This is the latest userfaultfd patchset. The postcopy live migration
feature on the qemu side is mostly ready to be merged and it entirely
depends on the userfaultfd syscall to be merged as well. So it'd be great
if this patchset could be reviewed for merging in -mm.
Userfaults allow to implement on demand paging from userland and more
generally they allow userland to more efficiently take control of the
behavior of page faults than what was available before (PROT_NONE +
SIGSEGV trap).
The use cases are:
1) KVM postcopy live migration (one form of cloud memory
externalization).
KVM postcopy live migration is the primary driver of this work:
http://blog.zhaw.ch/icclab/setting-up-post-copy-live-migration-in-openstack/http://lists.gnu.org/archive/html/qemu-devel/2015-02/msg04873.html
2) postcopy live migration of binaries inside linux containers:
http://thread.gmane.org/gmane.linux.kernel.mm/132662
3) KVM postcopy live snapshotting (allowing to limit/throttle the
memory usage, unlike fork would, plus the avoidance of fork
overhead in the first place).
While the wrprotect tracking is not implemented yet, the syscall API is
already contemplating the wrprotect fault tracking and it's generic enough
to allow its later implementation in a backwards compatible fashion.
4) KVM userfaults on shared memory. The UFFDIO_COPY lowlevel method
should be extended to work also on tmpfs and then the
uffdio_register.ioctls will notify userland that UFFDIO_COPY is
available even when the registered virtual memory range is tmpfs
backed.
5) alternate mechanism to notify web browsers or apps on embedded
devices that volatile pages have been reclaimed. This basically
avoids the need to run a syscall before the app can access with the
CPU the virtual regions marked volatile. This depends on point 4)
to be fulfilled first, as volatile pages happily apply to tmpfs.
Even though there wasn't a real use case requesting it yet, it also
allows to implement distributed shared memory in a way that readonly
shared mappings can exist simultaneously in different hosts and they
can be become exclusive at the first wrprotect fault.
This patch (of 22):
Add documentation.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Sanidhya Kashyap <sanidhya.gatech@gmail.com>
Cc: zhang.zhanghailiang@huawei.com
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Change the "enabled" parameter to be configurable at runtime. Remove the
enabled check from init(), and move it to the frontswap store() function;
when enabled, pages will be stored, and when disabled, pages won't be
stored.
This is almost identical to Seth's patch from 2 years ago:
http://lkml.iu.edu/hypermail/linux/kernel/1307.2/04289.html
[akpm@linux-foundation.org: tweak documentation]
Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Suggested-by: Seth Jennings <sjennings@variantweb.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a very subtle difference between mmap()+mlock() vs
mmap(MAP_LOCKED) semantic. The former one fails if the population of the
area fails while the later one doesn't. This basically means that
mmap(MAPLOCKED) areas might see major fault after mmap syscall returns
which is not the case for mlock. mmap man page has already been altered
but Documentation/vm/unevictable-lru.txt deserves a clarification as well.
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reported-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
of the i2o docs, some new Chinese translations, and, hopefully, the README
fix that will end the flow of identical patches to that file.
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Merge tag 'docs-for-linus' of git://git.lwn.net/linux-2.6
Pull documentation updates from Jonathan Corbet:
"Numerous fixes, the overdue removal of the i2o docs, some new Chinese
translations, and, hopefully, the README fix that will end the flow of
identical patches to that file"
* tag 'docs-for-linus' of git://git.lwn.net/linux-2.6: (34 commits)
Documentation/memcg: update memcg/kmem status
Documentation: blackfin: Makefile: Typo building issue
Documentation/vm/pagemap.txt: correct location of page-types tool
Documentation/memory-barriers.txt: typo fix
doc: Add guest_nice column to example output of `cat /proc/stat'
Documentation/kernel-parameters: Move "eagerfpu" to its right place
Documentation: gpio: Update ACPI part of the document to mention _DSD
docs/completion.txt: Various tweaks and corrections
doc: completion: context, scope and language fixes
Documentation:Update Documentation/zh_CN/arm64/memory.txt
Documentation:Update Documentation/zh_CN/arm64/booting.txt
Documentation: Chinese translation of arm64/legacy_instructions.txt
DocBook media: fix broken EIA hyperlink
Documentation: tweak the maintainers entry
README: Change gzip/bzip2 to xz compression format
README: Update version number reference
doc:pci: Fix typo in Documentation/PCI
Documentation: drm: Use '->' when describing access through pointers.
Documentation: Remove mentioning of block barriers
Documentation/email-clients.txt: Fix one grammar mistake, add extra info about TB
...
munmap(2) of hugetlb memory requires a length that is hugepage aligned,
otherwise it may fail. Add this to the documentation.
This also cleans up the documentation and separates it into logical units:
one part refers to MAP_HUGETLB and another part refers to requirements for
shared memory segments.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Joern Engel <joern@logfs.org>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Eric B Munson <emunson@akamai.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add min_size mount option to the hugetlbfs documentation. Also, add the
missing pagesize option and mention that size can be specified as bytes or
a percentage of huge page pool.
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>
The memory compaction code uses the migration code to do most of the
work in compaction. However, the compaction code interacts with the
unevictable LRU differently than migration code and this difference
should be noted in the documentation.
[akpm@linux-foundation.org: identify /proc/sys/vm/compact_unevictable directly]
Signed-off-by: Eric B Munson <emunson@akamai.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, cleancache_register_ops returns the previous value of
cleancache_ops to allow chaining. However, chaining, as it is
implemented now, is extremely dangerous due to possible pool id
collisions. Suppose, a new cleancache driver is registered after the
previous one assigned an id to a super block. If the new driver assigns
the same id to another super block, which is perfectly possible, we will
have two different filesystems using the same id. No matter if the new
driver implements chaining or not, we are likely to get data corruption
with such a configuration eventually.
This patch therefore disables the ability to override cleancache_ops
altogether as potentially dangerous. If there is already cleancache
driver registered, all further calls to cleancache_register_ops will
return EBUSY. Since no user of cleancache implements chaining, we only
need to make minor changes to the code outside the cleancache core.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Stefan Hengelein <ilendir@googlemail.com>
Cc: Florian Schmaus <fschmaus@gmail.com>
Cc: Andor Daam <andor.daam@googlemail.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Bob Liu <lliubbo@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__mlock_vma_pages_range() doesn't necessarily mlock pages. It depends on
vma flags. The same codepath is used for MAP_POPULATE.
Let's rename __mlock_vma_pages_range() to populate_vma_page_range().
This patch also drops mlock_vma_pages_range() references from
documentation. It has gone in cea10a19b7 ("mm: directly use
__mlock_vma_pages_range() in find_extend_vma()").
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Michel Lespinasse <walken@google.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>
The page-types tool was relocated to tools/vm in the 3.4 kernel timeframe.
Signed-off-by: Randy Wright <rwright@hp.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
max_ptes_none specifies how many extra small pages (that are
not already mapped) can be allocated when collapsing a group
of small pages into one large page.
/sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_none
A higher value leads to use additional memory for programs.
A lower value leads to gain less thp performance. Value of
max_ptes_none can waste cpu time very little, you can
ignore it.
Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Add KPF_ZERO_PAGE flag for zero_page, so that userspace processes can
detect zero_page in /proc/kpageflags, and then do memory analysis more
accurately.
Signed-off-by: Yalin Wang <yalin.wang@sonymobile.com>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Konstantin Khlebnikov <koct9i@gmail.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>
Pull trivial tree changes from Jiri Kosina:
"Patches from trivial.git that keep the world turning around.
Mostly documentation and comment fixes, and a two corner-case code
fixes from Alan Cox"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial:
kexec, Kconfig: spell "architecture" properly
mm: fix cleancache debugfs directory path
blackfin: mach-common: ints-priority: remove unused function
doubletalk: probe failure causes OOPS
ARM: cache-l2x0.c: Make it clear that cache-l2x0 handles L310 cache controller
msdos_fs.h: fix 'fields' in comment
scsi: aic7xxx: fix comment
ARM: l2c: fix comment
ibmraid: fix writeable attribute with no store method
dynamic_debug: fix comment
doc: usbmon: fix spelling s/unpriviledged/unprivileged/
x86: init_mem_mapping(): use capital BIOS in comment
remap_file_pages(2) was invented to be able efficiently map parts of
huge file into limited 32-bit virtual address space such as in database
workloads.
Nonlinear mappings are pain to support and it seems there's no
legitimate use-cases nowadays since 64-bit systems are widely available.
Let's drop it and get rid of all these special-cased code.
The patch replaces the syscall with emulation which creates new VMA on
each remap_file_pages(), unless they it can be merged with an adjacent
one.
I didn't find *any* real code that uses remap_file_pages(2) to test
emulation impact on. I've checked Debian code search and source of all
packages in ALT Linux. No real users: libc wrappers, mentions in
strace, gdb, valgrind and this kind of stuff.
There are few basic tests in LTP for the syscall. They work just fine
with emulation.
To test performance impact, I've written small test case which
demonstrate pretty much worst case scenario: map 4G shmfs file, write to
begin of every page pgoff of the page, remap pages in reverse order,
read every page.
The test creates 1 million of VMAs if emulation is in use, so I had to
set vm.max_map_count to 1100000 to avoid -ENOMEM.
Before: 23.3 ( +- 4.31% ) seconds
After: 43.9 ( +- 0.85% ) seconds
Slowdown: 1.88x
I believe we can live with that.
Test case:
#define _GNU_SOURCE
#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/mman.h>
#define MB (1024UL * 1024)
#define SIZE (4096 * MB)
int main(int argc, char **argv)
{
unsigned long *p;
long i, pass;
for (pass = 0; pass < 10; pass++) {
p = mmap(NULL, SIZE, PROT_READ|PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS, -1, 0);
if (p == MAP_FAILED) {
perror("mmap");
return -1;
}
for (i = 0; i < SIZE / 4096; i++)
p[i * 4096 / sizeof(*p)] = i;
for (i = 0; i < SIZE / 4096; i++) {
if (remap_file_pages(p + i * 4096 / sizeof(*p), 4096,
0, (SIZE - 4096 * (i + 1)) >> 12, 0)) {
perror("remap_file_pages");
return -1;
}
}
for (i = SIZE / 4096 - 1; i >= 0; i--)
assert(p[i * 4096 / sizeof(*p)] == SIZE / 4096 - i - 1);
munmap(p, SIZE);
}
return 0;
}
[akpm@linux-foundation.org: fix spello]
[sasha.levin@oracle.com: initialize populate before usage]
[sasha.levin@oracle.com: grab file ref to prevent race while mmaping]
Signed-off-by: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Armin Rigo <arigo@tunes.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.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>
Minor fixes for cleancache about wrong debugfs paths
in documentation and code comment.
Signed-off-by: Marcin Jabrzyk <m.jabrzyk@samsung.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Merge second patchbomb from Andrew Morton:
- the rest of MM
- misc fs fixes
- add execveat() syscall
- new ratelimit feature for fault-injection
- decompressor updates
- ipc/ updates
- fallocate feature creep
- fsnotify cleanups
- a few other misc things
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (99 commits)
cgroups: Documentation: fix trivial typos and wrong paragraph numberings
parisc: percpu: update comments referring to __get_cpu_var
percpu: update local_ops.txt to reflect this_cpu operations
percpu: remove __get_cpu_var and __raw_get_cpu_var macros
fsnotify: remove destroy_list from fsnotify_mark
fsnotify: unify inode and mount marks handling
fallocate: create FAN_MODIFY and IN_MODIFY events
mm/cma: make kmemleak ignore CMA regions
slub: fix cpuset check in get_any_partial
slab: fix cpuset check in fallback_alloc
shmdt: use i_size_read() instead of ->i_size
ipc/shm.c: fix overly aggressive shmdt() when calls span multiple segments
ipc/msg: increase MSGMNI, remove scaling
ipc/sem.c: increase SEMMSL, SEMMNI, SEMOPM
ipc/sem.c: change memory barrier in sem_lock() to smp_rmb()
lib/decompress.c: consistency of compress formats for kernel image
decompress_bunzip2: off by one in get_next_block()
usr/Kconfig: make initrd compression algorithm selection not expert
fault-inject: add ratelimit option
ratelimit: add initialization macro
...
page owner is for the tracking about who allocated each page. This
document explains what is the page owner feature and what is the merit of
it. And, simple HOW-TO is also explained. See the document for detailed
information.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Jungsoo Son <jungsoo.son@lge.com>
Cc: Ingo Molnar <mingo@redhat.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>
This patch adds 1GB large page support information in
Documentation/vm/hugetlbpage.txt
Reference:
https://lkml.org/lkml/2014/10/31/366
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Commit 75897d60 (hugetlb: allow sticky directory mount option) added
support for mounting hugetlbfs with sticky option set, like /tmp is
usually mounted, but forgot to document that.
Acked-by: Ken Chen <kenchen@google.com>
Signed-off-by: Kirill Smelkov <kirr@nexedi.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The remap_file_pages() system call is used to create a nonlinear
mapping, that is, a mapping in which the pages of the file are mapped
into a nonsequential order in memory. The advantage of using
remap_file_pages() over using repeated calls to mmap(2) is that the
former approach does not require the kernel to create additional VMA
(Virtual Memory Area) data structures.
Supporting of nonlinear mapping requires significant amount of
non-trivial code in kernel virtual memory subsystem including hot paths.
Also to get nonlinear mapping work kernel need a way to distinguish
normal page table entries from entries with file offset (pte_file).
Kernel reserves flag in PTE for this purpose. PTE flags are scarce
resource especially on some CPU architectures. It would be nice to free
up the flag for other usage.
Fortunately, there are not many users of remap_file_pages() in the wild.
It's only known that one enterprise RDBMS implementation uses the
syscall on 32-bit systems to map files bigger than can linearly fit into
32-bit virtual address space. This use-case is not critical anymore
since 64-bit systems are widely available.
The plan is to deprecate the syscall and replace it with an emulation.
The emulation will create new VMAs instead of nonlinear mappings. It's
going to work slower for rare users of remap_file_pages() but ABI is
preserved.
One side effect of emulation (apart from performance) is that user can
hit vm.max_map_count limit more easily due to additional VMAs. See
comment for DEFAULT_MAX_MAP_COUNT for more details on the limit.
[akpm@linux-foundation.org: fix spello]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Armin Rigo <arigo@tunes.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently memory error handler handles action optional errors in the
deferred manner by default. And if a recovery aware application wants
to handle it immediately, it can do it by setting PF_MCE_EARLY flag.
However, such signal can be sent only to the main thread, so it's
problematic if the application wants to have a dedicated thread to
handler such signals.
So this patch adds dedicated thread support to memory error handler. We
have PF_MCE_EARLY flags for each thread separately, so with this patch
AO signal is sent to the thread with PF_MCE_EARLY flag set, not the main
thread. If you want to implement a dedicated thread, you call prctl()
to set PF_MCE_EARLY on the thread.
Memory error handler collects processes to be killed, so this patch lets
it check PF_MCE_EARLY flag on each thread in the collecting routines.
No behavioral change for all non-early kill cases.
Tony said:
: The old behavior was crazy - someone with a multithreaded process might
: well expect that if they call prctl(PF_MCE_EARLY) in just one thread, then
: that thread would see the SIGBUS with si_code = BUS_MCEERR_A0 - even if
: that thread wasn't the main thread for the process.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Cc: Kamil Iskra <iskra@mcs.anl.gov>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Chen Gong <gong.chen@linux.jf.intel.com>
Cc: <stable@vger.kernel.org> [3.2+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull trivial tree changes from Jiri Kosina:
"Usual pile of patches from trivial tree that make the world go round"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (23 commits)
staging: go7007: remove reference to CONFIG_KMOD
aic7xxx: Remove obsolete preprocessor define
of: dma: doc fixes
doc: fix incorrect formula to calculate CommitLimit value
doc: Note need of bc in the kernel build from 3.10 onwards
mm: Fix printk typo in dmapool.c
modpost: Fix comment typo "Modules.symvers"
Kconfig.debug: Grammar s/addition/additional/
wimax: Spelling s/than/that/, wording s/destinatary/recipient/
aic7xxx: Spelling s/termnation/termination/
arm64: mm: Remove superfluous "the" in comment
of: Spelling s/anonymouns/anonymous/
dma: imx-sdma: Spelling s/determnine/determine/
ath10k: Improve grammar in comments
ath6kl: Spelling s/determnine/determine/
of: Improve grammar for of_alias_get_id() documentation
drm/exynos: Spelling s/contro/control/
radio-bcm2048.c: fix wrong overflow check
doc: printk-formats: do not mention casts for u64/s64
doc: spelling error changes
...
In document numa_memory_policy.txt, the following examples for flag
MPOL_F_RELATIVE_NODES are incorrect.
For example, consider a task that is attached to a cpuset with
mems 2-5 that sets an Interleave policy over the same set with
MPOL_F_RELATIVE_NODES. If the cpuset's mems change to 3-7, the
interleave now occurs over nodes 3,5-6. If the cpuset's mems
then change to 0,2-3,5, then the interleave occurs over nodes
0,3,5.
According to the comment of the patch adding flag MPOL_F_RELATIVE_NODES,
the nodemasks the user specifies should be considered relative to the
current task's mems_allowed.
(https://lkml.org/lkml/2008/2/29/428)
And according to numa_memory_policy.txt, if the user's nodemask includes
nodes that are outside the range of the new set of allowed nodes, then
the remap wraps around to the beginning of the nodemask and, if not
already set, sets the node in the mempolicy nodemask.
So in the example, if the user specifies 2-5, for a task whose
mems_allowed is 3-7, the nodemasks should be remapped the third, fourth,
fifth, sixth node in mems_allowed. like the following:
mems_allowed: 3 4 5 6 7
relative index: 0 1 2 3 4
5
So the nodemasks should be remapped to 3,5-7, but not 3,5-6.
And for a task whose mems_allowed is 0,2-3,5, the nodemasks should be
remapped to 0,2-3,5, but not 0,3,5.
mems_allowed: 0 2 3 5
relative index: 0 1 2 3
4 5
Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix double words "the the" in various files
within Documentations.
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Some of the 00-INDEX files are somewhat outdated and some folders does
not contain 00-INDEX at all. Only outdated (with the notably exception
of spi) indexes are touched here, the 169 folders without 00-INDEX has
not been touched.
New 00-INDEX
- spi/* was added in a series of commits dating back to 2006
Added files (missing in (*/)00-INDEX)
- dmatest.txt was added by commit 851b7e16a0 ("dmatest: run test via
debugfs")
- this_cpu_ops.txt was added by commit a1b2a555d6 ("percpu: add
documentation on this_cpu operations")
- ww-mutex-design.txt was added by commit 040a0a3710 ("mutex: Add
support for wound/wait style locks")
- bcache.txt was added by commit cafe563591 ("bcache: A block layer
cache")
- kernel-per-CPU-kthreads.txt was added by commit 49717cb404
("kthread: Document ways of reducing OS jitter due to per-CPU
kthreads")
- phy.txt was added by commit ff76496347 ("drivers: phy: add generic
PHY framework")
- block/null_blk was added by commit 12f8f4fc03 ("null_blk:
documentation")
- module-signing.txt was added by commit 3cafea3076 ("Add
Documentation/module-signing.txt file")
- assoc_array.txt was added by commit 3cb989501c ("Add a generic
associative array implementation.")
- arm/IXP4xx was part of the initial repo
- arm/cluster-pm-race-avoidance.txt was added by commit 7fe31d28e8
("ARM: mcpm: introduce helpers for platform coherency exit/setup")
- arm/firmware.txt was added by commit 7366b92a77 ("ARM: Add
interface for registering and calling firmware-specific operations")
- arm/kernel_mode_neon.txt was added by commit 2afd0a0524 ("ARM:
7825/1: document the use of NEON in kernel mode")
- arm/tcm.txt was added by commit bc581770cf ("ARM: 5580/2: ARM TCM
(Tightly-Coupled Memory) support v3")
- arm/vlocks.txt was added by commit 9762f12d3e ("ARM: mcpm: Add
baremetal voting mutexes")
- blackfin/gptimers-example.c, Makefile was added by commit
4b60779d5e ("Blackfin: add an example showing how to use the
gptimers API")
- devicetree/usage-model.txt was added by commit 31134efc68 ("dt:
Linux DT usage model documentation")
- fb/api.txt was added by commit fb21c2f428 ("fbdev: Add FOURCC-based
format configuration API")
- fb/sm501.txt was added by commit e6a0498071 ("video, sm501: add
edid and commandline support")
- fb/udlfb.txt was added by commit 96f8d864af ("fbdev: move udlfb out
of staging.")
- filesystems/Makefile was added by commit 1e0051ae48
("Documentation/fs/: split txt and source files")
- filesystems/nfs/nfsd-admin-interfaces.txt was added by commit
8a4c6e19cf ("nfsd: document kernel interfaces for nfsd
configuration")
- ide/warm-plug-howto.txt was added by commit f74c91413e ("ide: add
warm-plug support for IDE devices (take 2)")
- laptops/Makefile was added by commit d49129accc
("Documentation/laptop/: split txt and source files")
- leds/leds-blinkm.txt was added by commit b54cf35a7f ("LEDS: add
BlinkM RGB LED driver, documentation and update MAINTAINERS")
- leds/ledtrig-oneshot.txt was added by commit 5e417281cd ("leds: add
oneshot trigger")
- leds/ledtrig-transient.txt was added by commit 44e1e9f8e7 ("leds:
add new transient trigger for one shot timer activation")
- m68k/README.buddha was part of the initial repo
- networking/LICENSE.(qla3xxx|qlcnic|qlge) was added by commits
40839129f7, c4e84bde1d, 5a4faa8737
- networking/Makefile was added by commit 3794f3e812 ("docsrc: build
Documentation/ sources")
- networking/i40evf.txt was added by commit 105bf2fe6b ("i40evf: add
driver to kernel build system")
- networking/ipsec.txt was added by commit b3c6efbc36 ("xfrm: Add
file to document IPsec corner case")
- networking/mac80211-auth-assoc-deauth.txt was added by commit
3cd7920a2b ("mac80211: add auth/assoc/deauth flow diagram")
- networking/netlink_mmap.txt was added by commit 5683264c39
("netlink: add documentation for memory mapped I/O")
- networking/nf_conntrack-sysctl.txt was added by commit c9f9e0e159
("netfilter: doc: add nf_conntrack sysctl api documentation") lan)
- networking/team.txt was added by commit 3d249d4ca7 ("net: introduce
ethernet teaming device")
- networking/vxlan.txt was added by commit d342894c5d ("vxlan:
virtual extensible lan")
- power/runtime_pm.txt was added by commit 5e928f77a0 ("PM: Introduce
core framework for run-time PM of I/O devices (rev. 17)")
- power/charger-manager.txt was added by commit 3bb3dbbd56
("power_supply: Add initial Charger-Manager driver")
- RCU/lockdep-splat.txt was added by commit d7bd2d68aa ("rcu:
Document interpretation of RCU-lockdep splats")
- s390/kvm.txt was added by 5ecee4b (KVM: s390: API documentation)
- s390/qeth.txt was added by commit b4d72c08b3 ("qeth: bridgeport
support - basic control")
- scheduler/sched-bwc.txt was added by commit 88ebc08ea9 ("sched: Add
documentation for bandwidth control")
- scsi/advansys.txt was added by commit 4bd6d7f356 ("[SCSI] advansys:
Move documentation to Documentation/scsi")
- scsi/bfa.txt was added by commit 1ec90174bd ("[SCSI] bfa: add
readme file")
- scsi/bnx2fc.txt was added by commit 12b8fc10ea ("[SCSI] bnx2fc: Add
driver documentation")
- scsi/cxgb3i.txt was added by commit c3673464eb ("[SCSI] cxgb3i: Add
cxgb3i iSCSI driver.")
- scsi/hpsa.txt was added by commit 992ebcf14f ("[SCSI] hpsa: Add
hpsa.txt to Documentation/scsi")
- scsi/link_power_management_policy.txt was added by commit
ca77329fb7 ("[libata] Link power management infrastructure")
- scsi/osd.txt was added by commit 78e0c621de ("[SCSI] osd:
Documentation for OSD library")
- scsi/scsi-parameter.txt was created/moved by commit 163475fb11
("Documentation: move SCSI parameters to their own text file")
- serial/driver was part of the initial repo
- serial/n_gsm.txt was added by commit 323e84122e ("n_gsm: add a
documentation")
- timers/Makefile was added by commit 3794f3e812 ("docsrc: build
Documentation/ sources")
- virt/kvm/s390.txt was added by commit d9101fca3d ("KVM: s390:
diagnose call documentation")
- vm/split_page_table_lock was added by commit 49076ec2cc ("mm:
dynamically allocate page->ptl if it cannot be embedded to struct
page")
- w1/slaves/w1_ds28e04 was added by commit fbf7f7b4e2 ("w1: Add
1-wire slave device driver for DS28E04-100")
- w1/masters/omap-hdq was added by commit e0a29382c6 ("hdq:
documentation for OMAP HDQ")
- x86/early-microcode.txt was added by commit 0d91ea86a8 ("x86, doc:
Documentation for early microcode loading")
- x86/earlyprintk.txt was added by commit a1aade4788 ("x86/doc:
mini-howto for using earlyprintk=dbgp")
- x86/entry_64.txt was added by commit 8b4777a4b5 ("x86-64: Document
some of entry_64.S")
- x86/pat.txt was added by commit d27554d874 ("x86: PAT
documentation")
Moved files
- arm/kernel_user_helpers.txt was moved out of arch/arm/kernel by
commit 37b8304642 ("ARM: kuser: move interface documentation out of
the source code")
- efi-stub.txt was moved out of x86/ and down into Documentation/ in
commit 4172fe2f8a ("EFI stub documentation updates")
- laptops/hpfall.c was moved out of hwmon/ and into laptops/ in commit
efcfed9bad ("Move hp_accel to drivers/platform/x86")
- commit 5616c23ad9 ("x86: doc: move x86-generic documentation from
Doc/x86/i386"):
* x86/usb-legacy-support.txt
* x86/boot.txt
* x86/zero_page.txt
- power/video_extension.txt was moved to acpi in commit 70e66e4df1
("ACPI / video: move video_extension.txt to Documentation/acpi")
Removed files (left in 00-INDEX)
- memory.txt was removed by commit 00ea8990aa ("memory.txt: remove
stray information")
- gpio.txt was moved to gpio/ in commit fd8e198cfc ("Documentation:
gpiolib: document new interface")
- networking/DLINK.txt was removed by commit 168e06ae26
("drivers/net: delete old parallel port de600/de620 drivers")
- serial/hayes-esp.txt was removed by commit f53a2ade0b ("tty: esp:
remove broken driver")
- s390/TAPE was removed by commit 9e280f6693 ("[S390] remove tape
block docu")
- vm/locking was removed by commit 57ea8171d2 ("mm: documentation:
remove hopelessly out-of-date locking doc")
- laptops/acer-wmi.txt was remvoed by commit 020036678e ("acer-wmi:
Delete out-of-date documentation")
Typos/misc issues
- rpc-server-gss.txt was added as knfsd-rpcgss.txt in commit
030d794bf4 ("SUNRPC: Use gssproxy upcall for server RPCGSS
authentication.")
- commit b88cf73d92 ("net: add missing entries to
Documentation/networking/00-INDEX")
* generic-hdlc.txt was added as generic_hdlc.txt
* spider_net.txt was added as spider-net.txt
- w1/master/mxc-w1 was added as mxc_w1 by commit a5fd9139f7 ("w1: add
1-wire master driver for i.MX27 / i.MX31")
- s390/zfcpdump.txt was added as zfcpdump by commit 6920c12a40
("[S390] Add Documentation/s390/00-INDEX.")
Signed-off-by: Henrik Austad <henrik@austad.us>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [rcu bits]
Acked-by: Rob Landley <rob@landley.net>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Mark Brown <broonie@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Len Brown <len.brown@intel.com>
Cc: James Bottomley <JBottomley@parallels.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Documentation/vm/locking is a blast from the past. In the entire git
history, it has had precisely Three modifications. Two of those look to
be pure renames, and the third was from 2005.
The doc contains such gems as:
> The page_table_lock is grabbed while holding the
> kernel_lock spinning monitor.
> Page stealers hold kernel_lock to protect against a bunch of
> races.
Or this which talks about mmap_sem:
> 4. The exception to this rule is expand_stack, which just
> takes the read lock and the page_table_lock, this is ok
> because it doesn't really modify fields anybody relies on.
expand_stack() doesn't take any locks any more directly, and the
mmap_sem acquisition was long ago moved up in to the page fault code
itself.
It could be argued that we need to rewrite this, but it is dangerous to
leave it as-is. It will confuse more people than it helps.
Signed-off-by: Dave Hansen <dave.hansen@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some applications that run on HPC clusters are designed around the
availability of RAM and the overcommit ratio is fine tuned to get the
maximum usage of memory without swapping. With growing memory, the
1%-of-all-RAM grain provided by overcommit_ratio has become too coarse
for these workload (on a 2TB machine it represents no less than 20GB).
This patch adds the new overcommit_kbytes sysctl variable that allow a
much finer grain.
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix nommu build]
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are two code paths how page with pmd page table can be freed:
pmd_free() and pmd_free_tlb().
I've missed the second one and didn't add page table destructor call
there. It leads to leak of page->ptl for pmd page tables, if
dynamically allocated page->ptl is in use.
The patch adds the missed destructor and modifies documentation
accordingly.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Andrey Vagin <avagin@openvz.org>
Tested-by: Andrey Vagin <avagin@openvz.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull trivial tree updates from Jiri Kosina:
"Usual earth-shaking, news-breaking, rocket science pile from
trivial.git"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (23 commits)
doc: usb: Fix typo in Documentation/usb/gadget_configs.txt
doc: add missing files to timers/00-INDEX
timekeeping: Fix some trivial typos in comments
mm: Fix some trivial typos in comments
irq: Fix some trivial typos in comments
NUMA: fix typos in Kconfig help text
mm: update 00-INDEX
doc: Documentation/DMA-attributes.txt fix typo
DRM: comment: `halve' -> `half'
Docs: Kconfig: `devlopers' -> `developers'
doc: typo on word accounting in kprobes.c in mutliple architectures
treewide: fix "usefull" typo
treewide: fix "distingush" typo
mm/Kconfig: Grammar s/an/a/
kexec: Typo s/the/then/
Documentation/kvm: Update cpuid documentation for steal time and pv eoi
treewide: Fix common typo in "identify"
__page_to_pfn: Fix typo in comment
Correct some typos for word frequency
clk: fixed-factor: Fix a trivial typo
...
If split page table lock is in use, we embed the lock into struct page
of table's page. We have to disable split lock, if spinlock_t is too
big be to be embedded, like when DEBUG_SPINLOCK or DEBUG_LOCK_ALLOC
enabled.
This patch add support for dynamic allocation of split page table lock
if we can't embed it to struct page.
page->ptl is unsigned long now and we use it as spinlock_t if
sizeof(spinlock_t) <= sizeof(long), otherwise it's pointer to spinlock_t.
The spinlock_t allocated in pgtable_page_ctor() for PTE table and in
pgtable_pmd_page_ctor() for PMD table. All other helpers converted to
support dynamically allocated page->ptl.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The following files moved files out of Documentation/vm/
c6dd897f ("mm: move page-types.c from Documentation to tools/vm")
f0f57b2b ("move hugepage test examples to tools/testing/selftests/vm)
Remove these files from vm/00-INDEX.
The following commits added new files do Documentation/vm/
4fe4746a ("mm/fs: cleancache documentation") added vm/cleancache.txt
d65bfacb ("mm: highmem documentation") added vm/highmem.txt
1c9bf22c ("thp: transparent hugepage support documentation") added
vm/transhuge.txt
0f8975ec ("mm: soft-dirty bits for user memory changes tracking")
61b0d760 ("zswap: add documentation")
27c6aec2 ("mm: frontswap: config and doc files")
Add the missing documentation-files with a short description to 00-INDEX
Signed-off-by: Henrik Austad <henrik@austad.us>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Pavel reported that in case if vma area get unmapped and then mapped (or
expanded) in-place, the soft dirty tracker won't be able to recognize this
situation since it works on pte level and ptes are get zapped on unmap,
loosing soft dirty bit of course.
So to resolve this situation we need to track actions on vma level, there
VM_SOFTDIRTY flag comes in. When new vma area created (or old expanded)
we set this bit, and keep it here until application calls for clearing
soft dirty bit.
Thus when user space application track memory changes now it can detect if
vma area is renewed.
Reported-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Rob Landley <rob@landley.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Explicitly mention/recommend using the libhugetlbfs test cases when
changing related kernel code. Developers that are unaware of the project
can easily miss this and introduce potential regressions that may or may
not be caught by community review.
Also do some cleanups that make the document visually easier to view at a
first glance.
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Transparent huge zero page is used during the page fault instead of in
khugepaged.
# ls /sys/kernel/mm/transparent_hugepage/
defrag enabled khugepaged use_zero_page
# ls /sys/kernel/mm/transparent_hugepage/khugepaged/
alloc_sleep_millisecs defrag full_scans max_ptes_none pages_collapsed pages_to_scan scan_sleep_millisecs
This patch corrects the documentation just like the codes done.
Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Acked-by: 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>
Pull trivial tree updates from Jiri Kosina:
"The usual stuff from trivial tree"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (34 commits)
treewide: relase -> release
Documentation/cgroups/memory.txt: fix stat file documentation
sysctl/net.txt: delete reference to obsolete 2.4.x kernel
spinlock_api_smp.h: fix preprocessor comments
treewide: Fix typo in printk
doc: device tree: clarify stuff in usage-model.txt.
open firmware: "/aliasas" -> "/aliases"
md: bcache: Fixed a typo with the word 'arithmetic'
irq/generic-chip: fix a few kernel-doc entries
frv: Convert use of typedef ctl_table to struct ctl_table
sgi: xpc: Convert use of typedef ctl_table to struct ctl_table
doc: clk: Fix incorrect wording
Documentation/arm/IXP4xx fix a typo
Documentation/networking/ieee802154 fix a typo
Documentation/DocBook/media/v4l fix a typo
Documentation/video4linux/si476x.txt fix a typo
Documentation/virtual/kvm/api.txt fix a typo
Documentation/early-userspace/README fix a typo
Documentation/video4linux/soc-camera.txt fix a typo
lguest: fix CONFIG_PAE -> CONFIG_x86_PAE in comment
...
In order to reuse bits from pagemap entries gracefully, we leave the
entries as is but on pagemap open emit a warning in dmesg, that bits
55-60 are about to change in a couple of releases. Next, if a user
issues soft-dirty clear command via the clear_refs file (it was disabled
before v3.9) we assume that he's aware of the new pagemap format, note
that fact and report the bits in pagemap in the new manner.
The "migration strategy" looks like this then:
1. existing users are not affected -- they don't touch soft-dirty feature, thus
see old bits in pagemap, but are warned and have time to fix themselves
2. those who use soft-dirty know about new pagemap format
3. some time soon we get rid of any signs of page-shift in pagemap as well as
this trick with clear-soft-dirty affecting pagemap format.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.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>
The soft-dirty is a bit on a PTE which helps to track which pages a task
writes to. In order to do this tracking one should
1. Clear soft-dirty bits from PTEs ("echo 4 > /proc/PID/clear_refs)
2. Wait some time.
3. Read soft-dirty bits (55'th in /proc/PID/pagemap2 entries)
To do this tracking, the writable bit is cleared from PTEs when the
soft-dirty bit is. Thus, after this, when the task tries to modify a
page at some virtual address the #PF occurs and the kernel sets the
soft-dirty bit on the respective PTE.
Note, that although all the task's address space is marked as r/o after
the soft-dirty bits clear, the #PF-s that occur after that are processed
fast. This is so, since the pages are still mapped to physical memory,
and thus all the kernel does is finds this fact out and puts back
writable, dirty and soft-dirty bits on the PTE.
Another thing to note, is that when mremap moves PTEs they are marked
with soft-dirty as well, since from the user perspective mremap modifies
the virtual memory at mremap's new address.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.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>
Add user_reserve_kbytes knob.
Limit the growth of the memory reserved for other user processes to
min(3% current process size, user_reserve_pages). Only about 8MB is
necessary to enable recovery in the default mode, and only a few hundred
MB are required even when overcommit is disabled.
user_reserve_pages defaults to min(3% free pages, 128MB)
I arrived at 128MB by taking the max VSZ of sshd, login, bash, and top ...
then adding the RSS of each.
This only affects OVERCOMMIT_NEVER mode.
Background
1. user reserve
__vm_enough_memory reserves a hardcoded 3% of the current process size for
other applications when overcommit is disabled. This was done so that a
user could recover if they launched a memory hogging process. Without the
reserve, a user would easily run into a message such as:
bash: fork: Cannot allocate memory
2. admin reserve
Additionally, a hardcoded 3% of free memory is reserved for root in both
overcommit 'guess' and 'never' modes. This was intended to prevent a
scenario where root-cant-log-in and perform recovery operations.
Note that this reserve shrinks, and doesn't guarantee a useful reserve.
Motivation
The two hardcoded memory reserves should be updated to account for current
memory sizes.
Also, the admin reserve would be more useful if it didn't shrink too much.
When the current code was originally written, 1GB was considered
"enterprise". Now the 3% reserve can grow to multiple GB on large memory
systems, and it only needs to be a few hundred MB at most to enable a user
or admin to recover a system with an unwanted memory hogging process.
I've found that reducing these reserves is especially beneficial for a
specific type of application load:
* single application system
* one or few processes (e.g. one per core)
* allocating all available memory
* not initializing every page immediately
* long running
I've run scientific clusters with this sort of load. A long running job
sometimes failed many hours (weeks of CPU time) into a calculation. They
weren't initializing all of their memory immediately, and they weren't
using calloc, so I put systems into overcommit 'never' mode. These
clusters run diskless and have no swap.
However, with the current reserves, a user wishing to allocate as much
memory as possible to one process may be prevented from using, for
example, almost 2GB out of 32GB.
The effect is less, but still significant when a user starts a job with
one process per core. I have repeatedly seen a set of processes
requesting the same amount of memory fail because one of them could not
allocate the amount of memory a user would expect to be able to allocate.
For example, Message Passing Interfce (MPI) processes, one per core. And
it is similar for other parallel programming frameworks.
Changing this reserve code will make the overcommit never mode more useful
by allowing applications to allocate nearly all of the available memory.
Also, the new admin_reserve_kbytes will be safer than the current behavior
since the hardcoded 3% of available memory reserve can shrink to something
useless in the case where applications have grabbed all available memory.
Risks
* "bash: fork: Cannot allocate memory"
The downside of the first patch-- which creates a tunable user reserve
that is only used in overcommit 'never' mode--is that an admin can set
it so low that a user may not be able to kill their process, even if
they already have a shell prompt.
Of course, a user can get in the same predicament with the current 3%
reserve--they just have to launch processes until 3% becomes negligible.
* root-cant-log-in problem
The second patch, adding the tunable rootuser_reserve_pages, allows
the admin to shoot themselves in the foot by setting it too small. They
can easily get the system into a state where root-can't-log-in.
However, the new admin_reserve_kbytes will be safer than the current
behavior since the hardcoded 3% of available memory reserve can shrink
to something useless in the case where applications have grabbed all
available memory.
Alternatives
* Memory cgroups provide a more flexible way to limit application memory.
Not everyone wants to set up cgroups or deal with their overhead.
* We could create a fourth overcommit mode which provides smaller reserves.
The size of useful reserves may be drastically different depending
on the whether the system is embedded or enterprise.
* Force users to initialize all of their memory or use calloc.
Some users don't want/expect the system to overcommit when they malloc.
Overcommit 'never' mode is for this scenario, and it should work well.
The new user and admin reserve tunables are simple to use, with low
overhead compared to cgroups. The patches preserve current behavior where
3% of memory is less than 128MB, except that the admin reserve doesn't
shrink to an unusable size under pressure. The code allows admins to tune
for embedded and enterprise usage.
FAQ
* How is the root-cant-login problem addressed?
What happens if admin_reserve_pages is set to 0?
Root is free to shoot themselves in the foot by setting
admin_reserve_kbytes too low.
On x86_64, the minimum useful reserve is:
8MB for overcommit 'guess'
128MB for overcommit 'never'
admin_reserve_pages defaults to min(3% free memory, 8MB)
So, anyone switching to 'never' mode needs to adjust
admin_reserve_pages.
* How do you calculate a minimum useful reserve?
A user or the admin needs enough memory to login and perform
recovery operations, which includes, at a minimum:
sshd or login + bash (or some other shell) + top (or ps, kill, etc.)
For overcommit 'guess', we can sum resident set sizes (RSS)
because we only need enough memory to handle what the recovery
programs will typically use. On x86_64 this is about 8MB.
For overcommit 'never', we can take the max of their virtual sizes (VSZ)
and add the sum of their RSS. We use VSZ instead of RSS because mode
forces us to ensure we can fulfill all of the requested memory allocations--
even if the programs only use a fraction of what they ask for.
On x86_64 this is about 128MB.
When swap is enabled, reserves are useful even when they are as
small as 10MB, regardless of overcommit mode.
When both swap and overcommit are disabled, then the admin should
tune the reserves higher to be absolutley safe. Over 230MB each
was safest in my testing.
* What happens if user_reserve_pages is set to 0?
Note, this only affects overcomitt 'never' mode.
Then a user will be able to allocate all available memory minus
admin_reserve_kbytes.
However, they will easily see a message such as:
"bash: fork: Cannot allocate memory"
And they won't be able to recover/kill their application.
The admin should be able to recover the system if
admin_reserve_kbytes is set appropriately.
* What's the difference between overcommit 'guess' and 'never'?
"Guess" allows an allocation if there are enough free + reclaimable
pages. It has a hardcoded 3% of free pages reserved for root.
"Never" allows an allocation if there is enough swap + a configurable
percentage (default is 50) of physical RAM. It has a hardcoded 3% of
free pages reserved for root, like "Guess" mode. It also has a
hardcoded 3% of the current process size reserved for additional
applications.
* Why is overcommit 'guess' not suitable even when an app eventually
writes to every page? It takes free pages, file pages, available
swap pages, reclaimable slab pages into consideration. In other words,
these are all pages available, then why isn't overcommit suitable?
Because it only looks at the present state of the system. It
does not take into account the memory that other applications have
malloced, but haven't initialized yet. It overcommits the system.
Test Summary
There was little change in behavior in the default overcommit 'guess'
mode with swap enabled before and after the patch. This was expected.
Systems run most predictably (i.e. no oom kills) in overcommit 'never'
mode with swap enabled. This also allowed the most memory to be allocated
to a user application.
Overcommit 'guess' mode without swap is a bad idea. It is easy to
crash the system. None of the other tested combinations crashed.
This matches my experience on the Roadrunner supercomputer.
Without the tunable user reserve, a system in overcommit 'never' mode
and without swap does not allow the admin to recover, although the
admin can.
With the new tunable reserves, a system in overcommit 'never' mode
and without swap can be configured to:
1. maximize user-allocatable memory, running close to the edge of
recoverability
2. maximize recoverability, sacrificing allocatable memory to
ensure that a user cannot take down a system
Test Description
Fedora 18 VM - 4 x86_64 cores, 5725MB RAM, 4GB Swap
System is booted into multiuser console mode, with unnecessary services
turned off. Caches were dropped before each test.
Hogs are user memtester processes that attempt to allocate all free memory
as reported by /proc/meminfo
In overcommit 'never' mode, memory_ratio=100
Test Results
3.9.0-rc1-mm1
Overcommit | Swap | Hogs | MB Got/Wanted | OOMs | User Recovery | Admin Recovery
---------- ---- ---- ------------- ---- ------------- --------------
guess yes 1 5432/5432 no yes yes
guess yes 4 5444/5444 1 yes yes
guess no 1 5302/5449 no yes yes
guess no 4 - crash no no
never yes 1 5460/5460 1 yes yes
never yes 4 5460/5460 1 yes yes
never no 1 5218/5432 no no yes
never no 4 5203/5448 no no yes
3.9.0-rc1-mm1-tunablereserves
User and Admin Recovery show their respective reserves, if applicable.
Overcommit | Swap | Hogs | MB Got/Wanted | OOMs | User Recovery | Admin Recovery
---------- ---- ---- ------------- ---- ------------- --------------
guess yes 1 5419/5419 no - yes 8MB yes
guess yes 4 5436/5436 1 - yes 8MB yes
guess no 1 5440/5440 * - yes 8MB yes
guess no 4 - crash - no 8MB no
* process would successfully mlock, then the oom killer would pick it
never yes 1 5446/5446 no 10MB yes 20MB yes
never yes 4 5456/5456 no 10MB yes 20MB yes
never no 1 5387/5429 no 128MB no 8MB barely
never no 1 5323/5428 no 226MB barely 8MB barely
never no 1 5323/5428 no 226MB barely 8MB barely
never no 1 5359/5448 no 10MB no 10MB barely
never no 1 5323/5428 no 0MB no 10MB barely
never no 1 5332/5428 no 0MB no 50MB yes
never no 1 5293/5429 no 0MB no 90MB yes
never no 1 5001/5427 no 230MB yes 338MB yes
never no 4* 4998/5424 no 230MB yes 338MB yes
* more memtesters were launched, able to allocate approximately another 100MB
Future Work
- Test larger memory systems.
- Test an embedded image.
- Test other architectures.
- Time malloc microbenchmarks.
- Would it be useful to be able to set overcommit policy for
each memory cgroup?
- Some lines are slightly above 80 chars.
Perhaps define a macro to convert between pages and kb?
Other places in the kernel do this.
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: make init_user_reserve() static]
Signed-off-by: Andrew Shewmaker <agshew@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Added slightly more detail to the Documentation of merge_across_nodes, a
few comments in areas indicated by review, and renamed get_ksm_page()'s
argument from "locked" to "lock_it". No functional change.
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Petr Holasek <pholasek@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Izik Eidus <izik.eidus@ravellosystems.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Here's a KSM series, based on mmotm 2013-01-23-17-04: starting with
Petr's v7 "KSM: numa awareness sysfs knob"; then fixing the two issues
we had with that, fully enabling KSM page migration on the way.
(A different kind of KSM/NUMA issue which I've certainly not begun to
address here: when KSM pages are unmerged, there's usually no sense in
preferring to allocate the new pages local to the caller's node.)
This patch:
Introduces new sysfs boolean knob /sys/kernel/mm/ksm/merge_across_nodes
which control merging pages across different numa nodes. When it is set
to zero only pages from the same node are merged, otherwise pages from
all nodes can be merged together (default behavior).
Typical use-case could be a lot of KVM guests on NUMA machine and cpus
from more distant nodes would have significant increase of access
latency to the merged ksm page. Sysfs knob was choosen for higher
variability when some users still prefers higher amount of saved
physical memory regardless of access latency.
Every numa node has its own stable & unstable trees because of faster
searching and inserting. Changing of merge_across_nodes value is
possible only when there are not any ksm shared pages in system.
I've tested this patch on numa machines with 2, 4 and 8 nodes and
measured speed of memory access inside of KVM guests with memory pinned
to one of nodes with this benchmark:
http://pholasek.fedorapeople.org/alloc_pg.c
Population standard deviations of access times in percentage of average
were following:
merge_across_nodes=1
2 nodes 1.4%
4 nodes 1.6%
8 nodes 1.7%
merge_across_nodes=0
2 nodes 1%
4 nodes 0.32%
8 nodes 0.018%
RFC: https://lkml.org/lkml/2011/11/30/91
v1: https://lkml.org/lkml/2012/1/23/46
v2: https://lkml.org/lkml/2012/6/29/105
v3: https://lkml.org/lkml/2012/9/14/550
v4: https://lkml.org/lkml/2012/9/23/137
v5: https://lkml.org/lkml/2012/12/10/540
v6: https://lkml.org/lkml/2012/12/23/154
v7: https://lkml.org/lkml/2012/12/27/225
Hugh notes that this patch brings two problems, whose solution needs
further support in mm/ksm.c, which follows in subsequent patches:
1) switching merge_across_nodes after running KSM is liable to oops
on stale nodes still left over from the previous stable tree;
2) memory hotremove may migrate KSM pages, but there is no provision
here for !merge_across_nodes to migrate nodes to the proper tree.
Signed-off-by: Petr Holasek <pholasek@redhat.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Izik Eidus <izik.eidus@ravellosystems.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge misc VM changes from Andrew Morton:
"The rest of most-of-MM. The other MM bits await a slab merge.
This patch includes the addition of a huge zero_page. Not a
performance boost but it an save large amounts of physical memory in
some situations.
Also a bunch of Fujitsu engineers are working on memory hotplug.
Which, as it turns out, was badly broken. About half of their patches
are included here; the remainder are 3.8 material."
However, this merge disables CONFIG_MOVABLE_NODE, which was totally
broken. We don't add new features with "default y", nor do we add
Kconfig questions that are incomprehensible to most people without any
help text. Does the feature even make sense without compaction or
memory hotplug?
* akpm: (54 commits)
mm/bootmem.c: remove unused wrapper function reserve_bootmem_generic()
mm/memory.c: remove unused code from do_wp_page()
asm-generic, mm: pgtable: consolidate zero page helpers
mm/hugetlb.c: fix warning on freeing hwpoisoned hugepage
hwpoison, hugetlbfs: fix RSS-counter warning
hwpoison, hugetlbfs: fix "bad pmd" warning in unmapping hwpoisoned hugepage
mm: protect against concurrent vma expansion
memcg: do not check for mm in __mem_cgroup_count_vm_event
tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)
mm: provide more accurate estimation of pages occupied by memmap
fs/buffer.c: remove redundant initialization in alloc_page_buffers()
fs/buffer.c: do not inline exported function
writeback: fix a typo in comment
mm: introduce new field "managed_pages" to struct zone
mm, oom: remove statically defined arch functions of same name
mm, oom: remove redundant sleep in pagefault oom handler
mm, oom: cleanup pagefault oom handler
memory_hotplug: allow online/offline memory to result movable node
numa: add CONFIG_MOVABLE_NODE for movable-dedicated node
mm, memcg: avoid unnecessary function call when memcg is disabled
...
By default kernel tries to use huge zero page on read page fault. It's
possible to disable huge zero page by writing 0 or enable it back by
writing 1:
echo 0 >/sys/kernel/mm/transparent_hugepage/khugepaged/use_zero_page
echo 1 >/sys/kernel/mm/transparent_hugepage/khugepaged/use_zero_page
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hzp_alloc is incremented every time a huge zero page is successfully
allocated. It includes allocations which where dropped due
race with other allocation. Note, it doesn't count every map
of the huge zero page, only its allocation.
hzp_alloc_failed is incremented if kernel fails to allocate huge zero
page and falls back to using small pages.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pass vma instead of mm and add address parameter.
In most cases we already have vma on the stack. We provides
split_huge_page_pmd_mm() for few cases when we have mm, but not vma.
This change is preparation to huge zero pmd splitting implementation.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
page_evictable(page, vma) is an irritant: almost all its callers pass
NULL for vma. Remove the vma arg and use mlocked_vma_newpage(vma, page)
explicitly in the couple of places it's needed. But in those places we
don't even need page_evictable() itself! They're dealing with a freshly
allocated anonymous page, which has no "mapping" and cannot be mlocked yet.
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michel Lespinasse <walken@google.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A long time ago, in v2.4, VM_RESERVED kept swapout process off VMA,
currently it lost original meaning but still has some effects:
| effect | alternative flags
-+------------------------+---------------------------------------------
1| account as reserved_vm | VM_IO
2| skip in core dump | VM_IO, VM_DONTDUMP
3| do not merge or expand | VM_IO, VM_DONTEXPAND, VM_HUGETLB, VM_PFNMAP
4| do not mlock | VM_IO, VM_DONTEXPAND, VM_HUGETLB, VM_PFNMAP
This patch removes reserved_vm counter from mm_struct. Seems like nobody
cares about it, it does not exported into userspace directly, it only
reduces total_vm showed in proc.
Thus VM_RESERVED can be replaced with VM_IO or pair VM_DONTEXPAND | VM_DONTDUMP.
remap_pfn_range() and io_remap_pfn_range() set VM_IO|VM_DONTEXPAND|VM_DONTDUMP.
remap_vmalloc_range() set VM_DONTEXPAND | VM_DONTDUMP.
[akpm@linux-foundation.org: drivers/vfio/pci/vfio_pci.c fixup]
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Carsten Otte <cotte@de.ibm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Kentaro Takeda <takedakn@nttdata.co.jp>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Venkatesh Pallipadi <venki@google.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit f0f57b2b14 ("mm: move hugepage test examples to
tools/testing/selftests/vm") moved map_hugetlb.c, hugepage-shm.c and
hugepage-mmap.c tests into tools/testing/selftests/vm/ directory, but it
didn't update hugetlbpage.txt
Signed-off-by: Zhouping Liu <sanweidaying@gmail.com>
Acked-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In some environments, dramatic performance savings may be obtained because
swapped pages are saved in RAM (or a RAM-like device) instead of a swap disk.
This tag provides the basic infrastructure along with some changes to the
existing backends.
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Merge tag 'stable/frontswap.v16-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/mm
Pull frontswap feature from Konrad Rzeszutek Wilk:
"Frontswap provides a "transcendent memory" interface for swap pages.
In some environments, dramatic performance savings may be obtained
because swapped pages are saved in RAM (or a RAM-like device) instead
of a swap disk. This tag provides the basic infrastructure along with
some changes to the existing backends."
Fix up trivial conflict in mm/Makefile due to removal of swap token code
changing a line next to the new frontswap entry.
This pull request came in before the merge window even opened, it got
delayed to after the merge window by me just wanting to make sure it had
actual users. Apparently IBM is using this on their embedded side, and
Jan Beulich says that it's already made available for SLES and OpenSUSE
users.
Also acked by Rik van Riel, and Konrad points to other people liking it
too. So in it goes.
By Dan Magenheimer (4) and Konrad Rzeszutek Wilk (2)
via Konrad Rzeszutek Wilk
* tag 'stable/frontswap.v16-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/mm:
frontswap: s/put_page/store/g s/get_page/load
MAINTAINER: Add myself for the frontswap API
mm: frontswap: config and doc files
mm: frontswap: core frontswap functionality
mm: frontswap: core swap subsystem hooks and headers
mm: frontswap: add frontswap header file
Pull slab updates from Pekka Enberg:
"Mainly a bunch of SLUB fixes from Joonsoo Kim"
* 'slab/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux:
slub: use __SetPageSlab function to set PG_slab flag
slub: fix a memory leak in get_partial_node()
slub: remove unused argument of init_kmem_cache_node()
slub: fix a possible memory leak
Documentations: Fix slabinfo.c directory in vm/slub.txt
slub: fix incorrect return type of get_any_partial()
This is an implementation of Andrew's proposal to extend the pagemap file
bits to report what is missing about tasks' working set.
The problem with the working set detection is multilateral. In the criu
(checkpoint/restore) project we dump the tasks' memory into image files
and to do it properly we need to detect which pages inside mappings are
really in use. The mincore syscall I though could help with this did not.
First, it doesn't report swapped pages, thus we cannot find out which
parts of anonymous mappings to dump. Next, it does report pages from page
cache as present even if they are not mapped, and it doesn't make that has
not been cow-ed.
Note, that issue with swap pages is critical -- we must dump swap pages to
image file. But the issues with file pages are optimization -- we can
take all file pages to image, this would be correct, but if we know that a
page is not mapped or not cow-ed, we can remove them from dump file. The
dump would still be self-consistent, though significantly smaller in size
(up to 10 times smaller on real apps).
Andrew noticed, that the proc pagemap file solved 2 of 3 above issues --
it reports whether a page is present or swapped and it doesn't report not
mapped page cache pages. But, it doesn't distinguish cow-ed file pages
from not cow-ed.
I would like to make the last unused bit in this file to report whether the
page mapped into respective pte is PageAnon or not.
[comment stolen from Pavel Emelyanov's v1 patch]
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: 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>
Update Documentation/vm/transhuge.txt and
Documentation/filesystems/proc.txt with some information on monitoring
transparent huge page usage and the associated overhead.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch 4of4 adds configuration and documentation files including a FAQ.
[v14: updated docs/FAQ to use zcache and RAMster as examples]
[v10: no change]
[v9: akpm@linux-foundation.org: sysfs->debugfs; no longer need Doc/ABI file]
[v8: rebase to 3.0-rc4]
[v7: rebase to 3.0-rc3]
[v6: rebase to 3.0-rc1]
[v5: change config default to n]
[v4: rebase to 2.6.39]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Acked-by: Jan Beulich <JBeulich@novell.com>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Because the place of slabinfo.c changed.So update in slub.txt.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
hugepage-mmap.c, hugepage-shm.c and map_hugetlb.c in Documentation/vm are
simple pass/fail tests, It's better to promote them to
tools/testing/selftests.
Thanks suggestion of Andrew Morton about this. They all need firstly
setting up proper nr_hugepages and hugepage-mmap need to mount hugetlbfs.
So I add a shell script run_vmtests to do such work which will call the
three test programs and check the return value of them.
Changes to original code including below:
a. add run_vmtests script
b. return error when read_bytes mismatch with writed bytes.
c. coding style fixes: do not use assignment in if condition
[akpm@linux-foundation.org: build the targets before trying to execute them]
[akpm@linux-foundation.org: Documentation/vm/ no longer has a Makefile. Fixes "make clean"]
Signed-off-by: Dave Young <dyoung@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
tools/ is the better place for vm tools which are used by many people.
Moving them to tools also make them open to more users instead of hide in
Documentation folder.
This patch moves page-types.c to tools/vm/page-types.c. Also add a
Makefile in tools/vm and fix two coding style problems: a) change const
arrary to 'const char * const', b) change a space to tab for indent.
Signed-off-by: Dave Young <dyoung@redhat.com>
Acked-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
into debugfs, and use __read_mostly as neccessary.
Also add a MAINTAINER file for cleancache API files.
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Merge tag 'stable/for-linus-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/mm
Pull cleancache changes from Konrad Rzeszutek Wilk:
"This has some patches for the cleancache API that should have been
submitted a _long_ time ago. They are basically cleanups:
- rename of flush to invalidate
- moving reporting of statistics into debugfs
- use __read_mostly as necessary.
Oh, and also the MAINTAINERS file change. The files (except the
MAINTAINERS file) have been in #linux-next for months now. The late
addition of MAINTAINERS file is a brain-fart on my side - didn't
realize I needed that just until I was typing this up - and I based
that patch on v3.3 - so the tree is on top of v3.3."
* tag 'stable/for-linus-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/mm:
MAINTAINERS: Adding cleancache API to the list.
mm: cleancache: Use __read_mostly as appropiate.
mm: cleancache: report statistics via debugfs instead of sysfs.
mm: zcache/tmem/cleancache: s/flush/invalidate/
mm: cleancache: s/flush/invalidate/
page-types, which is a common user of pagemap, gets aware of thp with this
patch. This helps system admins and kernel hackers know about how thp
works. Here is a sample output of page-types over a thp:
$ page-types -p <pid> --raw --list
voffset offset len flags
...
7f9d40200 3f8400 1 ___U_lA____Ma_bH______t____________
7f9d40201 3f8401 1ff ________________T_____t____________
flags page-count MB symbolic-flags long-symbolic-flags
0x0000000000410000 511 1 ________________T_____t____________ compound_tail,thp
0x000000000040d868 1 0 ___U_lA____Ma_bH______t____________ uptodate,lru,active,mmap,anonymous,swapbacked,compound_head,thp
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Wu Fengguang <fengguang.wu@intel.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Per akpm suggestions alter the use of the term flush to be
invalidate. The next patch will do this across all MM.
This change is completely cosmetic.
[v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 3]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Jan Beulich <JBeulich@novell.com>
Reviewed-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
[v10: Fixed fs: move code out of buffer.c conflict change]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
slub_max_order default is 3 (aka PAGE_ALLOC_COSTLY_ORDER), not 1
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (59 commits)
MAINTAINERS: linux-m32r is moderated for non-subscribers
linux@lists.openrisc.net is moderated for non-subscribers
Drop default from "DM365 codec select" choice
parisc: Kconfig: cleanup Kernel page size default
Kconfig: remove redundant CONFIG_ prefix on two symbols
cris: remove arch/cris/arch-v32/lib/nand_init.S
microblaze: add missing CONFIG_ prefixes
h8300: drop puzzling Kconfig dependencies
MAINTAINERS: microblaze-uclinux@itee.uq.edu.au is moderated for non-subscribers
tty: drop superfluous dependency in Kconfig
ARM: mxc: fix Kconfig typo 'i.MX51'
Fix file references in Kconfig files
aic7xxx: fix Kconfig references to READMEs
Fix file references in drivers/ide/
thinkpad_acpi: Fix printk typo 'bluestooth'
bcmring: drop commented out line in Kconfig
btmrvl_sdio: fix typo 'btmrvl_sdio_sd6888'
doc: raw1394: Trivial typo fix
CIFS: Don't free volume_info->UNC until we are entirely done with it.
treewide: Correct spelling of successfully in comments
...
There are numerous broken references to Documentation files (in other
Documentation files, in comments, etc.). These broken references are
caused by typo's in the references, and by renames or removals of the
Documentation files. Some broken references are simply odd.
Fix these broken references, sometimes by dropping the irrelevant text
they were part of.
Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Commit e27e6151b1 ("mm/thp: use conventional format for boolean
attributes") changed
/sys/kernel/mm/transparent_hugepage/khugepaged/defrag
to be tuned by using 1 (enabled) or 0 (disabled) instead of "yes" and
"no", respectively.
Update the documentation.
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
slabinfo.c has been moved from Documentaion/vm/ to
tools/slub/ by commit:0d24db337e6d81c0c620ab65cc6947bd6553f742
Update the slub.txt doc to reflect this change too.
Signed-off-by: Jason Liu <jason.hui@linaro.org>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
According to commit 676db4af04 ("cgroupfs: create /sys/fs/cgroup to
mount cgroupfs on") the canonical mountpoint for the cgroup filesystem
is /sys/fs/cgroup. Hence, this should be used in the documentation.
Signed-off-by: Jörg Sommer <joerg@alea.gnuu.de>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/djm/tmem:
xen: cleancache shim to Xen Transcendent Memory
ocfs2: add cleancache support
ext4: add cleancache support
btrfs: add cleancache support
ext3: add cleancache support
mm/fs: add hooks to support cleancache
mm: cleancache core ops functions and config
fs: add field to superblock to support cleancache
mm/fs: cleancache documentation
Fix up trivial conflict in fs/btrfs/extent_io.c due to includes
This patchset introduces cleancache, an optional new feature exposed
by the VFS layer that potentially dramatically increases page cache
effectiveness for many workloads in many environments at a negligible
cost. It does this by providing an interface to transcendent memory,
which is memory/storage that is not otherwise visible to and/or directly
addressable by the kernel.
Instead of being discarded, hooks in the reclaim code "put" clean
pages to cleancache. Filesystems that "opt-in" may "get" pages
from cleancache that were previously put, but pages in cleancache are
"ephemeral", meaning they may disappear at any time. And the size
of cleancache is entirely dynamic and unknowable to the kernel.
Filesystems currently supported by this patchset include ext3, ext4,
btrfs, and ocfs2. Other filesystems (especially those built entirely
on VFS) should be easy to add, but should first be thoroughly tested to
ensure coherency.
Details and a FAQ are provided in Documentation/vm/cleancache.txt
This first patch of eight in this cleancache series only adds two
new documentation files.
[v8: minor documentation changes by author]
[v3: akpm@linux-foundation.org: document sysfs API]
[v3: hch@infradead.org: move detailed description to Documentation/vm]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Jeremy Fitzhardinge <jeremy@goop.org>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Rik Van Riel <riel@redhat.com>
Cc: Jan Beulich <JBeulich@novell.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Andreas Dilger <adilger@sun.com>
Cc: Ted Ts'o <tytso@mit.edu>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Straightforward conversion of i_mmap_lock to a mutex.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Tony Luck <tony.luck@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
page-types.c doesn't supply a way to specify the debugfs path and the
original debugfs path is not usual on most machines. This patch supplies
a way to auto mount debugfs if needed.
This patch is heavily inspired by tools/perf/utils/debugfs.c
[akpm@linux-foundation.org: make functions static]
[akpm@linux-foundation.org: fix debugfs_mount() signature]
Signed-off-by: Chen Gong <gong.chen@linux.intel.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
commit 6837765963 ("mm: remove CONFIG_UNEVICTABLE_LRU config option")
has removed the configoption so we should sync up the doc as well.
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This patch fixes a build breakage introduced by commit
f5ac4916e9840292edd33c7a52b10364526547f3 ("slub: move slabinfo.c to
tools/slub/slabinfo.c") that was repoted by Stephen:
After merging the slab tree, today's linux-next build (x86_64 allmodconfig)
failed like this:
gcc: /scratch/sfr/next/Documentation/vm/slabinfo.c: No such file or directory
gcc: no input files
Caused by commit f5ac4916e9840292edd33c7a52b10364526547f3 ("slub: move
slabinfo.c to tools/slub/slabinfo.c"). Missing update to
Documentation/vm/Makefile?
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
We now have a tools directory for these things.
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Document outlining some of the highmem issues, started by me, edited by
David.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Miller <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The page-types utility still uses an out of date name for the
unpoison interface: debugfs:hwpoison/renew-pfn
This patch renames and fixes it.
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Kamezawa Hiroyuki requested documentation for the numa_mem_id() and slab
related changes. He suggested Documentation/vm/numa for this
documentation. Looking at this file, it seems to me to be hopelessly out
of date relative to current Linux NUMA support. At the risk of going down
a rathole, I have made an attempt to rewrite the doc at a slightly higher
level [I think] and provide pointers to other in-tree documents and
out-of-tree man pages that cover the details.
Let the games begin.
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
documentation: slightly more correct value for MAP_HUGETLB in map_hugetlb.c
still not correct for alpha, mips, parisc or xtensa but working out of
the box in the most common architectures without having to deal with
complicated macros or including architecture specific headers.
Signed-off-by: Carlo Marcelo Arenas Belon <carenas@sajinet.com.pe>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix obvious cases of "it's" being used when "its" was meant.
Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Documentation/vm/:
Expose example and tool source files in the Documentation/ directory in
their own files instead of being buried (almost hidden) in readme/txt files.
This should help to prevent bitrot.
This will make them more visible/usable to users who may need
to use them, to developers who may need to test with them, and
to anyone who would fix/update them if they were more visible.
Also, if any of these possibly should not be in the kernel tree at
all, it will be clearer that they are here and we can discuss if
they should be removed.
Also build the recently-added map_hugetlb.c.
Make several functions static to prevent linker warnings.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Eric B Munson <ebmunson@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch allow to inject faults only for specific slabs.
In order to preserve default behavior cache filter is off by
default (all caches are faulty).
One may define specific set of slabs like this:
# mark skbuff_head_cache as faulty
echo 1 > /sys/kernel/slab/skbuff_head_cache/failslab
# Turn on cache filter (off by default)
echo 1 > /sys/kernel/debug/failslab/cache-filter
# Turn on fault injection
echo 1 > /sys/kernel/debug/failslab/times
echo 1 > /sys/kernel/debug/failslab/probability
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
The hwpoison test suite need to inject hwpoison to a collection of
selected task pages, and must not touch pages not owned by them and
thus kill important system processes such as init. (But it's OK to
mis-hwpoison free/unowned pages as well as shared clean pages.
Mis-hwpoison of shared dirty pages will kill all tasks, so the test
suite will target all or non of such tasks in the first place.)
The memory cgroup serves this purpose well. We can put the target
processes under the control of a memory cgroup, and tell the hwpoison
injection code to only kill pages associated with some active memory
cgroup.
The prerequisite for doing hwpoison stress tests with mem_cgroup is,
the mem_cgroup code tracks task pages _accurately_ (unless page is
locked). Which we believe is/should be true.
The benefits are simplification of hwpoison injector code. Also the
mem_cgroup code will automatically be tested by hwpoison test cases.
The alternative interfaces pin-pfn/unpin-pfn can also delegate the
(process and page flags) filtering functions reliably to user space.
However prototype implementation shows that this scheme adds more
complexity than we wanted.
Example test case:
mkdir /cgroup/hwpoison
usemem -m 100 -s 1000 &
echo `jobs -p` > /cgroup/hwpoison/tasks
memcg_ino=$(ls -id /cgroup/hwpoison | cut -f1 -d' ')
echo $memcg_ino > /debug/hwpoison/corrupt-filter-memcg
page-types -p `pidof init` --hwpoison # shall do nothing
page-types -p `pidof usemem` --hwpoison # poison its pages
[AK: Fix documentation]
[Add fix for problem noticed by Li Zefan <lizf@cn.fujitsu.com>;
dentry in the css could be NULL]
CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Hugh Dickins <hugh.dickins@tiscali.co.uk>
CC: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
CC: Balbir Singh <balbir@linux.vnet.ibm.com>
CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Li Zefan <lizf@cn.fujitsu.com>
CC: Paul Menage <menage@google.com>
CC: Nick Piggin <npiggin@suse.de>
CC: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
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