.176417-4-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:45 +03:00
#endif /* CONFIG_USERFAULTFD */
static void record_subpages_vmas(struct page *page, struct vm_area_struct *vma,
int refs, struct page **pages,
struct vm_area_struct **vmas)
{
int nr;
for (nr = 0; nr < refs; nr++) {
if (likely(pages))
pages[nr] = mem_map_offset(page, nr);
if (vmas)
vmas[nr] = vma;
}
}
mm/gup: trigger FAULT_FLAG_UNSHARE when R/O-pinning a possibly shared anonymous page Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. Let's implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. This change implies that whenever user space *wrote* to a private mapping (IOW, we have an anonymous page mapped), that GUP pins will always remain consistent: reliable R/O GUP pins of anonymous pages. As a side note, this commit fixes the COW security issue for hugetlb with FOLL_PIN as documented in: https://lore.kernel.org/r/3ae33b08-d9ef-f846-56fb-645e3b9b4c66@redhat.com The vmsplice reproducer still applies, because vmsplice uses FOLL_GET instead of FOLL_PIN. Note that follow_huge_pmd() doesn't apply because we cannot end up in there with FOLL_PIN. This commit is heavily based on prototype patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-17-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
static inline bool __follow_hugetlb_must_fault(unsigned int flags, pte_t *pte,
bool *unshare)
{
pte_t pteval = huge_ptep_get(pte);
*unshare = false;
if (is_swap_pte(pteval))
return true;
if (huge_pte_write(pteval))
return false;
if (flags & FOLL_WRITE)
return true;
if (gup_must_unshare(flags, pte_page(pteval))) {
*unshare = true;
return true;
}
return false;
}
long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
struct page **pages, struct vm_area_struct **vmas,
unsigned long *position, unsigned long *nr_pages,
mm/gup: rename "nonblocking" to "locked" where proper Patch series "mm: Page fault enhancements", v6. This series contains cleanups and enhancements to current page fault logic. The whole idea comes from the discussion between Andrea and Linus on the bug reported by syzbot here: https://lkml.org/lkml/2017/11/2/833 Basically it does two things: (a) Allows the page fault logic to be more interactive on not only SIGKILL, but also the rest of userspace signals, and, (b) Allows the page fault retry (VM_FAULT_RETRY) to happen for more than once. For (a): with the changes we should be able to react faster when page faults are working in parallel with userspace signals like SIGSTOP and SIGCONT (and more), and with that we can remove the buggy part in userfaultfd and benefit the whole page fault mechanism on faster signal processing to reach the userspace. For (b), we should be able to allow the page fault handler to loop for even more than twice. Some context: for now since we have FAULT_FLAG_ALLOW_RETRY we can allow to retry the page fault once with the same interrupt context, however never more than twice. This can be not only a potential cleanup to remove this assumption since AFAIU the code itself doesn't really have this twice-only limitation (though that should be a protective approach in the past), at the same time it'll greatly simplify future works like userfaultfd write-protect where it's possible to retry for more than twice (please have a look at [1] below for a possible user that might require the page fault to be handled for a third time; if we can remove the retry limitation we can simply drop that patch and those complexity). This patch (of 16): There's plenty of places around __get_user_pages() that has a parameter "nonblocking" which does not really mean that "it won't block" (because it can really block) but instead it shows whether the mmap_sem is released by up_read() during the page fault handling mostly when VM_FAULT_RETRY is returned. We have the correct naming in e.g. get_user_pages_locked() or get_user_pages_remote() as "locked", however there're still many places that are using the "nonblocking" as name. Renaming the places to "locked" where proper to better suite the functionality of the variable. While at it, fixing up some of the comments accordingly. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Brian Geffon <bgeffon@google.com> Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Reviewed-by: Jerome Glisse <jglisse@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Martin Cracauer <cracauer@cons.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: Pavel Emelyanov <xemul@openvz.org> Link: http://lkml.kernel.org/r/20200220155353.8676-2-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:07:58 +03:00
long i, unsigned int flags, int *locked)
{
unsigned long pfn_offset;
unsigned long vaddr = *position;
unsigned long remainder = *nr_pages;
struct hstate *h = hstate_vma(vma);
mm/hugetlb: grab head page refcount once for group of subpages Patch series "mm/hugetlb: follow_hugetlb_page() improvements", v2. While looking at ZONE_DEVICE struct page reuse particularly the last patch[0], I found two possible improvements for follow_hugetlb_page() which is solely used for get_user_pages()/pin_user_pages(). The first patch batches page refcount updates while the second tidies up storing the subpages/vmas. Both together bring the cost of slow variant of gup() cost from ~87.6k usecs to ~5.8k usecs. libhugetlbfs tests seem to pass as well gup_test benchmarks with hugetlbfs vmas. This patch (of 2): follow_hugetlb_page() once it locks the pmd/pud, checks all its N subpages in a huge page and grabs a reference for each one. Similar to gup-fast, have follow_hugetlb_page() grab the head page refcount only after counting all its subpages that are part of the just faulted huge page. Consequently we reduce the number of atomics necessary to pin said huge page, which improves non-fast gup() considerably: - 16G with 1G huge page size gup_test -f /mnt/huge/file -m 16384 -r 10 -L -S -n 512 -w PIN_LONGTERM_BENCHMARK: ~87.6k us -> ~12.8k us Link: https://lkml.kernel.org/r/20210128182632.24562-1-joao.m.martins@oracle.com Link: https://lkml.kernel.org/r/20210128182632.24562-2-joao.m.martins@oracle.com Signed-off-by: Joao Martins <joao.m.martins@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:07:12 +03:00
int err = -EFAULT, refs;
while (vaddr < vma->vm_end && remainder) {
pte_t *pte;
spinlock_t *ptl = NULL;
mm/gup: trigger FAULT_FLAG_UNSHARE when R/O-pinning a possibly shared anonymous page Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. Let's implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. This change implies that whenever user space *wrote* to a private mapping (IOW, we have an anonymous page mapped), that GUP pins will always remain consistent: reliable R/O GUP pins of anonymous pages. As a side note, this commit fixes the COW security issue for hugetlb with FOLL_PIN as documented in: https://lore.kernel.org/r/3ae33b08-d9ef-f846-56fb-645e3b9b4c66@redhat.com The vmsplice reproducer still applies, because vmsplice uses FOLL_GET instead of FOLL_PIN. Note that follow_huge_pmd() doesn't apply because we cannot end up in there with FOLL_PIN. This commit is heavily based on prototype patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-17-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
bool unshare = false;
int absent;
struct page *page;
/*
* If we have a pending SIGKILL, don't keep faulting pages and
* potentially allocating memory.
*/
if (fatal_signal_pending(current)) {
remainder = 0;
break;
}
/*
* Some archs (sparc64, sh*) have multiple pte_ts to
* each hugepage. We have to make sure we get the
* first, for the page indexing below to work.
*
* Note that page table lock is not held when pte is null.
*/
mm/hugetlb: add size parameter to huge_pte_offset() A poisoned or migrated hugepage is stored as a swap entry in the page tables. On architectures that support hugepages consisting of contiguous page table entries (such as on arm64) this leads to ambiguity in determining the page table entry to return in huge_pte_offset() when a poisoned entry is encountered. Let's remove the ambiguity by adding a size parameter to convey additional information about the requested address. Also fixup the definition/usage of huge_pte_offset() throughout the tree. Link: http://lkml.kernel.org/r/20170522133604.11392-4-punit.agrawal@arm.com Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Acked-by: Steve Capper <steve.capper@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: James Hogan <james.hogan@imgtec.com> (odd fixer:METAG ARCHITECTURE) Cc: Ralf Baechle <ralf@linux-mips.org> (supporter:MIPS) Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Rich Felker <dalias@libc.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-07 01:39:42 +03:00
pte = huge_pte_offset(mm, vaddr & huge_page_mask(h),
huge_page_size(h));
if (pte)
ptl = huge_pte_lock(h, mm, pte);
absent = !pte || huge_pte_none(huge_ptep_get(pte));
/*
* When coredumping, it suits get_dump_page if we just return
* an error where there's an empty slot with no huge pagecache
* to back it. This way, we avoid allocating a hugepage, and
* the sparse dumpfile avoids allocating disk blocks, but its
* huge holes still show up with zeroes where they need to be.
*/
if (absent && (flags & FOLL_DUMP) &&
!hugetlbfs_pagecache_present(h, vma, vaddr)) {
if (pte)
spin_unlock(ptl);
remainder = 0;
break;
}
hugetlbfs: add swap entry check in follow_hugetlb_page() With applying the previous patch "hugetlbfs: stop setting VM_DONTDUMP in initializing vma(VM_HUGETLB)" to reenable hugepage coredump, if a memory error happens on a hugepage and the affected processes try to access the error hugepage, we hit VM_BUG_ON(atomic_read(&page->_count) <= 0) in get_page(). The reason for this bug is that coredump-related code doesn't recognise "hugepage hwpoison entry" with which a pmd entry is replaced when a memory error occurs on a hugepage. In other words, physical address information is stored in different bit layout between hugepage hwpoison entry and pmd entry, so follow_hugetlb_page() which is called in get_dump_page() returns a wrong page from a given address. The expected behavior is like this: absent is_swap_pte FOLL_DUMP Expected behavior ------------------------------------------------------------------- true false false hugetlb_fault false true false hugetlb_fault false false false return page true false true skip page (to avoid allocation) false true true hugetlb_fault false false true return page With this patch, we can call hugetlb_fault() and take proper actions (we wait for migration entries, fail with VM_FAULT_HWPOISON_LARGE for hwpoisoned entries,) and as the result we can dump all hugepages except for hwpoisoned ones. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: David Rientjes <rientjes@google.com> Cc: <stable@vger.kernel.org> [2.6.34+?] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-18 02:58:30 +04:00
/*
* We need call hugetlb_fault for both hugepages under migration
* (in which case hugetlb_fault waits for the migration,) and
* hwpoisoned hugepages (in which case we need to prevent the
* caller from accessing to them.) In order to do this, we use
* here is_swap_pte instead of is_hugetlb_entry_migration and
* is_hugetlb_entry_hwpoisoned. This is because it simply covers
* both cases, and because we can't follow correct pages
* directly from any kind of swap entries.
*/
mm/gup: trigger FAULT_FLAG_UNSHARE when R/O-pinning a possibly shared anonymous page Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. Let's implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. This change implies that whenever user space *wrote* to a private mapping (IOW, we have an anonymous page mapped), that GUP pins will always remain consistent: reliable R/O GUP pins of anonymous pages. As a side note, this commit fixes the COW security issue for hugetlb with FOLL_PIN as documented in: https://lore.kernel.org/r/3ae33b08-d9ef-f846-56fb-645e3b9b4c66@redhat.com The vmsplice reproducer still applies, because vmsplice uses FOLL_GET instead of FOLL_PIN. Note that follow_huge_pmd() doesn't apply because we cannot end up in there with FOLL_PIN. This commit is heavily based on prototype patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-17-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
if (absent ||
__follow_hugetlb_must_fault(flags, pte, &unshare)) {
vm_fault_t ret;
unsigned int fault_flags = 0;
if (pte)
spin_unlock(ptl);
if (flags & FOLL_WRITE)
fault_flags |= FAULT_FLAG_WRITE;
mm/gup: trigger FAULT_FLAG_UNSHARE when R/O-pinning a possibly shared anonymous page Whenever GUP currently ends up taking a R/O pin on an anonymous page that might be shared -- mapped R/O and !PageAnonExclusive() -- any write fault on the page table entry will end up replacing the mapped anonymous page due to COW, resulting in the GUP pin no longer being consistent with the page actually mapped into the page table. The possible ways to deal with this situation are: (1) Ignore and pin -- what we do right now. (2) Fail to pin -- which would be rather surprising to callers and could break user space. (3) Trigger unsharing and pin the now exclusive page -- reliable R/O pins. Let's implement 3) because it provides the clearest semantics and allows for checking in unpin_user_pages() and friends for possible BUGs: when trying to unpin a page that's no longer exclusive, clearly something went very wrong and might result in memory corruptions that might be hard to debug. So we better have a nice way to spot such issues. This change implies that whenever user space *wrote* to a private mapping (IOW, we have an anonymous page mapped), that GUP pins will always remain consistent: reliable R/O GUP pins of anonymous pages. As a side note, this commit fixes the COW security issue for hugetlb with FOLL_PIN as documented in: https://lore.kernel.org/r/3ae33b08-d9ef-f846-56fb-645e3b9b4c66@redhat.com The vmsplice reproducer still applies, because vmsplice uses FOLL_GET instead of FOLL_PIN. Note that follow_huge_pmd() doesn't apply because we cannot end up in there with FOLL_PIN. This commit is heavily based on prototype patches by Andrea. Link: https://lkml.kernel.org/r/20220428083441.37290-17-david@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Co-developed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
else if (unshare)
fault_flags |= FAULT_FLAG_UNSHARE;
mm/gup: rename "nonblocking" to "locked" where proper Patch series "mm: Page fault enhancements", v6. This series contains cleanups and enhancements to current page fault logic. The whole idea comes from the discussion between Andrea and Linus on the bug reported by syzbot here: https://lkml.org/lkml/2017/11/2/833 Basically it does two things: (a) Allows the page fault logic to be more interactive on not only SIGKILL, but also the rest of userspace signals, and, (b) Allows the page fault retry (VM_FAULT_RETRY) to happen for more than once. For (a): with the changes we should be able to react faster when page faults are working in parallel with userspace signals like SIGSTOP and SIGCONT (and more), and with that we can remove the buggy part in userfaultfd and benefit the whole page fault mechanism on faster signal processing to reach the userspace. For (b), we should be able to allow the page fault handler to loop for even more than twice. Some context: for now since we have FAULT_FLAG_ALLOW_RETRY we can allow to retry the page fault once with the same interrupt context, however never more than twice. This can be not only a potential cleanup to remove this assumption since AFAIU the code itself doesn't really have this twice-only limitation (though that should be a protective approach in the past), at the same time it'll greatly simplify future works like userfaultfd write-protect where it's possible to retry for more than twice (please have a look at [1] below for a possible user that might require the page fault to be handled for a third time; if we can remove the retry limitation we can simply drop that patch and those complexity). This patch (of 16): There's plenty of places around __get_user_pages() that has a parameter "nonblocking" which does not really mean that "it won't block" (because it can really block) but instead it shows whether the mmap_sem is released by up_read() during the page fault handling mostly when VM_FAULT_RETRY is returned. We have the correct naming in e.g. get_user_pages_locked() or get_user_pages_remote() as "locked", however there're still many places that are using the "nonblocking" as name. Renaming the places to "locked" where proper to better suite the functionality of the variable. While at it, fixing up some of the comments accordingly. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Brian Geffon <bgeffon@google.com> Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Reviewed-by: Jerome Glisse <jglisse@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Martin Cracauer <cracauer@cons.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: Pavel Emelyanov <xemul@openvz.org> Link: http://lkml.kernel.org/r/20200220155353.8676-2-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:07:58 +03:00
if (locked)
mm/gup: allow to react to fatal signals The existing gup code does not react to the fatal signals in many code paths. For example, in one retry path of gup we're still using down_read() rather than down_read_killable(). Also, when doing page faults we don't pass in FAULT_FLAG_KILLABLE as well, which means that within the faulting process we'll wait in non-killable way as well. These were spotted by Linus during the code review of some other patches. Let's allow the gup code to react to fatal signals to improve the responsiveness of threads when during gup and being killed. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Brian Geffon <bgeffon@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: David Hildenbrand <david@redhat.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Martin Cracauer <cracauer@cons.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Matthew Wilcox <willy@infradead.org> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Link: http://lkml.kernel.org/r/20200220160256.9887-1-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:08:53 +03:00
fault_flags |= FAULT_FLAG_ALLOW_RETRY |
FAULT_FLAG_KILLABLE;
if (flags & FOLL_NOWAIT)
fault_flags |= FAULT_FLAG_ALLOW_RETRY |
FAULT_FLAG_RETRY_NOWAIT;
if (flags & FOLL_TRIED) {
/*
* Note: FAULT_FLAG_ALLOW_RETRY and
* FAULT_FLAG_TRIED can co-exist
*/
fault_flags |= FAULT_FLAG_TRIED;
}
ret = hugetlb_fault(mm, vma, vaddr, fault_flags);
if (ret & VM_FAULT_ERROR) {
mm/hugetlb.c: __get_user_pages ignores certain follow_hugetlb_page errors Commit 9a291a7c9428 ("mm/hugetlb: report -EHWPOISON not -EFAULT when FOLL_HWPOISON is specified") causes __get_user_pages to ignore certain errors from follow_hugetlb_page. After such error, __get_user_pages subsequently calls faultin_page on the same VMA and start address that follow_hugetlb_page failed on instead of returning the error immediately as it should. In follow_hugetlb_page, when hugetlb_fault returns a value covered under VM_FAULT_ERROR, follow_hugetlb_page returns it without setting nr_pages to 0 as __get_user_pages expects in this case, which causes the following to happen in __get_user_pages: the "while (nr_pages)" check succeeds, we skip the "if (!vma..." check because we got a VMA the last time around, we find no page with follow_page_mask, and we call faultin_page, which calls hugetlb_fault for the second time. This issue also slightly changes how __get_user_pages works. Before, it only returned error if it had made no progress (i = 0). But now, follow_hugetlb_page can clobber "i" with an error code since its new return path doesn't check for progress. So if "i" is nonzero before a failing call to follow_hugetlb_page, that indication of progress is lost and __get_user_pages can return error even if some pages were successfully pinned. To fix this, change follow_hugetlb_page so that it updates nr_pages, allowing __get_user_pages to fail immediately and restoring the "error only if no progress" behavior to __get_user_pages. Tested that __get_user_pages returns when expected on error from hugetlb_fault in follow_hugetlb_page. Fixes: 9a291a7c9428 ("mm/hugetlb: report -EHWPOISON not -EFAULT when FOLL_HWPOISON is specified") Link: http://lkml.kernel.org/r/1500406795-58462-1-git-send-email-daniel.m.jordan@oracle.com Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Acked-by: Punit Agrawal <punit.agrawal@arm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: James Morse <james.morse@arm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: zhong jiang <zhongjiang@huawei.com> Cc: <stable@vger.kernel.org> [4.12.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-02 23:31:47 +03:00
err = vm_fault_to_errno(ret, flags);
remainder = 0;
break;
}
if (ret & VM_FAULT_RETRY) {
mm/gup: rename "nonblocking" to "locked" where proper Patch series "mm: Page fault enhancements", v6. This series contains cleanups and enhancements to current page fault logic. The whole idea comes from the discussion between Andrea and Linus on the bug reported by syzbot here: https://lkml.org/lkml/2017/11/2/833 Basically it does two things: (a) Allows the page fault logic to be more interactive on not only SIGKILL, but also the rest of userspace signals, and, (b) Allows the page fault retry (VM_FAULT_RETRY) to happen for more than once. For (a): with the changes we should be able to react faster when page faults are working in parallel with userspace signals like SIGSTOP and SIGCONT (and more), and with that we can remove the buggy part in userfaultfd and benefit the whole page fault mechanism on faster signal processing to reach the userspace. For (b), we should be able to allow the page fault handler to loop for even more than twice. Some context: for now since we have FAULT_FLAG_ALLOW_RETRY we can allow to retry the page fault once with the same interrupt context, however never more than twice. This can be not only a potential cleanup to remove this assumption since AFAIU the code itself doesn't really have this twice-only limitation (though that should be a protective approach in the past), at the same time it'll greatly simplify future works like userfaultfd write-protect where it's possible to retry for more than twice (please have a look at [1] below for a possible user that might require the page fault to be handled for a third time; if we can remove the retry limitation we can simply drop that patch and those complexity). This patch (of 16): There's plenty of places around __get_user_pages() that has a parameter "nonblocking" which does not really mean that "it won't block" (because it can really block) but instead it shows whether the mmap_sem is released by up_read() during the page fault handling mostly when VM_FAULT_RETRY is returned. We have the correct naming in e.g. get_user_pages_locked() or get_user_pages_remote() as "locked", however there're still many places that are using the "nonblocking" as name. Renaming the places to "locked" where proper to better suite the functionality of the variable. While at it, fixing up some of the comments accordingly. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Brian Geffon <bgeffon@google.com> Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Reviewed-by: Jerome Glisse <jglisse@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Martin Cracauer <cracauer@cons.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: Pavel Emelyanov <xemul@openvz.org> Link: http://lkml.kernel.org/r/20200220155353.8676-2-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:07:58 +03:00
if (locked &&
!(fault_flags & FAULT_FLAG_RETRY_NOWAIT))
mm/gup: rename "nonblocking" to "locked" where proper Patch series "mm: Page fault enhancements", v6. This series contains cleanups and enhancements to current page fault logic. The whole idea comes from the discussion between Andrea and Linus on the bug reported by syzbot here: https://lkml.org/lkml/2017/11/2/833 Basically it does two things: (a) Allows the page fault logic to be more interactive on not only SIGKILL, but also the rest of userspace signals, and, (b) Allows the page fault retry (VM_FAULT_RETRY) to happen for more than once. For (a): with the changes we should be able to react faster when page faults are working in parallel with userspace signals like SIGSTOP and SIGCONT (and more), and with that we can remove the buggy part in userfaultfd and benefit the whole page fault mechanism on faster signal processing to reach the userspace. For (b), we should be able to allow the page fault handler to loop for even more than twice. Some context: for now since we have FAULT_FLAG_ALLOW_RETRY we can allow to retry the page fault once with the same interrupt context, however never more than twice. This can be not only a potential cleanup to remove this assumption since AFAIU the code itself doesn't really have this twice-only limitation (though that should be a protective approach in the past), at the same time it'll greatly simplify future works like userfaultfd write-protect where it's possible to retry for more than twice (please have a look at [1] below for a possible user that might require the page fault to be handled for a third time; if we can remove the retry limitation we can simply drop that patch and those complexity). This patch (of 16): There's plenty of places around __get_user_pages() that has a parameter "nonblocking" which does not really mean that "it won't block" (because it can really block) but instead it shows whether the mmap_sem is released by up_read() during the page fault handling mostly when VM_FAULT_RETRY is returned. We have the correct naming in e.g. get_user_pages_locked() or get_user_pages_remote() as "locked", however there're still many places that are using the "nonblocking" as name. Renaming the places to "locked" where proper to better suite the functionality of the variable. While at it, fixing up some of the comments accordingly. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Brian Geffon <bgeffon@google.com> Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Reviewed-by: Jerome Glisse <jglisse@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Martin Cracauer <cracauer@cons.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: Pavel Emelyanov <xemul@openvz.org> Link: http://lkml.kernel.org/r/20200220155353.8676-2-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:07:58 +03:00
*locked = 0;
*nr_pages = 0;
/*
* VM_FAULT_RETRY must not return an
* error, it will return zero
* instead.
*
* No need to update "position" as the
* caller will not check it after
* *nr_pages is set to 0.
*/
return i;
}
continue;
}
pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
page = pte_page(huge_ptep_get(pte));
mm/gup: sanity-check with CONFIG_DEBUG_VM that anonymous pages are exclusive when (un)pinning Let's verify when (un)pinning anonymous pages that we always deal with exclusive anonymous pages, which guarantees that we'll have a reliable PIN, meaning that we cannot end up with the GUP pin being inconsistent with he pages mapped into the page tables due to a COW triggered by a write fault. When pinning pages, after conditionally triggering GUP unsharing of possibly shared anonymous pages, we should always only see exclusive anonymous pages. Note that anonymous pages that are mapped writable must be marked exclusive, otherwise we'd have a BUG. When pinning during ordinary GUP, simply add a check after our conditional GUP-triggered unsharing checks. As we know exactly how the page is mapped, we know exactly in which page we have to check for PageAnonExclusive(). When pinning via GUP-fast we have to be careful, because we can race with fork(): verify only after we made sure via the seqcount that we didn't race with concurrent fork() that we didn't end up pinning a possibly shared anonymous page. Similarly, when unpinning, verify that the pages are still marked as exclusive: otherwise something turned the pages possibly shared, which can result in random memory corruptions, which we really want to catch. With only the pinned pages at hand and not the actual page table entries we have to be a bit careful: hugetlb pages are always mapped via a single logical page table entry referencing the head page and PG_anon_exclusive of the head page applies. Anon THP are a bit more complicated, because we might have obtained the page reference either via a PMD or a PTE -- depending on the mapping type we either have to check PageAnonExclusive of the head page (PMD-mapped THP) or the tail page (PTE-mapped THP) applies: as we don't know and to make our life easier, check that either is set. Take care to not verify in case we're unpinning during GUP-fast because we detected concurrent fork(): we might stumble over an anonymous page that is now shared. Link: https://lkml.kernel.org/r/20220428083441.37290-18-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:45 +03:00
VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) &&
!PageAnonExclusive(page), page);
/*
* If subpage information not requested, update counters
* and skip the same_page loop below.
*/
if (!pages && !vmas && !pfn_offset &&
(vaddr + huge_page_size(h) < vma->vm_end) &&
(remainder >= pages_per_huge_page(h))) {
vaddr += huge_page_size(h);
remainder -= pages_per_huge_page(h);
i += pages_per_huge_page(h);
spin_unlock(ptl);
continue;
}
/* vaddr may not be aligned to PAGE_SIZE */
refs = min3(pages_per_huge_page(h) - pfn_offset, remainder,
(vma->vm_end - ALIGN_DOWN(vaddr, PAGE_SIZE)) >> PAGE_SHIFT);
mm/hugetlb: grab head page refcount once for group of subpages Patch series "mm/hugetlb: follow_hugetlb_page() improvements", v2. While looking at ZONE_DEVICE struct page reuse particularly the last patch[0], I found two possible improvements for follow_hugetlb_page() which is solely used for get_user_pages()/pin_user_pages(). The first patch batches page refcount updates while the second tidies up storing the subpages/vmas. Both together bring the cost of slow variant of gup() cost from ~87.6k usecs to ~5.8k usecs. libhugetlbfs tests seem to pass as well gup_test benchmarks with hugetlbfs vmas. This patch (of 2): follow_hugetlb_page() once it locks the pmd/pud, checks all its N subpages in a huge page and grabs a reference for each one. Similar to gup-fast, have follow_hugetlb_page() grab the head page refcount only after counting all its subpages that are part of the just faulted huge page. Consequently we reduce the number of atomics necessary to pin said huge page, which improves non-fast gup() considerably: - 16G with 1G huge page size gup_test -f /mnt/huge/file -m 16384 -r 10 -L -S -n 512 -w PIN_LONGTERM_BENCHMARK: ~87.6k us -> ~12.8k us Link: https://lkml.kernel.org/r/20210128182632.24562-1-joao.m.martins@oracle.com Link: https://lkml.kernel.org/r/20210128182632.24562-2-joao.m.martins@oracle.com Signed-off-by: Joao Martins <joao.m.martins@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:07:12 +03:00
if (pages || vmas)
record_subpages_vmas(mem_map_offset(page, pfn_offset),
vma, refs,
likely(pages) ? pages + i : NULL,
vmas ? vmas + i : NULL);
if (pages) {
mm/hugetlb: grab head page refcount once for group of subpages Patch series "mm/hugetlb: follow_hugetlb_page() improvements", v2. While looking at ZONE_DEVICE struct page reuse particularly the last patch[0], I found two possible improvements for follow_hugetlb_page() which is solely used for get_user_pages()/pin_user_pages(). The first patch batches page refcount updates while the second tidies up storing the subpages/vmas. Both together bring the cost of slow variant of gup() cost from ~87.6k usecs to ~5.8k usecs. libhugetlbfs tests seem to pass as well gup_test benchmarks with hugetlbfs vmas. This patch (of 2): follow_hugetlb_page() once it locks the pmd/pud, checks all its N subpages in a huge page and grabs a reference for each one. Similar to gup-fast, have follow_hugetlb_page() grab the head page refcount only after counting all its subpages that are part of the just faulted huge page. Consequently we reduce the number of atomics necessary to pin said huge page, which improves non-fast gup() considerably: - 16G with 1G huge page size gup_test -f /mnt/huge/file -m 16384 -r 10 -L -S -n 512 -w PIN_LONGTERM_BENCHMARK: ~87.6k us -> ~12.8k us Link: https://lkml.kernel.org/r/20210128182632.24562-1-joao.m.martins@oracle.com Link: https://lkml.kernel.org/r/20210128182632.24562-2-joao.m.martins@oracle.com Signed-off-by: Joao Martins <joao.m.martins@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:07:12 +03:00
/*
* try_grab_folio() should always succeed here,
mm/hugetlb: grab head page refcount once for group of subpages Patch series "mm/hugetlb: follow_hugetlb_page() improvements", v2. While looking at ZONE_DEVICE struct page reuse particularly the last patch[0], I found two possible improvements for follow_hugetlb_page() which is solely used for get_user_pages()/pin_user_pages(). The first patch batches page refcount updates while the second tidies up storing the subpages/vmas. Both together bring the cost of slow variant of gup() cost from ~87.6k usecs to ~5.8k usecs. libhugetlbfs tests seem to pass as well gup_test benchmarks with hugetlbfs vmas. This patch (of 2): follow_hugetlb_page() once it locks the pmd/pud, checks all its N subpages in a huge page and grabs a reference for each one. Similar to gup-fast, have follow_hugetlb_page() grab the head page refcount only after counting all its subpages that are part of the just faulted huge page. Consequently we reduce the number of atomics necessary to pin said huge page, which improves non-fast gup() considerably: - 16G with 1G huge page size gup_test -f /mnt/huge/file -m 16384 -r 10 -L -S -n 512 -w PIN_LONGTERM_BENCHMARK: ~87.6k us -> ~12.8k us Link: https://lkml.kernel.org/r/20210128182632.24562-1-joao.m.martins@oracle.com Link: https://lkml.kernel.org/r/20210128182632.24562-2-joao.m.martins@oracle.com Signed-off-by: Joao Martins <joao.m.martins@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:07:12 +03:00
* because: a) we hold the ptl lock, and b) we've just
* checked that the huge page is present in the page
* tables. If the huge page is present, then the tail
* pages must also be present. The ptl prevents the
* head page and tail pages from being rearranged in
* any way. So this page must be available at this
* point, unless the page refcount overflowed:
*/
if (WARN_ON_ONCE(!try_grab_folio(pages[i], refs,
flags))) {
mm/hugetlb: grab head page refcount once for group of subpages Patch series "mm/hugetlb: follow_hugetlb_page() improvements", v2. While looking at ZONE_DEVICE struct page reuse particularly the last patch[0], I found two possible improvements for follow_hugetlb_page() which is solely used for get_user_pages()/pin_user_pages(). The first patch batches page refcount updates while the second tidies up storing the subpages/vmas. Both together bring the cost of slow variant of gup() cost from ~87.6k usecs to ~5.8k usecs. libhugetlbfs tests seem to pass as well gup_test benchmarks with hugetlbfs vmas. This patch (of 2): follow_hugetlb_page() once it locks the pmd/pud, checks all its N subpages in a huge page and grabs a reference for each one. Similar to gup-fast, have follow_hugetlb_page() grab the head page refcount only after counting all its subpages that are part of the just faulted huge page. Consequently we reduce the number of atomics necessary to pin said huge page, which improves non-fast gup() considerably: - 16G with 1G huge page size gup_test -f /mnt/huge/file -m 16384 -r 10 -L -S -n 512 -w PIN_LONGTERM_BENCHMARK: ~87.6k us -> ~12.8k us Link: https://lkml.kernel.org/r/20210128182632.24562-1-joao.m.martins@oracle.com Link: https://lkml.kernel.org/r/20210128182632.24562-2-joao.m.martins@oracle.com Signed-off-by: Joao Martins <joao.m.martins@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:07:12 +03:00
spin_unlock(ptl);
remainder = 0;
err = -ENOMEM;
break;
}
}
vaddr += (refs << PAGE_SHIFT);
remainder -= refs;
i += refs;
spin_unlock(ptl);
}
*nr_pages = remainder;
/*
* setting position is actually required only if remainder is
* not zero but it's faster not to add a "if (remainder)"
* branch.
*/
*position = vaddr;
mm/hugetlb.c: __get_user_pages ignores certain follow_hugetlb_page errors Commit 9a291a7c9428 ("mm/hugetlb: report -EHWPOISON not -EFAULT when FOLL_HWPOISON is specified") causes __get_user_pages to ignore certain errors from follow_hugetlb_page. After such error, __get_user_pages subsequently calls faultin_page on the same VMA and start address that follow_hugetlb_page failed on instead of returning the error immediately as it should. In follow_hugetlb_page, when hugetlb_fault returns a value covered under VM_FAULT_ERROR, follow_hugetlb_page returns it without setting nr_pages to 0 as __get_user_pages expects in this case, which causes the following to happen in __get_user_pages: the "while (nr_pages)" check succeeds, we skip the "if (!vma..." check because we got a VMA the last time around, we find no page with follow_page_mask, and we call faultin_page, which calls hugetlb_fault for the second time. This issue also slightly changes how __get_user_pages works. Before, it only returned error if it had made no progress (i = 0). But now, follow_hugetlb_page can clobber "i" with an error code since its new return path doesn't check for progress. So if "i" is nonzero before a failing call to follow_hugetlb_page, that indication of progress is lost and __get_user_pages can return error even if some pages were successfully pinned. To fix this, change follow_hugetlb_page so that it updates nr_pages, allowing __get_user_pages to fail immediately and restoring the "error only if no progress" behavior to __get_user_pages. Tested that __get_user_pages returns when expected on error from hugetlb_fault in follow_hugetlb_page. Fixes: 9a291a7c9428 ("mm/hugetlb: report -EHWPOISON not -EFAULT when FOLL_HWPOISON is specified") Link: http://lkml.kernel.org/r/1500406795-58462-1-git-send-email-daniel.m.jordan@oracle.com Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Acked-by: Punit Agrawal <punit.agrawal@arm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: James Morse <james.morse@arm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: zhong jiang <zhongjiang@huawei.com> Cc: <stable@vger.kernel.org> [4.12.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-02 23:31:47 +03:00
return i ? i : err;
}
[PATCH] Enable mprotect on huge pages 2.6.16-rc3 uses hugetlb on-demand paging, but it doesn_t support hugetlb mprotect. From: David Gibson <david@gibson.dropbear.id.au> Remove a test from the mprotect() path which checks that the mprotect()ed range on a hugepage VMA is hugepage aligned (yes, really, the sense of is_aligned_hugepage_range() is the opposite of what you'd guess :-/). In fact, we don't need this test. If the given addresses match the beginning/end of a hugepage VMA they must already be suitably aligned. If they don't, then mprotect_fixup() will attempt to split the VMA. The very first test in split_vma() will check for a badly aligned address on a hugepage VMA and return -EINVAL if necessary. From: "Chen, Kenneth W" <kenneth.w.chen@intel.com> On i386 and x86-64, pte flag _PAGE_PSE collides with _PAGE_PROTNONE. The identify of hugetlb pte is lost when changing page protection via mprotect. A page fault occurs later will trigger a bug check in huge_pte_alloc(). The fix is to always make new pte a hugetlb pte and also to clean up legacy code where _PAGE_PRESENT is forced on in the pre-faulting day. Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 11:08:50 +03:00
unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
[PATCH] Enable mprotect on huge pages 2.6.16-rc3 uses hugetlb on-demand paging, but it doesn_t support hugetlb mprotect. From: David Gibson <david@gibson.dropbear.id.au> Remove a test from the mprotect() path which checks that the mprotect()ed range on a hugepage VMA is hugepage aligned (yes, really, the sense of is_aligned_hugepage_range() is the opposite of what you'd guess :-/). In fact, we don't need this test. If the given addresses match the beginning/end of a hugepage VMA they must already be suitably aligned. If they don't, then mprotect_fixup() will attempt to split the VMA. The very first test in split_vma() will check for a badly aligned address on a hugepage VMA and return -EINVAL if necessary. From: "Chen, Kenneth W" <kenneth.w.chen@intel.com> On i386 and x86-64, pte flag _PAGE_PSE collides with _PAGE_PROTNONE. The identify of hugetlb pte is lost when changing page protection via mprotect. A page fault occurs later will trigger a bug check in huge_pte_alloc(). The fix is to always make new pte a hugetlb pte and also to clean up legacy code where _PAGE_PRESENT is forced on in the pre-faulting day. Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 11:08:50 +03:00
unsigned long address, unsigned long end, pgprot_t newprot)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long start = address;
pte_t *ptep;
pte_t pte;
struct hstate *h = hstate_vma(vma);
unsigned long pages = 0;
bool shared_pmd = false;
struct mmu_notifier_range range;
/*
* In the case of shared PMDs, the area to flush could be beyond
* start/end. Set range.start/range.end to cover the maximum possible
* range if PMD sharing is possible.
*/
mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_VMA,
0, vma, mm, start, end);
adjust_range_if_pmd_sharing_possible(vma, &range.start, &range.end);
[PATCH] Enable mprotect on huge pages 2.6.16-rc3 uses hugetlb on-demand paging, but it doesn_t support hugetlb mprotect. From: David Gibson <david@gibson.dropbear.id.au> Remove a test from the mprotect() path which checks that the mprotect()ed range on a hugepage VMA is hugepage aligned (yes, really, the sense of is_aligned_hugepage_range() is the opposite of what you'd guess :-/). In fact, we don't need this test. If the given addresses match the beginning/end of a hugepage VMA they must already be suitably aligned. If they don't, then mprotect_fixup() will attempt to split the VMA. The very first test in split_vma() will check for a badly aligned address on a hugepage VMA and return -EINVAL if necessary. From: "Chen, Kenneth W" <kenneth.w.chen@intel.com> On i386 and x86-64, pte flag _PAGE_PSE collides with _PAGE_PROTNONE. The identify of hugetlb pte is lost when changing page protection via mprotect. A page fault occurs later will trigger a bug check in huge_pte_alloc(). The fix is to always make new pte a hugetlb pte and also to clean up legacy code where _PAGE_PRESENT is forced on in the pre-faulting day. Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 11:08:50 +03:00
BUG_ON(address >= end);
flush_cache_range(vma, range.start, range.end);
[PATCH] Enable mprotect on huge pages 2.6.16-rc3 uses hugetlb on-demand paging, but it doesn_t support hugetlb mprotect. From: David Gibson <david@gibson.dropbear.id.au> Remove a test from the mprotect() path which checks that the mprotect()ed range on a hugepage VMA is hugepage aligned (yes, really, the sense of is_aligned_hugepage_range() is the opposite of what you'd guess :-/). In fact, we don't need this test. If the given addresses match the beginning/end of a hugepage VMA they must already be suitably aligned. If they don't, then mprotect_fixup() will attempt to split the VMA. The very first test in split_vma() will check for a badly aligned address on a hugepage VMA and return -EINVAL if necessary. From: "Chen, Kenneth W" <kenneth.w.chen@intel.com> On i386 and x86-64, pte flag _PAGE_PSE collides with _PAGE_PROTNONE. The identify of hugetlb pte is lost when changing page protection via mprotect. A page fault occurs later will trigger a bug check in huge_pte_alloc(). The fix is to always make new pte a hugetlb pte and also to clean up legacy code where _PAGE_PRESENT is forced on in the pre-faulting day. Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 11:08:50 +03:00
mmu_notifier_invalidate_range_start(&range);
i_mmap_lock_write(vma->vm_file->f_mapping);
for (; address < end; address += huge_page_size(h)) {
spinlock_t *ptl;
mm/hugetlb: add size parameter to huge_pte_offset() A poisoned or migrated hugepage is stored as a swap entry in the page tables. On architectures that support hugepages consisting of contiguous page table entries (such as on arm64) this leads to ambiguity in determining the page table entry to return in huge_pte_offset() when a poisoned entry is encountered. Let's remove the ambiguity by adding a size parameter to convey additional information about the requested address. Also fixup the definition/usage of huge_pte_offset() throughout the tree. Link: http://lkml.kernel.org/r/20170522133604.11392-4-punit.agrawal@arm.com Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Acked-by: Steve Capper <steve.capper@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: James Hogan <james.hogan@imgtec.com> (odd fixer:METAG ARCHITECTURE) Cc: Ralf Baechle <ralf@linux-mips.org> (supporter:MIPS) Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Rich Felker <dalias@libc.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-07 01:39:42 +03:00
ptep = huge_pte_offset(mm, address, huge_page_size(h));
[PATCH] Enable mprotect on huge pages 2.6.16-rc3 uses hugetlb on-demand paging, but it doesn_t support hugetlb mprotect. From: David Gibson <david@gibson.dropbear.id.au> Remove a test from the mprotect() path which checks that the mprotect()ed range on a hugepage VMA is hugepage aligned (yes, really, the sense of is_aligned_hugepage_range() is the opposite of what you'd guess :-/). In fact, we don't need this test. If the given addresses match the beginning/end of a hugepage VMA they must already be suitably aligned. If they don't, then mprotect_fixup() will attempt to split the VMA. The very first test in split_vma() will check for a badly aligned address on a hugepage VMA and return -EINVAL if necessary. From: "Chen, Kenneth W" <kenneth.w.chen@intel.com> On i386 and x86-64, pte flag _PAGE_PSE collides with _PAGE_PROTNONE. The identify of hugetlb pte is lost when changing page protection via mprotect. A page fault occurs later will trigger a bug check in huge_pte_alloc(). The fix is to always make new pte a hugetlb pte and also to clean up legacy code where _PAGE_PRESENT is forced on in the pre-faulting day. Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 11:08:50 +03:00
if (!ptep)
continue;
ptl = huge_pte_lock(h, mm, ptep);
hugetlbfs: remove call to huge_pte_alloc without i_mmap_rwsem Commit c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") requires callers of huge_pte_alloc to hold i_mmap_rwsem in at least read mode. This is because the explicit locking in huge_pmd_share (called by huge_pte_alloc) was removed. When restructuring the code, the call to huge_pte_alloc in the else block at the beginning of hugetlb_fault was missed. Unfortunately, that else clause is exercised when there is no page table entry. This will likely lead to a call to huge_pmd_share. If huge_pmd_share thinks pmd sharing is possible, it will traverse the mapping tree (i_mmap) without holding i_mmap_rwsem. If someone else is modifying the tree, bad things such as addressing exceptions or worse could happen. Simply remove the else clause. It should have been removed previously. The code following the else will call huge_pte_alloc with the appropriate locking. To prevent this type of issue in the future, add routines to assert that i_mmap_rwsem is held, and call these routines in huge pmd sharing routines. Fixes: c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") Suggested-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A.Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/e670f327-5cf9-1959-96e4-6dc7cc30d3d5@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 04:31:38 +03:00
if (huge_pmd_unshare(mm, vma, &address, ptep)) {
pages++;
spin_unlock(ptl);
shared_pmd = true;
[PATCH] shared page table for hugetlb page Following up with the work on shared page table done by Dave McCracken. This set of patch target shared page table for hugetlb memory only. The shared page table is particular useful in the situation of large number of independent processes sharing large shared memory segments. In the normal page case, the amount of memory saved from process' page table is quite significant. For hugetlb, the saving on page table memory is not the primary objective (as hugetlb itself already cuts down page table overhead significantly), instead, the purpose of using shared page table on hugetlb is to allow faster TLB refill and smaller cache pollution upon TLB miss. With PT sharing, pte entries are shared among hundreds of processes, the cache consumption used by all the page table is smaller and in return, application gets much higher cache hit ratio. One other effect is that cache hit ratio with hardware page walker hitting on pte in cache will be higher and this helps to reduce tlb miss latency. These two effects contribute to higher application performance. Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Acked-by: Hugh Dickins <hugh@veritas.com> Cc: Dave McCracken <dmccr@us.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Adam Litke <agl@us.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 07:32:03 +03:00
continue;
}
pte = huge_ptep_get(ptep);
if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
spin_unlock(ptl);
continue;
}
if (unlikely(is_hugetlb_entry_migration(pte))) {
swp_entry_t entry = pte_to_swp_entry(pte);
mm: remember exclusively mapped anonymous pages with PG_anon_exclusive Let's mark exclusively mapped anonymous pages with PG_anon_exclusive as exclusive, and use that information to make GUP pins reliable and stay consistent with the page mapped into the page table even if the page table entry gets write-protected. With that information at hand, we can extend our COW logic to always reuse anonymous pages that are exclusive. For anonymous pages that might be shared, the existing logic applies. As already documented, PG_anon_exclusive is usually only expressive in combination with a page table entry. Especially PTE vs. PMD-mapped anonymous pages require more thought, some examples: due to mremap() we can easily have a single compound page PTE-mapped into multiple page tables exclusively in a single process -- multiple page table locks apply. Further, due to MADV_WIPEONFORK we might not necessarily write-protect all PTEs, and only some subpages might be pinned. Long story short: once PTE-mapped, we have to track information about exclusivity per sub-page, but until then, we can just track it for the compound page in the head page and not having to update a whole bunch of subpages all of the time for a simple PMD mapping of a THP. For simplicity, this commit mostly talks about "anonymous pages", while it's for THP actually "the part of an anonymous folio referenced via a page table entry". To not spill PG_anon_exclusive code all over the mm code-base, we let the anon rmap code to handle all PG_anon_exclusive logic it can easily handle. If a writable, present page table entry points at an anonymous (sub)page, that (sub)page must be PG_anon_exclusive. If GUP wants to take a reliably pin (FOLL_PIN) on an anonymous page references via a present page table entry, it must only pin if PG_anon_exclusive is set for the mapped (sub)page. This commit doesn't adjust GUP, so this is only implicitly handled for FOLL_WRITE, follow-up commits will teach GUP to also respect it for FOLL_PIN without FOLL_WRITE, to make all GUP pins of anonymous pages fully reliable. Whenever an anonymous page is to be shared (fork(), KSM), or when temporarily unmapping an anonymous page (swap, migration), the relevant PG_anon_exclusive bit has to be cleared to mark the anonymous page possibly shared. Clearing will fail if there are GUP pins on the page: * For fork(), this means having to copy the page and not being able to share it. fork() protects against concurrent GUP using the PT lock and the src_mm->write_protect_seq. * For KSM, this means sharing will fail. For swap this means, unmapping will fail, For migration this means, migration will fail early. All three cases protect against concurrent GUP using the PT lock and a proper clear/invalidate+flush of the relevant page table entry. This fixes memory corruptions reported for FOLL_PIN | FOLL_WRITE, when a pinned page gets mapped R/O and the successive write fault ends up replacing the page instead of reusing it. It improves the situation for O_DIRECT/vmsplice/... that still use FOLL_GET instead of FOLL_PIN, if fork() is *not* involved, however swapout and fork() are still problematic. Properly using FOLL_PIN instead of FOLL_GET for these GUP users will fix the issue for them. I. Details about basic handling I.1. Fresh anonymous pages page_add_new_anon_rmap() and hugepage_add_new_anon_rmap() will mark the given page exclusive via __page_set_anon_rmap(exclusive=1). As that is the mechanism fresh anonymous pages come into life (besides migration code where we copy the page->mapping), all fresh anonymous pages will start out as exclusive. I.2. COW reuse handling of anonymous pages When a COW handler stumbles over a (sub)page that's marked exclusive, it simply reuses it. Otherwise, the handler tries harder under page lock to detect if the (sub)page is exclusive and can be reused. If exclusive, page_move_anon_rmap() will mark the given (sub)page exclusive. Note that hugetlb code does not yet check for PageAnonExclusive(), as it still uses the old COW logic that is prone to the COW security issue because hugetlb code cannot really tolerate unnecessary/wrong COW as huge pages are a scarce resource. I.3. Migration handling try_to_migrate() has to try marking an exclusive anonymous page shared via page_try_share_anon_rmap(). If it fails because there are GUP pins on the page, unmap fails. migrate_vma_collect_pmd() and __split_huge_pmd_locked() are handled similarly. Writable migration entries implicitly point at shared anonymous pages. For readable migration entries that information is stored via a new "readable-exclusive" migration entry, specific to anonymous pages. When restoring a migration entry in remove_migration_pte(), information about exlusivity is detected via the migration entry type, and RMAP_EXCLUSIVE is set accordingly for page_add_anon_rmap()/hugepage_add_anon_rmap() to restore that information. I.4. Swapout handling try_to_unmap() has to try marking the mapped page possibly shared via page_try_share_anon_rmap(). If it fails because there are GUP pins on the page, unmap fails. For now, information about exclusivity is lost. In the future, we might want to remember that information in the swap entry in some cases, however, it requires more thought, care, and a way to store that information in swap entries. I.5. Swapin handling do_swap_page() will never stumble over exclusive anonymous pages in the swap cache, as try_to_migrate() prohibits that. do_swap_page() always has to detect manually if an anonymous page is exclusive and has to set RMAP_EXCLUSIVE for page_add_anon_rmap() accordingly. I.6. THP handling __split_huge_pmd_locked() has to move the information about exclusivity from the PMD to the PTEs. a) In case we have a readable-exclusive PMD migration entry, simply insert readable-exclusive PTE migration entries. b) In case we have a present PMD entry and we don't want to freeze ("convert to migration entries"), simply forward PG_anon_exclusive to all sub-pages, no need to temporarily clear the bit. c) In case we have a present PMD entry and want to freeze, handle it similar to try_to_migrate(): try marking the page shared first. In case we fail, we ignore the "freeze" instruction and simply split ordinarily. try_to_migrate() will properly fail because the THP is still mapped via PTEs. When splitting a compound anonymous folio (THP), the information about exclusivity is implicitly handled via the migration entries: no need to replicate PG_anon_exclusive manually. I.7. fork() handling fork() handling is relatively easy, because PG_anon_exclusive is only expressive for some page table entry types. a) Present anonymous pages page_try_dup_anon_rmap() will mark the given subpage shared -- which will fail if the page is pinned. If it failed, we have to copy (or PTE-map a PMD to handle it on the PTE level). Note that device exclusive entries are just a pointer at a PageAnon() page. fork() will first convert a device exclusive entry to a present page table and handle it just like present anonymous pages. b) Device private entry Device private entries point at PageAnon() pages that cannot be mapped directly and, therefore, cannot get pinned. page_try_dup_anon_rmap() will mark the given subpage shared, which cannot fail because they cannot get pinned. c) HW poison entries PG_anon_exclusive will remain untouched and is stale -- the page table entry is just a placeholder after all. d) Migration entries Writable and readable-exclusive entries are converted to readable entries: possibly shared. I.8. mprotect() handling mprotect() only has to properly handle the new readable-exclusive migration entry: When write-protecting a migration entry that points at an anonymous page, remember the information about exclusivity via the "readable-exclusive" migration entry type. II. Migration and GUP-fast Whenever replacing a present page table entry that maps an exclusive anonymous page by a migration entry, we have to mark the page possibly shared and synchronize against GUP-fast by a proper clear/invalidate+flush to make the following scenario impossible: 1. try_to_migrate() places a migration entry after checking for GUP pins and marks the page possibly shared. 2. GUP-fast pins the page due to lack of synchronization 3. fork() converts the "writable/readable-exclusive" migration entry into a readable migration entry 4. Migration fails due to the GUP pin (failing to freeze the refcount) 5. Migration entries are restored. PG_anon_exclusive is lost -> We have a pinned page that is not marked exclusive anymore. Note that we move information about exclusivity from the page to the migration entry as it otherwise highly overcomplicates fork() and PTE-mapping a THP. III. Swapout and GUP-fast Whenever replacing a present page table entry that maps an exclusive anonymous page by a swap entry, we have to mark the page possibly shared and synchronize against GUP-fast by a proper clear/invalidate+flush to make the following scenario impossible: 1. try_to_unmap() places a swap entry after checking for GUP pins and clears exclusivity information on the page. 2. GUP-fast pins the page due to lack of synchronization. -> We have a pinned page that is not marked exclusive anymore. If we'd ever store information about exclusivity in the swap entry, similar to migration handling, the same considerations as in II would apply. This is future work. Link: https://lkml.kernel.org/r/20220428083441.37290-13-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:44 +03:00
struct page *page = pfn_swap_entry_to_page(entry);
mm: remember exclusively mapped anonymous pages with PG_anon_exclusive Let's mark exclusively mapped anonymous pages with PG_anon_exclusive as exclusive, and use that information to make GUP pins reliable and stay consistent with the page mapped into the page table even if the page table entry gets write-protected. With that information at hand, we can extend our COW logic to always reuse anonymous pages that are exclusive. For anonymous pages that might be shared, the existing logic applies. As already documented, PG_anon_exclusive is usually only expressive in combination with a page table entry. Especially PTE vs. PMD-mapped anonymous pages require more thought, some examples: due to mremap() we can easily have a single compound page PTE-mapped into multiple page tables exclusively in a single process -- multiple page table locks apply. Further, due to MADV_WIPEONFORK we might not necessarily write-protect all PTEs, and only some subpages might be pinned. Long story short: once PTE-mapped, we have to track information about exclusivity per sub-page, but until then, we can just track it for the compound page in the head page and not having to update a whole bunch of subpages all of the time for a simple PMD mapping of a THP. For simplicity, this commit mostly talks about "anonymous pages", while it's for THP actually "the part of an anonymous folio referenced via a page table entry". To not spill PG_anon_exclusive code all over the mm code-base, we let the anon rmap code to handle all PG_anon_exclusive logic it can easily handle. If a writable, present page table entry points at an anonymous (sub)page, that (sub)page must be PG_anon_exclusive. If GUP wants to take a reliably pin (FOLL_PIN) on an anonymous page references via a present page table entry, it must only pin if PG_anon_exclusive is set for the mapped (sub)page. This commit doesn't adjust GUP, so this is only implicitly handled for FOLL_WRITE, follow-up commits will teach GUP to also respect it for FOLL_PIN without FOLL_WRITE, to make all GUP pins of anonymous pages fully reliable. Whenever an anonymous page is to be shared (fork(), KSM), or when temporarily unmapping an anonymous page (swap, migration), the relevant PG_anon_exclusive bit has to be cleared to mark the anonymous page possibly shared. Clearing will fail if there are GUP pins on the page: * For fork(), this means having to copy the page and not being able to share it. fork() protects against concurrent GUP using the PT lock and the src_mm->write_protect_seq. * For KSM, this means sharing will fail. For swap this means, unmapping will fail, For migration this means, migration will fail early. All three cases protect against concurrent GUP using the PT lock and a proper clear/invalidate+flush of the relevant page table entry. This fixes memory corruptions reported for FOLL_PIN | FOLL_WRITE, when a pinned page gets mapped R/O and the successive write fault ends up replacing the page instead of reusing it. It improves the situation for O_DIRECT/vmsplice/... that still use FOLL_GET instead of FOLL_PIN, if fork() is *not* involved, however swapout and fork() are still problematic. Properly using FOLL_PIN instead of FOLL_GET for these GUP users will fix the issue for them. I. Details about basic handling I.1. Fresh anonymous pages page_add_new_anon_rmap() and hugepage_add_new_anon_rmap() will mark the given page exclusive via __page_set_anon_rmap(exclusive=1). As that is the mechanism fresh anonymous pages come into life (besides migration code where we copy the page->mapping), all fresh anonymous pages will start out as exclusive. I.2. COW reuse handling of anonymous pages When a COW handler stumbles over a (sub)page that's marked exclusive, it simply reuses it. Otherwise, the handler tries harder under page lock to detect if the (sub)page is exclusive and can be reused. If exclusive, page_move_anon_rmap() will mark the given (sub)page exclusive. Note that hugetlb code does not yet check for PageAnonExclusive(), as it still uses the old COW logic that is prone to the COW security issue because hugetlb code cannot really tolerate unnecessary/wrong COW as huge pages are a scarce resource. I.3. Migration handling try_to_migrate() has to try marking an exclusive anonymous page shared via page_try_share_anon_rmap(). If it fails because there are GUP pins on the page, unmap fails. migrate_vma_collect_pmd() and __split_huge_pmd_locked() are handled similarly. Writable migration entries implicitly point at shared anonymous pages. For readable migration entries that information is stored via a new "readable-exclusive" migration entry, specific to anonymous pages. When restoring a migration entry in remove_migration_pte(), information about exlusivity is detected via the migration entry type, and RMAP_EXCLUSIVE is set accordingly for page_add_anon_rmap()/hugepage_add_anon_rmap() to restore that information. I.4. Swapout handling try_to_unmap() has to try marking the mapped page possibly shared via page_try_share_anon_rmap(). If it fails because there are GUP pins on the page, unmap fails. For now, information about exclusivity is lost. In the future, we might want to remember that information in the swap entry in some cases, however, it requires more thought, care, and a way to store that information in swap entries. I.5. Swapin handling do_swap_page() will never stumble over exclusive anonymous pages in the swap cache, as try_to_migrate() prohibits that. do_swap_page() always has to detect manually if an anonymous page is exclusive and has to set RMAP_EXCLUSIVE for page_add_anon_rmap() accordingly. I.6. THP handling __split_huge_pmd_locked() has to move the information about exclusivity from the PMD to the PTEs. a) In case we have a readable-exclusive PMD migration entry, simply insert readable-exclusive PTE migration entries. b) In case we have a present PMD entry and we don't want to freeze ("convert to migration entries"), simply forward PG_anon_exclusive to all sub-pages, no need to temporarily clear the bit. c) In case we have a present PMD entry and want to freeze, handle it similar to try_to_migrate(): try marking the page shared first. In case we fail, we ignore the "freeze" instruction and simply split ordinarily. try_to_migrate() will properly fail because the THP is still mapped via PTEs. When splitting a compound anonymous folio (THP), the information about exclusivity is implicitly handled via the migration entries: no need to replicate PG_anon_exclusive manually. I.7. fork() handling fork() handling is relatively easy, because PG_anon_exclusive is only expressive for some page table entry types. a) Present anonymous pages page_try_dup_anon_rmap() will mark the given subpage shared -- which will fail if the page is pinned. If it failed, we have to copy (or PTE-map a PMD to handle it on the PTE level). Note that device exclusive entries are just a pointer at a PageAnon() page. fork() will first convert a device exclusive entry to a present page table and handle it just like present anonymous pages. b) Device private entry Device private entries point at PageAnon() pages that cannot be mapped directly and, therefore, cannot get pinned. page_try_dup_anon_rmap() will mark the given subpage shared, which cannot fail because they cannot get pinned. c) HW poison entries PG_anon_exclusive will remain untouched and is stale -- the page table entry is just a placeholder after all. d) Migration entries Writable and readable-exclusive entries are converted to readable entries: possibly shared. I.8. mprotect() handling mprotect() only has to properly handle the new readable-exclusive migration entry: When write-protecting a migration entry that points at an anonymous page, remember the information about exclusivity via the "readable-exclusive" migration entry type. II. Migration and GUP-fast Whenever replacing a present page table entry that maps an exclusive anonymous page by a migration entry, we have to mark the page possibly shared and synchronize against GUP-fast by a proper clear/invalidate+flush to make the following scenario impossible: 1. try_to_migrate() places a migration entry after checking for GUP pins and marks the page possibly shared. 2. GUP-fast pins the page due to lack of synchronization 3. fork() converts the "writable/readable-exclusive" migration entry into a readable migration entry 4. Migration fails due to the GUP pin (failing to freeze the refcount) 5. Migration entries are restored. PG_anon_exclusive is lost -> We have a pinned page that is not marked exclusive anymore. Note that we move information about exclusivity from the page to the migration entry as it otherwise highly overcomplicates fork() and PTE-mapping a THP. III. Swapout and GUP-fast Whenever replacing a present page table entry that maps an exclusive anonymous page by a swap entry, we have to mark the page possibly shared and synchronize against GUP-fast by a proper clear/invalidate+flush to make the following scenario impossible: 1. try_to_unmap() places a swap entry after checking for GUP pins and clears exclusivity information on the page. 2. GUP-fast pins the page due to lack of synchronization. -> We have a pinned page that is not marked exclusive anymore. If we'd ever store information about exclusivity in the swap entry, similar to migration handling, the same considerations as in II would apply. This is future work. Link: https://lkml.kernel.org/r/20220428083441.37290-13-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:44 +03:00
if (!is_readable_migration_entry(entry)) {
pte_t newpte;
mm: remember exclusively mapped anonymous pages with PG_anon_exclusive Let's mark exclusively mapped anonymous pages with PG_anon_exclusive as exclusive, and use that information to make GUP pins reliable and stay consistent with the page mapped into the page table even if the page table entry gets write-protected. With that information at hand, we can extend our COW logic to always reuse anonymous pages that are exclusive. For anonymous pages that might be shared, the existing logic applies. As already documented, PG_anon_exclusive is usually only expressive in combination with a page table entry. Especially PTE vs. PMD-mapped anonymous pages require more thought, some examples: due to mremap() we can easily have a single compound page PTE-mapped into multiple page tables exclusively in a single process -- multiple page table locks apply. Further, due to MADV_WIPEONFORK we might not necessarily write-protect all PTEs, and only some subpages might be pinned. Long story short: once PTE-mapped, we have to track information about exclusivity per sub-page, but until then, we can just track it for the compound page in the head page and not having to update a whole bunch of subpages all of the time for a simple PMD mapping of a THP. For simplicity, this commit mostly talks about "anonymous pages", while it's for THP actually "the part of an anonymous folio referenced via a page table entry". To not spill PG_anon_exclusive code all over the mm code-base, we let the anon rmap code to handle all PG_anon_exclusive logic it can easily handle. If a writable, present page table entry points at an anonymous (sub)page, that (sub)page must be PG_anon_exclusive. If GUP wants to take a reliably pin (FOLL_PIN) on an anonymous page references via a present page table entry, it must only pin if PG_anon_exclusive is set for the mapped (sub)page. This commit doesn't adjust GUP, so this is only implicitly handled for FOLL_WRITE, follow-up commits will teach GUP to also respect it for FOLL_PIN without FOLL_WRITE, to make all GUP pins of anonymous pages fully reliable. Whenever an anonymous page is to be shared (fork(), KSM), or when temporarily unmapping an anonymous page (swap, migration), the relevant PG_anon_exclusive bit has to be cleared to mark the anonymous page possibly shared. Clearing will fail if there are GUP pins on the page: * For fork(), this means having to copy the page and not being able to share it. fork() protects against concurrent GUP using the PT lock and the src_mm->write_protect_seq. * For KSM, this means sharing will fail. For swap this means, unmapping will fail, For migration this means, migration will fail early. All three cases protect against concurrent GUP using the PT lock and a proper clear/invalidate+flush of the relevant page table entry. This fixes memory corruptions reported for FOLL_PIN | FOLL_WRITE, when a pinned page gets mapped R/O and the successive write fault ends up replacing the page instead of reusing it. It improves the situation for O_DIRECT/vmsplice/... that still use FOLL_GET instead of FOLL_PIN, if fork() is *not* involved, however swapout and fork() are still problematic. Properly using FOLL_PIN instead of FOLL_GET for these GUP users will fix the issue for them. I. Details about basic handling I.1. Fresh anonymous pages page_add_new_anon_rmap() and hugepage_add_new_anon_rmap() will mark the given page exclusive via __page_set_anon_rmap(exclusive=1). As that is the mechanism fresh anonymous pages come into life (besides migration code where we copy the page->mapping), all fresh anonymous pages will start out as exclusive. I.2. COW reuse handling of anonymous pages When a COW handler stumbles over a (sub)page that's marked exclusive, it simply reuses it. Otherwise, the handler tries harder under page lock to detect if the (sub)page is exclusive and can be reused. If exclusive, page_move_anon_rmap() will mark the given (sub)page exclusive. Note that hugetlb code does not yet check for PageAnonExclusive(), as it still uses the old COW logic that is prone to the COW security issue because hugetlb code cannot really tolerate unnecessary/wrong COW as huge pages are a scarce resource. I.3. Migration handling try_to_migrate() has to try marking an exclusive anonymous page shared via page_try_share_anon_rmap(). If it fails because there are GUP pins on the page, unmap fails. migrate_vma_collect_pmd() and __split_huge_pmd_locked() are handled similarly. Writable migration entries implicitly point at shared anonymous pages. For readable migration entries that information is stored via a new "readable-exclusive" migration entry, specific to anonymous pages. When restoring a migration entry in remove_migration_pte(), information about exlusivity is detected via the migration entry type, and RMAP_EXCLUSIVE is set accordingly for page_add_anon_rmap()/hugepage_add_anon_rmap() to restore that information. I.4. Swapout handling try_to_unmap() has to try marking the mapped page possibly shared via page_try_share_anon_rmap(). If it fails because there are GUP pins on the page, unmap fails. For now, information about exclusivity is lost. In the future, we might want to remember that information in the swap entry in some cases, however, it requires more thought, care, and a way to store that information in swap entries. I.5. Swapin handling do_swap_page() will never stumble over exclusive anonymous pages in the swap cache, as try_to_migrate() prohibits that. do_swap_page() always has to detect manually if an anonymous page is exclusive and has to set RMAP_EXCLUSIVE for page_add_anon_rmap() accordingly. I.6. THP handling __split_huge_pmd_locked() has to move the information about exclusivity from the PMD to the PTEs. a) In case we have a readable-exclusive PMD migration entry, simply insert readable-exclusive PTE migration entries. b) In case we have a present PMD entry and we don't want to freeze ("convert to migration entries"), simply forward PG_anon_exclusive to all sub-pages, no need to temporarily clear the bit. c) In case we have a present PMD entry and want to freeze, handle it similar to try_to_migrate(): try marking the page shared first. In case we fail, we ignore the "freeze" instruction and simply split ordinarily. try_to_migrate() will properly fail because the THP is still mapped via PTEs. When splitting a compound anonymous folio (THP), the information about exclusivity is implicitly handled via the migration entries: no need to replicate PG_anon_exclusive manually. I.7. fork() handling fork() handling is relatively easy, because PG_anon_exclusive is only expressive for some page table entry types. a) Present anonymous pages page_try_dup_anon_rmap() will mark the given subpage shared -- which will fail if the page is pinned. If it failed, we have to copy (or PTE-map a PMD to handle it on the PTE level). Note that device exclusive entries are just a pointer at a PageAnon() page. fork() will first convert a device exclusive entry to a present page table and handle it just like present anonymous pages. b) Device private entry Device private entries point at PageAnon() pages that cannot be mapped directly and, therefore, cannot get pinned. page_try_dup_anon_rmap() will mark the given subpage shared, which cannot fail because they cannot get pinned. c) HW poison entries PG_anon_exclusive will remain untouched and is stale -- the page table entry is just a placeholder after all. d) Migration entries Writable and readable-exclusive entries are converted to readable entries: possibly shared. I.8. mprotect() handling mprotect() only has to properly handle the new readable-exclusive migration entry: When write-protecting a migration entry that points at an anonymous page, remember the information about exclusivity via the "readable-exclusive" migration entry type. II. Migration and GUP-fast Whenever replacing a present page table entry that maps an exclusive anonymous page by a migration entry, we have to mark the page possibly shared and synchronize against GUP-fast by a proper clear/invalidate+flush to make the following scenario impossible: 1. try_to_migrate() places a migration entry after checking for GUP pins and marks the page possibly shared. 2. GUP-fast pins the page due to lack of synchronization 3. fork() converts the "writable/readable-exclusive" migration entry into a readable migration entry 4. Migration fails due to the GUP pin (failing to freeze the refcount) 5. Migration entries are restored. PG_anon_exclusive is lost -> We have a pinned page that is not marked exclusive anymore. Note that we move information about exclusivity from the page to the migration entry as it otherwise highly overcomplicates fork() and PTE-mapping a THP. III. Swapout and GUP-fast Whenever replacing a present page table entry that maps an exclusive anonymous page by a swap entry, we have to mark the page possibly shared and synchronize against GUP-fast by a proper clear/invalidate+flush to make the following scenario impossible: 1. try_to_unmap() places a swap entry after checking for GUP pins and clears exclusivity information on the page. 2. GUP-fast pins the page due to lack of synchronization. -> We have a pinned page that is not marked exclusive anymore. If we'd ever store information about exclusivity in the swap entry, similar to migration handling, the same considerations as in II would apply. This is future work. Link: https://lkml.kernel.org/r/20220428083441.37290-13-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:44 +03:00
if (PageAnon(page))
entry = make_readable_exclusive_migration_entry(
swp_offset(entry));
else
entry = make_readable_migration_entry(
swp_offset(entry));
newpte = swp_entry_to_pte(entry);
mm/hugetlb: introduce set_huge_swap_pte_at() helper set_huge_pte_at(), an architecture callback to populate hugepage ptes, does not provide the range of virtual memory that is targeted. This leads to ambiguity when dealing with swap entries on architectures that support hugepages consisting of contiguous ptes. Fix the problem by introducing an overridable helper that is called when populating the page tables with swap entries. The size of the targeted region is provided to the helper to help determine the number of entries to be updated. Provide a default implementation that maintains the current behaviour. [punit.agrawal@arm.com: v4] Link: http://lkml.kernel.org/r/20170524115409.31309-8-punit.agrawal@arm.com [punit.agrawal@arm.com: add an empty definition for set_huge_swap_pte_at()] Link: http://lkml.kernel.org/r/20170525171331.31469-1-punit.agrawal@arm.com Link: http://lkml.kernel.org/r/20170522133604.11392-6-punit.agrawal@arm.com Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Acked-by: Steve Capper <steve.capper@arm.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-07 01:39:50 +03:00
set_huge_swap_pte_at(mm, address, ptep,
newpte, huge_page_size(h));
pages++;
}
spin_unlock(ptl);
continue;
}
if (!huge_pte_none(pte)) {
pte_t old_pte;
mm/hugetlb: change parameters of arch_make_huge_pte() Patch series "Subject: [PATCH v2 0/5] Implement huge VMAP and VMALLOC on powerpc 8xx", v2. This series implements huge VMAP and VMALLOC on powerpc 8xx. Powerpc 8xx has 4 page sizes: - 4k - 16k - 512k - 8M At the time being, vmalloc and vmap only support huge pages which are leaf at PMD level. Here the PMD level is 4M, it doesn't correspond to any supported page size. For now, implement use of 16k and 512k pages which is done at PTE level. Support of 8M pages will be implemented later, it requires use of hugepd tables. To allow this, the architecture provides two functions: - arch_vmap_pte_range_map_size() which tells vmap_pte_range() what page size to use. A stub returning PAGE_SIZE is provided when the architecture doesn't provide this function. - arch_vmap_pte_supported_shift() which tells __vmalloc_node_range() what page shift to use for a given area size. A stub returning PAGE_SHIFT is provided when the architecture doesn't provide this function. This patch (of 5): At the time being, arch_make_huge_pte() has the following prototype: pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, struct page *page, int writable); vma is used to get the pages shift or size. vma is also used on Sparc to get vm_flags. page is not used. writable is not used. In order to use this function without a vma, replace vma by shift and flags. Also remove the used parameters. Link: https://lkml.kernel.org/r/cover.1620795204.git.christophe.leroy@csgroup.eu Link: https://lkml.kernel.org/r/f4633ac6a7da2f22f31a04a89e0a7026bb78b15b.1620795204.git.christophe.leroy@csgroup.eu Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:00 +03:00
unsigned int shift = huge_page_shift(hstate_vma(vma));
old_pte = huge_ptep_modify_prot_start(vma, address, ptep);
pte = huge_pte_modify(old_pte, newprot);
mm/hugetlb: change parameters of arch_make_huge_pte() Patch series "Subject: [PATCH v2 0/5] Implement huge VMAP and VMALLOC on powerpc 8xx", v2. This series implements huge VMAP and VMALLOC on powerpc 8xx. Powerpc 8xx has 4 page sizes: - 4k - 16k - 512k - 8M At the time being, vmalloc and vmap only support huge pages which are leaf at PMD level. Here the PMD level is 4M, it doesn't correspond to any supported page size. For now, implement use of 16k and 512k pages which is done at PTE level. Support of 8M pages will be implemented later, it requires use of hugepd tables. To allow this, the architecture provides two functions: - arch_vmap_pte_range_map_size() which tells vmap_pte_range() what page size to use. A stub returning PAGE_SIZE is provided when the architecture doesn't provide this function. - arch_vmap_pte_supported_shift() which tells __vmalloc_node_range() what page shift to use for a given area size. A stub returning PAGE_SHIFT is provided when the architecture doesn't provide this function. This patch (of 5): At the time being, arch_make_huge_pte() has the following prototype: pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, struct page *page, int writable); vma is used to get the pages shift or size. vma is also used on Sparc to get vm_flags. page is not used. writable is not used. In order to use this function without a vma, replace vma by shift and flags. Also remove the used parameters. Link: https://lkml.kernel.org/r/cover.1620795204.git.christophe.leroy@csgroup.eu Link: https://lkml.kernel.org/r/f4633ac6a7da2f22f31a04a89e0a7026bb78b15b.1620795204.git.christophe.leroy@csgroup.eu Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 04:48:00 +03:00
pte = arch_make_huge_pte(pte, shift, vma->vm_flags);
huge_ptep_modify_prot_commit(vma, address, ptep, old_pte, pte);
pages++;
[PATCH] Enable mprotect on huge pages 2.6.16-rc3 uses hugetlb on-demand paging, but it doesn_t support hugetlb mprotect. From: David Gibson <david@gibson.dropbear.id.au> Remove a test from the mprotect() path which checks that the mprotect()ed range on a hugepage VMA is hugepage aligned (yes, really, the sense of is_aligned_hugepage_range() is the opposite of what you'd guess :-/). In fact, we don't need this test. If the given addresses match the beginning/end of a hugepage VMA they must already be suitably aligned. If they don't, then mprotect_fixup() will attempt to split the VMA. The very first test in split_vma() will check for a badly aligned address on a hugepage VMA and return -EINVAL if necessary. From: "Chen, Kenneth W" <kenneth.w.chen@intel.com> On i386 and x86-64, pte flag _PAGE_PSE collides with _PAGE_PROTNONE. The identify of hugetlb pte is lost when changing page protection via mprotect. A page fault occurs later will trigger a bug check in huge_pte_alloc(). The fix is to always make new pte a hugetlb pte and also to clean up legacy code where _PAGE_PRESENT is forced on in the pre-faulting day. Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 11:08:50 +03:00
}
spin_unlock(ptl);
[PATCH] Enable mprotect on huge pages 2.6.16-rc3 uses hugetlb on-demand paging, but it doesn_t support hugetlb mprotect. From: David Gibson <david@gibson.dropbear.id.au> Remove a test from the mprotect() path which checks that the mprotect()ed range on a hugepage VMA is hugepage aligned (yes, really, the sense of is_aligned_hugepage_range() is the opposite of what you'd guess :-/). In fact, we don't need this test. If the given addresses match the beginning/end of a hugepage VMA they must already be suitably aligned. If they don't, then mprotect_fixup() will attempt to split the VMA. The very first test in split_vma() will check for a badly aligned address on a hugepage VMA and return -EINVAL if necessary. From: "Chen, Kenneth W" <kenneth.w.chen@intel.com> On i386 and x86-64, pte flag _PAGE_PSE collides with _PAGE_PROTNONE. The identify of hugetlb pte is lost when changing page protection via mprotect. A page fault occurs later will trigger a bug check in huge_pte_alloc(). The fix is to always make new pte a hugetlb pte and also to clean up legacy code where _PAGE_PRESENT is forced on in the pre-faulting day. Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 11:08:50 +03:00
}
mm: hugetlbfs: close race during teardown of hugetlbfs shared page tables If a process creates a large hugetlbfs mapping that is eligible for page table sharing and forks heavily with children some of whom fault and others which destroy the mapping then it is possible for page tables to get corrupted. Some teardowns of the mapping encounter a "bad pmd" and output a message to the kernel log. The final teardown will trigger a BUG_ON in mm/filemap.c. This was reproduced in 3.4 but is known to have existed for a long time and goes back at least as far as 2.6.37. It was probably was introduced in 2.6.20 by [39dde65c: shared page table for hugetlb page]. The messages look like this; [ ..........] Lots of bad pmd messages followed by this [ 127.164256] mm/memory.c:391: bad pmd ffff880412e04fe8(80000003de4000e7). [ 127.164257] mm/memory.c:391: bad pmd ffff880412e04ff0(80000003de6000e7). [ 127.164258] mm/memory.c:391: bad pmd ffff880412e04ff8(80000003de0000e7). [ 127.186778] ------------[ cut here ]------------ [ 127.186781] kernel BUG at mm/filemap.c:134! [ 127.186782] invalid opcode: 0000 [#1] SMP [ 127.186783] CPU 7 [ 127.186784] Modules linked in: af_packet cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf ext3 jbd dm_mod coretemp crc32c_intel usb_storage ghash_clmulni_intel aesni_intel i2c_i801 r8169 mii uas sr_mod cdrom sg iTCO_wdt iTCO_vendor_support shpchp serio_raw cryptd aes_x86_64 e1000e pci_hotplug dcdbas aes_generic container microcode ext4 mbcache jbd2 crc16 sd_mod crc_t10dif i915 drm_kms_helper drm i2c_algo_bit ehci_hcd ahci libahci usbcore rtc_cmos usb_common button i2c_core intel_agp video intel_gtt fan processor thermal thermal_sys hwmon ata_generic pata_atiixp libata scsi_mod [ 127.186801] [ 127.186802] Pid: 9017, comm: hugetlbfs-test Not tainted 3.4.0-autobuild #53 Dell Inc. OptiPlex 990/06D7TR [ 127.186804] RIP: 0010:[<ffffffff810ed6ce>] [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160 [ 127.186809] RSP: 0000:ffff8804144b5c08 EFLAGS: 00010002 [ 127.186810] RAX: 0000000000000001 RBX: ffffea000a5c9000 RCX: 00000000ffffffc0 [ 127.186811] RDX: 0000000000000000 RSI: 0000000000000009 RDI: ffff88042dfdad00 [ 127.186812] RBP: ffff8804144b5c18 R08: 0000000000000009 R09: 0000000000000003 [ 127.186813] R10: 0000000000000000 R11: 000000000000002d R12: ffff880412ff83d8 [ 127.186814] R13: ffff880412ff83d8 R14: 0000000000000000 R15: ffff880412ff83d8 [ 127.186815] FS: 00007fe18ed2c700(0000) GS:ffff88042dce0000(0000) knlGS:0000000000000000 [ 127.186816] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 127.186817] CR2: 00007fe340000503 CR3: 0000000417a14000 CR4: 00000000000407e0 [ 127.186818] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 127.186819] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 127.186820] Process hugetlbfs-test (pid: 9017, threadinfo ffff8804144b4000, task ffff880417f803c0) [ 127.186821] Stack: [ 127.186822] ffffea000a5c9000 0000000000000000 ffff8804144b5c48 ffffffff810ed83b [ 127.186824] ffff8804144b5c48 000000000000138a 0000000000001387 ffff8804144b5c98 [ 127.186825] ffff8804144b5d48 ffffffff811bc925 ffff8804144b5cb8 0000000000000000 [ 127.186827] Call Trace: [ 127.186829] [<ffffffff810ed83b>] delete_from_page_cache+0x3b/0x80 [ 127.186832] [<ffffffff811bc925>] truncate_hugepages+0x115/0x220 [ 127.186834] [<ffffffff811bca43>] hugetlbfs_evict_inode+0x13/0x30 [ 127.186837] [<ffffffff811655c7>] evict+0xa7/0x1b0 [ 127.186839] [<ffffffff811657a3>] iput_final+0xd3/0x1f0 [ 127.186840] [<ffffffff811658f9>] iput+0x39/0x50 [ 127.186842] [<ffffffff81162708>] d_kill+0xf8/0x130 [ 127.186843] [<ffffffff81162812>] dput+0xd2/0x1a0 [ 127.186845] [<ffffffff8114e2d0>] __fput+0x170/0x230 [ 127.186848] [<ffffffff81236e0e>] ? rb_erase+0xce/0x150 [ 127.186849] [<ffffffff8114e3ad>] fput+0x1d/0x30 [ 127.186851] [<ffffffff81117db7>] remove_vma+0x37/0x80 [ 127.186853] [<ffffffff81119182>] do_munmap+0x2d2/0x360 [ 127.186855] [<ffffffff811cc639>] sys_shmdt+0xc9/0x170 [ 127.186857] [<ffffffff81410a39>] system_call_fastpath+0x16/0x1b [ 127.186858] Code: 0f 1f 44 00 00 48 8b 43 08 48 8b 00 48 8b 40 28 8b b0 40 03 00 00 85 f6 0f 88 df fe ff ff 48 89 df e8 e7 cb 05 00 e9 d2 fe ff ff <0f> 0b 55 83 e2 fd 48 89 e5 48 83 ec 30 48 89 5d d8 4c 89 65 e0 [ 127.186868] RIP [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160 [ 127.186870] RSP <ffff8804144b5c08> [ 127.186871] ---[ end trace 7cbac5d1db69f426 ]--- The bug is a race and not always easy to reproduce. To reproduce it I was doing the following on a single socket I7-based machine with 16G of RAM. $ hugeadm --pool-pages-max DEFAULT:13G $ echo $((18*1048576*1024)) > /proc/sys/kernel/shmmax $ echo $((18*1048576*1024)) > /proc/sys/kernel/shmall $ for i in `seq 1 9000`; do ./hugetlbfs-test; done On my particular machine, it usually triggers within 10 minutes but enabling debug options can change the timing such that it never hits. Once the bug is triggered, the machine is in trouble and needs to be rebooted. The machine will respond but processes accessing proc like "ps aux" will hang due to the BUG_ON. shutdown will also hang and needs a hard reset or a sysrq-b. The basic problem is a race between page table sharing and teardown. For the most part page table sharing depends on i_mmap_mutex. In some cases, it is also taking the mm->page_table_lock for the PTE updates but with shared page tables, it is the i_mmap_mutex that is more important. Unfortunately it appears to be also insufficient. Consider the following situation Process A Process B --------- --------- hugetlb_fault shmdt LockWrite(mmap_sem) do_munmap unmap_region unmap_vmas unmap_single_vma unmap_hugepage_range Lock(i_mmap_mutex) Lock(mm->page_table_lock) huge_pmd_unshare/unmap tables <--- (1) Unlock(mm->page_table_lock) Unlock(i_mmap_mutex) huge_pte_alloc ... Lock(i_mmap_mutex) ... vma_prio_walk, find svma, spte ... Lock(mm->page_table_lock) ... share spte ... Unlock(mm->page_table_lock) ... Unlock(i_mmap_mutex) ... hugetlb_no_page <--- (2) free_pgtables unlink_file_vma hugetlb_free_pgd_range remove_vma_list In this scenario, it is possible for Process A to share page tables with Process B that is trying to tear them down. The i_mmap_mutex on its own does not prevent Process A walking Process B's page tables. At (1) above, the page tables are not shared yet so it unmaps the PMDs. Process A sets up page table sharing and at (2) faults a new entry. Process B then trips up on it in free_pgtables. This patch fixes the problem by adding a new function __unmap_hugepage_range_final that is only called when the VMA is about to be destroyed. This function clears VM_MAYSHARE during unmap_hugepage_range() under the i_mmap_mutex. This makes the VMA ineligible for sharing and avoids the race. Superficially this looks like it would then be vunerable to truncate and madvise issues but hugetlbfs has its own truncate handlers so does not use unmap_mapping_range() and does not support madvise(DONTNEED). This should be treated as a -stable candidate if it is merged. Test program is as follows. The test case was mostly written by Michal Hocko with a few minor changes to reproduce this bug. ==== CUT HERE ==== static size_t huge_page_size = (2UL << 20); static size_t nr_huge_page_A = 512; static size_t nr_huge_page_B = 5632; unsigned int get_random(unsigned int max) { struct timeval tv; gettimeofday(&tv, NULL); srandom(tv.tv_usec); return random() % max; } static void play(void *addr, size_t size) { unsigned char *start = addr, *end = start + size, *a; start += get_random(size/2); /* we could itterate on huge pages but let's give it more time. */ for (a = start; a < end; a += 4096) *a = 0; } int main(int argc, char **argv) { key_t key = IPC_PRIVATE; size_t sizeA = nr_huge_page_A * huge_page_size; size_t sizeB = nr_huge_page_B * huge_page_size; int shmidA, shmidB; void *addrA = NULL, *addrB = NULL; int nr_children = 300, n = 0; if ((shmidA = shmget(key, sizeA, IPC_CREAT|SHM_HUGETLB|0660)) == -1) { perror("shmget:"); return 1; } if ((addrA = shmat(shmidA, addrA, SHM_R|SHM_W)) == (void *)-1UL) { perror("shmat"); return 1; } if ((shmidB = shmget(key, sizeB, IPC_CREAT|SHM_HUGETLB|0660)) == -1) { perror("shmget:"); return 1; } if ((addrB = shmat(shmidB, addrB, SHM_R|SHM_W)) == (void *)-1UL) { perror("shmat"); return 1; } fork_child: switch(fork()) { case 0: switch (n%3) { case 0: play(addrA, sizeA); break; case 1: play(addrB, sizeB); break; case 2: break; } break; case -1: perror("fork:"); break; default: if (++n < nr_children) goto fork_child; play(addrA, sizeA); break; } shmdt(addrA); shmdt(addrB); do { wait(NULL); } while (--n > 0); shmctl(shmidA, IPC_RMID, NULL); shmctl(shmidB, IPC_RMID, NULL); return 0; } [akpm@linux-foundation.org: name the declaration's args, fix CONFIG_HUGETLBFS=n build] Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-08-01 03:46:20 +04:00
/*
* Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
mm: hugetlbfs: close race during teardown of hugetlbfs shared page tables If a process creates a large hugetlbfs mapping that is eligible for page table sharing and forks heavily with children some of whom fault and others which destroy the mapping then it is possible for page tables to get corrupted. Some teardowns of the mapping encounter a "bad pmd" and output a message to the kernel log. The final teardown will trigger a BUG_ON in mm/filemap.c. This was reproduced in 3.4 but is known to have existed for a long time and goes back at least as far as 2.6.37. It was probably was introduced in 2.6.20 by [39dde65c: shared page table for hugetlb page]. The messages look like this; [ ..........] Lots of bad pmd messages followed by this [ 127.164256] mm/memory.c:391: bad pmd ffff880412e04fe8(80000003de4000e7). [ 127.164257] mm/memory.c:391: bad pmd ffff880412e04ff0(80000003de6000e7). [ 127.164258] mm/memory.c:391: bad pmd ffff880412e04ff8(80000003de0000e7). [ 127.186778] ------------[ cut here ]------------ [ 127.186781] kernel BUG at mm/filemap.c:134! [ 127.186782] invalid opcode: 0000 [#1] SMP [ 127.186783] CPU 7 [ 127.186784] Modules linked in: af_packet cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf ext3 jbd dm_mod coretemp crc32c_intel usb_storage ghash_clmulni_intel aesni_intel i2c_i801 r8169 mii uas sr_mod cdrom sg iTCO_wdt iTCO_vendor_support shpchp serio_raw cryptd aes_x86_64 e1000e pci_hotplug dcdbas aes_generic container microcode ext4 mbcache jbd2 crc16 sd_mod crc_t10dif i915 drm_kms_helper drm i2c_algo_bit ehci_hcd ahci libahci usbcore rtc_cmos usb_common button i2c_core intel_agp video intel_gtt fan processor thermal thermal_sys hwmon ata_generic pata_atiixp libata scsi_mod [ 127.186801] [ 127.186802] Pid: 9017, comm: hugetlbfs-test Not tainted 3.4.0-autobuild #53 Dell Inc. OptiPlex 990/06D7TR [ 127.186804] RIP: 0010:[<ffffffff810ed6ce>] [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160 [ 127.186809] RSP: 0000:ffff8804144b5c08 EFLAGS: 00010002 [ 127.186810] RAX: 0000000000000001 RBX: ffffea000a5c9000 RCX: 00000000ffffffc0 [ 127.186811] RDX: 0000000000000000 RSI: 0000000000000009 RDI: ffff88042dfdad00 [ 127.186812] RBP: ffff8804144b5c18 R08: 0000000000000009 R09: 0000000000000003 [ 127.186813] R10: 0000000000000000 R11: 000000000000002d R12: ffff880412ff83d8 [ 127.186814] R13: ffff880412ff83d8 R14: 0000000000000000 R15: ffff880412ff83d8 [ 127.186815] FS: 00007fe18ed2c700(0000) GS:ffff88042dce0000(0000) knlGS:0000000000000000 [ 127.186816] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 127.186817] CR2: 00007fe340000503 CR3: 0000000417a14000 CR4: 00000000000407e0 [ 127.186818] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 127.186819] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 127.186820] Process hugetlbfs-test (pid: 9017, threadinfo ffff8804144b4000, task ffff880417f803c0) [ 127.186821] Stack: [ 127.186822] ffffea000a5c9000 0000000000000000 ffff8804144b5c48 ffffffff810ed83b [ 127.186824] ffff8804144b5c48 000000000000138a 0000000000001387 ffff8804144b5c98 [ 127.186825] ffff8804144b5d48 ffffffff811bc925 ffff8804144b5cb8 0000000000000000 [ 127.186827] Call Trace: [ 127.186829] [<ffffffff810ed83b>] delete_from_page_cache+0x3b/0x80 [ 127.186832] [<ffffffff811bc925>] truncate_hugepages+0x115/0x220 [ 127.186834] [<ffffffff811bca43>] hugetlbfs_evict_inode+0x13/0x30 [ 127.186837] [<ffffffff811655c7>] evict+0xa7/0x1b0 [ 127.186839] [<ffffffff811657a3>] iput_final+0xd3/0x1f0 [ 127.186840] [<ffffffff811658f9>] iput+0x39/0x50 [ 127.186842] [<ffffffff81162708>] d_kill+0xf8/0x130 [ 127.186843] [<ffffffff81162812>] dput+0xd2/0x1a0 [ 127.186845] [<ffffffff8114e2d0>] __fput+0x170/0x230 [ 127.186848] [<ffffffff81236e0e>] ? rb_erase+0xce/0x150 [ 127.186849] [<ffffffff8114e3ad>] fput+0x1d/0x30 [ 127.186851] [<ffffffff81117db7>] remove_vma+0x37/0x80 [ 127.186853] [<ffffffff81119182>] do_munmap+0x2d2/0x360 [ 127.186855] [<ffffffff811cc639>] sys_shmdt+0xc9/0x170 [ 127.186857] [<ffffffff81410a39>] system_call_fastpath+0x16/0x1b [ 127.186858] Code: 0f 1f 44 00 00 48 8b 43 08 48 8b 00 48 8b 40 28 8b b0 40 03 00 00 85 f6 0f 88 df fe ff ff 48 89 df e8 e7 cb 05 00 e9 d2 fe ff ff <0f> 0b 55 83 e2 fd 48 89 e5 48 83 ec 30 48 89 5d d8 4c 89 65 e0 [ 127.186868] RIP [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160 [ 127.186870] RSP <ffff8804144b5c08> [ 127.186871] ---[ end trace 7cbac5d1db69f426 ]--- The bug is a race and not always easy to reproduce. To reproduce it I was doing the following on a single socket I7-based machine with 16G of RAM. $ hugeadm --pool-pages-max DEFAULT:13G $ echo $((18*1048576*1024)) > /proc/sys/kernel/shmmax $ echo $((18*1048576*1024)) > /proc/sys/kernel/shmall $ for i in `seq 1 9000`; do ./hugetlbfs-test; done On my particular machine, it usually triggers within 10 minutes but enabling debug options can change the timing such that it never hits. Once the bug is triggered, the machine is in trouble and needs to be rebooted. The machine will respond but processes accessing proc like "ps aux" will hang due to the BUG_ON. shutdown will also hang and needs a hard reset or a sysrq-b. The basic problem is a race between page table sharing and teardown. For the most part page table sharing depends on i_mmap_mutex. In some cases, it is also taking the mm->page_table_lock for the PTE updates but with shared page tables, it is the i_mmap_mutex that is more important. Unfortunately it appears to be also insufficient. Consider the following situation Process A Process B --------- --------- hugetlb_fault shmdt LockWrite(mmap_sem) do_munmap unmap_region unmap_vmas unmap_single_vma unmap_hugepage_range Lock(i_mmap_mutex) Lock(mm->page_table_lock) huge_pmd_unshare/unmap tables <--- (1) Unlock(mm->page_table_lock) Unlock(i_mmap_mutex) huge_pte_alloc ... Lock(i_mmap_mutex) ... vma_prio_walk, find svma, spte ... Lock(mm->page_table_lock) ... share spte ... Unlock(mm->page_table_lock) ... Unlock(i_mmap_mutex) ... hugetlb_no_page <--- (2) free_pgtables unlink_file_vma hugetlb_free_pgd_range remove_vma_list In this scenario, it is possible for Process A to share page tables with Process B that is trying to tear them down. The i_mmap_mutex on its own does not prevent Process A walking Process B's page tables. At (1) above, the page tables are not shared yet so it unmaps the PMDs. Process A sets up page table sharing and at (2) faults a new entry. Process B then trips up on it in free_pgtables. This patch fixes the problem by adding a new function __unmap_hugepage_range_final that is only called when the VMA is about to be destroyed. This function clears VM_MAYSHARE during unmap_hugepage_range() under the i_mmap_mutex. This makes the VMA ineligible for sharing and avoids the race. Superficially this looks like it would then be vunerable to truncate and madvise issues but hugetlbfs has its own truncate handlers so does not use unmap_mapping_range() and does not support madvise(DONTNEED). This should be treated as a -stable candidate if it is merged. Test program is as follows. The test case was mostly written by Michal Hocko with a few minor changes to reproduce this bug. ==== CUT HERE ==== static size_t huge_page_size = (2UL << 20); static size_t nr_huge_page_A = 512; static size_t nr_huge_page_B = 5632; unsigned int get_random(unsigned int max) { struct timeval tv; gettimeofday(&tv, NULL); srandom(tv.tv_usec); return random() % max; } static void play(void *addr, size_t size) { unsigned char *start = addr, *end = start + size, *a; start += get_random(size/2); /* we could itterate on huge pages but let's give it more time. */ for (a = start; a < end; a += 4096) *a = 0; } int main(int argc, char **argv) { key_t key = IPC_PRIVATE; size_t sizeA = nr_huge_page_A * huge_page_size; size_t sizeB = nr_huge_page_B * huge_page_size; int shmidA, shmidB; void *addrA = NULL, *addrB = NULL; int nr_children = 300, n = 0; if ((shmidA = shmget(key, sizeA, IPC_CREAT|SHM_HUGETLB|0660)) == -1) { perror("shmget:"); return 1; } if ((addrA = shmat(shmidA, addrA, SHM_R|SHM_W)) == (void *)-1UL) { perror("shmat"); return 1; } if ((shmidB = shmget(key, sizeB, IPC_CREAT|SHM_HUGETLB|0660)) == -1) { perror("shmget:"); return 1; } if ((addrB = shmat(shmidB, addrB, SHM_R|SHM_W)) == (void *)-1UL) { perror("shmat"); return 1; } fork_child: switch(fork()) { case 0: switch (n%3) { case 0: play(addrA, sizeA); break; case 1: play(addrB, sizeB); break; case 2: break; } break; case -1: perror("fork:"); break; default: if (++n < nr_children) goto fork_child; play(addrA, sizeA); break; } shmdt(addrA); shmdt(addrB); do { wait(NULL); } while (--n > 0); shmctl(shmidA, IPC_RMID, NULL); shmctl(shmidB, IPC_RMID, NULL); return 0; } [akpm@linux-foundation.org: name the declaration's args, fix CONFIG_HUGETLBFS=n build] Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-08-01 03:46:20 +04:00
* may have cleared our pud entry and done put_page on the page table:
* once we release i_mmap_rwsem, another task can do the final put_page
* and that page table be reused and filled with junk. If we actually
* did unshare a page of pmds, flush the range corresponding to the pud.
mm: hugetlbfs: close race during teardown of hugetlbfs shared page tables If a process creates a large hugetlbfs mapping that is eligible for page table sharing and forks heavily with children some of whom fault and others which destroy the mapping then it is possible for page tables to get corrupted. Some teardowns of the mapping encounter a "bad pmd" and output a message to the kernel log. The final teardown will trigger a BUG_ON in mm/filemap.c. This was reproduced in 3.4 but is known to have existed for a long time and goes back at least as far as 2.6.37. It was probably was introduced in 2.6.20 by [39dde65c: shared page table for hugetlb page]. The messages look like this; [ ..........] Lots of bad pmd messages followed by this [ 127.164256] mm/memory.c:391: bad pmd ffff880412e04fe8(80000003de4000e7). [ 127.164257] mm/memory.c:391: bad pmd ffff880412e04ff0(80000003de6000e7). [ 127.164258] mm/memory.c:391: bad pmd ffff880412e04ff8(80000003de0000e7). [ 127.186778] ------------[ cut here ]------------ [ 127.186781] kernel BUG at mm/filemap.c:134! [ 127.186782] invalid opcode: 0000 [#1] SMP [ 127.186783] CPU 7 [ 127.186784] Modules linked in: af_packet cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf ext3 jbd dm_mod coretemp crc32c_intel usb_storage ghash_clmulni_intel aesni_intel i2c_i801 r8169 mii uas sr_mod cdrom sg iTCO_wdt iTCO_vendor_support shpchp serio_raw cryptd aes_x86_64 e1000e pci_hotplug dcdbas aes_generic container microcode ext4 mbcache jbd2 crc16 sd_mod crc_t10dif i915 drm_kms_helper drm i2c_algo_bit ehci_hcd ahci libahci usbcore rtc_cmos usb_common button i2c_core intel_agp video intel_gtt fan processor thermal thermal_sys hwmon ata_generic pata_atiixp libata scsi_mod [ 127.186801] [ 127.186802] Pid: 9017, comm: hugetlbfs-test Not tainted 3.4.0-autobuild #53 Dell Inc. OptiPlex 990/06D7TR [ 127.186804] RIP: 0010:[<ffffffff810ed6ce>] [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160 [ 127.186809] RSP: 0000:ffff8804144b5c08 EFLAGS: 00010002 [ 127.186810] RAX: 0000000000000001 RBX: ffffea000a5c9000 RCX: 00000000ffffffc0 [ 127.186811] RDX: 0000000000000000 RSI: 0000000000000009 RDI: ffff88042dfdad00 [ 127.186812] RBP: ffff8804144b5c18 R08: 0000000000000009 R09: 0000000000000003 [ 127.186813] R10: 0000000000000000 R11: 000000000000002d R12: ffff880412ff83d8 [ 127.186814] R13: ffff880412ff83d8 R14: 0000000000000000 R15: ffff880412ff83d8 [ 127.186815] FS: 00007fe18ed2c700(0000) GS:ffff88042dce0000(0000) knlGS:0000000000000000 [ 127.186816] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 127.186817] CR2: 00007fe340000503 CR3: 0000000417a14000 CR4: 00000000000407e0 [ 127.186818] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 127.186819] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 127.186820] Process hugetlbfs-test (pid: 9017, threadinfo ffff8804144b4000, task ffff880417f803c0) [ 127.186821] Stack: [ 127.186822] ffffea000a5c9000 0000000000000000 ffff8804144b5c48 ffffffff810ed83b [ 127.186824] ffff8804144b5c48 000000000000138a 0000000000001387 ffff8804144b5c98 [ 127.186825] ffff8804144b5d48 ffffffff811bc925 ffff8804144b5cb8 0000000000000000 [ 127.186827] Call Trace: [ 127.186829] [<ffffffff810ed83b>] delete_from_page_cache+0x3b/0x80 [ 127.186832] [<ffffffff811bc925>] truncate_hugepages+0x115/0x220 [ 127.186834] [<ffffffff811bca43>] hugetlbfs_evict_inode+0x13/0x30 [ 127.186837] [<ffffffff811655c7>] evict+0xa7/0x1b0 [ 127.186839] [<ffffffff811657a3>] iput_final+0xd3/0x1f0 [ 127.186840] [<ffffffff811658f9>] iput+0x39/0x50 [ 127.186842] [<ffffffff81162708>] d_kill+0xf8/0x130 [ 127.186843] [<ffffffff81162812>] dput+0xd2/0x1a0 [ 127.186845] [<ffffffff8114e2d0>] __fput+0x170/0x230 [ 127.186848] [<ffffffff81236e0e>] ? rb_erase+0xce/0x150 [ 127.186849] [<ffffffff8114e3ad>] fput+0x1d/0x30 [ 127.186851] [<ffffffff81117db7>] remove_vma+0x37/0x80 [ 127.186853] [<ffffffff81119182>] do_munmap+0x2d2/0x360 [ 127.186855] [<ffffffff811cc639>] sys_shmdt+0xc9/0x170 [ 127.186857] [<ffffffff81410a39>] system_call_fastpath+0x16/0x1b [ 127.186858] Code: 0f 1f 44 00 00 48 8b 43 08 48 8b 00 48 8b 40 28 8b b0 40 03 00 00 85 f6 0f 88 df fe ff ff 48 89 df e8 e7 cb 05 00 e9 d2 fe ff ff <0f> 0b 55 83 e2 fd 48 89 e5 48 83 ec 30 48 89 5d d8 4c 89 65 e0 [ 127.186868] RIP [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160 [ 127.186870] RSP <ffff8804144b5c08> [ 127.186871] ---[ end trace 7cbac5d1db69f426 ]--- The bug is a race and not always easy to reproduce. To reproduce it I was doing the following on a single socket I7-based machine with 16G of RAM. $ hugeadm --pool-pages-max DEFAULT:13G $ echo $((18*1048576*1024)) > /proc/sys/kernel/shmmax $ echo $((18*1048576*1024)) > /proc/sys/kernel/shmall $ for i in `seq 1 9000`; do ./hugetlbfs-test; done On my particular machine, it usually triggers within 10 minutes but enabling debug options can change the timing such that it never hits. Once the bug is triggered, the machine is in trouble and needs to be rebooted. The machine will respond but processes accessing proc like "ps aux" will hang due to the BUG_ON. shutdown will also hang and needs a hard reset or a sysrq-b. The basic problem is a race between page table sharing and teardown. For the most part page table sharing depends on i_mmap_mutex. In some cases, it is also taking the mm->page_table_lock for the PTE updates but with shared page tables, it is the i_mmap_mutex that is more important. Unfortunately it appears to be also insufficient. Consider the following situation Process A Process B --------- --------- hugetlb_fault shmdt LockWrite(mmap_sem) do_munmap unmap_region unmap_vmas unmap_single_vma unmap_hugepage_range Lock(i_mmap_mutex) Lock(mm->page_table_lock) huge_pmd_unshare/unmap tables <--- (1) Unlock(mm->page_table_lock) Unlock(i_mmap_mutex) huge_pte_alloc ... Lock(i_mmap_mutex) ... vma_prio_walk, find svma, spte ... Lock(mm->page_table_lock) ... share spte ... Unlock(mm->page_table_lock) ... Unlock(i_mmap_mutex) ... hugetlb_no_page <--- (2) free_pgtables unlink_file_vma hugetlb_free_pgd_range remove_vma_list In this scenario, it is possible for Process A to share page tables with Process B that is trying to tear them down. The i_mmap_mutex on its own does not prevent Process A walking Process B's page tables. At (1) above, the page tables are not shared yet so it unmaps the PMDs. Process A sets up page table sharing and at (2) faults a new entry. Process B then trips up on it in free_pgtables. This patch fixes the problem by adding a new function __unmap_hugepage_range_final that is only called when the VMA is about to be destroyed. This function clears VM_MAYSHARE during unmap_hugepage_range() under the i_mmap_mutex. This makes the VMA ineligible for sharing and avoids the race. Superficially this looks like it would then be vunerable to truncate and madvise issues but hugetlbfs has its own truncate handlers so does not use unmap_mapping_range() and does not support madvise(DONTNEED). This should be treated as a -stable candidate if it is merged. Test program is as follows. The test case was mostly written by Michal Hocko with a few minor changes to reproduce this bug. ==== CUT HERE ==== static size_t huge_page_size = (2UL << 20); static size_t nr_huge_page_A = 512; static size_t nr_huge_page_B = 5632; unsigned int get_random(unsigned int max) { struct timeval tv; gettimeofday(&tv, NULL); srandom(tv.tv_usec); return random() % max; } static void play(void *addr, size_t size) { unsigned char *start = addr, *end = start + size, *a; start += get_random(size/2); /* we could itterate on huge pages but let's give it more time. */ for (a = start; a < end; a += 4096) *a = 0; } int main(int argc, char **argv) { key_t key = IPC_PRIVATE; size_t sizeA = nr_huge_page_A * huge_page_size; size_t sizeB = nr_huge_page_B * huge_page_size; int shmidA, shmidB; void *addrA = NULL, *addrB = NULL; int nr_children = 300, n = 0; if ((shmidA = shmget(key, sizeA, IPC_CREAT|SHM_HUGETLB|0660)) == -1) { perror("shmget:"); return 1; } if ((addrA = shmat(shmidA, addrA, SHM_R|SHM_W)) == (void *)-1UL) { perror("shmat"); return 1; } if ((shmidB = shmget(key, sizeB, IPC_CREAT|SHM_HUGETLB|0660)) == -1) { perror("shmget:"); return 1; } if ((addrB = shmat(shmidB, addrB, SHM_R|SHM_W)) == (void *)-1UL) { perror("shmat"); return 1; } fork_child: switch(fork()) { case 0: switch (n%3) { case 0: play(addrA, sizeA); break; case 1: play(addrB, sizeB); break; case 2: break; } break; case -1: perror("fork:"); break; default: if (++n < nr_children) goto fork_child; play(addrA, sizeA); break; } shmdt(addrA); shmdt(addrB); do { wait(NULL); } while (--n > 0); shmctl(shmidA, IPC_RMID, NULL); shmctl(shmidB, IPC_RMID, NULL); return 0; } [akpm@linux-foundation.org: name the declaration's args, fix CONFIG_HUGETLBFS=n build] Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-08-01 03:46:20 +04:00
*/
if (shared_pmd)
flush_hugetlb_tlb_range(vma, range.start, range.end);
else
flush_hugetlb_tlb_range(vma, start, end);
mm/mmu_notifier: avoid double notification when it is useless This patch only affects users of mmu_notifier->invalidate_range callback which are device drivers related to ATS/PASID, CAPI, IOMMUv2, SVM ... and it is an optimization for those users. Everyone else is unaffected by it. When clearing a pte/pmd we are given a choice to notify the event under the page table lock (notify version of *_clear_flush helpers do call the mmu_notifier_invalidate_range). But that notification is not necessary in all cases. This patch removes almost all cases where it is useless to have a call to mmu_notifier_invalidate_range before mmu_notifier_invalidate_range_end. It also adds documentation in all those cases explaining why. Below is a more in depth analysis of why this is fine to do this: For secondary TLB (non CPU TLB) like IOMMU TLB or device TLB (when device use thing like ATS/PASID to get the IOMMU to walk the CPU page table to access a process virtual address space). There is only 2 cases when you need to notify those secondary TLB while holding page table lock when clearing a pte/pmd: A) page backing address is free before mmu_notifier_invalidate_range_end B) a page table entry is updated to point to a new page (COW, write fault on zero page, __replace_page(), ...) Case A is obvious you do not want to take the risk for the device to write to a page that might now be used by something completely different. Case B is more subtle. For correctness it requires the following sequence to happen: - take page table lock - clear page table entry and notify (pmd/pte_huge_clear_flush_notify()) - set page table entry to point to new page If clearing the page table entry is not followed by a notify before setting the new pte/pmd value then you can break memory model like C11 or C++11 for the device. Consider the following scenario (device use a feature similar to ATS/ PASID): Two address addrA and addrB such that |addrA - addrB| >= PAGE_SIZE we assume they are write protected for COW (other case of B apply too). [Time N] ----------------------------------------------------------------- CPU-thread-0 {try to write to addrA} CPU-thread-1 {try to write to addrB} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {read addrA and populate device TLB} DEV-thread-2 {read addrB and populate device TLB} [Time N+1] --------------------------------------------------------------- CPU-thread-0 {COW_step0: {mmu_notifier_invalidate_range_start(addrA)}} CPU-thread-1 {COW_step0: {mmu_notifier_invalidate_range_start(addrB)}} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+2] --------------------------------------------------------------- CPU-thread-0 {COW_step1: {update page table point to new page for addrA}} CPU-thread-1 {COW_step1: {update page table point to new page for addrB}} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+3] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {preempted} CPU-thread-2 {write to addrA which is a write to new page} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+3] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {preempted} CPU-thread-2 {} CPU-thread-3 {write to addrB which is a write to new page} DEV-thread-0 {} DEV-thread-2 {} [Time N+4] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {COW_step3: {mmu_notifier_invalidate_range_end(addrB)}} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+5] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {read addrA from old page} DEV-thread-2 {read addrB from new page} So here because at time N+2 the clear page table entry was not pair with a notification to invalidate the secondary TLB, the device see the new value for addrB before seing the new value for addrA. This break total memory ordering for the device. When changing a pte to write protect or to point to a new write protected page with same content (KSM) it is ok to delay invalidate_range callback to mmu_notifier_invalidate_range_end() outside the page table lock. This is true even if the thread doing page table update is preempted right after releasing page table lock before calling mmu_notifier_invalidate_range_end Thanks to Andrea for thinking of a problematic scenario for COW. [jglisse@redhat.com: v2] Link: http://lkml.kernel.org/r/20171017031003.7481-2-jglisse@redhat.com Link: http://lkml.kernel.org/r/20170901173011.10745-1-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Alistair Popple <alistair@popple.id.au> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Andrew Donnellan <andrew.donnellan@au1.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-16 04:34:07 +03:00
/*
* No need to call mmu_notifier_invalidate_range() we are downgrading
* page table protection not changing it to point to a new page.
*
* See Documentation/vm/mmu_notifier.rst
mm/mmu_notifier: avoid double notification when it is useless This patch only affects users of mmu_notifier->invalidate_range callback which are device drivers related to ATS/PASID, CAPI, IOMMUv2, SVM ... and it is an optimization for those users. Everyone else is unaffected by it. When clearing a pte/pmd we are given a choice to notify the event under the page table lock (notify version of *_clear_flush helpers do call the mmu_notifier_invalidate_range). But that notification is not necessary in all cases. This patch removes almost all cases where it is useless to have a call to mmu_notifier_invalidate_range before mmu_notifier_invalidate_range_end. It also adds documentation in all those cases explaining why. Below is a more in depth analysis of why this is fine to do this: For secondary TLB (non CPU TLB) like IOMMU TLB or device TLB (when device use thing like ATS/PASID to get the IOMMU to walk the CPU page table to access a process virtual address space). There is only 2 cases when you need to notify those secondary TLB while holding page table lock when clearing a pte/pmd: A) page backing address is free before mmu_notifier_invalidate_range_end B) a page table entry is updated to point to a new page (COW, write fault on zero page, __replace_page(), ...) Case A is obvious you do not want to take the risk for the device to write to a page that might now be used by something completely different. Case B is more subtle. For correctness it requires the following sequence to happen: - take page table lock - clear page table entry and notify (pmd/pte_huge_clear_flush_notify()) - set page table entry to point to new page If clearing the page table entry is not followed by a notify before setting the new pte/pmd value then you can break memory model like C11 or C++11 for the device. Consider the following scenario (device use a feature similar to ATS/ PASID): Two address addrA and addrB such that |addrA - addrB| >= PAGE_SIZE we assume they are write protected for COW (other case of B apply too). [Time N] ----------------------------------------------------------------- CPU-thread-0 {try to write to addrA} CPU-thread-1 {try to write to addrB} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {read addrA and populate device TLB} DEV-thread-2 {read addrB and populate device TLB} [Time N+1] --------------------------------------------------------------- CPU-thread-0 {COW_step0: {mmu_notifier_invalidate_range_start(addrA)}} CPU-thread-1 {COW_step0: {mmu_notifier_invalidate_range_start(addrB)}} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+2] --------------------------------------------------------------- CPU-thread-0 {COW_step1: {update page table point to new page for addrA}} CPU-thread-1 {COW_step1: {update page table point to new page for addrB}} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+3] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {preempted} CPU-thread-2 {write to addrA which is a write to new page} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+3] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {preempted} CPU-thread-2 {} CPU-thread-3 {write to addrB which is a write to new page} DEV-thread-0 {} DEV-thread-2 {} [Time N+4] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {COW_step3: {mmu_notifier_invalidate_range_end(addrB)}} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {} DEV-thread-2 {} [Time N+5] --------------------------------------------------------------- CPU-thread-0 {preempted} CPU-thread-1 {} CPU-thread-2 {} CPU-thread-3 {} DEV-thread-0 {read addrA from old page} DEV-thread-2 {read addrB from new page} So here because at time N+2 the clear page table entry was not pair with a notification to invalidate the secondary TLB, the device see the new value for addrB before seing the new value for addrA. This break total memory ordering for the device. When changing a pte to write protect or to point to a new write protected page with same content (KSM) it is ok to delay invalidate_range callback to mmu_notifier_invalidate_range_end() outside the page table lock. This is true even if the thread doing page table update is preempted right after releasing page table lock before calling mmu_notifier_invalidate_range_end Thanks to Andrea for thinking of a problematic scenario for COW. [jglisse@redhat.com: v2] Link: http://lkml.kernel.org/r/20171017031003.7481-2-jglisse@redhat.com Link: http://lkml.kernel.org/r/20170901173011.10745-1-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Alistair Popple <alistair@popple.id.au> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Andrew Donnellan <andrew.donnellan@au1.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-16 04:34:07 +03:00
*/
i_mmap_unlock_write(vma->vm_file->f_mapping);
mmu_notifier_invalidate_range_end(&range);
return pages << h->order;
[PATCH] Enable mprotect on huge pages 2.6.16-rc3 uses hugetlb on-demand paging, but it doesn_t support hugetlb mprotect. From: David Gibson <david@gibson.dropbear.id.au> Remove a test from the mprotect() path which checks that the mprotect()ed range on a hugepage VMA is hugepage aligned (yes, really, the sense of is_aligned_hugepage_range() is the opposite of what you'd guess :-/). In fact, we don't need this test. If the given addresses match the beginning/end of a hugepage VMA they must already be suitably aligned. If they don't, then mprotect_fixup() will attempt to split the VMA. The very first test in split_vma() will check for a badly aligned address on a hugepage VMA and return -EINVAL if necessary. From: "Chen, Kenneth W" <kenneth.w.chen@intel.com> On i386 and x86-64, pte flag _PAGE_PSE collides with _PAGE_PROTNONE. The identify of hugetlb pte is lost when changing page protection via mprotect. A page fault occurs later will trigger a bug check in huge_pte_alloc(). The fix is to always make new pte a hugetlb pte and also to clean up legacy code where _PAGE_PRESENT is forced on in the pre-faulting day. Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 11:08:50 +03:00
}
/* Return true if reservation was successful, false otherwise. */
bool hugetlb_reserve_pages(struct inode *inode,
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
long from, long to,
Do not account for the address space used by hugetlbfs using VM_ACCOUNT When overcommit is disabled, the core VM accounts for pages used by anonymous shared, private mappings and special mappings. It keeps track of VMAs that should be accounted for with VM_ACCOUNT and VMAs that never had a reserve with VM_NORESERVE. Overcommit for hugetlbfs is much riskier than overcommit for base pages due to contiguity requirements. It avoids overcommiting on both shared and private mappings using reservation counters that are checked and updated during mmap(). This ensures (within limits) that hugepages exist in the future when faults occurs or it is too easy to applications to be SIGKILLed. As hugetlbfs makes its own reservations of a different unit to the base page size, VM_ACCOUNT should never be set. Even if the units were correct, we would double account for the usage in the core VM and hugetlbfs. VM_NORESERVE may be set because an application can request no reserves be made for hugetlbfs at the risk of getting killed later. With commit fc8744adc870a8d4366908221508bb113d8b72ee, VM_NORESERVE and VM_ACCOUNT are getting unconditionally set for hugetlbfs-backed mappings. This breaks the accounting for both the core VM and hugetlbfs, can trigger an OOM storm when hugepage pools are too small lockups and corrupted counters otherwise are used. This patch brings hugetlbfs more in line with how the core VM treats VM_NORESERVE but prevents VM_ACCOUNT being set. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-02-10 17:02:27 +03:00
struct vm_area_struct *vma,
vm_flags_t vm_flags)
{
long chg, add = -1;
struct hstate *h = hstate_inode(inode);
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
struct hugepage_subpool *spool = subpool_inode(inode);
struct resv_map *resv_map;
struct hugetlb_cgroup *h_cg = NULL;
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
long gbl_reserve, regions_needed = 0;
hugetlbfs: check for pgoff value overflow A vma with vm_pgoff large enough to overflow a loff_t type when converted to a byte offset can be passed via the remap_file_pages system call. The hugetlbfs mmap routine uses the byte offset to calculate reservations and file size. A sequence such as: mmap(0x20a00000, 0x600000, 0, 0x66033, -1, 0); remap_file_pages(0x20a00000, 0x600000, 0, 0x20000000000000, 0); will result in the following when task exits/file closed, kernel BUG at mm/hugetlb.c:749! Call Trace: hugetlbfs_evict_inode+0x2f/0x40 evict+0xcb/0x190 __dentry_kill+0xcb/0x150 __fput+0x164/0x1e0 task_work_run+0x84/0xa0 exit_to_usermode_loop+0x7d/0x80 do_syscall_64+0x18b/0x190 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 The overflowed pgoff value causes hugetlbfs to try to set up a mapping with a negative range (end < start) that leaves invalid state which causes the BUG. The previous overflow fix to this code was incomplete and did not take the remap_file_pages system call into account. [mike.kravetz@oracle.com: v3] Link: http://lkml.kernel.org/r/20180309002726.7248-1-mike.kravetz@oracle.com [akpm@linux-foundation.org: include mmdebug.h] [akpm@linux-foundation.org: fix -ve left shift count on sh] Link: http://lkml.kernel.org/r/20180308210502.15952-1-mike.kravetz@oracle.com Fixes: 045c7a3f53d9 ("hugetlbfs: fix offset overflow in hugetlbfs mmap") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Nic Losby <blurbdust@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Yisheng Xie <xieyisheng1@huawei.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-03-23 02:17:13 +03:00
/* This should never happen */
if (from > to) {
VM_WARN(1, "%s called with a negative range\n", __func__);
return false;
hugetlbfs: check for pgoff value overflow A vma with vm_pgoff large enough to overflow a loff_t type when converted to a byte offset can be passed via the remap_file_pages system call. The hugetlbfs mmap routine uses the byte offset to calculate reservations and file size. A sequence such as: mmap(0x20a00000, 0x600000, 0, 0x66033, -1, 0); remap_file_pages(0x20a00000, 0x600000, 0, 0x20000000000000, 0); will result in the following when task exits/file closed, kernel BUG at mm/hugetlb.c:749! Call Trace: hugetlbfs_evict_inode+0x2f/0x40 evict+0xcb/0x190 __dentry_kill+0xcb/0x150 __fput+0x164/0x1e0 task_work_run+0x84/0xa0 exit_to_usermode_loop+0x7d/0x80 do_syscall_64+0x18b/0x190 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 The overflowed pgoff value causes hugetlbfs to try to set up a mapping with a negative range (end < start) that leaves invalid state which causes the BUG. The previous overflow fix to this code was incomplete and did not take the remap_file_pages system call into account. [mike.kravetz@oracle.com: v3] Link: http://lkml.kernel.org/r/20180309002726.7248-1-mike.kravetz@oracle.com [akpm@linux-foundation.org: include mmdebug.h] [akpm@linux-foundation.org: fix -ve left shift count on sh] Link: http://lkml.kernel.org/r/20180308210502.15952-1-mike.kravetz@oracle.com Fixes: 045c7a3f53d9 ("hugetlbfs: fix offset overflow in hugetlbfs mmap") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reported-by: Nic Losby <blurbdust@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Yisheng Xie <xieyisheng1@huawei.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-03-23 02:17:13 +03:00
}
/*
* Only apply hugepage reservation if asked. At fault time, an
* attempt will be made for VM_NORESERVE to allocate a page
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
* without using reserves
*/
if (vm_flags & VM_NORESERVE)
return true;
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
/*
* Shared mappings base their reservation on the number of pages that
* are already allocated on behalf of the file. Private mappings need
* to reserve the full area even if read-only as mprotect() may be
* called to make the mapping read-write. Assume !vma is a shm mapping
*/
if (!vma || vma->vm_flags & VM_MAYSHARE) {
/*
* resv_map can not be NULL as hugetlb_reserve_pages is only
* called for inodes for which resv_maps were created (see
* hugetlbfs_get_inode).
*/
resv_map = inode_resv_map(inode);
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
chg = region_chg(resv_map, from, to, &regions_needed);
} else {
hugetlb_cgroup: add reservation accounting for private mappings Normally the pointer to the cgroup to uncharge hangs off the struct page, and gets queried when it's time to free the page. With hugetlb_cgroup reservations, this is not possible. Because it's possible for a page to be reserved by one task and actually faulted in by another task. The best place to put the hugetlb_cgroup pointer to uncharge for reservations is in the resv_map. But, because the resv_map has different semantics for private and shared mappings, the code patch to charge/uncharge shared and private mappings is different. This patch implements charging and uncharging for private mappings. For private mappings, the counter to uncharge is in resv_map->reservation_counter. On initializing the resv_map this is set to NULL. On reservation of a region in private mapping, the tasks hugetlb_cgroup is charged and the hugetlb_cgroup is placed is resv_map->reservation_counter. On hugetlb_vm_op_close, we uncharge resv_map->reservation_counter. [akpm@linux-foundation.org: forward declare struct resv_map] Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Link: http://lkml.kernel.org/r/20200211213128.73302-3-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:21 +03:00
/* Private mapping. */
resv_map = resv_map_alloc();
if (!resv_map)
return false;
hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:23 +04:00
chg = to - from;
hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 08:27:32 +04:00
set_vma_resv_map(vma, resv_map);
set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
}
if (chg < 0)
goto out_err;
if (hugetlb_cgroup_charge_cgroup_rsvd(hstate_index(h),
chg * pages_per_huge_page(h), &h_cg) < 0)
goto out_err;
if (vma && !(vma->vm_flags & VM_MAYSHARE) && h_cg) {
/* For private mappings, the hugetlb_cgroup uncharge info hangs
* of the resv_map.
*/
resv_map_set_hugetlb_cgroup_uncharge_info(resv_map, h_cg, h);
}
/*
* There must be enough pages in the subpool for the mapping. If
* the subpool has a minimum size, there may be some global
* reservations already in place (gbl_reserve).
*/
gbl_reserve = hugepage_subpool_get_pages(spool, chg);
if (gbl_reserve < 0)
goto out_uncharge_cgroup;
Do not account for the address space used by hugetlbfs using VM_ACCOUNT When overcommit is disabled, the core VM accounts for pages used by anonymous shared, private mappings and special mappings. It keeps track of VMAs that should be accounted for with VM_ACCOUNT and VMAs that never had a reserve with VM_NORESERVE. Overcommit for hugetlbfs is much riskier than overcommit for base pages due to contiguity requirements. It avoids overcommiting on both shared and private mappings using reservation counters that are checked and updated during mmap(). This ensures (within limits) that hugepages exist in the future when faults occurs or it is too easy to applications to be SIGKILLed. As hugetlbfs makes its own reservations of a different unit to the base page size, VM_ACCOUNT should never be set. Even if the units were correct, we would double account for the usage in the core VM and hugetlbfs. VM_NORESERVE may be set because an application can request no reserves be made for hugetlbfs at the risk of getting killed later. With commit fc8744adc870a8d4366908221508bb113d8b72ee, VM_NORESERVE and VM_ACCOUNT are getting unconditionally set for hugetlbfs-backed mappings. This breaks the accounting for both the core VM and hugetlbfs, can trigger an OOM storm when hugepage pools are too small lockups and corrupted counters otherwise are used. This patch brings hugetlbfs more in line with how the core VM treats VM_NORESERVE but prevents VM_ACCOUNT being set. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-02-10 17:02:27 +03:00
/*
* Check enough hugepages are available for the reservation.
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
* Hand the pages back to the subpool if there are not
Do not account for the address space used by hugetlbfs using VM_ACCOUNT When overcommit is disabled, the core VM accounts for pages used by anonymous shared, private mappings and special mappings. It keeps track of VMAs that should be accounted for with VM_ACCOUNT and VMAs that never had a reserve with VM_NORESERVE. Overcommit for hugetlbfs is much riskier than overcommit for base pages due to contiguity requirements. It avoids overcommiting on both shared and private mappings using reservation counters that are checked and updated during mmap(). This ensures (within limits) that hugepages exist in the future when faults occurs or it is too easy to applications to be SIGKILLed. As hugetlbfs makes its own reservations of a different unit to the base page size, VM_ACCOUNT should never be set. Even if the units were correct, we would double account for the usage in the core VM and hugetlbfs. VM_NORESERVE may be set because an application can request no reserves be made for hugetlbfs at the risk of getting killed later. With commit fc8744adc870a8d4366908221508bb113d8b72ee, VM_NORESERVE and VM_ACCOUNT are getting unconditionally set for hugetlbfs-backed mappings. This breaks the accounting for both the core VM and hugetlbfs, can trigger an OOM storm when hugepage pools are too small lockups and corrupted counters otherwise are used. This patch brings hugetlbfs more in line with how the core VM treats VM_NORESERVE but prevents VM_ACCOUNT being set. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-02-10 17:02:27 +03:00
*/
if (hugetlb_acct_memory(h, gbl_reserve) < 0)
goto out_put_pages;
/*
* Account for the reservations made. Shared mappings record regions
* that have reservations as they are shared by multiple VMAs.
* When the last VMA disappears, the region map says how much
* the reservation was and the page cache tells how much of
* the reservation was consumed. Private mappings are per-VMA and
* only the consumed reservations are tracked. When the VMA
* disappears, the original reservation is the VMA size and the
* consumed reservations are stored in the map. Hence, nothing
* else has to be done for private mappings here
*/
if (!vma || vma->vm_flags & VM_MAYSHARE) {
add = region_add(resv_map, from, to, regions_needed, h, h_cg);
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
if (unlikely(add < 0)) {
hugetlb_acct_memory(h, -gbl_reserve);
goto out_put_pages;
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
} else if (unlikely(chg > add)) {
/*
* pages in this range were added to the reserve
* map between region_chg and region_add. This
* indicates a race with alloc_huge_page. Adjust
* the subpool and reserve counts modified above
* based on the difference.
*/
long rsv_adjust;
hugetlb_cgroup: fix imbalanced css_get and css_put pair for shared mappings The current implementation of hugetlb_cgroup for shared mappings could have different behavior. Consider the following two scenarios: 1.Assume initial css reference count of hugetlb_cgroup is 1: 1.1 Call hugetlb_reserve_pages with from = 1, to = 2. So css reference count is 2 associated with 1 file_region. 1.2 Call hugetlb_reserve_pages with from = 2, to = 3. So css reference count is 3 associated with 2 file_region. 1.3 coalesce_file_region will coalesce these two file_regions into one. So css reference count is 3 associated with 1 file_region now. 2.Assume initial css reference count of hugetlb_cgroup is 1 again: 2.1 Call hugetlb_reserve_pages with from = 1, to = 3. So css reference count is 2 associated with 1 file_region. Therefore, we might have one file_region while holding one or more css reference counts. This inconsistency could lead to imbalanced css_get() and css_put() pair. If we do css_put one by one (i.g. hole punch case), scenario 2 would put one more css reference. If we do css_put all together (i.g. truncate case), scenario 1 will leak one css reference. The imbalanced css_get() and css_put() pair would result in a non-zero reference when we try to destroy the hugetlb cgroup. The hugetlb cgroup directory is removed __but__ associated resource is not freed. This might result in OOM or can not create a new hugetlb cgroup in a busy workload ultimately. In order to fix this, we have to make sure that one file_region must hold exactly one css reference. So in coalesce_file_region case, we should release one css reference before coalescence. Also only put css reference when the entire file_region is removed. The last thing to note is that the caller of region_add() will only hold one reference to h_cg->css for the whole contiguous reservation region. But this area might be scattered when there are already some file_regions reside in it. As a result, many file_regions may share only one h_cg->css reference. In order to ensure that one file_region must hold exactly one css reference, we should do css_get() for each file_region and release the reference held by caller when they are done. [linmiaohe@huawei.com: fix imbalanced css_get and css_put pair for shared mappings] Link: https://lkml.kernel.org/r/20210316023002.53921-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210301120540.37076-1-linmiaohe@huawei.com Fixes: 075a61d07a8e ("hugetlb_cgroup: add accounting for shared mappings") Reported-by: kernel test robot <lkp@intel.com> (auto build test ERROR) Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Wanpeng Li <liwp.linux@gmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-25 07:37:17 +03:00
/*
* hugetlb_cgroup_uncharge_cgroup_rsvd() will put the
* reference to h_cg->css. See comment below for detail.
*/
hugetlb_cgroup_uncharge_cgroup_rsvd(
hstate_index(h),
(chg - add) * pages_per_huge_page(h), h_cg);
rsv_adjust = hugepage_subpool_put_pages(spool,
chg - add);
hugetlb_acct_memory(h, -rsv_adjust);
hugetlb_cgroup: fix imbalanced css_get and css_put pair for shared mappings The current implementation of hugetlb_cgroup for shared mappings could have different behavior. Consider the following two scenarios: 1.Assume initial css reference count of hugetlb_cgroup is 1: 1.1 Call hugetlb_reserve_pages with from = 1, to = 2. So css reference count is 2 associated with 1 file_region. 1.2 Call hugetlb_reserve_pages with from = 2, to = 3. So css reference count is 3 associated with 2 file_region. 1.3 coalesce_file_region will coalesce these two file_regions into one. So css reference count is 3 associated with 1 file_region now. 2.Assume initial css reference count of hugetlb_cgroup is 1 again: 2.1 Call hugetlb_reserve_pages with from = 1, to = 3. So css reference count is 2 associated with 1 file_region. Therefore, we might have one file_region while holding one or more css reference counts. This inconsistency could lead to imbalanced css_get() and css_put() pair. If we do css_put one by one (i.g. hole punch case), scenario 2 would put one more css reference. If we do css_put all together (i.g. truncate case), scenario 1 will leak one css reference. The imbalanced css_get() and css_put() pair would result in a non-zero reference when we try to destroy the hugetlb cgroup. The hugetlb cgroup directory is removed __but__ associated resource is not freed. This might result in OOM or can not create a new hugetlb cgroup in a busy workload ultimately. In order to fix this, we have to make sure that one file_region must hold exactly one css reference. So in coalesce_file_region case, we should release one css reference before coalescence. Also only put css reference when the entire file_region is removed. The last thing to note is that the caller of region_add() will only hold one reference to h_cg->css for the whole contiguous reservation region. But this area might be scattered when there are already some file_regions reside in it. As a result, many file_regions may share only one h_cg->css reference. In order to ensure that one file_region must hold exactly one css reference, we should do css_get() for each file_region and release the reference held by caller when they are done. [linmiaohe@huawei.com: fix imbalanced css_get and css_put pair for shared mappings] Link: https://lkml.kernel.org/r/20210316023002.53921-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210301120540.37076-1-linmiaohe@huawei.com Fixes: 075a61d07a8e ("hugetlb_cgroup: add accounting for shared mappings") Reported-by: kernel test robot <lkp@intel.com> (auto build test ERROR) Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Wanpeng Li <liwp.linux@gmail.com> Cc: Mina Almasry <almasrymina@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-03-25 07:37:17 +03:00
} else if (h_cg) {
/*
* The file_regions will hold their own reference to
* h_cg->css. So we should release the reference held
* via hugetlb_cgroup_charge_cgroup_rsvd() when we are
* done.
*/
hugetlb_cgroup_put_rsvd_cgroup(h_cg);
}
}
return true;
out_put_pages:
/* put back original number of pages, chg */
(void)hugepage_subpool_put_pages(spool, chg);
out_uncharge_cgroup:
hugetlb_cgroup_uncharge_cgroup_rsvd(hstate_index(h),
chg * pages_per_huge_page(h), h_cg);
out_err:
mm/hugetlb: add cache of descriptors to resv_map for region_add hugetlbfs is used today by applications that want a high degree of control over huge page usage. Often, large hugetlbfs files are used to map a large number huge pages into the application processes. The applications know when page ranges within these large files will no longer be used, and ideally would like to release them back to the subpool or global pools for other uses. The fallocate() system call provides an interface for preallocation and hole punching within files. This patch set adds fallocate functionality to hugetlbfs. fallocate hole punch will want to remove a specific range of pages. When pages are removed, their associated entries in the region/reserve map will also be removed. This will break an assumption in the region_chg/region_add calling sequence. If a new region descriptor must be allocated, it is done as part of the region_chg processing. In this way, region_add can not fail because it does not need to attempt an allocation. To prepare for fallocate hole punch, create a "cache" of descriptors that can be used by region_add if necessary. region_chg will ensure there are sufficient entries in the cache. It will be necessary to track the number of in progress add operations to know a sufficient number of descriptors reside in the cache. A new routine region_abort is added to adjust this in progress count when add operations are aborted. vma_abort_reservation is also added for callers creating reservations with vma_needs_reservation/vma_commit_reservation. [akpm@linux-foundation.org: fix typo in comment, use more cols] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:28 +03:00
if (!vma || vma->vm_flags & VM_MAYSHARE)
hugetlb: disable region_add file_region coalescing A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:25 +03:00
/* Only call region_abort if the region_chg succeeded but the
* region_add failed or didn't run.
*/
if (chg >= 0 && add < 0)
region_abort(resv_map, from, to, regions_needed);
if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
kref_put(&resv_map->refs, resv_map_release);
return false;
}
hugetlbfs: truncate_hugepages() takes a range of pages Modify truncate_hugepages() to take a range of pages (start, end) instead of simply start. If an end value of LLONG_MAX is passed, the current "truncate" functionality is maintained. Existing callers are modified to pass LLONG_MAX as end of range. By keying off end == LLONG_MAX, the routine behaves differently for truncate and hole punch. Page removal is now synchronized with page allocation via faults by using the fault mutex table. The hole punch case can experience the rare region_del error and must handle accordingly. Add the routine hugetlb_fix_reserve_counts to fix up reserve counts in the case where region_del returns an error. Since the routine handles more than just the truncate case, it is renamed to remove_inode_hugepages(). To be consistent, the routine truncate_huge_page() is renamed remove_huge_page(). Downstream of remove_inode_hugepages(), the routine hugetlb_unreserve_pages() is also modified to take a range of pages. hugetlb_unreserve_pages is modified to detect an error from region_del and pass it back to the caller. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:41 +03:00
long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
long freed)
{
struct hstate *h = hstate_inode(inode);
struct resv_map *resv_map = inode_resv_map(inode);
long chg = 0;
hugepages: fix use after free bug in "quota" handling hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:12 +04:00
struct hugepage_subpool *spool = subpool_inode(inode);
long gbl_reserve;
/*
* Since this routine can be called in the evict inode path for all
* hugetlbfs inodes, resv_map could be NULL.
*/
hugetlbfs: truncate_hugepages() takes a range of pages Modify truncate_hugepages() to take a range of pages (start, end) instead of simply start. If an end value of LLONG_MAX is passed, the current "truncate" functionality is maintained. Existing callers are modified to pass LLONG_MAX as end of range. By keying off end == LLONG_MAX, the routine behaves differently for truncate and hole punch. Page removal is now synchronized with page allocation via faults by using the fault mutex table. The hole punch case can experience the rare region_del error and must handle accordingly. Add the routine hugetlb_fix_reserve_counts to fix up reserve counts in the case where region_del returns an error. Since the routine handles more than just the truncate case, it is renamed to remove_inode_hugepages(). To be consistent, the routine truncate_huge_page() is renamed remove_huge_page(). Downstream of remove_inode_hugepages(), the routine hugetlb_unreserve_pages() is also modified to take a range of pages. hugetlb_unreserve_pages is modified to detect an error from region_del and pass it back to the caller. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:41 +03:00
if (resv_map) {
chg = region_del(resv_map, start, end);
/*
* region_del() can fail in the rare case where a region
* must be split and another region descriptor can not be
* allocated. If end == LONG_MAX, it will not fail.
*/
if (chg < 0)
return chg;
}
spin_lock(&inode->i_lock);
inode->i_blocks -= (blocks_per_huge_page(h) * freed);
spin_unlock(&inode->i_lock);
/*
* If the subpool has a minimum size, the number of global
* reservations to be released may be adjusted.
*
* Note that !resv_map implies freed == 0. So (chg - freed)
* won't go negative.
*/
gbl_reserve = hugepage_subpool_put_pages(spool, (chg - freed));
hugetlb_acct_memory(h, -gbl_reserve);
hugetlbfs: truncate_hugepages() takes a range of pages Modify truncate_hugepages() to take a range of pages (start, end) instead of simply start. If an end value of LLONG_MAX is passed, the current "truncate" functionality is maintained. Existing callers are modified to pass LLONG_MAX as end of range. By keying off end == LLONG_MAX, the routine behaves differently for truncate and hole punch. Page removal is now synchronized with page allocation via faults by using the fault mutex table. The hole punch case can experience the rare region_del error and must handle accordingly. Add the routine hugetlb_fix_reserve_counts to fix up reserve counts in the case where region_del returns an error. Since the routine handles more than just the truncate case, it is renamed to remove_inode_hugepages(). To be consistent, the routine truncate_huge_page() is renamed remove_huge_page(). Downstream of remove_inode_hugepages(), the routine hugetlb_unreserve_pages() is also modified to take a range of pages. hugetlb_unreserve_pages is modified to detect an error from region_del and pass it back to the caller. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 01:01:41 +03:00
return 0;
}
#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
static unsigned long page_table_shareable(struct vm_area_struct *svma,
struct vm_area_struct *vma,
unsigned long addr, pgoff_t idx)
{
unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
svma->vm_start;
unsigned long sbase = saddr & PUD_MASK;
unsigned long s_end = sbase + PUD_SIZE;
/* Allow segments to share if only one is marked locked */
mm: introduce VM_LOCKONFAULT The cost of faulting in all memory to be locked can be very high when working with large mappings. If only portions of the mapping will be used this can incur a high penalty for locking. For the example of a large file, this is the usage pattern for a large statical language model (probably applies to other statical or graphical models as well). For the security example, any application transacting in data that cannot be swapped out (credit card data, medical records, etc). This patch introduces the ability to request that pages are not pre-faulted, but are placed on the unevictable LRU when they are finally faulted in. The VM_LOCKONFAULT flag will be used together with VM_LOCKED and has no effect when set without VM_LOCKED. Setting the VM_LOCKONFAULT flag for a VMA will cause pages faulted into that VMA to be added to the unevictable LRU when they are faulted or if they are already present, but will not cause any missing pages to be faulted in. Exposing this new lock state means that we cannot overload the meaning of the FOLL_POPULATE flag any longer. Prior to this patch it was used to mean that the VMA for a fault was locked. This means we need the new FOLL_MLOCK flag to communicate the locked state of a VMA. FOLL_POPULATE will now only control if the VMA should be populated and in the case of VM_LOCKONFAULT, it will not be set. Signed-off-by: Eric B Munson <emunson@akamai.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@suse.cz> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06 05:51:36 +03:00
unsigned long vm_flags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
unsigned long svm_flags = svma->vm_flags & VM_LOCKED_CLEAR_MASK;
/*
* match the virtual addresses, permission and the alignment of the
* page table page.
*/
if (pmd_index(addr) != pmd_index(saddr) ||
vm_flags != svm_flags ||
!range_in_vma(svma, sbase, s_end))
return 0;
return saddr;
}
static bool vma_shareable(struct vm_area_struct *vma, unsigned long addr)
{
unsigned long base = addr & PUD_MASK;
unsigned long end = base + PUD_SIZE;
/*
* check on proper vm_flags and page table alignment
*/
mm: migration: fix migration of huge PMD shared pages The page migration code employs try_to_unmap() to try and unmap the source page. This is accomplished by using rmap_walk to find all vmas where the page is mapped. This search stops when page mapcount is zero. For shared PMD huge pages, the page map count is always 1 no matter the number of mappings. Shared mappings are tracked via the reference count of the PMD page. Therefore, try_to_unmap stops prematurely and does not completely unmap all mappings of the source page. This problem can result is data corruption as writes to the original source page can happen after contents of the page are copied to the target page. Hence, data is lost. This problem was originally seen as DB corruption of shared global areas after a huge page was soft offlined due to ECC memory errors. DB developers noticed they could reproduce the issue by (hotplug) offlining memory used to back huge pages. A simple testcase can reproduce the problem by creating a shared PMD mapping (note that this must be at least PUD_SIZE in size and PUD_SIZE aligned (1GB on x86)), and using migrate_pages() to migrate process pages between nodes while continually writing to the huge pages being migrated. To fix, have the try_to_unmap_one routine check for huge PMD sharing by calling huge_pmd_unshare for hugetlbfs huge pages. If it is a shared mapping it will be 'unshared' which removes the page table entry and drops the reference on the PMD page. After this, flush caches and TLB. mmu notifiers are called before locking page tables, but we can not be sure of PMD sharing until page tables are locked. Therefore, check for the possibility of PMD sharing before locking so that notifiers can prepare for the worst possible case. Link: http://lkml.kernel.org/r/20180823205917.16297-2-mike.kravetz@oracle.com [mike.kravetz@oracle.com: make _range_in_vma() a static inline] Link: http://lkml.kernel.org/r/6063f215-a5c8-2f0c-465a-2c515ddc952d@oracle.com Fixes: 39dde65c9940 ("shared page table for hugetlb page") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-10-06 01:51:29 +03:00
if (vma->vm_flags & VM_MAYSHARE && range_in_vma(vma, base, end))
return true;
return false;
}
hugetlb/userfaultfd: forbid huge pmd sharing when uffd enabled Huge pmd sharing could bring problem to userfaultfd. The thing is that userfaultfd is running its logic based on the special bits on page table entries, however the huge pmd sharing could potentially share page table entries for different address ranges. That could cause issues on either: - When sharing huge pmd page tables for an uffd write protected range, the newly mapped huge pmd range will also be write protected unexpectedly, or, - When we try to write protect a range of huge pmd shared range, we'll first do huge_pmd_unshare() in hugetlb_change_protection(), however that also means the UFFDIO_WRITEPROTECT could be silently skipped for the shared region, which could lead to data loss. While at it, a few other things are done altogether: - Move want_pmd_share() from mm/hugetlb.c into linux/hugetlb.h, because that's definitely something that arch code would like to use too - ARM64 currently directly check against CONFIG_ARCH_WANT_HUGE_PMD_SHARE when trying to share huge pmd. Switch to the want_pmd_share() helper. - Move vma_shareable() from huge_pmd_share() into want_pmd_share(). [peterx@redhat.com: fix build with !ARCH_WANT_HUGE_PMD_SHARE] Link: https://lkml.kernel.org/r/20210310185359.88297-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210218231202.15426-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:33:04 +03:00
bool want_pmd_share(struct vm_area_struct *vma, unsigned long addr)
{
#ifdef CONFIG_USERFAULTFD
if (uffd_disable_huge_pmd_share(vma))
return false;
#endif
return vma_shareable(vma, addr);
}
mm: migration: fix migration of huge PMD shared pages The page migration code employs try_to_unmap() to try and unmap the source page. This is accomplished by using rmap_walk to find all vmas where the page is mapped. This search stops when page mapcount is zero. For shared PMD huge pages, the page map count is always 1 no matter the number of mappings. Shared mappings are tracked via the reference count of the PMD page. Therefore, try_to_unmap stops prematurely and does not completely unmap all mappings of the source page. This problem can result is data corruption as writes to the original source page can happen after contents of the page are copied to the target page. Hence, data is lost. This problem was originally seen as DB corruption of shared global areas after a huge page was soft offlined due to ECC memory errors. DB developers noticed they could reproduce the issue by (hotplug) offlining memory used to back huge pages. A simple testcase can reproduce the problem by creating a shared PMD mapping (note that this must be at least PUD_SIZE in size and PUD_SIZE aligned (1GB on x86)), and using migrate_pages() to migrate process pages between nodes while continually writing to the huge pages being migrated. To fix, have the try_to_unmap_one routine check for huge PMD sharing by calling huge_pmd_unshare for hugetlbfs huge pages. If it is a shared mapping it will be 'unshared' which removes the page table entry and drops the reference on the PMD page. After this, flush caches and TLB. mmu notifiers are called before locking page tables, but we can not be sure of PMD sharing until page tables are locked. Therefore, check for the possibility of PMD sharing before locking so that notifiers can prepare for the worst possible case. Link: http://lkml.kernel.org/r/20180823205917.16297-2-mike.kravetz@oracle.com [mike.kravetz@oracle.com: make _range_in_vma() a static inline] Link: http://lkml.kernel.org/r/6063f215-a5c8-2f0c-465a-2c515ddc952d@oracle.com Fixes: 39dde65c9940 ("shared page table for hugetlb page") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-10-06 01:51:29 +03:00
/*
* Determine if start,end range within vma could be mapped by shared pmd.
* If yes, adjust start and end to cover range associated with possible
* shared pmd mappings.
*/
void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
unsigned long *start, unsigned long *end)
{
mm/hugetlb.c: fix unnecessary address expansion of pmd sharing The current code would unnecessarily expand the address range. Consider one example, (start, end) = (1G-2M, 3G+2M), and (vm_start, vm_end) = (1G-4M, 3G+4M), the expected adjustment should be keep (1G-2M, 3G+2M) without expand. But the current result will be (1G-4M, 3G+4M). Actually, the range (1G-4M, 1G) and (3G, 3G+4M) would never been involved in pmd sharing. After this patch, we will check that the vma span at least one PUD aligned size and the start,end range overlap the aligned range of vma. With above example, the aligned vma range is (1G, 3G), so if (start, end) range is within (1G-4M, 1G), or within (3G, 3G+4M), then no adjustment to both start and end. Otherwise, we will have chance to adjust start downwards or end upwards without exceeding (vm_start, vm_end). Mike: : The 'adjusted range' is used for calls to mmu notifiers and cache(tlb) : flushing. Since the current code unnecessarily expands the range in some : cases, more entries than necessary would be flushed. This would/could : result in performance degradation. However, this is highly dependent on : the user runtime. Is there a combination of vma layout and calls to : actually hit this issue? If the issue is hit, will those entries : unnecessarily flushed be used again and need to be unnecessarily reloaded? Link: https://lkml.kernel.org/r/20210104081631.2921415-1-lixinhai.lxh@gmail.com Fixes: 75802ca66354 ("mm/hugetlb: fix calculation of adjust_range_if_pmd_sharing_possible") Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:06:54 +03:00
unsigned long v_start = ALIGN(vma->vm_start, PUD_SIZE),
v_end = ALIGN_DOWN(vma->vm_end, PUD_SIZE);
mm: migration: fix migration of huge PMD shared pages The page migration code employs try_to_unmap() to try and unmap the source page. This is accomplished by using rmap_walk to find all vmas where the page is mapped. This search stops when page mapcount is zero. For shared PMD huge pages, the page map count is always 1 no matter the number of mappings. Shared mappings are tracked via the reference count of the PMD page. Therefore, try_to_unmap stops prematurely and does not completely unmap all mappings of the source page. This problem can result is data corruption as writes to the original source page can happen after contents of the page are copied to the target page. Hence, data is lost. This problem was originally seen as DB corruption of shared global areas after a huge page was soft offlined due to ECC memory errors. DB developers noticed they could reproduce the issue by (hotplug) offlining memory used to back huge pages. A simple testcase can reproduce the problem by creating a shared PMD mapping (note that this must be at least PUD_SIZE in size and PUD_SIZE aligned (1GB on x86)), and using migrate_pages() to migrate process pages between nodes while continually writing to the huge pages being migrated. To fix, have the try_to_unmap_one routine check for huge PMD sharing by calling huge_pmd_unshare for hugetlbfs huge pages. If it is a shared mapping it will be 'unshared' which removes the page table entry and drops the reference on the PMD page. After this, flush caches and TLB. mmu notifiers are called before locking page tables, but we can not be sure of PMD sharing until page tables are locked. Therefore, check for the possibility of PMD sharing before locking so that notifiers can prepare for the worst possible case. Link: http://lkml.kernel.org/r/20180823205917.16297-2-mike.kravetz@oracle.com [mike.kravetz@oracle.com: make _range_in_vma() a static inline] Link: http://lkml.kernel.org/r/6063f215-a5c8-2f0c-465a-2c515ddc952d@oracle.com Fixes: 39dde65c9940 ("shared page table for hugetlb page") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-10-06 01:51:29 +03:00
mm/hugetlb.c: fix unnecessary address expansion of pmd sharing The current code would unnecessarily expand the address range. Consider one example, (start, end) = (1G-2M, 3G+2M), and (vm_start, vm_end) = (1G-4M, 3G+4M), the expected adjustment should be keep (1G-2M, 3G+2M) without expand. But the current result will be (1G-4M, 3G+4M). Actually, the range (1G-4M, 1G) and (3G, 3G+4M) would never been involved in pmd sharing. After this patch, we will check that the vma span at least one PUD aligned size and the start,end range overlap the aligned range of vma. With above example, the aligned vma range is (1G, 3G), so if (start, end) range is within (1G-4M, 1G), or within (3G, 3G+4M), then no adjustment to both start and end. Otherwise, we will have chance to adjust start downwards or end upwards without exceeding (vm_start, vm_end). Mike: : The 'adjusted range' is used for calls to mmu notifiers and cache(tlb) : flushing. Since the current code unnecessarily expands the range in some : cases, more entries than necessary would be flushed. This would/could : result in performance degradation. However, this is highly dependent on : the user runtime. Is there a combination of vma layout and calls to : actually hit this issue? If the issue is hit, will those entries : unnecessarily flushed be used again and need to be unnecessarily reloaded? Link: https://lkml.kernel.org/r/20210104081631.2921415-1-lixinhai.lxh@gmail.com Fixes: 75802ca66354 ("mm/hugetlb: fix calculation of adjust_range_if_pmd_sharing_possible") Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:06:54 +03:00
/*
* vma needs to span at least one aligned PUD size, and the range
* must be at least partially within in.
mm/hugetlb.c: fix unnecessary address expansion of pmd sharing The current code would unnecessarily expand the address range. Consider one example, (start, end) = (1G-2M, 3G+2M), and (vm_start, vm_end) = (1G-4M, 3G+4M), the expected adjustment should be keep (1G-2M, 3G+2M) without expand. But the current result will be (1G-4M, 3G+4M). Actually, the range (1G-4M, 1G) and (3G, 3G+4M) would never been involved in pmd sharing. After this patch, we will check that the vma span at least one PUD aligned size and the start,end range overlap the aligned range of vma. With above example, the aligned vma range is (1G, 3G), so if (start, end) range is within (1G-4M, 1G), or within (3G, 3G+4M), then no adjustment to both start and end. Otherwise, we will have chance to adjust start downwards or end upwards without exceeding (vm_start, vm_end). Mike: : The 'adjusted range' is used for calls to mmu notifiers and cache(tlb) : flushing. Since the current code unnecessarily expands the range in some : cases, more entries than necessary would be flushed. This would/could : result in performance degradation. However, this is highly dependent on : the user runtime. Is there a combination of vma layout and calls to : actually hit this issue? If the issue is hit, will those entries : unnecessarily flushed be used again and need to be unnecessarily reloaded? Link: https://lkml.kernel.org/r/20210104081631.2921415-1-lixinhai.lxh@gmail.com Fixes: 75802ca66354 ("mm/hugetlb: fix calculation of adjust_range_if_pmd_sharing_possible") Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:06:54 +03:00
*/
if (!(vma->vm_flags & VM_MAYSHARE) || !(v_end > v_start) ||
(*end <= v_start) || (*start >= v_end))
mm: migration: fix migration of huge PMD shared pages The page migration code employs try_to_unmap() to try and unmap the source page. This is accomplished by using rmap_walk to find all vmas where the page is mapped. This search stops when page mapcount is zero. For shared PMD huge pages, the page map count is always 1 no matter the number of mappings. Shared mappings are tracked via the reference count of the PMD page. Therefore, try_to_unmap stops prematurely and does not completely unmap all mappings of the source page. This problem can result is data corruption as writes to the original source page can happen after contents of the page are copied to the target page. Hence, data is lost. This problem was originally seen as DB corruption of shared global areas after a huge page was soft offlined due to ECC memory errors. DB developers noticed they could reproduce the issue by (hotplug) offlining memory used to back huge pages. A simple testcase can reproduce the problem by creating a shared PMD mapping (note that this must be at least PUD_SIZE in size and PUD_SIZE aligned (1GB on x86)), and using migrate_pages() to migrate process pages between nodes while continually writing to the huge pages being migrated. To fix, have the try_to_unmap_one routine check for huge PMD sharing by calling huge_pmd_unshare for hugetlbfs huge pages. If it is a shared mapping it will be 'unshared' which removes the page table entry and drops the reference on the PMD page. After this, flush caches and TLB. mmu notifiers are called before locking page tables, but we can not be sure of PMD sharing until page tables are locked. Therefore, check for the possibility of PMD sharing before locking so that notifiers can prepare for the worst possible case. Link: http://lkml.kernel.org/r/20180823205917.16297-2-mike.kravetz@oracle.com [mike.kravetz@oracle.com: make _range_in_vma() a static inline] Link: http://lkml.kernel.org/r/6063f215-a5c8-2f0c-465a-2c515ddc952d@oracle.com Fixes: 39dde65c9940 ("shared page table for hugetlb page") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-10-06 01:51:29 +03:00
return;
mm/hugetlb: fix calculation of adjust_range_if_pmd_sharing_possible This is found by code observation only. Firstly, the worst case scenario should assume the whole range was covered by pmd sharing. The old algorithm might not work as expected for ranges like (1g-2m, 1g+2m), where the adjusted range should be (0, 1g+2m) but the expected range should be (0, 2g). Since at it, remove the loop since it should not be required. With that, the new code should be faster too when the invalidating range is huge. Mike said: : With range (1g-2m, 1g+2m) within a vma (0, 2g) the existing code will only : adjust to (0, 1g+2m) which is incorrect. : : We should cc stable. The original reason for adjusting the range was to : prevent data corruption (getting wrong page). Since the range is not : always adjusted correctly, the potential for corruption still exists. : : However, I am fairly confident that adjust_range_if_pmd_sharing_possible : is only gong to be called in two cases: : : 1) for a single page : 2) for range == entire vma : : In those cases, the current code should produce the correct results. : : To be safe, let's just cc stable. Fixes: 017b1660df89 ("mm: migration: fix migration of huge PMD shared pages") Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/20200730201636.74778-1-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-07 09:26:11 +03:00
/* Extend the range to be PUD aligned for a worst case scenario */
mm/hugetlb.c: fix unnecessary address expansion of pmd sharing The current code would unnecessarily expand the address range. Consider one example, (start, end) = (1G-2M, 3G+2M), and (vm_start, vm_end) = (1G-4M, 3G+4M), the expected adjustment should be keep (1G-2M, 3G+2M) without expand. But the current result will be (1G-4M, 3G+4M). Actually, the range (1G-4M, 1G) and (3G, 3G+4M) would never been involved in pmd sharing. After this patch, we will check that the vma span at least one PUD aligned size and the start,end range overlap the aligned range of vma. With above example, the aligned vma range is (1G, 3G), so if (start, end) range is within (1G-4M, 1G), or within (3G, 3G+4M), then no adjustment to both start and end. Otherwise, we will have chance to adjust start downwards or end upwards without exceeding (vm_start, vm_end). Mike: : The 'adjusted range' is used for calls to mmu notifiers and cache(tlb) : flushing. Since the current code unnecessarily expands the range in some : cases, more entries than necessary would be flushed. This would/could : result in performance degradation. However, this is highly dependent on : the user runtime. Is there a combination of vma layout and calls to : actually hit this issue? If the issue is hit, will those entries : unnecessarily flushed be used again and need to be unnecessarily reloaded? Link: https://lkml.kernel.org/r/20210104081631.2921415-1-lixinhai.lxh@gmail.com Fixes: 75802ca66354 ("mm/hugetlb: fix calculation of adjust_range_if_pmd_sharing_possible") Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:06:54 +03:00
if (*start > v_start)
*start = ALIGN_DOWN(*start, PUD_SIZE);
mm: migration: fix migration of huge PMD shared pages The page migration code employs try_to_unmap() to try and unmap the source page. This is accomplished by using rmap_walk to find all vmas where the page is mapped. This search stops when page mapcount is zero. For shared PMD huge pages, the page map count is always 1 no matter the number of mappings. Shared mappings are tracked via the reference count of the PMD page. Therefore, try_to_unmap stops prematurely and does not completely unmap all mappings of the source page. This problem can result is data corruption as writes to the original source page can happen after contents of the page are copied to the target page. Hence, data is lost. This problem was originally seen as DB corruption of shared global areas after a huge page was soft offlined due to ECC memory errors. DB developers noticed they could reproduce the issue by (hotplug) offlining memory used to back huge pages. A simple testcase can reproduce the problem by creating a shared PMD mapping (note that this must be at least PUD_SIZE in size and PUD_SIZE aligned (1GB on x86)), and using migrate_pages() to migrate process pages between nodes while continually writing to the huge pages being migrated. To fix, have the try_to_unmap_one routine check for huge PMD sharing by calling huge_pmd_unshare for hugetlbfs huge pages. If it is a shared mapping it will be 'unshared' which removes the page table entry and drops the reference on the PMD page. After this, flush caches and TLB. mmu notifiers are called before locking page tables, but we can not be sure of PMD sharing until page tables are locked. Therefore, check for the possibility of PMD sharing before locking so that notifiers can prepare for the worst possible case. Link: http://lkml.kernel.org/r/20180823205917.16297-2-mike.kravetz@oracle.com [mike.kravetz@oracle.com: make _range_in_vma() a static inline] Link: http://lkml.kernel.org/r/6063f215-a5c8-2f0c-465a-2c515ddc952d@oracle.com Fixes: 39dde65c9940 ("shared page table for hugetlb page") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-10-06 01:51:29 +03:00
mm/hugetlb.c: fix unnecessary address expansion of pmd sharing The current code would unnecessarily expand the address range. Consider one example, (start, end) = (1G-2M, 3G+2M), and (vm_start, vm_end) = (1G-4M, 3G+4M), the expected adjustment should be keep (1G-2M, 3G+2M) without expand. But the current result will be (1G-4M, 3G+4M). Actually, the range (1G-4M, 1G) and (3G, 3G+4M) would never been involved in pmd sharing. After this patch, we will check that the vma span at least one PUD aligned size and the start,end range overlap the aligned range of vma. With above example, the aligned vma range is (1G, 3G), so if (start, end) range is within (1G-4M, 1G), or within (3G, 3G+4M), then no adjustment to both start and end. Otherwise, we will have chance to adjust start downwards or end upwards without exceeding (vm_start, vm_end). Mike: : The 'adjusted range' is used for calls to mmu notifiers and cache(tlb) : flushing. Since the current code unnecessarily expands the range in some : cases, more entries than necessary would be flushed. This would/could : result in performance degradation. However, this is highly dependent on : the user runtime. Is there a combination of vma layout and calls to : actually hit this issue? If the issue is hit, will those entries : unnecessarily flushed be used again and need to be unnecessarily reloaded? Link: https://lkml.kernel.org/r/20210104081631.2921415-1-lixinhai.lxh@gmail.com Fixes: 75802ca66354 ("mm/hugetlb: fix calculation of adjust_range_if_pmd_sharing_possible") Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:06:54 +03:00
if (*end < v_end)
*end = ALIGN(*end, PUD_SIZE);
mm: migration: fix migration of huge PMD shared pages The page migration code employs try_to_unmap() to try and unmap the source page. This is accomplished by using rmap_walk to find all vmas where the page is mapped. This search stops when page mapcount is zero. For shared PMD huge pages, the page map count is always 1 no matter the number of mappings. Shared mappings are tracked via the reference count of the PMD page. Therefore, try_to_unmap stops prematurely and does not completely unmap all mappings of the source page. This problem can result is data corruption as writes to the original source page can happen after contents of the page are copied to the target page. Hence, data is lost. This problem was originally seen as DB corruption of shared global areas after a huge page was soft offlined due to ECC memory errors. DB developers noticed they could reproduce the issue by (hotplug) offlining memory used to back huge pages. A simple testcase can reproduce the problem by creating a shared PMD mapping (note that this must be at least PUD_SIZE in size and PUD_SIZE aligned (1GB on x86)), and using migrate_pages() to migrate process pages between nodes while continually writing to the huge pages being migrated. To fix, have the try_to_unmap_one routine check for huge PMD sharing by calling huge_pmd_unshare for hugetlbfs huge pages. If it is a shared mapping it will be 'unshared' which removes the page table entry and drops the reference on the PMD page. After this, flush caches and TLB. mmu notifiers are called before locking page tables, but we can not be sure of PMD sharing until page tables are locked. Therefore, check for the possibility of PMD sharing before locking so that notifiers can prepare for the worst possible case. Link: http://lkml.kernel.org/r/20180823205917.16297-2-mike.kravetz@oracle.com [mike.kravetz@oracle.com: make _range_in_vma() a static inline] Link: http://lkml.kernel.org/r/6063f215-a5c8-2f0c-465a-2c515ddc952d@oracle.com Fixes: 39dde65c9940 ("shared page table for hugetlb page") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-10-06 01:51:29 +03:00
}
/*
* Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc()
* and returns the corresponding pte. While this is not necessary for the
* !shared pmd case because we can allocate the pmd later as well, it makes the
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
* code much cleaner.
*
* This routine must be called with i_mmap_rwsem held in at least read mode if
* sharing is possible. For hugetlbfs, this prevents removal of any page
* table entries associated with the address space. This is important as we
* are setting up sharing based on existing page table entries (mappings).
*/
hugetlb: pass vma into huge_pte_alloc() and huge_pmd_share() Patch series "hugetlb: Disable huge pmd unshare for uffd-wp", v4. This series tries to disable huge pmd unshare of hugetlbfs backed memory for uffd-wp. Although uffd-wp of hugetlbfs is still during rfc stage, the idea of this series may be needed for multiple tasks (Axel's uffd minor fault series, and Mike's soft dirty series), so I picked it out from the larger series. This patch (of 4): It is a preparation work to be able to behave differently in the per architecture huge_pte_alloc() according to different VMA attributes. Pass it deeper into huge_pmd_share() so that we can avoid the find_vma() call. [peterx@redhat.com: build fix] Link: https://lkml.kernel.org/r/20210304164653.GB397383@xz-x1Link: https://lkml.kernel.org/r/20210218230633.15028-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210218230633.15028-2-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:33:00 +03:00
pte_t *huge_pmd_share(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, pud_t *pud)
{
struct address_space *mapping = vma->vm_file->f_mapping;
pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
vma->vm_pgoff;
struct vm_area_struct *svma;
unsigned long saddr;
pte_t *spte = NULL;
pte_t *pte;
spinlock_t *ptl;
i_mmap_assert_locked(mapping);
vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) {
if (svma == vma)
continue;
saddr = page_table_shareable(svma, vma, addr, idx);
if (saddr) {
mm/hugetlb: add size parameter to huge_pte_offset() A poisoned or migrated hugepage is stored as a swap entry in the page tables. On architectures that support hugepages consisting of contiguous page table entries (such as on arm64) this leads to ambiguity in determining the page table entry to return in huge_pte_offset() when a poisoned entry is encountered. Let's remove the ambiguity by adding a size parameter to convey additional information about the requested address. Also fixup the definition/usage of huge_pte_offset() throughout the tree. Link: http://lkml.kernel.org/r/20170522133604.11392-4-punit.agrawal@arm.com Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Acked-by: Steve Capper <steve.capper@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: James Hogan <james.hogan@imgtec.com> (odd fixer:METAG ARCHITECTURE) Cc: Ralf Baechle <ralf@linux-mips.org> (supporter:MIPS) Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Rich Felker <dalias@libc.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-07 01:39:42 +03:00
spte = huge_pte_offset(svma->vm_mm, saddr,
vma_mmu_pagesize(svma));
if (spte) {
get_page(virt_to_page(spte));
break;
}
}
}
if (!spte)
goto out;
ptl = huge_pte_lock(hstate_vma(vma), mm, spte);
mm: account pmd page tables to the process Dave noticed that unprivileged process can allocate significant amount of memory -- >500 MiB on x86_64 -- and stay unnoticed by oom-killer and memory cgroup. The trick is to allocate a lot of PMD page tables. Linux kernel doesn't account PMD tables to the process, only PTE. The use-cases below use few tricks to allocate a lot of PMD page tables while keeping VmRSS and VmPTE low. oom_score for the process will be 0. #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/mman.h> #include <sys/prctl.h> #define PUD_SIZE (1UL << 30) #define PMD_SIZE (1UL << 21) #define NR_PUD 130000 int main(void) { char *addr = NULL; unsigned long i; prctl(PR_SET_THP_DISABLE); for (i = 0; i < NR_PUD ; i++) { addr = mmap(addr + PUD_SIZE, PUD_SIZE, PROT_WRITE|PROT_READ, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); if (addr == MAP_FAILED) { perror("mmap"); break; } *addr = 'x'; munmap(addr, PMD_SIZE); mmap(addr, PMD_SIZE, PROT_WRITE|PROT_READ, MAP_ANONYMOUS|MAP_PRIVATE|MAP_FIXED, -1, 0); if (addr == MAP_FAILED) perror("re-mmap"), exit(1); } printf("PID %d consumed %lu KiB in PMD page tables\n", getpid(), i * 4096 >> 10); return pause(); } The patch addresses the issue by account PMD tables to the process the same way we account PTE. The main place where PMD tables is accounted is __pmd_alloc() and free_pmd_range(). But there're few corner cases: - HugeTLB can share PMD page tables. The patch handles by accounting the table to all processes who share it. - x86 PAE pre-allocates few PMD tables on fork. - Architectures with FIRST_USER_ADDRESS > 0. We need to adjust sanity check on exit(2). Accounting only happens on configuration where PMD page table's level is present (PMD is not folded). As with nr_ptes we use per-mm counter. The counter value is used to calculate baseline for badness score by oom-killer. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: David Rientjes <rientjes@google.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 02:26:50 +03:00
if (pud_none(*pud)) {
pud_populate(mm, pud,
(pmd_t *)((unsigned long)spte & PAGE_MASK));
mm_inc_nr_pmds(mm);
mm: account pmd page tables to the process Dave noticed that unprivileged process can allocate significant amount of memory -- >500 MiB on x86_64 -- and stay unnoticed by oom-killer and memory cgroup. The trick is to allocate a lot of PMD page tables. Linux kernel doesn't account PMD tables to the process, only PTE. The use-cases below use few tricks to allocate a lot of PMD page tables while keeping VmRSS and VmPTE low. oom_score for the process will be 0. #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/mman.h> #include <sys/prctl.h> #define PUD_SIZE (1UL << 30) #define PMD_SIZE (1UL << 21) #define NR_PUD 130000 int main(void) { char *addr = NULL; unsigned long i; prctl(PR_SET_THP_DISABLE); for (i = 0; i < NR_PUD ; i++) { addr = mmap(addr + PUD_SIZE, PUD_SIZE, PROT_WRITE|PROT_READ, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); if (addr == MAP_FAILED) { perror("mmap"); break; } *addr = 'x'; munmap(addr, PMD_SIZE); mmap(addr, PMD_SIZE, PROT_WRITE|PROT_READ, MAP_ANONYMOUS|MAP_PRIVATE|MAP_FIXED, -1, 0); if (addr == MAP_FAILED) perror("re-mmap"), exit(1); } printf("PID %d consumed %lu KiB in PMD page tables\n", getpid(), i * 4096 >> 10); return pause(); } The patch addresses the issue by account PMD tables to the process the same way we account PTE. The main place where PMD tables is accounted is __pmd_alloc() and free_pmd_range(). But there're few corner cases: - HugeTLB can share PMD page tables. The patch handles by accounting the table to all processes who share it. - x86 PAE pre-allocates few PMD tables on fork. - Architectures with FIRST_USER_ADDRESS > 0. We need to adjust sanity check on exit(2). Accounting only happens on configuration where PMD page table's level is present (PMD is not folded). As with nr_ptes we use per-mm counter. The counter value is used to calculate baseline for badness score by oom-killer. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: David Rientjes <rientjes@google.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 02:26:50 +03:00
} else {
put_page(virt_to_page(spte));
mm: account pmd page tables to the process Dave noticed that unprivileged process can allocate significant amount of memory -- >500 MiB on x86_64 -- and stay unnoticed by oom-killer and memory cgroup. The trick is to allocate a lot of PMD page tables. Linux kernel doesn't account PMD tables to the process, only PTE. The use-cases below use few tricks to allocate a lot of PMD page tables while keeping VmRSS and VmPTE low. oom_score for the process will be 0. #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/mman.h> #include <sys/prctl.h> #define PUD_SIZE (1UL << 30) #define PMD_SIZE (1UL << 21) #define NR_PUD 130000 int main(void) { char *addr = NULL; unsigned long i; prctl(PR_SET_THP_DISABLE); for (i = 0; i < NR_PUD ; i++) { addr = mmap(addr + PUD_SIZE, PUD_SIZE, PROT_WRITE|PROT_READ, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); if (addr == MAP_FAILED) { perror("mmap"); break; } *addr = 'x'; munmap(addr, PMD_SIZE); mmap(addr, PMD_SIZE, PROT_WRITE|PROT_READ, MAP_ANONYMOUS|MAP_PRIVATE|MAP_FIXED, -1, 0); if (addr == MAP_FAILED) perror("re-mmap"), exit(1); } printf("PID %d consumed %lu KiB in PMD page tables\n", getpid(), i * 4096 >> 10); return pause(); } The patch addresses the issue by account PMD tables to the process the same way we account PTE. The main place where PMD tables is accounted is __pmd_alloc() and free_pmd_range(). But there're few corner cases: - HugeTLB can share PMD page tables. The patch handles by accounting the table to all processes who share it. - x86 PAE pre-allocates few PMD tables on fork. - Architectures with FIRST_USER_ADDRESS > 0. We need to adjust sanity check on exit(2). Accounting only happens on configuration where PMD page table's level is present (PMD is not folded). As with nr_ptes we use per-mm counter. The counter value is used to calculate baseline for badness score by oom-killer. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: David Rientjes <rientjes@google.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 02:26:50 +03:00
}
spin_unlock(ptl);
out:
pte = (pte_t *)pmd_alloc(mm, pud, addr);
return pte;
}
/*
* unmap huge page backed by shared pte.
*
* Hugetlb pte page is ref counted at the time of mapping. If pte is shared
* indicated by page_count > 1, unmap is achieved by clearing pud and
* decrementing the ref count. If count == 1, the pte page is not shared.
*
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:11:05 +03:00
* Called with page table lock held and i_mmap_rwsem held in write mode.
*
* returns: 1 successfully unmapped a shared pte page
* 0 the underlying pte page is not shared, or it is the last user
*/
hugetlbfs: remove call to huge_pte_alloc without i_mmap_rwsem Commit c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") requires callers of huge_pte_alloc to hold i_mmap_rwsem in at least read mode. This is because the explicit locking in huge_pmd_share (called by huge_pte_alloc) was removed. When restructuring the code, the call to huge_pte_alloc in the else block at the beginning of hugetlb_fault was missed. Unfortunately, that else clause is exercised when there is no page table entry. This will likely lead to a call to huge_pmd_share. If huge_pmd_share thinks pmd sharing is possible, it will traverse the mapping tree (i_mmap) without holding i_mmap_rwsem. If someone else is modifying the tree, bad things such as addressing exceptions or worse could happen. Simply remove the else clause. It should have been removed previously. The code following the else will call huge_pte_alloc with the appropriate locking. To prevent this type of issue in the future, add routines to assert that i_mmap_rwsem is held, and call these routines in huge pmd sharing routines. Fixes: c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") Suggested-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A.Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/e670f327-5cf9-1959-96e4-6dc7cc30d3d5@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 04:31:38 +03:00
int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long *addr, pte_t *ptep)
{
pgd_t *pgd = pgd_offset(mm, *addr);
p4d_t *p4d = p4d_offset(pgd, *addr);
pud_t *pud = pud_offset(p4d, *addr);
hugetlbfs: remove call to huge_pte_alloc without i_mmap_rwsem Commit c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") requires callers of huge_pte_alloc to hold i_mmap_rwsem in at least read mode. This is because the explicit locking in huge_pmd_share (called by huge_pte_alloc) was removed. When restructuring the code, the call to huge_pte_alloc in the else block at the beginning of hugetlb_fault was missed. Unfortunately, that else clause is exercised when there is no page table entry. This will likely lead to a call to huge_pmd_share. If huge_pmd_share thinks pmd sharing is possible, it will traverse the mapping tree (i_mmap) without holding i_mmap_rwsem. If someone else is modifying the tree, bad things such as addressing exceptions or worse could happen. Simply remove the else clause. It should have been removed previously. The code following the else will call huge_pte_alloc with the appropriate locking. To prevent this type of issue in the future, add routines to assert that i_mmap_rwsem is held, and call these routines in huge pmd sharing routines. Fixes: c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") Suggested-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A.Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/e670f327-5cf9-1959-96e4-6dc7cc30d3d5@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 04:31:38 +03:00
i_mmap_assert_write_locked(vma->vm_file->f_mapping);
BUG_ON(page_count(virt_to_page(ptep)) == 0);
if (page_count(virt_to_page(ptep)) == 1)
return 0;
pud_clear(pud);
put_page(virt_to_page(ptep));
mm: account pmd page tables to the process Dave noticed that unprivileged process can allocate significant amount of memory -- >500 MiB on x86_64 -- and stay unnoticed by oom-killer and memory cgroup. The trick is to allocate a lot of PMD page tables. Linux kernel doesn't account PMD tables to the process, only PTE. The use-cases below use few tricks to allocate a lot of PMD page tables while keeping VmRSS and VmPTE low. oom_score for the process will be 0. #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/mman.h> #include <sys/prctl.h> #define PUD_SIZE (1UL << 30) #define PMD_SIZE (1UL << 21) #define NR_PUD 130000 int main(void) { char *addr = NULL; unsigned long i; prctl(PR_SET_THP_DISABLE); for (i = 0; i < NR_PUD ; i++) { addr = mmap(addr + PUD_SIZE, PUD_SIZE, PROT_WRITE|PROT_READ, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); if (addr == MAP_FAILED) { perror("mmap"); break; } *addr = 'x'; munmap(addr, PMD_SIZE); mmap(addr, PMD_SIZE, PROT_WRITE|PROT_READ, MAP_ANONYMOUS|MAP_PRIVATE|MAP_FIXED, -1, 0); if (addr == MAP_FAILED) perror("re-mmap"), exit(1); } printf("PID %d consumed %lu KiB in PMD page tables\n", getpid(), i * 4096 >> 10); return pause(); } The patch addresses the issue by account PMD tables to the process the same way we account PTE. The main place where PMD tables is accounted is __pmd_alloc() and free_pmd_range(). But there're few corner cases: - HugeTLB can share PMD page tables. The patch handles by accounting the table to all processes who share it. - x86 PAE pre-allocates few PMD tables on fork. - Architectures with FIRST_USER_ADDRESS > 0. We need to adjust sanity check on exit(2). Accounting only happens on configuration where PMD page table's level is present (PMD is not folded). As with nr_ptes we use per-mm counter. The counter value is used to calculate baseline for badness score by oom-killer. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: David Rientjes <rientjes@google.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 02:26:50 +03:00
mm_dec_nr_pmds(mm);
*addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
return 1;
}
hugetlb/userfaultfd: forbid huge pmd sharing when uffd enabled Huge pmd sharing could bring problem to userfaultfd. The thing is that userfaultfd is running its logic based on the special bits on page table entries, however the huge pmd sharing could potentially share page table entries for different address ranges. That could cause issues on either: - When sharing huge pmd page tables for an uffd write protected range, the newly mapped huge pmd range will also be write protected unexpectedly, or, - When we try to write protect a range of huge pmd shared range, we'll first do huge_pmd_unshare() in hugetlb_change_protection(), however that also means the UFFDIO_WRITEPROTECT could be silently skipped for the shared region, which could lead to data loss. While at it, a few other things are done altogether: - Move want_pmd_share() from mm/hugetlb.c into linux/hugetlb.h, because that's definitely something that arch code would like to use too - ARM64 currently directly check against CONFIG_ARCH_WANT_HUGE_PMD_SHARE when trying to share huge pmd. Switch to the want_pmd_share() helper. - Move vma_shareable() from huge_pmd_share() into want_pmd_share(). [peterx@redhat.com: fix build with !ARCH_WANT_HUGE_PMD_SHARE] Link: https://lkml.kernel.org/r/20210310185359.88297-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210218231202.15426-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:33:04 +03:00
#else /* !CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
hugetlb: pass vma into huge_pte_alloc() and huge_pmd_share() Patch series "hugetlb: Disable huge pmd unshare for uffd-wp", v4. This series tries to disable huge pmd unshare of hugetlbfs backed memory for uffd-wp. Although uffd-wp of hugetlbfs is still during rfc stage, the idea of this series may be needed for multiple tasks (Axel's uffd minor fault series, and Mike's soft dirty series), so I picked it out from the larger series. This patch (of 4): It is a preparation work to be able to behave differently in the per architecture huge_pte_alloc() according to different VMA attributes. Pass it deeper into huge_pmd_share() so that we can avoid the find_vma() call. [peterx@redhat.com: build fix] Link: https://lkml.kernel.org/r/20210304164653.GB397383@xz-x1Link: https://lkml.kernel.org/r/20210218230633.15028-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210218230633.15028-2-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:33:00 +03:00
pte_t *huge_pmd_share(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, pud_t *pud)
{
return NULL;
}
hugetlbfs: remove call to huge_pte_alloc without i_mmap_rwsem Commit c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") requires callers of huge_pte_alloc to hold i_mmap_rwsem in at least read mode. This is because the explicit locking in huge_pmd_share (called by huge_pte_alloc) was removed. When restructuring the code, the call to huge_pte_alloc in the else block at the beginning of hugetlb_fault was missed. Unfortunately, that else clause is exercised when there is no page table entry. This will likely lead to a call to huge_pmd_share. If huge_pmd_share thinks pmd sharing is possible, it will traverse the mapping tree (i_mmap) without holding i_mmap_rwsem. If someone else is modifying the tree, bad things such as addressing exceptions or worse could happen. Simply remove the else clause. It should have been removed previously. The code following the else will call huge_pte_alloc with the appropriate locking. To prevent this type of issue in the future, add routines to assert that i_mmap_rwsem is held, and call these routines in huge pmd sharing routines. Fixes: c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") Suggested-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A.Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/e670f327-5cf9-1959-96e4-6dc7cc30d3d5@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 04:31:38 +03:00
int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long *addr, pte_t *ptep)
{
return 0;
}
mm: migration: fix migration of huge PMD shared pages The page migration code employs try_to_unmap() to try and unmap the source page. This is accomplished by using rmap_walk to find all vmas where the page is mapped. This search stops when page mapcount is zero. For shared PMD huge pages, the page map count is always 1 no matter the number of mappings. Shared mappings are tracked via the reference count of the PMD page. Therefore, try_to_unmap stops prematurely and does not completely unmap all mappings of the source page. This problem can result is data corruption as writes to the original source page can happen after contents of the page are copied to the target page. Hence, data is lost. This problem was originally seen as DB corruption of shared global areas after a huge page was soft offlined due to ECC memory errors. DB developers noticed they could reproduce the issue by (hotplug) offlining memory used to back huge pages. A simple testcase can reproduce the problem by creating a shared PMD mapping (note that this must be at least PUD_SIZE in size and PUD_SIZE aligned (1GB on x86)), and using migrate_pages() to migrate process pages between nodes while continually writing to the huge pages being migrated. To fix, have the try_to_unmap_one routine check for huge PMD sharing by calling huge_pmd_unshare for hugetlbfs huge pages. If it is a shared mapping it will be 'unshared' which removes the page table entry and drops the reference on the PMD page. After this, flush caches and TLB. mmu notifiers are called before locking page tables, but we can not be sure of PMD sharing until page tables are locked. Therefore, check for the possibility of PMD sharing before locking so that notifiers can prepare for the worst possible case. Link: http://lkml.kernel.org/r/20180823205917.16297-2-mike.kravetz@oracle.com [mike.kravetz@oracle.com: make _range_in_vma() a static inline] Link: http://lkml.kernel.org/r/6063f215-a5c8-2f0c-465a-2c515ddc952d@oracle.com Fixes: 39dde65c9940 ("shared page table for hugetlb page") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-10-06 01:51:29 +03:00
void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
unsigned long *start, unsigned long *end)
{
}
hugetlb/userfaultfd: forbid huge pmd sharing when uffd enabled Huge pmd sharing could bring problem to userfaultfd. The thing is that userfaultfd is running its logic based on the special bits on page table entries, however the huge pmd sharing could potentially share page table entries for different address ranges. That could cause issues on either: - When sharing huge pmd page tables for an uffd write protected range, the newly mapped huge pmd range will also be write protected unexpectedly, or, - When we try to write protect a range of huge pmd shared range, we'll first do huge_pmd_unshare() in hugetlb_change_protection(), however that also means the UFFDIO_WRITEPROTECT could be silently skipped for the shared region, which could lead to data loss. While at it, a few other things are done altogether: - Move want_pmd_share() from mm/hugetlb.c into linux/hugetlb.h, because that's definitely something that arch code would like to use too - ARM64 currently directly check against CONFIG_ARCH_WANT_HUGE_PMD_SHARE when trying to share huge pmd. Switch to the want_pmd_share() helper. - Move vma_shareable() from huge_pmd_share() into want_pmd_share(). [peterx@redhat.com: fix build with !ARCH_WANT_HUGE_PMD_SHARE] Link: https://lkml.kernel.org/r/20210310185359.88297-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210218231202.15426-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:33:04 +03:00
bool want_pmd_share(struct vm_area_struct *vma, unsigned long addr)
{
return false;
}
#endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
#ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
hugetlb: pass vma into huge_pte_alloc() and huge_pmd_share() Patch series "hugetlb: Disable huge pmd unshare for uffd-wp", v4. This series tries to disable huge pmd unshare of hugetlbfs backed memory for uffd-wp. Although uffd-wp of hugetlbfs is still during rfc stage, the idea of this series may be needed for multiple tasks (Axel's uffd minor fault series, and Mike's soft dirty series), so I picked it out from the larger series. This patch (of 4): It is a preparation work to be able to behave differently in the per architecture huge_pte_alloc() according to different VMA attributes. Pass it deeper into huge_pmd_share() so that we can avoid the find_vma() call. [peterx@redhat.com: build fix] Link: https://lkml.kernel.org/r/20210304164653.GB397383@xz-x1Link: https://lkml.kernel.org/r/20210218230633.15028-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210218230633.15028-2-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:33:00 +03:00
pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, unsigned long sz)
{
pgd_t *pgd;
p4d_t *p4d;
pud_t *pud;
pte_t *pte = NULL;
pgd = pgd_offset(mm, addr);
p4d = p4d_alloc(mm, pgd, addr);
if (!p4d)
return NULL;
pud = pud_alloc(mm, p4d, addr);
if (pud) {
if (sz == PUD_SIZE) {
pte = (pte_t *)pud;
} else {
BUG_ON(sz != PMD_SIZE);
hugetlb/userfaultfd: forbid huge pmd sharing when uffd enabled Huge pmd sharing could bring problem to userfaultfd. The thing is that userfaultfd is running its logic based on the special bits on page table entries, however the huge pmd sharing could potentially share page table entries for different address ranges. That could cause issues on either: - When sharing huge pmd page tables for an uffd write protected range, the newly mapped huge pmd range will also be write protected unexpectedly, or, - When we try to write protect a range of huge pmd shared range, we'll first do huge_pmd_unshare() in hugetlb_change_protection(), however that also means the UFFDIO_WRITEPROTECT could be silently skipped for the shared region, which could lead to data loss. While at it, a few other things are done altogether: - Move want_pmd_share() from mm/hugetlb.c into linux/hugetlb.h, because that's definitely something that arch code would like to use too - ARM64 currently directly check against CONFIG_ARCH_WANT_HUGE_PMD_SHARE when trying to share huge pmd. Switch to the want_pmd_share() helper. - Move vma_shareable() from huge_pmd_share() into want_pmd_share(). [peterx@redhat.com: fix build with !ARCH_WANT_HUGE_PMD_SHARE] Link: https://lkml.kernel.org/r/20210310185359.88297-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210218231202.15426-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:33:04 +03:00
if (want_pmd_share(vma, addr) && pud_none(*pud))
hugetlb: pass vma into huge_pte_alloc() and huge_pmd_share() Patch series "hugetlb: Disable huge pmd unshare for uffd-wp", v4. This series tries to disable huge pmd unshare of hugetlbfs backed memory for uffd-wp. Although uffd-wp of hugetlbfs is still during rfc stage, the idea of this series may be needed for multiple tasks (Axel's uffd minor fault series, and Mike's soft dirty series), so I picked it out from the larger series. This patch (of 4): It is a preparation work to be able to behave differently in the per architecture huge_pte_alloc() according to different VMA attributes. Pass it deeper into huge_pmd_share() so that we can avoid the find_vma() call. [peterx@redhat.com: build fix] Link: https://lkml.kernel.org/r/20210304164653.GB397383@xz-x1Link: https://lkml.kernel.org/r/20210218230633.15028-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210218230633.15028-2-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:33:00 +03:00
pte = huge_pmd_share(mm, vma, addr, pud);
else
pte = (pte_t *)pmd_alloc(mm, pud, addr);
}
}
BUG_ON(pte && pte_present(*pte) && !pte_huge(*pte));
return pte;
}
mm/hugetlb.c: make huge_pte_offset() consistent and document behaviour When walking the page tables to resolve an address that points to !p*d_present() entry, huge_pte_offset() returns inconsistent values depending on the level of page table (PUD or PMD). It returns NULL in the case of a PUD entry while in the case of a PMD entry, it returns a pointer to the page table entry. A similar inconsitency exists when handling swap entries - returns NULL for a PUD entry while a pointer to the pte_t is retured for the PMD entry. Update huge_pte_offset() to make the behaviour consistent - return a pointer to the pte_t for hugepage or swap entries. Only return NULL in instances where we have a p*d_none() entry and the size parameter doesn't match the hugepage size at this level of the page table. Document the behaviour to clarify the expected behaviour of this function. This is to set clear semantics for architecture specific implementations of huge_pte_offset(). Discussions on the arm64 implementation of huge_pte_offset() (http://www.spinics.net/lists/linux-mm/msg133699.html) showed that there is benefit from returning a pte_t* in the case of p*d_none(). The fault handling code in hugetlb_fault() can handle p*d_none() entries and saves an extra round trip to huge_pte_alloc(). Other callers of huge_pte_offset() should be ok as well. [punit.agrawal@arm.com: v2] Link: http://lkml.kernel.org/r/20170725154114.24131-2-punit.agrawal@arm.com Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-07 02:21:01 +03:00
/*
* huge_pte_offset() - Walk the page table to resolve the hugepage
* entry at address @addr
*
mm/hugetlb: avoid unnecessary check on pud and pmd entry in huge_pte_offset When huge_pte_offset() is called, the parameter sz can only be PUD_SIZE or PMD_SIZE. If sz is PUD_SIZE and code can reach pud, then *pud must be none, or normal hugetlb entry, or non-present (migration or hwpoisoned) hugetlb entry, and we can directly return pud. When sz is PMD_SIZE, pud must be none or present, and if code can reach pmd, we can directly return pmd. So after this patch the code is simplified by first check on the parameter sz, and avoid unnecessary checks in current code. Same semantics of existing code is maintained. More details about relevant commits: commit 9b19df292c66 ("mm/hugetlb.c: make huge_pte_offset() consistent and document behaviour") changed the code path for pud and pmd handling, see comments about why this patch intends to change it. ... pud = pud_offset(p4d, addr); if (sz != PUD_SIZE && pud_none(*pud)) // [1] return NULL; /* hugepage or swap? */ if (pud_huge(*pud) || !pud_present(*pud)) // [2] return (pte_t *)pud; pmd = pmd_offset(pud, addr); if (sz != PMD_SIZE && pmd_none(*pmd)) // [3] return NULL; /* hugepage or swap? */ if (pmd_huge(*pmd) || !pmd_present(*pmd)) // [4] return (pte_t *)pmd; return NULL; // [5] ... [1]: this is necessary, return NULL for sz == PMD_SIZE; [2]: if sz == PUD_SIZE, all valid values of pud entry will cause return; [3]: dead code, sz != PMD_SIZE never true; [4]: all valid values of pmd entry will cause return; [5]: dead code, because of check in [4]. Now, this patch combines [1] and [2] for pud, and combines [3], [4] and [5] for pmd, so avoid unnecessary checks. I don't try to catch any invalid values in page table entry, as that will be checked by caller and avoid extra branch in this function. Also no assert on sz must equal PUD_SIZE or PMD_SIZE, since this function only call for hugetlb mapping. For commit 3c1d7e6ccb64 ("mm/hugetlb: fix a addressing exception caused by huge_pte_offset"), since we don't read the entry more than once now, variable pud_entry and pmd_entry are not needed. Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Longpeng <longpeng2@huawei.com> Link: http://lkml.kernel.org/r/1587794313-16849-1-git-send-email-lixinhai.lxh@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:53 +03:00
* Return: Pointer to page table entry (PUD or PMD) for
* address @addr, or NULL if a !p*d_present() entry is encountered and the
mm/hugetlb.c: make huge_pte_offset() consistent and document behaviour When walking the page tables to resolve an address that points to !p*d_present() entry, huge_pte_offset() returns inconsistent values depending on the level of page table (PUD or PMD). It returns NULL in the case of a PUD entry while in the case of a PMD entry, it returns a pointer to the page table entry. A similar inconsitency exists when handling swap entries - returns NULL for a PUD entry while a pointer to the pte_t is retured for the PMD entry. Update huge_pte_offset() to make the behaviour consistent - return a pointer to the pte_t for hugepage or swap entries. Only return NULL in instances where we have a p*d_none() entry and the size parameter doesn't match the hugepage size at this level of the page table. Document the behaviour to clarify the expected behaviour of this function. This is to set clear semantics for architecture specific implementations of huge_pte_offset(). Discussions on the arm64 implementation of huge_pte_offset() (http://www.spinics.net/lists/linux-mm/msg133699.html) showed that there is benefit from returning a pte_t* in the case of p*d_none(). The fault handling code in hugetlb_fault() can handle p*d_none() entries and saves an extra round trip to huge_pte_alloc(). Other callers of huge_pte_offset() should be ok as well. [punit.agrawal@arm.com: v2] Link: http://lkml.kernel.org/r/20170725154114.24131-2-punit.agrawal@arm.com Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-07 02:21:01 +03:00
* size @sz doesn't match the hugepage size at this level of the page
* table.
*/
mm/hugetlb: add size parameter to huge_pte_offset() A poisoned or migrated hugepage is stored as a swap entry in the page tables. On architectures that support hugepages consisting of contiguous page table entries (such as on arm64) this leads to ambiguity in determining the page table entry to return in huge_pte_offset() when a poisoned entry is encountered. Let's remove the ambiguity by adding a size parameter to convey additional information about the requested address. Also fixup the definition/usage of huge_pte_offset() throughout the tree. Link: http://lkml.kernel.org/r/20170522133604.11392-4-punit.agrawal@arm.com Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Acked-by: Steve Capper <steve.capper@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: James Hogan <james.hogan@imgtec.com> (odd fixer:METAG ARCHITECTURE) Cc: Ralf Baechle <ralf@linux-mips.org> (supporter:MIPS) Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Rich Felker <dalias@libc.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-07 01:39:42 +03:00
pte_t *huge_pte_offset(struct mm_struct *mm,
unsigned long addr, unsigned long sz)
{
pgd_t *pgd;
p4d_t *p4d;
mm/hugetlb: avoid unnecessary check on pud and pmd entry in huge_pte_offset When huge_pte_offset() is called, the parameter sz can only be PUD_SIZE or PMD_SIZE. If sz is PUD_SIZE and code can reach pud, then *pud must be none, or normal hugetlb entry, or non-present (migration or hwpoisoned) hugetlb entry, and we can directly return pud. When sz is PMD_SIZE, pud must be none or present, and if code can reach pmd, we can directly return pmd. So after this patch the code is simplified by first check on the parameter sz, and avoid unnecessary checks in current code. Same semantics of existing code is maintained. More details about relevant commits: commit 9b19df292c66 ("mm/hugetlb.c: make huge_pte_offset() consistent and document behaviour") changed the code path for pud and pmd handling, see comments about why this patch intends to change it. ... pud = pud_offset(p4d, addr); if (sz != PUD_SIZE && pud_none(*pud)) // [1] return NULL; /* hugepage or swap? */ if (pud_huge(*pud) || !pud_present(*pud)) // [2] return (pte_t *)pud; pmd = pmd_offset(pud, addr); if (sz != PMD_SIZE && pmd_none(*pmd)) // [3] return NULL; /* hugepage or swap? */ if (pmd_huge(*pmd) || !pmd_present(*pmd)) // [4] return (pte_t *)pmd; return NULL; // [5] ... [1]: this is necessary, return NULL for sz == PMD_SIZE; [2]: if sz == PUD_SIZE, all valid values of pud entry will cause return; [3]: dead code, sz != PMD_SIZE never true; [4]: all valid values of pmd entry will cause return; [5]: dead code, because of check in [4]. Now, this patch combines [1] and [2] for pud, and combines [3], [4] and [5] for pmd, so avoid unnecessary checks. I don't try to catch any invalid values in page table entry, as that will be checked by caller and avoid extra branch in this function. Also no assert on sz must equal PUD_SIZE or PMD_SIZE, since this function only call for hugetlb mapping. For commit 3c1d7e6ccb64 ("mm/hugetlb: fix a addressing exception caused by huge_pte_offset"), since we don't read the entry more than once now, variable pud_entry and pmd_entry are not needed. Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Longpeng <longpeng2@huawei.com> Link: http://lkml.kernel.org/r/1587794313-16849-1-git-send-email-lixinhai.lxh@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:53 +03:00
pud_t *pud;
pmd_t *pmd;
pgd = pgd_offset(mm, addr);
if (!pgd_present(*pgd))
return NULL;
p4d = p4d_offset(pgd, addr);
if (!p4d_present(*p4d))
return NULL;
mm/hugetlb.c: make huge_pte_offset() consistent and document behaviour When walking the page tables to resolve an address that points to !p*d_present() entry, huge_pte_offset() returns inconsistent values depending on the level of page table (PUD or PMD). It returns NULL in the case of a PUD entry while in the case of a PMD entry, it returns a pointer to the page table entry. A similar inconsitency exists when handling swap entries - returns NULL for a PUD entry while a pointer to the pte_t is retured for the PMD entry. Update huge_pte_offset() to make the behaviour consistent - return a pointer to the pte_t for hugepage or swap entries. Only return NULL in instances where we have a p*d_none() entry and the size parameter doesn't match the hugepage size at this level of the page table. Document the behaviour to clarify the expected behaviour of this function. This is to set clear semantics for architecture specific implementations of huge_pte_offset(). Discussions on the arm64 implementation of huge_pte_offset() (http://www.spinics.net/lists/linux-mm/msg133699.html) showed that there is benefit from returning a pte_t* in the case of p*d_none(). The fault handling code in hugetlb_fault() can handle p*d_none() entries and saves an extra round trip to huge_pte_alloc(). Other callers of huge_pte_offset() should be ok as well. [punit.agrawal@arm.com: v2] Link: http://lkml.kernel.org/r/20170725154114.24131-2-punit.agrawal@arm.com Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-07 02:21:01 +03:00
pud = pud_offset(p4d, addr);
mm/hugetlb: avoid unnecessary check on pud and pmd entry in huge_pte_offset When huge_pte_offset() is called, the parameter sz can only be PUD_SIZE or PMD_SIZE. If sz is PUD_SIZE and code can reach pud, then *pud must be none, or normal hugetlb entry, or non-present (migration or hwpoisoned) hugetlb entry, and we can directly return pud. When sz is PMD_SIZE, pud must be none or present, and if code can reach pmd, we can directly return pmd. So after this patch the code is simplified by first check on the parameter sz, and avoid unnecessary checks in current code. Same semantics of existing code is maintained. More details about relevant commits: commit 9b19df292c66 ("mm/hugetlb.c: make huge_pte_offset() consistent and document behaviour") changed the code path for pud and pmd handling, see comments about why this patch intends to change it. ... pud = pud_offset(p4d, addr); if (sz != PUD_SIZE && pud_none(*pud)) // [1] return NULL; /* hugepage or swap? */ if (pud_huge(*pud) || !pud_present(*pud)) // [2] return (pte_t *)pud; pmd = pmd_offset(pud, addr); if (sz != PMD_SIZE && pmd_none(*pmd)) // [3] return NULL; /* hugepage or swap? */ if (pmd_huge(*pmd) || !pmd_present(*pmd)) // [4] return (pte_t *)pmd; return NULL; // [5] ... [1]: this is necessary, return NULL for sz == PMD_SIZE; [2]: if sz == PUD_SIZE, all valid values of pud entry will cause return; [3]: dead code, sz != PMD_SIZE never true; [4]: all valid values of pmd entry will cause return; [5]: dead code, because of check in [4]. Now, this patch combines [1] and [2] for pud, and combines [3], [4] and [5] for pmd, so avoid unnecessary checks. I don't try to catch any invalid values in page table entry, as that will be checked by caller and avoid extra branch in this function. Also no assert on sz must equal PUD_SIZE or PMD_SIZE, since this function only call for hugetlb mapping. For commit 3c1d7e6ccb64 ("mm/hugetlb: fix a addressing exception caused by huge_pte_offset"), since we don't read the entry more than once now, variable pud_entry and pmd_entry are not needed. Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Longpeng <longpeng2@huawei.com> Link: http://lkml.kernel.org/r/1587794313-16849-1-git-send-email-lixinhai.lxh@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:53 +03:00
if (sz == PUD_SIZE)
/* must be pud huge, non-present or none */
return (pte_t *)pud;
mm/hugetlb: avoid unnecessary check on pud and pmd entry in huge_pte_offset When huge_pte_offset() is called, the parameter sz can only be PUD_SIZE or PMD_SIZE. If sz is PUD_SIZE and code can reach pud, then *pud must be none, or normal hugetlb entry, or non-present (migration or hwpoisoned) hugetlb entry, and we can directly return pud. When sz is PMD_SIZE, pud must be none or present, and if code can reach pmd, we can directly return pmd. So after this patch the code is simplified by first check on the parameter sz, and avoid unnecessary checks in current code. Same semantics of existing code is maintained. More details about relevant commits: commit 9b19df292c66 ("mm/hugetlb.c: make huge_pte_offset() consistent and document behaviour") changed the code path for pud and pmd handling, see comments about why this patch intends to change it. ... pud = pud_offset(p4d, addr); if (sz != PUD_SIZE && pud_none(*pud)) // [1] return NULL; /* hugepage or swap? */ if (pud_huge(*pud) || !pud_present(*pud)) // [2] return (pte_t *)pud; pmd = pmd_offset(pud, addr); if (sz != PMD_SIZE && pmd_none(*pmd)) // [3] return NULL; /* hugepage or swap? */ if (pmd_huge(*pmd) || !pmd_present(*pmd)) // [4] return (pte_t *)pmd; return NULL; // [5] ... [1]: this is necessary, return NULL for sz == PMD_SIZE; [2]: if sz == PUD_SIZE, all valid values of pud entry will cause return; [3]: dead code, sz != PMD_SIZE never true; [4]: all valid values of pmd entry will cause return; [5]: dead code, because of check in [4]. Now, this patch combines [1] and [2] for pud, and combines [3], [4] and [5] for pmd, so avoid unnecessary checks. I don't try to catch any invalid values in page table entry, as that will be checked by caller and avoid extra branch in this function. Also no assert on sz must equal PUD_SIZE or PMD_SIZE, since this function only call for hugetlb mapping. For commit 3c1d7e6ccb64 ("mm/hugetlb: fix a addressing exception caused by huge_pte_offset"), since we don't read the entry more than once now, variable pud_entry and pmd_entry are not needed. Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Longpeng <longpeng2@huawei.com> Link: http://lkml.kernel.org/r/1587794313-16849-1-git-send-email-lixinhai.lxh@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:53 +03:00
if (!pud_present(*pud))
mm/hugetlb.c: make huge_pte_offset() consistent and document behaviour When walking the page tables to resolve an address that points to !p*d_present() entry, huge_pte_offset() returns inconsistent values depending on the level of page table (PUD or PMD). It returns NULL in the case of a PUD entry while in the case of a PMD entry, it returns a pointer to the page table entry. A similar inconsitency exists when handling swap entries - returns NULL for a PUD entry while a pointer to the pte_t is retured for the PMD entry. Update huge_pte_offset() to make the behaviour consistent - return a pointer to the pte_t for hugepage or swap entries. Only return NULL in instances where we have a p*d_none() entry and the size parameter doesn't match the hugepage size at this level of the page table. Document the behaviour to clarify the expected behaviour of this function. This is to set clear semantics for architecture specific implementations of huge_pte_offset(). Discussions on the arm64 implementation of huge_pte_offset() (http://www.spinics.net/lists/linux-mm/msg133699.html) showed that there is benefit from returning a pte_t* in the case of p*d_none(). The fault handling code in hugetlb_fault() can handle p*d_none() entries and saves an extra round trip to huge_pte_alloc(). Other callers of huge_pte_offset() should be ok as well. [punit.agrawal@arm.com: v2] Link: http://lkml.kernel.org/r/20170725154114.24131-2-punit.agrawal@arm.com Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-07 02:21:01 +03:00
return NULL;
mm/hugetlb: avoid unnecessary check on pud and pmd entry in huge_pte_offset When huge_pte_offset() is called, the parameter sz can only be PUD_SIZE or PMD_SIZE. If sz is PUD_SIZE and code can reach pud, then *pud must be none, or normal hugetlb entry, or non-present (migration or hwpoisoned) hugetlb entry, and we can directly return pud. When sz is PMD_SIZE, pud must be none or present, and if code can reach pmd, we can directly return pmd. So after this patch the code is simplified by first check on the parameter sz, and avoid unnecessary checks in current code. Same semantics of existing code is maintained. More details about relevant commits: commit 9b19df292c66 ("mm/hugetlb.c: make huge_pte_offset() consistent and document behaviour") changed the code path for pud and pmd handling, see comments about why this patch intends to change it. ... pud = pud_offset(p4d, addr); if (sz != PUD_SIZE && pud_none(*pud)) // [1] return NULL; /* hugepage or swap? */ if (pud_huge(*pud) || !pud_present(*pud)) // [2] return (pte_t *)pud; pmd = pmd_offset(pud, addr); if (sz != PMD_SIZE && pmd_none(*pmd)) // [3] return NULL; /* hugepage or swap? */ if (pmd_huge(*pmd) || !pmd_present(*pmd)) // [4] return (pte_t *)pmd; return NULL; // [5] ... [1]: this is necessary, return NULL for sz == PMD_SIZE; [2]: if sz == PUD_SIZE, all valid values of pud entry will cause return; [3]: dead code, sz != PMD_SIZE never true; [4]: all valid values of pmd entry will cause return; [5]: dead code, because of check in [4]. Now, this patch combines [1] and [2] for pud, and combines [3], [4] and [5] for pmd, so avoid unnecessary checks. I don't try to catch any invalid values in page table entry, as that will be checked by caller and avoid extra branch in this function. Also no assert on sz must equal PUD_SIZE or PMD_SIZE, since this function only call for hugetlb mapping. For commit 3c1d7e6ccb64 ("mm/hugetlb: fix a addressing exception caused by huge_pte_offset"), since we don't read the entry more than once now, variable pud_entry and pmd_entry are not needed. Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Longpeng <longpeng2@huawei.com> Link: http://lkml.kernel.org/r/1587794313-16849-1-git-send-email-lixinhai.lxh@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:53 +03:00
/* must have a valid entry and size to go further */
mm/hugetlb.c: make huge_pte_offset() consistent and document behaviour When walking the page tables to resolve an address that points to !p*d_present() entry, huge_pte_offset() returns inconsistent values depending on the level of page table (PUD or PMD). It returns NULL in the case of a PUD entry while in the case of a PMD entry, it returns a pointer to the page table entry. A similar inconsitency exists when handling swap entries - returns NULL for a PUD entry while a pointer to the pte_t is retured for the PMD entry. Update huge_pte_offset() to make the behaviour consistent - return a pointer to the pte_t for hugepage or swap entries. Only return NULL in instances where we have a p*d_none() entry and the size parameter doesn't match the hugepage size at this level of the page table. Document the behaviour to clarify the expected behaviour of this function. This is to set clear semantics for architecture specific implementations of huge_pte_offset(). Discussions on the arm64 implementation of huge_pte_offset() (http://www.spinics.net/lists/linux-mm/msg133699.html) showed that there is benefit from returning a pte_t* in the case of p*d_none(). The fault handling code in hugetlb_fault() can handle p*d_none() entries and saves an extra round trip to huge_pte_alloc(). Other callers of huge_pte_offset() should be ok as well. [punit.agrawal@arm.com: v2] Link: http://lkml.kernel.org/r/20170725154114.24131-2-punit.agrawal@arm.com Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-07 02:21:01 +03:00
mm/hugetlb: avoid unnecessary check on pud and pmd entry in huge_pte_offset When huge_pte_offset() is called, the parameter sz can only be PUD_SIZE or PMD_SIZE. If sz is PUD_SIZE and code can reach pud, then *pud must be none, or normal hugetlb entry, or non-present (migration or hwpoisoned) hugetlb entry, and we can directly return pud. When sz is PMD_SIZE, pud must be none or present, and if code can reach pmd, we can directly return pmd. So after this patch the code is simplified by first check on the parameter sz, and avoid unnecessary checks in current code. Same semantics of existing code is maintained. More details about relevant commits: commit 9b19df292c66 ("mm/hugetlb.c: make huge_pte_offset() consistent and document behaviour") changed the code path for pud and pmd handling, see comments about why this patch intends to change it. ... pud = pud_offset(p4d, addr); if (sz != PUD_SIZE && pud_none(*pud)) // [1] return NULL; /* hugepage or swap? */ if (pud_huge(*pud) || !pud_present(*pud)) // [2] return (pte_t *)pud; pmd = pmd_offset(pud, addr); if (sz != PMD_SIZE && pmd_none(*pmd)) // [3] return NULL; /* hugepage or swap? */ if (pmd_huge(*pmd) || !pmd_present(*pmd)) // [4] return (pte_t *)pmd; return NULL; // [5] ... [1]: this is necessary, return NULL for sz == PMD_SIZE; [2]: if sz == PUD_SIZE, all valid values of pud entry will cause return; [3]: dead code, sz != PMD_SIZE never true; [4]: all valid values of pmd entry will cause return; [5]: dead code, because of check in [4]. Now, this patch combines [1] and [2] for pud, and combines [3], [4] and [5] for pmd, so avoid unnecessary checks. I don't try to catch any invalid values in page table entry, as that will be checked by caller and avoid extra branch in this function. Also no assert on sz must equal PUD_SIZE or PMD_SIZE, since this function only call for hugetlb mapping. For commit 3c1d7e6ccb64 ("mm/hugetlb: fix a addressing exception caused by huge_pte_offset"), since we don't read the entry more than once now, variable pud_entry and pmd_entry are not needed. Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Longpeng <longpeng2@huawei.com> Link: http://lkml.kernel.org/r/1587794313-16849-1-git-send-email-lixinhai.lxh@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 02:00:53 +03:00
pmd = pmd_offset(pud, addr);
/* must be pmd huge, non-present or none */
return (pte_t *)pmd;
}
mm/hugetlb: reduce arch dependent code around follow_huge_* Currently we have many duplicates in definitions around follow_huge_addr(), follow_huge_pmd(), and follow_huge_pud(), so this patch tries to remove the m. The basic idea is to put the default implementation for these functions in mm/hugetlb.c as weak symbols (regardless of CONFIG_ARCH_WANT_GENERAL_HUGETL B), and to implement arch-specific code only when the arch needs it. For follow_huge_addr(), only powerpc and ia64 have their own implementation, and in all other architectures this function just returns ERR_PTR(-EINVAL). So this patch sets returning ERR_PTR(-EINVAL) as default. As for follow_huge_(pmd|pud)(), if (pmd|pud)_huge() is implemented to always return 0 in your architecture (like in ia64 or sparc,) it's never called (the callsite is optimized away) no matter how implemented it is. So in such architectures, we don't need arch-specific implementation. In some architecture (like mips, s390 and tile,) their current arch-specific follow_huge_(pmd|pud)() are effectively identical with the common code, so this patch lets these architecture use the common code. One exception is metag, where pmd_huge() could return non-zero but it expects follow_huge_pmd() to always return NULL. This means that we need arch-specific implementation which returns NULL. This behavior looks strange to me (because non-zero pmd_huge() implies that the architecture supports PMD-based hugepage, so follow_huge_pmd() can/should return some relevant value,) but that's beyond this cleanup patch, so let's keep it. Justification of non-trivial changes: - in s390, follow_huge_pmd() checks !MACHINE_HAS_HPAGE at first, and this patch removes the check. This is OK because we can assume MACHINE_HAS_HPAGE is true when follow_huge_pmd() can be called (note that pmd_huge() has the same check and always returns 0 for !MACHINE_HAS_HPAGE.) - in s390 and mips, we use HPAGE_MASK instead of PMD_MASK as done in common code. This patch forces these archs use PMD_MASK, but it's OK because they are identical in both archs. In s390, both of HPAGE_SHIFT and PMD_SHIFT are 20. In mips, HPAGE_SHIFT is defined as (PAGE_SHIFT + PAGE_SHIFT - 3) and PMD_SHIFT is define as (PAGE_SHIFT + PAGE_SHIFT + PTE_ORDER - 3), but PTE_ORDER is always 0, so these are identical. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 02:25:15 +03:00
#endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
/*
* These functions are overwritable if your architecture needs its own
* behavior.
*/
struct page * __weak
follow_huge_addr(struct mm_struct *mm, unsigned long address,
int write)
{
return ERR_PTR(-EINVAL);
}
struct page * __weak
follow_huge_pd(struct vm_area_struct *vma,
unsigned long address, hugepd_t hpd, int flags, int pdshift)
{
WARN(1, "hugepd follow called with no support for hugepage directory format\n");
return NULL;
}
mm/hugetlb: reduce arch dependent code around follow_huge_* Currently we have many duplicates in definitions around follow_huge_addr(), follow_huge_pmd(), and follow_huge_pud(), so this patch tries to remove the m. The basic idea is to put the default implementation for these functions in mm/hugetlb.c as weak symbols (regardless of CONFIG_ARCH_WANT_GENERAL_HUGETL B), and to implement arch-specific code only when the arch needs it. For follow_huge_addr(), only powerpc and ia64 have their own implementation, and in all other architectures this function just returns ERR_PTR(-EINVAL). So this patch sets returning ERR_PTR(-EINVAL) as default. As for follow_huge_(pmd|pud)(), if (pmd|pud)_huge() is implemented to always return 0 in your architecture (like in ia64 or sparc,) it's never called (the callsite is optimized away) no matter how implemented it is. So in such architectures, we don't need arch-specific implementation. In some architecture (like mips, s390 and tile,) their current arch-specific follow_huge_(pmd|pud)() are effectively identical with the common code, so this patch lets these architecture use the common code. One exception is metag, where pmd_huge() could return non-zero but it expects follow_huge_pmd() to always return NULL. This means that we need arch-specific implementation which returns NULL. This behavior looks strange to me (because non-zero pmd_huge() implies that the architecture supports PMD-based hugepage, so follow_huge_pmd() can/should return some relevant value,) but that's beyond this cleanup patch, so let's keep it. Justification of non-trivial changes: - in s390, follow_huge_pmd() checks !MACHINE_HAS_HPAGE at first, and this patch removes the check. This is OK because we can assume MACHINE_HAS_HPAGE is true when follow_huge_pmd() can be called (note that pmd_huge() has the same check and always returns 0 for !MACHINE_HAS_HPAGE.) - in s390 and mips, we use HPAGE_MASK instead of PMD_MASK as done in common code. This patch forces these archs use PMD_MASK, but it's OK because they are identical in both archs. In s390, both of HPAGE_SHIFT and PMD_SHIFT are 20. In mips, HPAGE_SHIFT is defined as (PAGE_SHIFT + PAGE_SHIFT - 3) and PMD_SHIFT is define as (PAGE_SHIFT + PAGE_SHIFT + PTE_ORDER - 3), but PTE_ORDER is always 0, so these are identical. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 02:25:15 +03:00
struct page * __weak
follow_huge_pmd(struct mm_struct *mm, unsigned long address,
mm/hugetlb: take page table lock in follow_huge_pmd() We have a race condition between move_pages() and freeing hugepages, where move_pages() calls follow_page(FOLL_GET) for hugepages internally and tries to get its refcount without preventing concurrent freeing. This race crashes the kernel, so this patch fixes it by moving FOLL_GET code for hugepages into follow_huge_pmd() with taking the page table lock. This patch intentionally removes page==NULL check after pte_page. This is justified because pte_page() never returns NULL for any architectures or configurations. This patch changes the behavior of follow_huge_pmd() for tail pages and then tail pages can be pinned/returned. So the caller must be changed to properly handle the returned tail pages. We could have a choice to add the similar locking to follow_huge_(addr|pud) for consistency, but it's not necessary because currently these functions don't support FOLL_GET flag, so let's leave it for future development. Here is the reproducer: $ cat movepages.c #include <stdio.h> #include <stdlib.h> #include <numaif.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 #define PS 0x1000 int main(int argc, char *argv[]) { int i; int nr_hp = strtol(argv[1], NULL, 0); int nr_p = nr_hp * HPS / PS; int ret; void **addrs; int *status; int *nodes; pid_t pid; pid = strtol(argv[2], NULL, 0); addrs = malloc(sizeof(char *) * nr_p + 1); status = malloc(sizeof(char *) * nr_p + 1); nodes = malloc(sizeof(char *) * nr_p + 1); while (1) { for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 1; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 0; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); } return 0; } $ cat hugepage.c #include <stdio.h> #include <sys/mman.h> #include <string.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 int main(int argc, char *argv[]) { int nr_hp = strtol(argv[1], NULL, 0); char *p; while (1) { p = mmap((void *)ADDR_INPUT, nr_hp * HPS, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0); if (p != (void *)ADDR_INPUT) { perror("mmap"); break; } memset(p, 0, nr_hp * HPS); munmap(p, nr_hp * HPS); } } $ sysctl vm.nr_hugepages=40 $ ./hugepage 10 & $ ./movepages 10 $(pgrep -f hugepage) Fixes: e632a938d914 ("mm: migrate: add hugepage migration code to move_pages()") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: <stable@vger.kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 02:25:22 +03:00
pmd_t *pmd, int flags)
{
mm/hugetlb: take page table lock in follow_huge_pmd() We have a race condition between move_pages() and freeing hugepages, where move_pages() calls follow_page(FOLL_GET) for hugepages internally and tries to get its refcount without preventing concurrent freeing. This race crashes the kernel, so this patch fixes it by moving FOLL_GET code for hugepages into follow_huge_pmd() with taking the page table lock. This patch intentionally removes page==NULL check after pte_page. This is justified because pte_page() never returns NULL for any architectures or configurations. This patch changes the behavior of follow_huge_pmd() for tail pages and then tail pages can be pinned/returned. So the caller must be changed to properly handle the returned tail pages. We could have a choice to add the similar locking to follow_huge_(addr|pud) for consistency, but it's not necessary because currently these functions don't support FOLL_GET flag, so let's leave it for future development. Here is the reproducer: $ cat movepages.c #include <stdio.h> #include <stdlib.h> #include <numaif.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 #define PS 0x1000 int main(int argc, char *argv[]) { int i; int nr_hp = strtol(argv[1], NULL, 0); int nr_p = nr_hp * HPS / PS; int ret; void **addrs; int *status; int *nodes; pid_t pid; pid = strtol(argv[2], NULL, 0); addrs = malloc(sizeof(char *) * nr_p + 1); status = malloc(sizeof(char *) * nr_p + 1); nodes = malloc(sizeof(char *) * nr_p + 1); while (1) { for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 1; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 0; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); } return 0; } $ cat hugepage.c #include <stdio.h> #include <sys/mman.h> #include <string.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 int main(int argc, char *argv[]) { int nr_hp = strtol(argv[1], NULL, 0); char *p; while (1) { p = mmap((void *)ADDR_INPUT, nr_hp * HPS, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0); if (p != (void *)ADDR_INPUT) { perror("mmap"); break; } memset(p, 0, nr_hp * HPS); munmap(p, nr_hp * HPS); } } $ sysctl vm.nr_hugepages=40 $ ./hugepage 10 & $ ./movepages 10 $(pgrep -f hugepage) Fixes: e632a938d914 ("mm: migrate: add hugepage migration code to move_pages()") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: <stable@vger.kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 02:25:22 +03:00
struct page *page = NULL;
spinlock_t *ptl;
mm, hugetlb: use pte_present() instead of pmd_present() in follow_huge_pmd() I found the race condition which triggers the following bug when move_pages() and soft offline are called on a single hugetlb page concurrently. Soft offlining page 0x119400 at 0x700000000000 BUG: unable to handle kernel paging request at ffffea0011943820 IP: follow_huge_pmd+0x143/0x190 PGD 7ffd2067 PUD 7ffd1067 PMD 0 [61163.582052] Oops: 0000 [#1] SMP Modules linked in: binfmt_misc ppdev virtio_balloon parport_pc pcspkr i2c_piix4 parport i2c_core acpi_cpufreq ip_tables xfs libcrc32c ata_generic pata_acpi virtio_blk 8139too crc32c_intel ata_piix serio_raw libata virtio_pci 8139cp virtio_ring virtio mii floppy dm_mirror dm_region_hash dm_log dm_mod [last unloaded: cap_check] CPU: 0 PID: 22573 Comm: iterate_numa_mo Tainted: P OE 4.11.0-rc2-mm1+ #2 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 RIP: 0010:follow_huge_pmd+0x143/0x190 RSP: 0018:ffffc90004bdbcd0 EFLAGS: 00010202 RAX: 0000000465003e80 RBX: ffffea0004e34d30 RCX: 00003ffffffff000 RDX: 0000000011943800 RSI: 0000000000080001 RDI: 0000000465003e80 RBP: ffffc90004bdbd18 R08: 0000000000000000 R09: ffff880138d34000 R10: ffffea0004650000 R11: 0000000000c363b0 R12: ffffea0011943800 R13: ffff8801b8d34000 R14: ffffea0000000000 R15: 000077ff80000000 FS: 00007fc977710740(0000) GS:ffff88007dc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffea0011943820 CR3: 000000007a746000 CR4: 00000000001406f0 Call Trace: follow_page_mask+0x270/0x550 SYSC_move_pages+0x4ea/0x8f0 SyS_move_pages+0xe/0x10 do_syscall_64+0x67/0x180 entry_SYSCALL64_slow_path+0x25/0x25 RIP: 0033:0x7fc976e03949 RSP: 002b:00007ffe72221d88 EFLAGS: 00000246 ORIG_RAX: 0000000000000117 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc976e03949 RDX: 0000000000c22390 RSI: 0000000000001400 RDI: 0000000000005827 RBP: 00007ffe72221e00 R08: 0000000000c2c3a0 R09: 0000000000000004 R10: 0000000000c363b0 R11: 0000000000000246 R12: 0000000000400650 R13: 00007ffe72221ee0 R14: 0000000000000000 R15: 0000000000000000 Code: 81 e4 ff ff 1f 00 48 21 c2 49 c1 ec 0c 48 c1 ea 0c 4c 01 e2 49 bc 00 00 00 00 00 ea ff ff 48 c1 e2 06 49 01 d4 f6 45 bc 04 74 90 <49> 8b 7c 24 20 40 f6 c7 01 75 2b 4c 89 e7 8b 47 1c 85 c0 7e 2a RIP: follow_huge_pmd+0x143/0x190 RSP: ffffc90004bdbcd0 CR2: ffffea0011943820 ---[ end trace e4f81353a2d23232 ]--- Kernel panic - not syncing: Fatal exception Kernel Offset: disabled This bug is triggered when pmd_present() returns true for non-present hugetlb, so fixing the present check in follow_huge_pmd() prevents it. Using pmd_present() to determine present/non-present for hugetlb is not correct, because pmd_present() checks multiple bits (not only _PAGE_PRESENT) for historical reason and it can misjudge hugetlb state. Fixes: e66f17ff7177 ("mm/hugetlb: take page table lock in follow_huge_pmd()") Link: http://lkml.kernel.org/r/1490149898-20231-1-git-send-email-n-horiguchi@ah.jp.nec.com Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: <stable@vger.kernel.org> [4.0+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-04-01 01:11:55 +03:00
pte_t pte;
mm/gup: track FOLL_PIN pages Add tracking of pages that were pinned via FOLL_PIN. This tracking is implemented via overloading of page->_refcount: pins are added by adding GUP_PIN_COUNTING_BIAS (1024) to the refcount. This provides a fuzzy indication of pinning, and it can have false positives (and that's OK). Please see the pre-existing Documentation/core-api/pin_user_pages.rst for details. As mentioned in pin_user_pages.rst, callers who effectively set FOLL_PIN (typically via pin_user_pages*()) are required to ultimately free such pages via unpin_user_page(). Please also note the limitation, discussed in pin_user_pages.rst under the "TODO: for 1GB and larger huge pages" section. (That limitation will be removed in a following patch.) The effect of a FOLL_PIN flag is similar to that of FOLL_GET, and may be thought of as "FOLL_GET for DIO and/or RDMA use". Pages that have been pinned via FOLL_PIN are identifiable via a new function call: bool page_maybe_dma_pinned(struct page *page); What to do in response to encountering such a page, is left to later patchsets. There is discussion about this in [1], [2], [3], and [4]. This also changes a BUG_ON(), to a WARN_ON(), in follow_page_mask(). [1] Some slow progress on get_user_pages() (Apr 2, 2019): https://lwn.net/Articles/784574/ [2] DMA and get_user_pages() (LPC: Dec 12, 2018): https://lwn.net/Articles/774411/ [3] The trouble with get_user_pages() (Apr 30, 2018): https://lwn.net/Articles/753027/ [4] LWN kernel index: get_user_pages(): https://lwn.net/Kernel/Index/#Memory_management-get_user_pages [jhubbard@nvidia.com: add kerneldoc] Link: http://lkml.kernel.org/r/20200307021157.235726-1-jhubbard@nvidia.com [imbrenda@linux.ibm.com: if pin fails, we need to unpin, a simple put_page will not be enough] Link: http://lkml.kernel.org/r/20200306132537.783769-2-imbrenda@linux.ibm.com [akpm@linux-foundation.org: fix put_compound_head defined but not used] Suggested-by: Jan Kara <jack@suse.cz> Suggested-by: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200211001536.1027652-7-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:05:29 +03:00
mm/gup: disallow follow_page(FOLL_PIN) We want to change the way we handle R/O pins on anonymous pages that might be shared: if we detect a possibly shared anonymous page -- mapped R/O and not !PageAnonExclusive() -- we want to trigger unsharing via a page fault, resulting in an exclusive anonymous page that can be pinned reliably without getting replaced via COW on the next write fault. However, the required page fault will be problematic for follow_page(): in contrast to ordinary GUP, follow_page() doesn't trigger faults internally. So we would have to end up failing a R/O pin via follow_page(), although there is something mapped R/O into the page table, which might be rather surprising. We don't seem to have follow_page(FOLL_PIN) users, and it's a purely internal MM function. Let's just make our life easier and the semantics of follow_page() clearer by just disallowing FOLL_PIN for follow_page() completely. Link: https://lkml.kernel.org/r/20220428083441.37290-15-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-10 04:20:44 +03:00
/*
* FOLL_PIN is not supported for follow_page(). Ordinary GUP goes via
* follow_hugetlb_page().
*/
if (WARN_ON_ONCE(flags & FOLL_PIN))
mm/gup: track FOLL_PIN pages Add tracking of pages that were pinned via FOLL_PIN. This tracking is implemented via overloading of page->_refcount: pins are added by adding GUP_PIN_COUNTING_BIAS (1024) to the refcount. This provides a fuzzy indication of pinning, and it can have false positives (and that's OK). Please see the pre-existing Documentation/core-api/pin_user_pages.rst for details. As mentioned in pin_user_pages.rst, callers who effectively set FOLL_PIN (typically via pin_user_pages*()) are required to ultimately free such pages via unpin_user_page(). Please also note the limitation, discussed in pin_user_pages.rst under the "TODO: for 1GB and larger huge pages" section. (That limitation will be removed in a following patch.) The effect of a FOLL_PIN flag is similar to that of FOLL_GET, and may be thought of as "FOLL_GET for DIO and/or RDMA use". Pages that have been pinned via FOLL_PIN are identifiable via a new function call: bool page_maybe_dma_pinned(struct page *page); What to do in response to encountering such a page, is left to later patchsets. There is discussion about this in [1], [2], [3], and [4]. This also changes a BUG_ON(), to a WARN_ON(), in follow_page_mask(). [1] Some slow progress on get_user_pages() (Apr 2, 2019): https://lwn.net/Articles/784574/ [2] DMA and get_user_pages() (LPC: Dec 12, 2018): https://lwn.net/Articles/774411/ [3] The trouble with get_user_pages() (Apr 30, 2018): https://lwn.net/Articles/753027/ [4] LWN kernel index: get_user_pages(): https://lwn.net/Kernel/Index/#Memory_management-get_user_pages [jhubbard@nvidia.com: add kerneldoc] Link: http://lkml.kernel.org/r/20200307021157.235726-1-jhubbard@nvidia.com [imbrenda@linux.ibm.com: if pin fails, we need to unpin, a simple put_page will not be enough] Link: http://lkml.kernel.org/r/20200306132537.783769-2-imbrenda@linux.ibm.com [akpm@linux-foundation.org: fix put_compound_head defined but not used] Suggested-by: Jan Kara <jack@suse.cz> Suggested-by: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200211001536.1027652-7-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:05:29 +03:00
return NULL;
mm/hugetlb: take page table lock in follow_huge_pmd() We have a race condition between move_pages() and freeing hugepages, where move_pages() calls follow_page(FOLL_GET) for hugepages internally and tries to get its refcount without preventing concurrent freeing. This race crashes the kernel, so this patch fixes it by moving FOLL_GET code for hugepages into follow_huge_pmd() with taking the page table lock. This patch intentionally removes page==NULL check after pte_page. This is justified because pte_page() never returns NULL for any architectures or configurations. This patch changes the behavior of follow_huge_pmd() for tail pages and then tail pages can be pinned/returned. So the caller must be changed to properly handle the returned tail pages. We could have a choice to add the similar locking to follow_huge_(addr|pud) for consistency, but it's not necessary because currently these functions don't support FOLL_GET flag, so let's leave it for future development. Here is the reproducer: $ cat movepages.c #include <stdio.h> #include <stdlib.h> #include <numaif.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 #define PS 0x1000 int main(int argc, char *argv[]) { int i; int nr_hp = strtol(argv[1], NULL, 0); int nr_p = nr_hp * HPS / PS; int ret; void **addrs; int *status; int *nodes; pid_t pid; pid = strtol(argv[2], NULL, 0); addrs = malloc(sizeof(char *) * nr_p + 1); status = malloc(sizeof(char *) * nr_p + 1); nodes = malloc(sizeof(char *) * nr_p + 1); while (1) { for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 1; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 0; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); } return 0; } $ cat hugepage.c #include <stdio.h> #include <sys/mman.h> #include <string.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 int main(int argc, char *argv[]) { int nr_hp = strtol(argv[1], NULL, 0); char *p; while (1) { p = mmap((void *)ADDR_INPUT, nr_hp * HPS, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0); if (p != (void *)ADDR_INPUT) { perror("mmap"); break; } memset(p, 0, nr_hp * HPS); munmap(p, nr_hp * HPS); } } $ sysctl vm.nr_hugepages=40 $ ./hugepage 10 & $ ./movepages 10 $(pgrep -f hugepage) Fixes: e632a938d914 ("mm: migrate: add hugepage migration code to move_pages()") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: <stable@vger.kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 02:25:22 +03:00
retry:
ptl = pmd_lockptr(mm, pmd);
spin_lock(ptl);
/*
* make sure that the address range covered by this pmd is not
* unmapped from other threads.
*/
if (!pmd_huge(*pmd))
goto out;
mm, hugetlb: use pte_present() instead of pmd_present() in follow_huge_pmd() I found the race condition which triggers the following bug when move_pages() and soft offline are called on a single hugetlb page concurrently. Soft offlining page 0x119400 at 0x700000000000 BUG: unable to handle kernel paging request at ffffea0011943820 IP: follow_huge_pmd+0x143/0x190 PGD 7ffd2067 PUD 7ffd1067 PMD 0 [61163.582052] Oops: 0000 [#1] SMP Modules linked in: binfmt_misc ppdev virtio_balloon parport_pc pcspkr i2c_piix4 parport i2c_core acpi_cpufreq ip_tables xfs libcrc32c ata_generic pata_acpi virtio_blk 8139too crc32c_intel ata_piix serio_raw libata virtio_pci 8139cp virtio_ring virtio mii floppy dm_mirror dm_region_hash dm_log dm_mod [last unloaded: cap_check] CPU: 0 PID: 22573 Comm: iterate_numa_mo Tainted: P OE 4.11.0-rc2-mm1+ #2 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 RIP: 0010:follow_huge_pmd+0x143/0x190 RSP: 0018:ffffc90004bdbcd0 EFLAGS: 00010202 RAX: 0000000465003e80 RBX: ffffea0004e34d30 RCX: 00003ffffffff000 RDX: 0000000011943800 RSI: 0000000000080001 RDI: 0000000465003e80 RBP: ffffc90004bdbd18 R08: 0000000000000000 R09: ffff880138d34000 R10: ffffea0004650000 R11: 0000000000c363b0 R12: ffffea0011943800 R13: ffff8801b8d34000 R14: ffffea0000000000 R15: 000077ff80000000 FS: 00007fc977710740(0000) GS:ffff88007dc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffea0011943820 CR3: 000000007a746000 CR4: 00000000001406f0 Call Trace: follow_page_mask+0x270/0x550 SYSC_move_pages+0x4ea/0x8f0 SyS_move_pages+0xe/0x10 do_syscall_64+0x67/0x180 entry_SYSCALL64_slow_path+0x25/0x25 RIP: 0033:0x7fc976e03949 RSP: 002b:00007ffe72221d88 EFLAGS: 00000246 ORIG_RAX: 0000000000000117 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc976e03949 RDX: 0000000000c22390 RSI: 0000000000001400 RDI: 0000000000005827 RBP: 00007ffe72221e00 R08: 0000000000c2c3a0 R09: 0000000000000004 R10: 0000000000c363b0 R11: 0000000000000246 R12: 0000000000400650 R13: 00007ffe72221ee0 R14: 0000000000000000 R15: 0000000000000000 Code: 81 e4 ff ff 1f 00 48 21 c2 49 c1 ec 0c 48 c1 ea 0c 4c 01 e2 49 bc 00 00 00 00 00 ea ff ff 48 c1 e2 06 49 01 d4 f6 45 bc 04 74 90 <49> 8b 7c 24 20 40 f6 c7 01 75 2b 4c 89 e7 8b 47 1c 85 c0 7e 2a RIP: follow_huge_pmd+0x143/0x190 RSP: ffffc90004bdbcd0 CR2: ffffea0011943820 ---[ end trace e4f81353a2d23232 ]--- Kernel panic - not syncing: Fatal exception Kernel Offset: disabled This bug is triggered when pmd_present() returns true for non-present hugetlb, so fixing the present check in follow_huge_pmd() prevents it. Using pmd_present() to determine present/non-present for hugetlb is not correct, because pmd_present() checks multiple bits (not only _PAGE_PRESENT) for historical reason and it can misjudge hugetlb state. Fixes: e66f17ff7177 ("mm/hugetlb: take page table lock in follow_huge_pmd()") Link: http://lkml.kernel.org/r/1490149898-20231-1-git-send-email-n-horiguchi@ah.jp.nec.com Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: <stable@vger.kernel.org> [4.0+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-04-01 01:11:55 +03:00
pte = huge_ptep_get((pte_t *)pmd);
if (pte_present(pte)) {
page = pmd_page(*pmd) + ((address & ~PMD_MASK) >> PAGE_SHIFT);
mm/gup: track FOLL_PIN pages Add tracking of pages that were pinned via FOLL_PIN. This tracking is implemented via overloading of page->_refcount: pins are added by adding GUP_PIN_COUNTING_BIAS (1024) to the refcount. This provides a fuzzy indication of pinning, and it can have false positives (and that's OK). Please see the pre-existing Documentation/core-api/pin_user_pages.rst for details. As mentioned in pin_user_pages.rst, callers who effectively set FOLL_PIN (typically via pin_user_pages*()) are required to ultimately free such pages via unpin_user_page(). Please also note the limitation, discussed in pin_user_pages.rst under the "TODO: for 1GB and larger huge pages" section. (That limitation will be removed in a following patch.) The effect of a FOLL_PIN flag is similar to that of FOLL_GET, and may be thought of as "FOLL_GET for DIO and/or RDMA use". Pages that have been pinned via FOLL_PIN are identifiable via a new function call: bool page_maybe_dma_pinned(struct page *page); What to do in response to encountering such a page, is left to later patchsets. There is discussion about this in [1], [2], [3], and [4]. This also changes a BUG_ON(), to a WARN_ON(), in follow_page_mask(). [1] Some slow progress on get_user_pages() (Apr 2, 2019): https://lwn.net/Articles/784574/ [2] DMA and get_user_pages() (LPC: Dec 12, 2018): https://lwn.net/Articles/774411/ [3] The trouble with get_user_pages() (Apr 30, 2018): https://lwn.net/Articles/753027/ [4] LWN kernel index: get_user_pages(): https://lwn.net/Kernel/Index/#Memory_management-get_user_pages [jhubbard@nvidia.com: add kerneldoc] Link: http://lkml.kernel.org/r/20200307021157.235726-1-jhubbard@nvidia.com [imbrenda@linux.ibm.com: if pin fails, we need to unpin, a simple put_page will not be enough] Link: http://lkml.kernel.org/r/20200306132537.783769-2-imbrenda@linux.ibm.com [akpm@linux-foundation.org: fix put_compound_head defined but not used] Suggested-by: Jan Kara <jack@suse.cz> Suggested-by: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200211001536.1027652-7-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:05:29 +03:00
/*
* try_grab_page() should always succeed here, because: a) we
* hold the pmd (ptl) lock, and b) we've just checked that the
* huge pmd (head) page is present in the page tables. The ptl
* prevents the head page and tail pages from being rearranged
* in any way. So this page must be available at this point,
* unless the page refcount overflowed:
*/
if (WARN_ON_ONCE(!try_grab_page(page, flags))) {
page = NULL;
goto out;
}
mm/hugetlb: take page table lock in follow_huge_pmd() We have a race condition between move_pages() and freeing hugepages, where move_pages() calls follow_page(FOLL_GET) for hugepages internally and tries to get its refcount without preventing concurrent freeing. This race crashes the kernel, so this patch fixes it by moving FOLL_GET code for hugepages into follow_huge_pmd() with taking the page table lock. This patch intentionally removes page==NULL check after pte_page. This is justified because pte_page() never returns NULL for any architectures or configurations. This patch changes the behavior of follow_huge_pmd() for tail pages and then tail pages can be pinned/returned. So the caller must be changed to properly handle the returned tail pages. We could have a choice to add the similar locking to follow_huge_(addr|pud) for consistency, but it's not necessary because currently these functions don't support FOLL_GET flag, so let's leave it for future development. Here is the reproducer: $ cat movepages.c #include <stdio.h> #include <stdlib.h> #include <numaif.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 #define PS 0x1000 int main(int argc, char *argv[]) { int i; int nr_hp = strtol(argv[1], NULL, 0); int nr_p = nr_hp * HPS / PS; int ret; void **addrs; int *status; int *nodes; pid_t pid; pid = strtol(argv[2], NULL, 0); addrs = malloc(sizeof(char *) * nr_p + 1); status = malloc(sizeof(char *) * nr_p + 1); nodes = malloc(sizeof(char *) * nr_p + 1); while (1) { for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 1; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 0; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); } return 0; } $ cat hugepage.c #include <stdio.h> #include <sys/mman.h> #include <string.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 int main(int argc, char *argv[]) { int nr_hp = strtol(argv[1], NULL, 0); char *p; while (1) { p = mmap((void *)ADDR_INPUT, nr_hp * HPS, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0); if (p != (void *)ADDR_INPUT) { perror("mmap"); break; } memset(p, 0, nr_hp * HPS); munmap(p, nr_hp * HPS); } } $ sysctl vm.nr_hugepages=40 $ ./hugepage 10 & $ ./movepages 10 $(pgrep -f hugepage) Fixes: e632a938d914 ("mm: migrate: add hugepage migration code to move_pages()") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: <stable@vger.kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 02:25:22 +03:00
} else {
mm, hugetlb: use pte_present() instead of pmd_present() in follow_huge_pmd() I found the race condition which triggers the following bug when move_pages() and soft offline are called on a single hugetlb page concurrently. Soft offlining page 0x119400 at 0x700000000000 BUG: unable to handle kernel paging request at ffffea0011943820 IP: follow_huge_pmd+0x143/0x190 PGD 7ffd2067 PUD 7ffd1067 PMD 0 [61163.582052] Oops: 0000 [#1] SMP Modules linked in: binfmt_misc ppdev virtio_balloon parport_pc pcspkr i2c_piix4 parport i2c_core acpi_cpufreq ip_tables xfs libcrc32c ata_generic pata_acpi virtio_blk 8139too crc32c_intel ata_piix serio_raw libata virtio_pci 8139cp virtio_ring virtio mii floppy dm_mirror dm_region_hash dm_log dm_mod [last unloaded: cap_check] CPU: 0 PID: 22573 Comm: iterate_numa_mo Tainted: P OE 4.11.0-rc2-mm1+ #2 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 RIP: 0010:follow_huge_pmd+0x143/0x190 RSP: 0018:ffffc90004bdbcd0 EFLAGS: 00010202 RAX: 0000000465003e80 RBX: ffffea0004e34d30 RCX: 00003ffffffff000 RDX: 0000000011943800 RSI: 0000000000080001 RDI: 0000000465003e80 RBP: ffffc90004bdbd18 R08: 0000000000000000 R09: ffff880138d34000 R10: ffffea0004650000 R11: 0000000000c363b0 R12: ffffea0011943800 R13: ffff8801b8d34000 R14: ffffea0000000000 R15: 000077ff80000000 FS: 00007fc977710740(0000) GS:ffff88007dc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffea0011943820 CR3: 000000007a746000 CR4: 00000000001406f0 Call Trace: follow_page_mask+0x270/0x550 SYSC_move_pages+0x4ea/0x8f0 SyS_move_pages+0xe/0x10 do_syscall_64+0x67/0x180 entry_SYSCALL64_slow_path+0x25/0x25 RIP: 0033:0x7fc976e03949 RSP: 002b:00007ffe72221d88 EFLAGS: 00000246 ORIG_RAX: 0000000000000117 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc976e03949 RDX: 0000000000c22390 RSI: 0000000000001400 RDI: 0000000000005827 RBP: 00007ffe72221e00 R08: 0000000000c2c3a0 R09: 0000000000000004 R10: 0000000000c363b0 R11: 0000000000000246 R12: 0000000000400650 R13: 00007ffe72221ee0 R14: 0000000000000000 R15: 0000000000000000 Code: 81 e4 ff ff 1f 00 48 21 c2 49 c1 ec 0c 48 c1 ea 0c 4c 01 e2 49 bc 00 00 00 00 00 ea ff ff 48 c1 e2 06 49 01 d4 f6 45 bc 04 74 90 <49> 8b 7c 24 20 40 f6 c7 01 75 2b 4c 89 e7 8b 47 1c 85 c0 7e 2a RIP: follow_huge_pmd+0x143/0x190 RSP: ffffc90004bdbcd0 CR2: ffffea0011943820 ---[ end trace e4f81353a2d23232 ]--- Kernel panic - not syncing: Fatal exception Kernel Offset: disabled This bug is triggered when pmd_present() returns true for non-present hugetlb, so fixing the present check in follow_huge_pmd() prevents it. Using pmd_present() to determine present/non-present for hugetlb is not correct, because pmd_present() checks multiple bits (not only _PAGE_PRESENT) for historical reason and it can misjudge hugetlb state. Fixes: e66f17ff7177 ("mm/hugetlb: take page table lock in follow_huge_pmd()") Link: http://lkml.kernel.org/r/1490149898-20231-1-git-send-email-n-horiguchi@ah.jp.nec.com Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: <stable@vger.kernel.org> [4.0+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-04-01 01:11:55 +03:00
if (is_hugetlb_entry_migration(pte)) {
mm/hugetlb: take page table lock in follow_huge_pmd() We have a race condition between move_pages() and freeing hugepages, where move_pages() calls follow_page(FOLL_GET) for hugepages internally and tries to get its refcount without preventing concurrent freeing. This race crashes the kernel, so this patch fixes it by moving FOLL_GET code for hugepages into follow_huge_pmd() with taking the page table lock. This patch intentionally removes page==NULL check after pte_page. This is justified because pte_page() never returns NULL for any architectures or configurations. This patch changes the behavior of follow_huge_pmd() for tail pages and then tail pages can be pinned/returned. So the caller must be changed to properly handle the returned tail pages. We could have a choice to add the similar locking to follow_huge_(addr|pud) for consistency, but it's not necessary because currently these functions don't support FOLL_GET flag, so let's leave it for future development. Here is the reproducer: $ cat movepages.c #include <stdio.h> #include <stdlib.h> #include <numaif.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 #define PS 0x1000 int main(int argc, char *argv[]) { int i; int nr_hp = strtol(argv[1], NULL, 0); int nr_p = nr_hp * HPS / PS; int ret; void **addrs; int *status; int *nodes; pid_t pid; pid = strtol(argv[2], NULL, 0); addrs = malloc(sizeof(char *) * nr_p + 1); status = malloc(sizeof(char *) * nr_p + 1); nodes = malloc(sizeof(char *) * nr_p + 1); while (1) { for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 1; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 0; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); } return 0; } $ cat hugepage.c #include <stdio.h> #include <sys/mman.h> #include <string.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 int main(int argc, char *argv[]) { int nr_hp = strtol(argv[1], NULL, 0); char *p; while (1) { p = mmap((void *)ADDR_INPUT, nr_hp * HPS, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0); if (p != (void *)ADDR_INPUT) { perror("mmap"); break; } memset(p, 0, nr_hp * HPS); munmap(p, nr_hp * HPS); } } $ sysctl vm.nr_hugepages=40 $ ./hugepage 10 & $ ./movepages 10 $(pgrep -f hugepage) Fixes: e632a938d914 ("mm: migrate: add hugepage migration code to move_pages()") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: <stable@vger.kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 02:25:22 +03:00
spin_unlock(ptl);
__migration_entry_wait(mm, (pte_t *)pmd, ptl);
goto retry;
}
/*
* hwpoisoned entry is treated as no_page_table in
* follow_page_mask().
*/
}
out:
spin_unlock(ptl);
return page;
}
mm/hugetlb: reduce arch dependent code around follow_huge_* Currently we have many duplicates in definitions around follow_huge_addr(), follow_huge_pmd(), and follow_huge_pud(), so this patch tries to remove the m. The basic idea is to put the default implementation for these functions in mm/hugetlb.c as weak symbols (regardless of CONFIG_ARCH_WANT_GENERAL_HUGETL B), and to implement arch-specific code only when the arch needs it. For follow_huge_addr(), only powerpc and ia64 have their own implementation, and in all other architectures this function just returns ERR_PTR(-EINVAL). So this patch sets returning ERR_PTR(-EINVAL) as default. As for follow_huge_(pmd|pud)(), if (pmd|pud)_huge() is implemented to always return 0 in your architecture (like in ia64 or sparc,) it's never called (the callsite is optimized away) no matter how implemented it is. So in such architectures, we don't need arch-specific implementation. In some architecture (like mips, s390 and tile,) their current arch-specific follow_huge_(pmd|pud)() are effectively identical with the common code, so this patch lets these architecture use the common code. One exception is metag, where pmd_huge() could return non-zero but it expects follow_huge_pmd() to always return NULL. This means that we need arch-specific implementation which returns NULL. This behavior looks strange to me (because non-zero pmd_huge() implies that the architecture supports PMD-based hugepage, so follow_huge_pmd() can/should return some relevant value,) but that's beyond this cleanup patch, so let's keep it. Justification of non-trivial changes: - in s390, follow_huge_pmd() checks !MACHINE_HAS_HPAGE at first, and this patch removes the check. This is OK because we can assume MACHINE_HAS_HPAGE is true when follow_huge_pmd() can be called (note that pmd_huge() has the same check and always returns 0 for !MACHINE_HAS_HPAGE.) - in s390 and mips, we use HPAGE_MASK instead of PMD_MASK as done in common code. This patch forces these archs use PMD_MASK, but it's OK because they are identical in both archs. In s390, both of HPAGE_SHIFT and PMD_SHIFT are 20. In mips, HPAGE_SHIFT is defined as (PAGE_SHIFT + PAGE_SHIFT - 3) and PMD_SHIFT is define as (PAGE_SHIFT + PAGE_SHIFT + PTE_ORDER - 3), but PTE_ORDER is always 0, so these are identical. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 02:25:15 +03:00
struct page * __weak
follow_huge_pud(struct mm_struct *mm, unsigned long address,
mm/hugetlb: take page table lock in follow_huge_pmd() We have a race condition between move_pages() and freeing hugepages, where move_pages() calls follow_page(FOLL_GET) for hugepages internally and tries to get its refcount without preventing concurrent freeing. This race crashes the kernel, so this patch fixes it by moving FOLL_GET code for hugepages into follow_huge_pmd() with taking the page table lock. This patch intentionally removes page==NULL check after pte_page. This is justified because pte_page() never returns NULL for any architectures or configurations. This patch changes the behavior of follow_huge_pmd() for tail pages and then tail pages can be pinned/returned. So the caller must be changed to properly handle the returned tail pages. We could have a choice to add the similar locking to follow_huge_(addr|pud) for consistency, but it's not necessary because currently these functions don't support FOLL_GET flag, so let's leave it for future development. Here is the reproducer: $ cat movepages.c #include <stdio.h> #include <stdlib.h> #include <numaif.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 #define PS 0x1000 int main(int argc, char *argv[]) { int i; int nr_hp = strtol(argv[1], NULL, 0); int nr_p = nr_hp * HPS / PS; int ret; void **addrs; int *status; int *nodes; pid_t pid; pid = strtol(argv[2], NULL, 0); addrs = malloc(sizeof(char *) * nr_p + 1); status = malloc(sizeof(char *) * nr_p + 1); nodes = malloc(sizeof(char *) * nr_p + 1); while (1) { for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 1; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 0; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); } return 0; } $ cat hugepage.c #include <stdio.h> #include <sys/mman.h> #include <string.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 int main(int argc, char *argv[]) { int nr_hp = strtol(argv[1], NULL, 0); char *p; while (1) { p = mmap((void *)ADDR_INPUT, nr_hp * HPS, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0); if (p != (void *)ADDR_INPUT) { perror("mmap"); break; } memset(p, 0, nr_hp * HPS); munmap(p, nr_hp * HPS); } } $ sysctl vm.nr_hugepages=40 $ ./hugepage 10 & $ ./movepages 10 $(pgrep -f hugepage) Fixes: e632a938d914 ("mm: migrate: add hugepage migration code to move_pages()") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: <stable@vger.kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 02:25:22 +03:00
pud_t *pud, int flags)
{
mm/gup: track FOLL_PIN pages Add tracking of pages that were pinned via FOLL_PIN. This tracking is implemented via overloading of page->_refcount: pins are added by adding GUP_PIN_COUNTING_BIAS (1024) to the refcount. This provides a fuzzy indication of pinning, and it can have false positives (and that's OK). Please see the pre-existing Documentation/core-api/pin_user_pages.rst for details. As mentioned in pin_user_pages.rst, callers who effectively set FOLL_PIN (typically via pin_user_pages*()) are required to ultimately free such pages via unpin_user_page(). Please also note the limitation, discussed in pin_user_pages.rst under the "TODO: for 1GB and larger huge pages" section. (That limitation will be removed in a following patch.) The effect of a FOLL_PIN flag is similar to that of FOLL_GET, and may be thought of as "FOLL_GET for DIO and/or RDMA use". Pages that have been pinned via FOLL_PIN are identifiable via a new function call: bool page_maybe_dma_pinned(struct page *page); What to do in response to encountering such a page, is left to later patchsets. There is discussion about this in [1], [2], [3], and [4]. This also changes a BUG_ON(), to a WARN_ON(), in follow_page_mask(). [1] Some slow progress on get_user_pages() (Apr 2, 2019): https://lwn.net/Articles/784574/ [2] DMA and get_user_pages() (LPC: Dec 12, 2018): https://lwn.net/Articles/774411/ [3] The trouble with get_user_pages() (Apr 30, 2018): https://lwn.net/Articles/753027/ [4] LWN kernel index: get_user_pages(): https://lwn.net/Kernel/Index/#Memory_management-get_user_pages [jhubbard@nvidia.com: add kerneldoc] Link: http://lkml.kernel.org/r/20200307021157.235726-1-jhubbard@nvidia.com [imbrenda@linux.ibm.com: if pin fails, we need to unpin, a simple put_page will not be enough] Link: http://lkml.kernel.org/r/20200306132537.783769-2-imbrenda@linux.ibm.com [akpm@linux-foundation.org: fix put_compound_head defined but not used] Suggested-by: Jan Kara <jack@suse.cz> Suggested-by: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200211001536.1027652-7-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:05:29 +03:00
if (flags & (FOLL_GET | FOLL_PIN))
mm/hugetlb: take page table lock in follow_huge_pmd() We have a race condition between move_pages() and freeing hugepages, where move_pages() calls follow_page(FOLL_GET) for hugepages internally and tries to get its refcount without preventing concurrent freeing. This race crashes the kernel, so this patch fixes it by moving FOLL_GET code for hugepages into follow_huge_pmd() with taking the page table lock. This patch intentionally removes page==NULL check after pte_page. This is justified because pte_page() never returns NULL for any architectures or configurations. This patch changes the behavior of follow_huge_pmd() for tail pages and then tail pages can be pinned/returned. So the caller must be changed to properly handle the returned tail pages. We could have a choice to add the similar locking to follow_huge_(addr|pud) for consistency, but it's not necessary because currently these functions don't support FOLL_GET flag, so let's leave it for future development. Here is the reproducer: $ cat movepages.c #include <stdio.h> #include <stdlib.h> #include <numaif.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 #define PS 0x1000 int main(int argc, char *argv[]) { int i; int nr_hp = strtol(argv[1], NULL, 0); int nr_p = nr_hp * HPS / PS; int ret; void **addrs; int *status; int *nodes; pid_t pid; pid = strtol(argv[2], NULL, 0); addrs = malloc(sizeof(char *) * nr_p + 1); status = malloc(sizeof(char *) * nr_p + 1); nodes = malloc(sizeof(char *) * nr_p + 1); while (1) { for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 1; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 0; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); } return 0; } $ cat hugepage.c #include <stdio.h> #include <sys/mman.h> #include <string.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 int main(int argc, char *argv[]) { int nr_hp = strtol(argv[1], NULL, 0); char *p; while (1) { p = mmap((void *)ADDR_INPUT, nr_hp * HPS, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0); if (p != (void *)ADDR_INPUT) { perror("mmap"); break; } memset(p, 0, nr_hp * HPS); munmap(p, nr_hp * HPS); } } $ sysctl vm.nr_hugepages=40 $ ./hugepage 10 & $ ./movepages 10 $(pgrep -f hugepage) Fixes: e632a938d914 ("mm: migrate: add hugepage migration code to move_pages()") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: <stable@vger.kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 02:25:22 +03:00
return NULL;
mm/hugetlb: take page table lock in follow_huge_pmd() We have a race condition between move_pages() and freeing hugepages, where move_pages() calls follow_page(FOLL_GET) for hugepages internally and tries to get its refcount without preventing concurrent freeing. This race crashes the kernel, so this patch fixes it by moving FOLL_GET code for hugepages into follow_huge_pmd() with taking the page table lock. This patch intentionally removes page==NULL check after pte_page. This is justified because pte_page() never returns NULL for any architectures or configurations. This patch changes the behavior of follow_huge_pmd() for tail pages and then tail pages can be pinned/returned. So the caller must be changed to properly handle the returned tail pages. We could have a choice to add the similar locking to follow_huge_(addr|pud) for consistency, but it's not necessary because currently these functions don't support FOLL_GET flag, so let's leave it for future development. Here is the reproducer: $ cat movepages.c #include <stdio.h> #include <stdlib.h> #include <numaif.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 #define PS 0x1000 int main(int argc, char *argv[]) { int i; int nr_hp = strtol(argv[1], NULL, 0); int nr_p = nr_hp * HPS / PS; int ret; void **addrs; int *status; int *nodes; pid_t pid; pid = strtol(argv[2], NULL, 0); addrs = malloc(sizeof(char *) * nr_p + 1); status = malloc(sizeof(char *) * nr_p + 1); nodes = malloc(sizeof(char *) * nr_p + 1); while (1) { for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 1; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 0; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); } return 0; } $ cat hugepage.c #include <stdio.h> #include <sys/mman.h> #include <string.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 int main(int argc, char *argv[]) { int nr_hp = strtol(argv[1], NULL, 0); char *p; while (1) { p = mmap((void *)ADDR_INPUT, nr_hp * HPS, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0); if (p != (void *)ADDR_INPUT) { perror("mmap"); break; } memset(p, 0, nr_hp * HPS); munmap(p, nr_hp * HPS); } } $ sysctl vm.nr_hugepages=40 $ ./hugepage 10 & $ ./movepages 10 $(pgrep -f hugepage) Fixes: e632a938d914 ("mm: migrate: add hugepage migration code to move_pages()") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: <stable@vger.kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 02:25:22 +03:00
return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
}
struct page * __weak
follow_huge_pgd(struct mm_struct *mm, unsigned long address, pgd_t *pgd, int flags)
{
mm/gup: track FOLL_PIN pages Add tracking of pages that were pinned via FOLL_PIN. This tracking is implemented via overloading of page->_refcount: pins are added by adding GUP_PIN_COUNTING_BIAS (1024) to the refcount. This provides a fuzzy indication of pinning, and it can have false positives (and that's OK). Please see the pre-existing Documentation/core-api/pin_user_pages.rst for details. As mentioned in pin_user_pages.rst, callers who effectively set FOLL_PIN (typically via pin_user_pages*()) are required to ultimately free such pages via unpin_user_page(). Please also note the limitation, discussed in pin_user_pages.rst under the "TODO: for 1GB and larger huge pages" section. (That limitation will be removed in a following patch.) The effect of a FOLL_PIN flag is similar to that of FOLL_GET, and may be thought of as "FOLL_GET for DIO and/or RDMA use". Pages that have been pinned via FOLL_PIN are identifiable via a new function call: bool page_maybe_dma_pinned(struct page *page); What to do in response to encountering such a page, is left to later patchsets. There is discussion about this in [1], [2], [3], and [4]. This also changes a BUG_ON(), to a WARN_ON(), in follow_page_mask(). [1] Some slow progress on get_user_pages() (Apr 2, 2019): https://lwn.net/Articles/784574/ [2] DMA and get_user_pages() (LPC: Dec 12, 2018): https://lwn.net/Articles/774411/ [3] The trouble with get_user_pages() (Apr 30, 2018): https://lwn.net/Articles/753027/ [4] LWN kernel index: get_user_pages(): https://lwn.net/Kernel/Index/#Memory_management-get_user_pages [jhubbard@nvidia.com: add kerneldoc] Link: http://lkml.kernel.org/r/20200307021157.235726-1-jhubbard@nvidia.com [imbrenda@linux.ibm.com: if pin fails, we need to unpin, a simple put_page will not be enough] Link: http://lkml.kernel.org/r/20200306132537.783769-2-imbrenda@linux.ibm.com [akpm@linux-foundation.org: fix put_compound_head defined but not used] Suggested-by: Jan Kara <jack@suse.cz> Suggested-by: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200211001536.1027652-7-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 07:05:29 +03:00
if (flags & (FOLL_GET | FOLL_PIN))
return NULL;
return pte_page(*(pte_t *)pgd) + ((address & ~PGDIR_MASK) >> PAGE_SHIFT);
}
mm: migrate: make core migration code aware of hugepage Currently hugepage migration is available only for soft offlining, but it's also useful for some other users of page migration (clearly because users of hugepage can enjoy the benefit of mempolicy and memory hotplug.) So this patchset tries to extend such users to support hugepage migration. The target of this patchset is to enable hugepage migration for NUMA related system calls (migrate_pages(2), move_pages(2), and mbind(2)), and memory hotplug. This patchset does not add hugepage migration for memory compaction, because users of memory compaction mainly expect to construct thp by arranging raw pages, and there's little or no need to compact hugepages. CMA, another user of page migration, can have benefit from hugepage migration, but is not enabled to support it for now (just because of lack of testing and expertise in CMA.) Hugepage migration of non pmd-based hugepage (for example 1GB hugepage in x86_64, or hugepages in architectures like ia64) is not enabled for now (again, because of lack of testing.) As for how these are achived, I extended the API (migrate_pages()) to handle hugepage (with patch 1 and 2) and adjusted code of each caller to check and collect movable hugepages (with patch 3-7). Remaining 2 patches are kind of miscellaneous ones to avoid unexpected behavior. Patch 8 is about making sure that we only migrate pmd-based hugepages. And patch 9 is about choosing appropriate zone for hugepage allocation. My test is mainly functional one, simply kicking hugepage migration via each entry point and confirm that migration is done correctly. Test code is available here: git://github.com/Naoya-Horiguchi/test_hugepage_migration_extension.git And I always run libhugetlbfs test when changing hugetlbfs's code. With this patchset, no regression was found in the test. This patch (of 9): Before enabling each user of page migration to support hugepage, this patch enables the list of pages for migration to link not only LRU pages, but also hugepages. As a result, putback_movable_pages() and migrate_pages() can handle both of LRU pages and hugepages. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Acked-by: Hillf Danton <dhillf@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:21:59 +04:00
bool isolate_huge_page(struct page *page, struct list_head *list)
{
2015-04-16 02:14:38 +03:00
bool ret = true;
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
hugetlb: convert page_huge_active() HPageMigratable flag Use the new hugetlb page specific flag HPageMigratable to replace the page_huge_active interfaces. By it's name, page_huge_active implied that a huge page was on the active list. However, that is not really what code checking the flag wanted to know. It really wanted to determine if the huge page could be migrated. This happens when the page is actually added to the page cache and/or task page table. This is the reasoning behind the name change. The VM_BUG_ON_PAGE() calls in the *_huge_active() interfaces are not really necessary as we KNOW the page is a hugetlb page. Therefore, they are removed. The routine page_huge_active checked for PageHeadHuge before testing the active bit. This is unnecessary in the case where we hold a reference or lock and know it is a hugetlb head page. page_huge_active is also called without holding a reference or lock (scan_movable_pages), and can race with code freeing the page. The extra check in page_huge_active shortened the race window, but did not prevent the race. Offline code calling scan_movable_pages already deals with these races, so removing the check is acceptable. Add comment to racy code. [songmuchun@bytedance.com: remove set_page_huge_active() declaration from include/linux/hugetlb.h] Link: https://lkml.kernel.org/r/CAMZfGtUda+KoAZscU0718TN61cSFwp4zy=y2oZ=+6Z2TAZZwng@mail.gmail.com Link: https://lkml.kernel.org/r/20210122195231.324857-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:56 +03:00
if (!PageHeadHuge(page) ||
!HPageMigratable(page) ||
!get_page_unless_zero(page)) {
2015-04-16 02:14:38 +03:00
ret = false;
goto unlock;
}
hugetlb: convert page_huge_active() HPageMigratable flag Use the new hugetlb page specific flag HPageMigratable to replace the page_huge_active interfaces. By it's name, page_huge_active implied that a huge page was on the active list. However, that is not really what code checking the flag wanted to know. It really wanted to determine if the huge page could be migrated. This happens when the page is actually added to the page cache and/or task page table. This is the reasoning behind the name change. The VM_BUG_ON_PAGE() calls in the *_huge_active() interfaces are not really necessary as we KNOW the page is a hugetlb page. Therefore, they are removed. The routine page_huge_active checked for PageHeadHuge before testing the active bit. This is unnecessary in the case where we hold a reference or lock and know it is a hugetlb head page. page_huge_active is also called without holding a reference or lock (scan_movable_pages), and can race with code freeing the page. The extra check in page_huge_active shortened the race window, but did not prevent the race. Offline code calling scan_movable_pages already deals with these races, so removing the check is acceptable. Add comment to racy code. [songmuchun@bytedance.com: remove set_page_huge_active() declaration from include/linux/hugetlb.h] Link: https://lkml.kernel.org/r/CAMZfGtUda+KoAZscU0718TN61cSFwp4zy=y2oZ=+6Z2TAZZwng@mail.gmail.com Link: https://lkml.kernel.org/r/20210122195231.324857-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:56 +03:00
ClearHPageMigratable(page);
mm: migrate: make core migration code aware of hugepage Currently hugepage migration is available only for soft offlining, but it's also useful for some other users of page migration (clearly because users of hugepage can enjoy the benefit of mempolicy and memory hotplug.) So this patchset tries to extend such users to support hugepage migration. The target of this patchset is to enable hugepage migration for NUMA related system calls (migrate_pages(2), move_pages(2), and mbind(2)), and memory hotplug. This patchset does not add hugepage migration for memory compaction, because users of memory compaction mainly expect to construct thp by arranging raw pages, and there's little or no need to compact hugepages. CMA, another user of page migration, can have benefit from hugepage migration, but is not enabled to support it for now (just because of lack of testing and expertise in CMA.) Hugepage migration of non pmd-based hugepage (for example 1GB hugepage in x86_64, or hugepages in architectures like ia64) is not enabled for now (again, because of lack of testing.) As for how these are achived, I extended the API (migrate_pages()) to handle hugepage (with patch 1 and 2) and adjusted code of each caller to check and collect movable hugepages (with patch 3-7). Remaining 2 patches are kind of miscellaneous ones to avoid unexpected behavior. Patch 8 is about making sure that we only migrate pmd-based hugepages. And patch 9 is about choosing appropriate zone for hugepage allocation. My test is mainly functional one, simply kicking hugepage migration via each entry point and confirm that migration is done correctly. Test code is available here: git://github.com/Naoya-Horiguchi/test_hugepage_migration_extension.git And I always run libhugetlbfs test when changing hugetlbfs's code. With this patchset, no regression was found in the test. This patch (of 9): Before enabling each user of page migration to support hugepage, this patch enables the list of pages for migration to link not only LRU pages, but also hugepages. As a result, putback_movable_pages() and migrate_pages() can handle both of LRU pages and hugepages. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Acked-by: Hillf Danton <dhillf@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:21:59 +04:00
list_move_tail(&page->lru, list);
2015-04-16 02:14:38 +03:00
unlock:
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
2015-04-16 02:14:38 +03:00
return ret;
mm: migrate: make core migration code aware of hugepage Currently hugepage migration is available only for soft offlining, but it's also useful for some other users of page migration (clearly because users of hugepage can enjoy the benefit of mempolicy and memory hotplug.) So this patchset tries to extend such users to support hugepage migration. The target of this patchset is to enable hugepage migration for NUMA related system calls (migrate_pages(2), move_pages(2), and mbind(2)), and memory hotplug. This patchset does not add hugepage migration for memory compaction, because users of memory compaction mainly expect to construct thp by arranging raw pages, and there's little or no need to compact hugepages. CMA, another user of page migration, can have benefit from hugepage migration, but is not enabled to support it for now (just because of lack of testing and expertise in CMA.) Hugepage migration of non pmd-based hugepage (for example 1GB hugepage in x86_64, or hugepages in architectures like ia64) is not enabled for now (again, because of lack of testing.) As for how these are achived, I extended the API (migrate_pages()) to handle hugepage (with patch 1 and 2) and adjusted code of each caller to check and collect movable hugepages (with patch 3-7). Remaining 2 patches are kind of miscellaneous ones to avoid unexpected behavior. Patch 8 is about making sure that we only migrate pmd-based hugepages. And patch 9 is about choosing appropriate zone for hugepage allocation. My test is mainly functional one, simply kicking hugepage migration via each entry point and confirm that migration is done correctly. Test code is available here: git://github.com/Naoya-Horiguchi/test_hugepage_migration_extension.git And I always run libhugetlbfs test when changing hugetlbfs's code. With this patchset, no regression was found in the test. This patch (of 9): Before enabling each user of page migration to support hugepage, this patch enables the list of pages for migration to link not only LRU pages, but also hugepages. As a result, putback_movable_pages() and migrate_pages() can handle both of LRU pages and hugepages. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Acked-by: Hillf Danton <dhillf@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:21:59 +04:00
}
mm,hwpoison: fix race with hugetlb page allocation When hugetlb page fault (under overcommitting situation) and memory_failure() race, VM_BUG_ON_PAGE() is triggered by the following race: CPU0: CPU1: gather_surplus_pages() page = alloc_surplus_huge_page() memory_failure_hugetlb() get_hwpoison_page(page) __get_hwpoison_page(page) get_page_unless_zero(page) zero = put_page_testzero(page) VM_BUG_ON_PAGE(!zero, page) enqueue_huge_page(h, page) put_page(page) __get_hwpoison_page() only checks the page refcount before taking an additional one for memory error handling, which is not enough because there's a time window where compound pages have non-zero refcount during hugetlb page initialization. So make __get_hwpoison_page() check page status a bit more for hugetlb pages with get_hwpoison_huge_page(). Checking hugetlb-specific flags under hugetlb_lock makes sure that the hugetlb page is not transitive. It's notable that another new function, HWPoisonHandlable(), is helpful to prevent a race against other transitive page states (like a generic compound page just before PageHuge becomes true). Link: https://lkml.kernel.org/r/20210603233632.2964832-2-nao.horiguchi@gmail.com Fixes: ead07f6a867b ("mm/memory-failure: introduce get_hwpoison_page() for consistent refcount handling") Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reported-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Tony Luck <tony.luck@intel.com> Cc: <stable@vger.kernel.org> [5.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:13 +03:00
int get_hwpoison_huge_page(struct page *page, bool *hugetlb)
{
int ret = 0;
*hugetlb = false;
spin_lock_irq(&hugetlb_lock);
if (PageHeadHuge(page)) {
*hugetlb = true;
if (HPageFreed(page))
ret = 0;
else if (HPageMigratable(page))
mm,hwpoison: fix race with hugetlb page allocation When hugetlb page fault (under overcommitting situation) and memory_failure() race, VM_BUG_ON_PAGE() is triggered by the following race: CPU0: CPU1: gather_surplus_pages() page = alloc_surplus_huge_page() memory_failure_hugetlb() get_hwpoison_page(page) __get_hwpoison_page(page) get_page_unless_zero(page) zero = put_page_testzero(page) VM_BUG_ON_PAGE(!zero, page) enqueue_huge_page(h, page) put_page(page) __get_hwpoison_page() only checks the page refcount before taking an additional one for memory error handling, which is not enough because there's a time window where compound pages have non-zero refcount during hugetlb page initialization. So make __get_hwpoison_page() check page status a bit more for hugetlb pages with get_hwpoison_huge_page(). Checking hugetlb-specific flags under hugetlb_lock makes sure that the hugetlb page is not transitive. It's notable that another new function, HWPoisonHandlable(), is helpful to prevent a race against other transitive page states (like a generic compound page just before PageHuge becomes true). Link: https://lkml.kernel.org/r/20210603233632.2964832-2-nao.horiguchi@gmail.com Fixes: ead07f6a867b ("mm/memory-failure: introduce get_hwpoison_page() for consistent refcount handling") Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reported-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Tony Luck <tony.luck@intel.com> Cc: <stable@vger.kernel.org> [5.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:13 +03:00
ret = get_page_unless_zero(page);
else
ret = -EBUSY;
mm,hwpoison: fix race with hugetlb page allocation When hugetlb page fault (under overcommitting situation) and memory_failure() race, VM_BUG_ON_PAGE() is triggered by the following race: CPU0: CPU1: gather_surplus_pages() page = alloc_surplus_huge_page() memory_failure_hugetlb() get_hwpoison_page(page) __get_hwpoison_page(page) get_page_unless_zero(page) zero = put_page_testzero(page) VM_BUG_ON_PAGE(!zero, page) enqueue_huge_page(h, page) put_page(page) __get_hwpoison_page() only checks the page refcount before taking an additional one for memory error handling, which is not enough because there's a time window where compound pages have non-zero refcount during hugetlb page initialization. So make __get_hwpoison_page() check page status a bit more for hugetlb pages with get_hwpoison_huge_page(). Checking hugetlb-specific flags under hugetlb_lock makes sure that the hugetlb page is not transitive. It's notable that another new function, HWPoisonHandlable(), is helpful to prevent a race against other transitive page states (like a generic compound page just before PageHuge becomes true). Link: https://lkml.kernel.org/r/20210603233632.2964832-2-nao.horiguchi@gmail.com Fixes: ead07f6a867b ("mm/memory-failure: introduce get_hwpoison_page() for consistent refcount handling") Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reported-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Tony Luck <tony.luck@intel.com> Cc: <stable@vger.kernel.org> [5.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-16 04:23:13 +03:00
}
spin_unlock_irq(&hugetlb_lock);
return ret;
}
mm/hwpoison: fix race between hugetlb free/demotion and memory_failure_hugetlb() There is a race condition between memory_failure_hugetlb() and hugetlb free/demotion, which causes setting PageHWPoison flag on the wrong page. The one simple result is that wrong processes can be killed, but another (more serious) one is that the actual error is left unhandled, so no one prevents later access to it, and that might lead to more serious results like consuming corrupted data. Think about the below race window: CPU 1 CPU 2 memory_failure_hugetlb struct page *head = compound_head(p); hugetlb page might be freed to buddy, or even changed to another compound page. get_hwpoison_page -- page is not what we want now... The current code first does prechecks roughly and then reconfirms after taking refcount, but it's found that it makes code overly complicated, so move the prechecks in a single hugetlb_lock range. A newly introduced function, try_memory_failure_hugetlb(), always takes hugetlb_lock (even for non-hugetlb pages). That can be improved, but memory_failure() is rare in principle, so should not be a big problem. Link: https://lkml.kernel.org/r/20220408135323.1559401-2-naoya.horiguchi@linux.dev Fixes: 761ad8d7c7b5 ("mm: hwpoison: introduce memory_failure_hugetlb()") Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reported-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Yang Shi <shy828301@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-04-22 02:35:33 +03:00
int get_huge_page_for_hwpoison(unsigned long pfn, int flags)
{
int ret;
spin_lock_irq(&hugetlb_lock);
ret = __get_huge_page_for_hwpoison(pfn, flags);
spin_unlock_irq(&hugetlb_lock);
return ret;
}
mm: migrate: make core migration code aware of hugepage Currently hugepage migration is available only for soft offlining, but it's also useful for some other users of page migration (clearly because users of hugepage can enjoy the benefit of mempolicy and memory hotplug.) So this patchset tries to extend such users to support hugepage migration. The target of this patchset is to enable hugepage migration for NUMA related system calls (migrate_pages(2), move_pages(2), and mbind(2)), and memory hotplug. This patchset does not add hugepage migration for memory compaction, because users of memory compaction mainly expect to construct thp by arranging raw pages, and there's little or no need to compact hugepages. CMA, another user of page migration, can have benefit from hugepage migration, but is not enabled to support it for now (just because of lack of testing and expertise in CMA.) Hugepage migration of non pmd-based hugepage (for example 1GB hugepage in x86_64, or hugepages in architectures like ia64) is not enabled for now (again, because of lack of testing.) As for how these are achived, I extended the API (migrate_pages()) to handle hugepage (with patch 1 and 2) and adjusted code of each caller to check and collect movable hugepages (with patch 3-7). Remaining 2 patches are kind of miscellaneous ones to avoid unexpected behavior. Patch 8 is about making sure that we only migrate pmd-based hugepages. And patch 9 is about choosing appropriate zone for hugepage allocation. My test is mainly functional one, simply kicking hugepage migration via each entry point and confirm that migration is done correctly. Test code is available here: git://github.com/Naoya-Horiguchi/test_hugepage_migration_extension.git And I always run libhugetlbfs test when changing hugetlbfs's code. With this patchset, no regression was found in the test. This patch (of 9): Before enabling each user of page migration to support hugepage, this patch enables the list of pages for migration to link not only LRU pages, but also hugepages. As a result, putback_movable_pages() and migrate_pages() can handle both of LRU pages and hugepages. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Acked-by: Hillf Danton <dhillf@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:21:59 +04:00
void putback_active_hugepage(struct page *page)
{
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
hugetlb: convert page_huge_active() HPageMigratable flag Use the new hugetlb page specific flag HPageMigratable to replace the page_huge_active interfaces. By it's name, page_huge_active implied that a huge page was on the active list. However, that is not really what code checking the flag wanted to know. It really wanted to determine if the huge page could be migrated. This happens when the page is actually added to the page cache and/or task page table. This is the reasoning behind the name change. The VM_BUG_ON_PAGE() calls in the *_huge_active() interfaces are not really necessary as we KNOW the page is a hugetlb page. Therefore, they are removed. The routine page_huge_active checked for PageHeadHuge before testing the active bit. This is unnecessary in the case where we hold a reference or lock and know it is a hugetlb head page. page_huge_active is also called without holding a reference or lock (scan_movable_pages), and can race with code freeing the page. The extra check in page_huge_active shortened the race window, but did not prevent the race. Offline code calling scan_movable_pages already deals with these races, so removing the check is acceptable. Add comment to racy code. [songmuchun@bytedance.com: remove set_page_huge_active() declaration from include/linux/hugetlb.h] Link: https://lkml.kernel.org/r/CAMZfGtUda+KoAZscU0718TN61cSFwp4zy=y2oZ=+6Z2TAZZwng@mail.gmail.com Link: https://lkml.kernel.org/r/20210122195231.324857-3-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 23:08:56 +03:00
SetHPageMigratable(page);
mm: migrate: make core migration code aware of hugepage Currently hugepage migration is available only for soft offlining, but it's also useful for some other users of page migration (clearly because users of hugepage can enjoy the benefit of mempolicy and memory hotplug.) So this patchset tries to extend such users to support hugepage migration. The target of this patchset is to enable hugepage migration for NUMA related system calls (migrate_pages(2), move_pages(2), and mbind(2)), and memory hotplug. This patchset does not add hugepage migration for memory compaction, because users of memory compaction mainly expect to construct thp by arranging raw pages, and there's little or no need to compact hugepages. CMA, another user of page migration, can have benefit from hugepage migration, but is not enabled to support it for now (just because of lack of testing and expertise in CMA.) Hugepage migration of non pmd-based hugepage (for example 1GB hugepage in x86_64, or hugepages in architectures like ia64) is not enabled for now (again, because of lack of testing.) As for how these are achived, I extended the API (migrate_pages()) to handle hugepage (with patch 1 and 2) and adjusted code of each caller to check and collect movable hugepages (with patch 3-7). Remaining 2 patches are kind of miscellaneous ones to avoid unexpected behavior. Patch 8 is about making sure that we only migrate pmd-based hugepages. And patch 9 is about choosing appropriate zone for hugepage allocation. My test is mainly functional one, simply kicking hugepage migration via each entry point and confirm that migration is done correctly. Test code is available here: git://github.com/Naoya-Horiguchi/test_hugepage_migration_extension.git And I always run libhugetlbfs test when changing hugetlbfs's code. With this patchset, no regression was found in the test. This patch (of 9): Before enabling each user of page migration to support hugepage, this patch enables the list of pages for migration to link not only LRU pages, but also hugepages. As a result, putback_movable_pages() and migrate_pages() can handle both of LRU pages and hugepages. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Acked-by: Hillf Danton <dhillf@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:21:59 +04:00
list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
mm: migrate: make core migration code aware of hugepage Currently hugepage migration is available only for soft offlining, but it's also useful for some other users of page migration (clearly because users of hugepage can enjoy the benefit of mempolicy and memory hotplug.) So this patchset tries to extend such users to support hugepage migration. The target of this patchset is to enable hugepage migration for NUMA related system calls (migrate_pages(2), move_pages(2), and mbind(2)), and memory hotplug. This patchset does not add hugepage migration for memory compaction, because users of memory compaction mainly expect to construct thp by arranging raw pages, and there's little or no need to compact hugepages. CMA, another user of page migration, can have benefit from hugepage migration, but is not enabled to support it for now (just because of lack of testing and expertise in CMA.) Hugepage migration of non pmd-based hugepage (for example 1GB hugepage in x86_64, or hugepages in architectures like ia64) is not enabled for now (again, because of lack of testing.) As for how these are achived, I extended the API (migrate_pages()) to handle hugepage (with patch 1 and 2) and adjusted code of each caller to check and collect movable hugepages (with patch 3-7). Remaining 2 patches are kind of miscellaneous ones to avoid unexpected behavior. Patch 8 is about making sure that we only migrate pmd-based hugepages. And patch 9 is about choosing appropriate zone for hugepage allocation. My test is mainly functional one, simply kicking hugepage migration via each entry point and confirm that migration is done correctly. Test code is available here: git://github.com/Naoya-Horiguchi/test_hugepage_migration_extension.git And I always run libhugetlbfs test when changing hugetlbfs's code. With this patchset, no regression was found in the test. This patch (of 9): Before enabling each user of page migration to support hugepage, this patch enables the list of pages for migration to link not only LRU pages, but also hugepages. As a result, putback_movable_pages() and migrate_pages() can handle both of LRU pages and hugepages. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Acked-by: Hillf Danton <dhillf@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-12 01:21:59 +04:00
put_page(page);
}
mm, hugetlb: do not rely on overcommit limit during migration hugepage migration relies on __alloc_buddy_huge_page to get a new page. This has 2 main disadvantages. 1) it doesn't allow to migrate any huge page if the pool is used completely which is not an exceptional case as the pool is static and unused memory is just wasted. 2) it leads to a weird semantic when migration between two numa nodes might increase the pool size of the destination NUMA node while the page is in use. The issue is caused by per NUMA node surplus pages tracking (see free_huge_page). Address both issues by changing the way how we allocate and account pages allocated for migration. Those should temporal by definition. So we mark them that way (we will abuse page flags in the 3rd page) and update free_huge_page to free such pages to the page allocator. Page migration path then just transfers the temporal status from the new page to the old one which will be freed on the last reference. The global surplus count will never change during this path but we still have to be careful when migrating a per-node suprlus page. This is now handled in move_hugetlb_state which is called from the migration path and it copies the hugetlb specific page state and fixes up the accounting when needed Rename __alloc_buddy_huge_page to __alloc_surplus_huge_page to better reflect its purpose. The new allocation routine for the migration path is __alloc_migrate_huge_page. The user visible effect of this patch is that migrated pages are really temporal and they travel between NUMA nodes as per the migration request: Before migration /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 After /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 with the previous implementation, both nodes would have nr_hugepages:1 until the page is freed. Link: http://lkml.kernel.org/r/20180103093213.26329-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:48 +03:00
void move_hugetlb_state(struct page *oldpage, struct page *newpage, int reason)
{
struct hstate *h = page_hstate(oldpage);
hugetlb_cgroup_migrate(oldpage, newpage);
set_page_owner_migrate_reason(newpage, reason);
/*
* transfer temporary state of the new huge page. This is
* reverse to other transitions because the newpage is going to
* be final while the old one will be freed so it takes over
* the temporary status.
*
* Also note that we have to transfer the per-node surplus state
* here as well otherwise the global surplus count will not match
* the per-node's.
*/
if (HPageTemporary(newpage)) {
mm, hugetlb: do not rely on overcommit limit during migration hugepage migration relies on __alloc_buddy_huge_page to get a new page. This has 2 main disadvantages. 1) it doesn't allow to migrate any huge page if the pool is used completely which is not an exceptional case as the pool is static and unused memory is just wasted. 2) it leads to a weird semantic when migration between two numa nodes might increase the pool size of the destination NUMA node while the page is in use. The issue is caused by per NUMA node surplus pages tracking (see free_huge_page). Address both issues by changing the way how we allocate and account pages allocated for migration. Those should temporal by definition. So we mark them that way (we will abuse page flags in the 3rd page) and update free_huge_page to free such pages to the page allocator. Page migration path then just transfers the temporal status from the new page to the old one which will be freed on the last reference. The global surplus count will never change during this path but we still have to be careful when migrating a per-node suprlus page. This is now handled in move_hugetlb_state which is called from the migration path and it copies the hugetlb specific page state and fixes up the accounting when needed Rename __alloc_buddy_huge_page to __alloc_surplus_huge_page to better reflect its purpose. The new allocation routine for the migration path is __alloc_migrate_huge_page. The user visible effect of this patch is that migrated pages are really temporal and they travel between NUMA nodes as per the migration request: Before migration /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 After /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 with the previous implementation, both nodes would have nr_hugepages:1 until the page is freed. Link: http://lkml.kernel.org/r/20180103093213.26329-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:48 +03:00
int old_nid = page_to_nid(oldpage);
int new_nid = page_to_nid(newpage);
SetHPageTemporary(oldpage);
ClearHPageTemporary(newpage);
mm, hugetlb: do not rely on overcommit limit during migration hugepage migration relies on __alloc_buddy_huge_page to get a new page. This has 2 main disadvantages. 1) it doesn't allow to migrate any huge page if the pool is used completely which is not an exceptional case as the pool is static and unused memory is just wasted. 2) it leads to a weird semantic when migration between two numa nodes might increase the pool size of the destination NUMA node while the page is in use. The issue is caused by per NUMA node surplus pages tracking (see free_huge_page). Address both issues by changing the way how we allocate and account pages allocated for migration. Those should temporal by definition. So we mark them that way (we will abuse page flags in the 3rd page) and update free_huge_page to free such pages to the page allocator. Page migration path then just transfers the temporal status from the new page to the old one which will be freed on the last reference. The global surplus count will never change during this path but we still have to be careful when migrating a per-node suprlus page. This is now handled in move_hugetlb_state which is called from the migration path and it copies the hugetlb specific page state and fixes up the accounting when needed Rename __alloc_buddy_huge_page to __alloc_surplus_huge_page to better reflect its purpose. The new allocation routine for the migration path is __alloc_migrate_huge_page. The user visible effect of this patch is that migrated pages are really temporal and they travel between NUMA nodes as per the migration request: Before migration /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 After /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 with the previous implementation, both nodes would have nr_hugepages:1 until the page is freed. Link: http://lkml.kernel.org/r/20180103093213.26329-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:48 +03:00
/*
* There is no need to transfer the per-node surplus state
* when we do not cross the node.
*/
if (new_nid == old_nid)
return;
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_lock_irq(&hugetlb_lock);
mm, hugetlb: do not rely on overcommit limit during migration hugepage migration relies on __alloc_buddy_huge_page to get a new page. This has 2 main disadvantages. 1) it doesn't allow to migrate any huge page if the pool is used completely which is not an exceptional case as the pool is static and unused memory is just wasted. 2) it leads to a weird semantic when migration between two numa nodes might increase the pool size of the destination NUMA node while the page is in use. The issue is caused by per NUMA node surplus pages tracking (see free_huge_page). Address both issues by changing the way how we allocate and account pages allocated for migration. Those should temporal by definition. So we mark them that way (we will abuse page flags in the 3rd page) and update free_huge_page to free such pages to the page allocator. Page migration path then just transfers the temporal status from the new page to the old one which will be freed on the last reference. The global surplus count will never change during this path but we still have to be careful when migrating a per-node suprlus page. This is now handled in move_hugetlb_state which is called from the migration path and it copies the hugetlb specific page state and fixes up the accounting when needed Rename __alloc_buddy_huge_page to __alloc_surplus_huge_page to better reflect its purpose. The new allocation routine for the migration path is __alloc_migrate_huge_page. The user visible effect of this patch is that migrated pages are really temporal and they travel between NUMA nodes as per the migration request: Before migration /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 After /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 with the previous implementation, both nodes would have nr_hugepages:1 until the page is freed. Link: http://lkml.kernel.org/r/20180103093213.26329-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:48 +03:00
if (h->surplus_huge_pages_node[old_nid]) {
h->surplus_huge_pages_node[old_nid]--;
h->surplus_huge_pages_node[new_nid]++;
}
hugetlb: make free_huge_page irq safe Commit c77c0a8ac4c5 ("mm/hugetlb: defer freeing of huge pages if in non-task context") was added to address the issue of free_huge_page being called from irq context. That commit hands off free_huge_page processing to a workqueue if !in_task. However, this doesn't cover all the cases as pointed out by 0day bot lockdep report [1]. : Possible interrupt unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(hugetlb_lock); : local_irq_disable(); : lock(slock-AF_INET); : lock(hugetlb_lock); : <Interrupt> : lock(slock-AF_INET); Shakeel has later explained that this is very likely TCP TX zerocopy from hugetlb pages scenario when the networking code drops a last reference to hugetlb page while having IRQ disabled. Hugetlb freeing path doesn't disable IRQ while holding hugetlb_lock so a lock dependency chain can lead to a deadlock. This commit addresses the issue by doing the following: - Make hugetlb_lock irq safe. This is mostly a simple process of changing spin_*lock calls to spin_*lock_irq* calls. - Make subpool lock irq safe in a similar manner. - Revert the !in_task check and workqueue handoff. [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/ Link: https://lkml.kernel.org/r/20210409205254.242291-8-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:35:07 +03:00
spin_unlock_irq(&hugetlb_lock);
mm, hugetlb: do not rely on overcommit limit during migration hugepage migration relies on __alloc_buddy_huge_page to get a new page. This has 2 main disadvantages. 1) it doesn't allow to migrate any huge page if the pool is used completely which is not an exceptional case as the pool is static and unused memory is just wasted. 2) it leads to a weird semantic when migration between two numa nodes might increase the pool size of the destination NUMA node while the page is in use. The issue is caused by per NUMA node surplus pages tracking (see free_huge_page). Address both issues by changing the way how we allocate and account pages allocated for migration. Those should temporal by definition. So we mark them that way (we will abuse page flags in the 3rd page) and update free_huge_page to free such pages to the page allocator. Page migration path then just transfers the temporal status from the new page to the old one which will be freed on the last reference. The global surplus count will never change during this path but we still have to be careful when migrating a per-node suprlus page. This is now handled in move_hugetlb_state which is called from the migration path and it copies the hugetlb specific page state and fixes up the accounting when needed Rename __alloc_buddy_huge_page to __alloc_surplus_huge_page to better reflect its purpose. The new allocation routine for the migration path is __alloc_migrate_huge_page. The user visible effect of this patch is that migrated pages are really temporal and they travel between NUMA nodes as per the migration request: Before migration /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 After /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:1 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0 with the previous implementation, both nodes would have nr_hugepages:1 until the page is freed. Link: http://lkml.kernel.org/r/20180103093213.26329-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 03:20:48 +03:00
}
}
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
hugetlb/userfaultfd: unshare all pmds for hugetlbfs when register wp Huge pmd sharing for hugetlbfs is racy with userfaultfd-wp because userfaultfd-wp is always based on pgtable entries, so they cannot be shared. Walk the hugetlb range and unshare all such mappings if there is, right before UFFDIO_REGISTER will succeed and return to userspace. This will pair with want_pmd_share() in hugetlb code so that huge pmd sharing is completely disabled for userfaultfd-wp registered range. Link: https://lkml.kernel.org/r/20210218231206.15524-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Peter Xu <peterx@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:33:13 +03:00
/*
* This function will unconditionally remove all the shared pmd pgtable entries
* within the specific vma for a hugetlbfs memory range.
*/
void hugetlb_unshare_all_pmds(struct vm_area_struct *vma)
{
struct hstate *h = hstate_vma(vma);
unsigned long sz = huge_page_size(h);
struct mm_struct *mm = vma->vm_mm;
struct mmu_notifier_range range;
unsigned long address, start, end;
spinlock_t *ptl;
pte_t *ptep;
if (!(vma->vm_flags & VM_MAYSHARE))
return;
start = ALIGN(vma->vm_start, PUD_SIZE);
end = ALIGN_DOWN(vma->vm_end, PUD_SIZE);
if (start >= end)
return;
flush_cache_range(vma, start, end);
hugetlb/userfaultfd: unshare all pmds for hugetlbfs when register wp Huge pmd sharing for hugetlbfs is racy with userfaultfd-wp because userfaultfd-wp is always based on pgtable entries, so they cannot be shared. Walk the hugetlb range and unshare all such mappings if there is, right before UFFDIO_REGISTER will succeed and return to userspace. This will pair with want_pmd_share() in hugetlb code so that huge pmd sharing is completely disabled for userfaultfd-wp registered range. Link: https://lkml.kernel.org/r/20210218231206.15524-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Peter Xu <peterx@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 04:33:13 +03:00
/*
* No need to call adjust_range_if_pmd_sharing_possible(), because
* we have already done the PUD_SIZE alignment.
*/
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
start, end);
mmu_notifier_invalidate_range_start(&range);
i_mmap_lock_write(vma->vm_file->f_mapping);
for (address = start; address < end; address += PUD_SIZE) {
unsigned long tmp = address;
ptep = huge_pte_offset(mm, address, sz);
if (!ptep)
continue;
ptl = huge_pte_lock(h, mm, ptep);
/* We don't want 'address' to be changed */
huge_pmd_unshare(mm, vma, &tmp, ptep);
spin_unlock(ptl);
}
flush_hugetlb_tlb_range(vma, start, end);
i_mmap_unlock_write(vma->vm_file->f_mapping);
/*
* No need to call mmu_notifier_invalidate_range(), see
* Documentation/vm/mmu_notifier.rst.
*/
mmu_notifier_invalidate_range_end(&range);
}
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
#ifdef CONFIG_CMA
static bool cma_reserve_called __initdata;
static int __init cmdline_parse_hugetlb_cma(char *p)
{
hugetlb: support node specified when using cma for gigantic hugepages Now the size of CMA area for gigantic hugepages runtime allocation is balanced for all online nodes, but we also want to specify the size of CMA per-node, or only one node in some cases, which are similar with patch [1]. For example, on some multi-nodes systems, each node's memory can be different, allocating the same size of CMA for each node is not suitable for the low-memory nodes. Meanwhile some workloads like DPDK mentioned by Zhenguo in patch [1] only need hugepages in one node. On the other hand, we have some machines with multiple types of memory, like DRAM and PMEM (persistent memory). On this system, we may want to specify all the hugepages only on DRAM node, or specify the proportion of DRAM node and PMEM node, to tuning the performance of the workloads. Thus this patch adds node format for 'hugetlb_cma' parameter to support specifying the size of CMA per-node. An example is as follows: hugetlb_cma=0:5G,2:5G which means allocating 5G size of CMA area on node 0 and node 2 respectively. And the users should use the node specific sysfs file to allocate the gigantic hugepages if specified the CMA size on that node. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com [1] Link: https://lkml.kernel.org/r/bb790775ca60bb8f4b26956bb3f6988f74e075c7.1634261144.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:46 +03:00
int nid, count = 0;
unsigned long tmp;
char *s = p;
while (*s) {
if (sscanf(s, "%lu%n", &tmp, &count) != 1)
break;
if (s[count] == ':') {
hugetlb: clean up potential spectre issue warnings Recently introduced code allows numa nodes to be specified on the kernel command line for hugetlb allocations or CMA reservations. The node values are user specified and used as indicies into arrays. This generated the following smatch warnings: mm/hugetlb.c:4170 hugepages_setup() warn: potential spectre issue 'default_hugepages_in_node' [w] mm/hugetlb.c:4172 hugepages_setup() warn: potential spectre issue 'parsed_hstate->max_huge_pages_node' [w] mm/hugetlb.c:6898 cmdline_parse_hugetlb_cma() warn: potential spectre issue 'hugetlb_cma_size_in_node' [w] (local cap) Clean up by using array_index_nospec to sanitize array indicies. The routine cmdline_parse_hugetlb_cma has the same overflow/truncation issue addressed in [1]. That is also fixed with this change. [1] https://lore.kernel.org/linux-mm/20220209134018.8242-1-liuyuntao10@huawei.com/ As Michal pointed out, this is unlikely to be exploitable because it is __init code. But the patch suppresses the warnings. [mike.kravetz@oracle.com: v2] Link: https://lkml.kernel.org/r/20220218212946.35441-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20220217234218.192885-1-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Liu Yuntao <liuyuntao10@huawei.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-03-23 00:45:20 +03:00
if (tmp >= MAX_NUMNODES)
hugetlb: support node specified when using cma for gigantic hugepages Now the size of CMA area for gigantic hugepages runtime allocation is balanced for all online nodes, but we also want to specify the size of CMA per-node, or only one node in some cases, which are similar with patch [1]. For example, on some multi-nodes systems, each node's memory can be different, allocating the same size of CMA for each node is not suitable for the low-memory nodes. Meanwhile some workloads like DPDK mentioned by Zhenguo in patch [1] only need hugepages in one node. On the other hand, we have some machines with multiple types of memory, like DRAM and PMEM (persistent memory). On this system, we may want to specify all the hugepages only on DRAM node, or specify the proportion of DRAM node and PMEM node, to tuning the performance of the workloads. Thus this patch adds node format for 'hugetlb_cma' parameter to support specifying the size of CMA per-node. An example is as follows: hugetlb_cma=0:5G,2:5G which means allocating 5G size of CMA area on node 0 and node 2 respectively. And the users should use the node specific sysfs file to allocate the gigantic hugepages if specified the CMA size on that node. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com [1] Link: https://lkml.kernel.org/r/bb790775ca60bb8f4b26956bb3f6988f74e075c7.1634261144.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:46 +03:00
break;
hugetlb: clean up potential spectre issue warnings Recently introduced code allows numa nodes to be specified on the kernel command line for hugetlb allocations or CMA reservations. The node values are user specified and used as indicies into arrays. This generated the following smatch warnings: mm/hugetlb.c:4170 hugepages_setup() warn: potential spectre issue 'default_hugepages_in_node' [w] mm/hugetlb.c:4172 hugepages_setup() warn: potential spectre issue 'parsed_hstate->max_huge_pages_node' [w] mm/hugetlb.c:6898 cmdline_parse_hugetlb_cma() warn: potential spectre issue 'hugetlb_cma_size_in_node' [w] (local cap) Clean up by using array_index_nospec to sanitize array indicies. The routine cmdline_parse_hugetlb_cma has the same overflow/truncation issue addressed in [1]. That is also fixed with this change. [1] https://lore.kernel.org/linux-mm/20220209134018.8242-1-liuyuntao10@huawei.com/ As Michal pointed out, this is unlikely to be exploitable because it is __init code. But the patch suppresses the warnings. [mike.kravetz@oracle.com: v2] Link: https://lkml.kernel.org/r/20220218212946.35441-1-mike.kravetz@oracle.com Link: https://lkml.kernel.org/r/20220217234218.192885-1-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Zhenguo Yao <yaozhenguo1@gmail.com> Cc: Liu Yuntao <liuyuntao10@huawei.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-03-23 00:45:20 +03:00
nid = array_index_nospec(tmp, MAX_NUMNODES);
hugetlb: support node specified when using cma for gigantic hugepages Now the size of CMA area for gigantic hugepages runtime allocation is balanced for all online nodes, but we also want to specify the size of CMA per-node, or only one node in some cases, which are similar with patch [1]. For example, on some multi-nodes systems, each node's memory can be different, allocating the same size of CMA for each node is not suitable for the low-memory nodes. Meanwhile some workloads like DPDK mentioned by Zhenguo in patch [1] only need hugepages in one node. On the other hand, we have some machines with multiple types of memory, like DRAM and PMEM (persistent memory). On this system, we may want to specify all the hugepages only on DRAM node, or specify the proportion of DRAM node and PMEM node, to tuning the performance of the workloads. Thus this patch adds node format for 'hugetlb_cma' parameter to support specifying the size of CMA per-node. An example is as follows: hugetlb_cma=0:5G,2:5G which means allocating 5G size of CMA area on node 0 and node 2 respectively. And the users should use the node specific sysfs file to allocate the gigantic hugepages if specified the CMA size on that node. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com [1] Link: https://lkml.kernel.org/r/bb790775ca60bb8f4b26956bb3f6988f74e075c7.1634261144.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:46 +03:00
s += count + 1;
tmp = memparse(s, &s);
hugetlb_cma_size_in_node[nid] = tmp;
hugetlb_cma_size += tmp;
/*
* Skip the separator if have one, otherwise
* break the parsing.
*/
if (*s == ',')
s++;
else
break;
} else {
hugetlb_cma_size = memparse(p, &p);
break;
}
}
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
return 0;
}
early_param("hugetlb_cma", cmdline_parse_hugetlb_cma);
void __init hugetlb_cma_reserve(int order)
{
unsigned long size, reserved, per_node;
hugetlb: support node specified when using cma for gigantic hugepages Now the size of CMA area for gigantic hugepages runtime allocation is balanced for all online nodes, but we also want to specify the size of CMA per-node, or only one node in some cases, which are similar with patch [1]. For example, on some multi-nodes systems, each node's memory can be different, allocating the same size of CMA for each node is not suitable for the low-memory nodes. Meanwhile some workloads like DPDK mentioned by Zhenguo in patch [1] only need hugepages in one node. On the other hand, we have some machines with multiple types of memory, like DRAM and PMEM (persistent memory). On this system, we may want to specify all the hugepages only on DRAM node, or specify the proportion of DRAM node and PMEM node, to tuning the performance of the workloads. Thus this patch adds node format for 'hugetlb_cma' parameter to support specifying the size of CMA per-node. An example is as follows: hugetlb_cma=0:5G,2:5G which means allocating 5G size of CMA area on node 0 and node 2 respectively. And the users should use the node specific sysfs file to allocate the gigantic hugepages if specified the CMA size on that node. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com [1] Link: https://lkml.kernel.org/r/bb790775ca60bb8f4b26956bb3f6988f74e075c7.1634261144.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:46 +03:00
bool node_specific_cma_alloc = false;
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
int nid;
cma_reserve_called = true;
hugetlb: support node specified when using cma for gigantic hugepages Now the size of CMA area for gigantic hugepages runtime allocation is balanced for all online nodes, but we also want to specify the size of CMA per-node, or only one node in some cases, which are similar with patch [1]. For example, on some multi-nodes systems, each node's memory can be different, allocating the same size of CMA for each node is not suitable for the low-memory nodes. Meanwhile some workloads like DPDK mentioned by Zhenguo in patch [1] only need hugepages in one node. On the other hand, we have some machines with multiple types of memory, like DRAM and PMEM (persistent memory). On this system, we may want to specify all the hugepages only on DRAM node, or specify the proportion of DRAM node and PMEM node, to tuning the performance of the workloads. Thus this patch adds node format for 'hugetlb_cma' parameter to support specifying the size of CMA per-node. An example is as follows: hugetlb_cma=0:5G,2:5G which means allocating 5G size of CMA area on node 0 and node 2 respectively. And the users should use the node specific sysfs file to allocate the gigantic hugepages if specified the CMA size on that node. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com [1] Link: https://lkml.kernel.org/r/bb790775ca60bb8f4b26956bb3f6988f74e075c7.1634261144.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:46 +03:00
if (!hugetlb_cma_size)
return;
for (nid = 0; nid < MAX_NUMNODES; nid++) {
if (hugetlb_cma_size_in_node[nid] == 0)
continue;
if (!node_online(nid)) {
hugetlb: support node specified when using cma for gigantic hugepages Now the size of CMA area for gigantic hugepages runtime allocation is balanced for all online nodes, but we also want to specify the size of CMA per-node, or only one node in some cases, which are similar with patch [1]. For example, on some multi-nodes systems, each node's memory can be different, allocating the same size of CMA for each node is not suitable for the low-memory nodes. Meanwhile some workloads like DPDK mentioned by Zhenguo in patch [1] only need hugepages in one node. On the other hand, we have some machines with multiple types of memory, like DRAM and PMEM (persistent memory). On this system, we may want to specify all the hugepages only on DRAM node, or specify the proportion of DRAM node and PMEM node, to tuning the performance of the workloads. Thus this patch adds node format for 'hugetlb_cma' parameter to support specifying the size of CMA per-node. An example is as follows: hugetlb_cma=0:5G,2:5G which means allocating 5G size of CMA area on node 0 and node 2 respectively. And the users should use the node specific sysfs file to allocate the gigantic hugepages if specified the CMA size on that node. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com [1] Link: https://lkml.kernel.org/r/bb790775ca60bb8f4b26956bb3f6988f74e075c7.1634261144.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:46 +03:00
pr_warn("hugetlb_cma: invalid node %d specified\n", nid);
hugetlb_cma_size -= hugetlb_cma_size_in_node[nid];
hugetlb_cma_size_in_node[nid] = 0;
continue;
}
if (hugetlb_cma_size_in_node[nid] < (PAGE_SIZE << order)) {
pr_warn("hugetlb_cma: cma area of node %d should be at least %lu MiB\n",
nid, (PAGE_SIZE << order) / SZ_1M);
hugetlb_cma_size -= hugetlb_cma_size_in_node[nid];
hugetlb_cma_size_in_node[nid] = 0;
} else {
node_specific_cma_alloc = true;
}
}
/* Validate the CMA size again in case some invalid nodes specified. */
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
if (!hugetlb_cma_size)
return;
if (hugetlb_cma_size < (PAGE_SIZE << order)) {
pr_warn("hugetlb_cma: cma area should be at least %lu MiB\n",
(PAGE_SIZE << order) / SZ_1M);
hugetlb: be sure to free demoted CMA pages to CMA When huge page demotion is fully implemented, gigantic pages can be demoted to a smaller huge page size. For example, on x86 a 1G page can be demoted to 512 2M pages. However, gigantic pages can potentially be allocated from CMA. If a gigantic page which was allocated from CMA is demoted, the corresponding demoted pages needs to be returned to CMA. Use the new interface cma_pages_valid() to determine if a non-gigantic hugetlb page should be freed to CMA. Also, clear mapping field of these pages as expected by cma_release. This also requires a change to CMA region creation for gigantic pages. CMA uses a per-region bit map to track allocations. When setting up the region, you specify how many pages each bit represents. Currently, only gigantic pages are allocated/freed from CMA so the region is set up such that one bit represents a gigantic page size allocation. With demote, a gigantic page (allocation) could be split into smaller size pages. And, these smaller size pages will be freed to CMA. So, since the per-region bit map needs to be set up to represent the smallest allocation/free size, it now needs to be set to the smallest huge page size which can be freed to CMA. Unfortunately, we set up the CMA region for huge pages before we set up huge pages sizes (hstates). So, technically we do not know the smallest huge page size as this can change via command line options and architecture specific code. Therefore, at region setup time we use HUGETLB_PAGE_ORDER as the smallest possible huge page size that can be given back to CMA. It is possible that this value is sub-optimal for some architectures/config options. If needed, this can be addressed in follow on work. Link: https://lkml.kernel.org/r/20211007181918.136982-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:27 +03:00
hugetlb_cma_size = 0;
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
return;
}
hugetlb: support node specified when using cma for gigantic hugepages Now the size of CMA area for gigantic hugepages runtime allocation is balanced for all online nodes, but we also want to specify the size of CMA per-node, or only one node in some cases, which are similar with patch [1]. For example, on some multi-nodes systems, each node's memory can be different, allocating the same size of CMA for each node is not suitable for the low-memory nodes. Meanwhile some workloads like DPDK mentioned by Zhenguo in patch [1] only need hugepages in one node. On the other hand, we have some machines with multiple types of memory, like DRAM and PMEM (persistent memory). On this system, we may want to specify all the hugepages only on DRAM node, or specify the proportion of DRAM node and PMEM node, to tuning the performance of the workloads. Thus this patch adds node format for 'hugetlb_cma' parameter to support specifying the size of CMA per-node. An example is as follows: hugetlb_cma=0:5G,2:5G which means allocating 5G size of CMA area on node 0 and node 2 respectively. And the users should use the node specific sysfs file to allocate the gigantic hugepages if specified the CMA size on that node. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com [1] Link: https://lkml.kernel.org/r/bb790775ca60bb8f4b26956bb3f6988f74e075c7.1634261144.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:46 +03:00
if (!node_specific_cma_alloc) {
/*
* If 3 GB area is requested on a machine with 4 numa nodes,
* let's allocate 1 GB on first three nodes and ignore the last one.
*/
per_node = DIV_ROUND_UP(hugetlb_cma_size, nr_online_nodes);
pr_info("hugetlb_cma: reserve %lu MiB, up to %lu MiB per node\n",
hugetlb_cma_size / SZ_1M, per_node / SZ_1M);
}
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
reserved = 0;
for_each_online_node(nid) {
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
int res;
char name[CMA_MAX_NAME];
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
hugetlb: support node specified when using cma for gigantic hugepages Now the size of CMA area for gigantic hugepages runtime allocation is balanced for all online nodes, but we also want to specify the size of CMA per-node, or only one node in some cases, which are similar with patch [1]. For example, on some multi-nodes systems, each node's memory can be different, allocating the same size of CMA for each node is not suitable for the low-memory nodes. Meanwhile some workloads like DPDK mentioned by Zhenguo in patch [1] only need hugepages in one node. On the other hand, we have some machines with multiple types of memory, like DRAM and PMEM (persistent memory). On this system, we may want to specify all the hugepages only on DRAM node, or specify the proportion of DRAM node and PMEM node, to tuning the performance of the workloads. Thus this patch adds node format for 'hugetlb_cma' parameter to support specifying the size of CMA per-node. An example is as follows: hugetlb_cma=0:5G,2:5G which means allocating 5G size of CMA area on node 0 and node 2 respectively. And the users should use the node specific sysfs file to allocate the gigantic hugepages if specified the CMA size on that node. Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com [1] Link: https://lkml.kernel.org/r/bb790775ca60bb8f4b26956bb3f6988f74e075c7.1634261144.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:46 +03:00
if (node_specific_cma_alloc) {
if (hugetlb_cma_size_in_node[nid] == 0)
continue;
size = hugetlb_cma_size_in_node[nid];
} else {
size = min(per_node, hugetlb_cma_size - reserved);
}
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
size = round_up(size, PAGE_SIZE << order);
snprintf(name, sizeof(name), "hugetlb%d", nid);
hugetlb: be sure to free demoted CMA pages to CMA When huge page demotion is fully implemented, gigantic pages can be demoted to a smaller huge page size. For example, on x86 a 1G page can be demoted to 512 2M pages. However, gigantic pages can potentially be allocated from CMA. If a gigantic page which was allocated from CMA is demoted, the corresponding demoted pages needs to be returned to CMA. Use the new interface cma_pages_valid() to determine if a non-gigantic hugetlb page should be freed to CMA. Also, clear mapping field of these pages as expected by cma_release. This also requires a change to CMA region creation for gigantic pages. CMA uses a per-region bit map to track allocations. When setting up the region, you specify how many pages each bit represents. Currently, only gigantic pages are allocated/freed from CMA so the region is set up such that one bit represents a gigantic page size allocation. With demote, a gigantic page (allocation) could be split into smaller size pages. And, these smaller size pages will be freed to CMA. So, since the per-region bit map needs to be set up to represent the smallest allocation/free size, it now needs to be set to the smallest huge page size which can be freed to CMA. Unfortunately, we set up the CMA region for huge pages before we set up huge pages sizes (hstates). So, technically we do not know the smallest huge page size as this can change via command line options and architecture specific code. Therefore, at region setup time we use HUGETLB_PAGE_ORDER as the smallest possible huge page size that can be given back to CMA. It is possible that this value is sub-optimal for some architectures/config options. If needed, this can be addressed in follow on work. Link: https://lkml.kernel.org/r/20211007181918.136982-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:27 +03:00
/*
* Note that 'order per bit' is based on smallest size that
* may be returned to CMA allocator in the case of
* huge page demotion.
*/
res = cma_declare_contiguous_nid(0, size, 0,
PAGE_SIZE << HUGETLB_PAGE_ORDER,
0, false, name,
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
&hugetlb_cma[nid], nid);
if (res) {
pr_warn("hugetlb_cma: reservation failed: err %d, node %d",
res, nid);
continue;
}
reserved += size;
pr_info("hugetlb_cma: reserved %lu MiB on node %d\n",
size / SZ_1M, nid);
if (reserved >= hugetlb_cma_size)
break;
}
hugetlb: be sure to free demoted CMA pages to CMA When huge page demotion is fully implemented, gigantic pages can be demoted to a smaller huge page size. For example, on x86 a 1G page can be demoted to 512 2M pages. However, gigantic pages can potentially be allocated from CMA. If a gigantic page which was allocated from CMA is demoted, the corresponding demoted pages needs to be returned to CMA. Use the new interface cma_pages_valid() to determine if a non-gigantic hugetlb page should be freed to CMA. Also, clear mapping field of these pages as expected by cma_release. This also requires a change to CMA region creation for gigantic pages. CMA uses a per-region bit map to track allocations. When setting up the region, you specify how many pages each bit represents. Currently, only gigantic pages are allocated/freed from CMA so the region is set up such that one bit represents a gigantic page size allocation. With demote, a gigantic page (allocation) could be split into smaller size pages. And, these smaller size pages will be freed to CMA. So, since the per-region bit map needs to be set up to represent the smallest allocation/free size, it now needs to be set to the smallest huge page size which can be freed to CMA. Unfortunately, we set up the CMA region for huge pages before we set up huge pages sizes (hstates). So, technically we do not know the smallest huge page size as this can change via command line options and architecture specific code. Therefore, at region setup time we use HUGETLB_PAGE_ORDER as the smallest possible huge page size that can be given back to CMA. It is possible that this value is sub-optimal for some architectures/config options. If needed, this can be addressed in follow on work. Link: https://lkml.kernel.org/r/20211007181918.136982-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Nghia Le <nghialm78@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 23:41:27 +03:00
if (!reserved)
/*
* hugetlb_cma_size is used to determine if allocations from
* cma are possible. Set to zero if no cma regions are set up.
*/
hugetlb_cma_size = 0;
mm: hugetlb: optionally allocate gigantic hugepages using cma Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andreas Schaufler <andreas.schaufler@gmx.de> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Aslan Bakirov <aslan@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-11 00:32:45 +03:00
}
void __init hugetlb_cma_check(void)
{
if (!hugetlb_cma_size || cma_reserve_called)
return;
pr_warn("hugetlb_cma: the option isn't supported by current arch\n");
}
#endif /* CONFIG_CMA */