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WSL2-Linux-Kernel
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WSL2-Linux-Kernel/mm
История
Linus Torvalds f81fdd0c4a mm: document warning in move_normal_pmd() and make it warn only once 
Naresh Kamboju reported that the LTP tests can cause warnings on i386
going back all the way to v5.0, and bisected it to commit 2c91bd4a4e
("mm: speed up mremap by 20x on large regions").

The warning in move_normal_pmd() is actually mostly correct, but we have
a very unusual special case at process creation time, when we may move
the stack down with an overlapping mode (kind of like a "memmove()"
except using the page tables).

And when you have just the right condition of "move a large initial
stack by the right alignment in the end, but with the early part of the
move being only page-aligned", we'll be in a situation where we're
trying to move a normal PMD entry on top of an already existing - but
now empty - PMD entry.

The warning is still worth having, in case it ever triggers other cases,
and perhaps as a reminder that we could do the stack move case more
efficiently (although it's clearly rare enough that it probably doesn't
matter).

But make it do WARN_ON_ONCE(), so that you can't flood the logs with it.

And add a *big* comment above it to explain and remind us what's going
on, because it took some figuring out to see how this could trigger.
Kudos to Joel Fernandes for debugging this.

Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Debugged-and-acked-by: Joel Fernandes <joel@joelfernandes.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2020-07-13 11:37:39 -07:00
..
kasan mm: remove __ARCH_HAS_5LEVEL_HACK and include/asm-generic/5level-fixup.h 2020-06-04 19:06:21 -07:00
Kconfig Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next 2020-06-07 17:25:29 -07:00
Kconfig.debug treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
Makefile The Kernel Concurrency Sanitizer (KCSAN) 2020-06-11 18:55:43 -07:00
backing-dev.c bdi: remove the name field in struct backing_dev_info 2020-05-09 16:15:13 -06:00
balloon_compaction.c
…
cleancache.c
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cma.c mm/cma.c: use exact_nid true to fix possible per-numa cma leak 2020-07-03 16:15:25 -07:00
cma.h
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cma_debug.c
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compaction.c mm, compaction: make capture control handling safe wrt interrupts 2020-06-26 00:27:36 -07:00
debug.c maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault 2020-06-17 10:57:41 -07:00
debug_page_ref.c
…
debug_vm_pgtable.c mm/debug_vm_pgtable: fix build failure with powerpc 8xx 2020-06-26 00:27:37 -07:00
dmapool.c
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early_ioremap.c
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fadvise.c mm: return void from various readahead functions 2020-06-02 10:59:06 -07:00
failslab.c
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filemap.c fs: Add IOCB_NOIO flag for generic_file_read_iter 2020-07-07 23:40:08 +02:00
frame_vector.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
frontswap.c mm/frontswap: fix some typos in frontswap.c 2020-06-04 19:06:24 -07:00
gup.c mm: Allow arches to provide ptep_get() 2020-06-20 22:14:53 +10:00
gup_benchmark.c
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highmem.c
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hmm.c mmap locking API: add mmap_assert_locked() and mmap_assert_write_locked() 2020-06-09 09:39:14 -07:00
huge_memory.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
hugetlb.c mm/hugetlb.c: fix pages per hugetlb calculation 2020-07-03 16:15:25 -07:00
hugetlb_cgroup.c
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hwpoison-inject.c
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init-mm.c mmap locking API: add MMAP_LOCK_INITIALIZER 2020-06-09 09:39:14 -07:00
internal.h mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
interval_tree.c
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khugepaged.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
kmemleak-test.c
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kmemleak.c
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ksm.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
list_lru.c mm/list_lru: fix a typo in comment "numbesr"->"numbers" 2020-06-04 19:06:24 -07:00
maccess.c maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault 2020-06-17 10:57:41 -07:00
madvise.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
mapping_dirty_helpers.c
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memblock.c mm/memblock: fix a typo in comment "implict"->"implicit" 2020-06-04 19:06:23 -07:00
memcontrol.c mm/memcontrol.c: prevent missed memory.low load tears 2020-06-26 00:27:37 -07:00
memfd.c
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memory-failure.c mm/memory-failure: send SIGBUS(BUS_MCEERR_AR) only to current thread 2020-06-11 18:17:47 -07:00
memory.c mm/memory: fix IO cost for anonymous page 2020-06-26 00:27:38 -07:00
memory_hotplug.c mm/memory_hotplug.c: fix false softlockup during pfn range removal 2020-06-26 00:27:38 -07:00
mempolicy.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
mempool.c
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memremap.c
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memtest.c
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migrate.c Raise gcc version requirement to 4.9 2020-07-08 10:48:35 -07:00
mincore.c mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
mlock.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
mm_init.c mm/mm_init.c: report kasan-tag information stored in page->flags 2020-06-02 10:59:12 -07:00
mmap.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
mmu_gather.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
mmu_notifier.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
mmzone.c
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mprotect.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
mremap.c mm: document warning in move_normal_pmd() and make it warn only once 2020-07-13 11:37:39 -07:00
msync.c mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
nommu.c mm: remove vmalloc_exec 2020-06-26 00:27:38 -07:00
oom_kill.c kernel: better document the use_mm/unuse_mm API contract 2020-06-10 19:14:18 -07:00
page-writeback.c mm/page-writeback: fix a typo in comment "effictive"->"effective" 2020-06-04 19:06:24 -07:00
page_alloc.c mm/page_alloc: fix documentation error 2020-07-03 16:15:25 -07:00
page_counter.c
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page_ext.c
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page_idle.c mm/page_idle.c: skip offline pages 2020-06-08 11:05:55 -07:00
page_io.c mm: don't include asm/pgtable.h if linux/mm.h is already included 2020-06-09 09:39:13 -07:00
page_isolation.c mm: Allow to offline unmovable PageOffline() pages via MEM_GOING_OFFLINE 2020-06-04 15:36:52 -04:00
page_owner.c mm: rename gfpflags_to_migratetype to gfp_migratetype for same convention 2020-06-03 20:09:45 -07:00
page_poison.c
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page_reporting.c
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page_reporting.h mm: introduce include/linux/pgtable.h 2020-06-09 09:39:13 -07:00
page_vma_mapped.c
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pagewalk.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
percpu-internal.h
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percpu-km.c
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percpu-stats.c
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percpu-vm.c
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percpu.c mm: remove the pgprot argument to __vmalloc 2020-06-02 10:59:11 -07:00
pgtable-generic.c mm: introduce include/linux/pgtable.h 2020-06-09 09:39:13 -07:00
process_vm_access.c mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
ptdump.c mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
readahead.c mm: use memalloc_nofs_save in readahead path 2020-06-02 10:59:07 -07:00
rmap.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
rodata_test.c maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault 2020-06-17 10:57:41 -07:00
shmem.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
shuffle.c
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shuffle.h
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slab.c mm/page_alloc: integrate classzone_idx and high_zoneidx 2020-06-03 20:09:44 -07:00
slab.h mm, slab: fix sign conversion problem in memcg_uncharge_slab() 2020-06-26 00:27:37 -07:00
slab_common.c mm/slab: use memzero_explicit() in kzfree() 2020-06-26 00:27:37 -07:00
slob.c
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slub.c slub: cure list_slab_objects() from double fix 2020-06-26 00:27:37 -07:00
sparse-vmemmap.c mm: don't include asm/pgtable.h if linux/mm.h is already included 2020-06-09 09:39:13 -07:00
sparse.c mm: don't include asm/pgtable.h if linux/mm.h is already included 2020-06-09 09:39:13 -07:00
swap.c mm/swap: fix for "mm: workingset: age nonresident information alongside anonymous pages" 2020-06-26 00:27:38 -07:00
swap_cgroup.c mm: memcontrol: make swap tracking an integral part of memory control 2020-06-03 20:09:48 -07:00
swap_slots.c
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swap_state.c mm: fix swap cache node allocation mask 2020-06-26 00:27:37 -07:00
swapfile.c mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
truncate.c
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usercopy.c
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userfaultfd.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
util.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
vmacache.c kernel: better document the use_mm/unuse_mm API contract 2020-06-10 19:14:18 -07:00
vmalloc.c mm: remove vmalloc_exec 2020-06-26 00:27:38 -07:00
vmpressure.c
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vmscan.c mm: workingset: age nonresident information alongside anonymous pages 2020-06-26 00:27:37 -07:00
vmstat.c mm/vmstat.c: convert to use DEFINE_SEQ_ATTRIBUTE macro 2020-06-04 19:06:26 -07:00
workingset.c mm: workingset: age nonresident information alongside anonymous pages 2020-06-26 00:27:37 -07:00
z3fold.c mm/z3fold: silence kmemleak false positives of slots 2020-05-28 11:35:40 -07:00
zbud.c mm: use false for bool variable 2020-06-04 19:06:24 -07:00
zpool.c
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zsmalloc.c mm: reorder includes after introduction of linux/pgtable.h 2020-06-09 09:39:13 -07:00
zswap.c
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