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a57dd9f235
commit ad33bb04b2a6cee6c1f99fabb15cddbf93ff0433 upstream. pmd_trans_unstable()/pmd_none_or_trans_huge_or_clear_bad() were introduced to locklessy (but atomically) detect when a pmd is a regular (stable) pmd or when the pmd is unstable and can infinitely transition from pmd_none() and pmd_trans_huge() from under us, while only holding the mmap_sem for reading (for writing not). While holding the mmap_sem only for reading, MADV_DONTNEED can run from under us and so before we can assume the pmd to be a regular stable pmd we need to compare it against pmd_none() and pmd_trans_huge() in an atomic way, with pmd_trans_unstable(). The old pmd_trans_huge() left a tiny window for a race. Useful applications are unlikely to notice the difference as doing MADV_DONTNEED concurrently with a page fault would lead to undefined behavior. [js] 3.12 backport: no pmd_devmap in 3.12 yet. [akpm@linux-foundation.org: tidy up comment grammar/layout] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-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> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Willy Tarreau <w@1wt.eu> |
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.. | ||
kasan | ||
backing-dev.c | ||
balloon_compaction.c | ||
bootmem.c | ||
bounce.c | ||
cleancache.c | ||
compaction.c | ||
debug-pagealloc.c | ||
dmapool.c | ||
early_ioremap.c | ||
fadvise.c | ||
failslab.c | ||
filemap.c | ||
filemap_xip.c | ||
fremap.c | ||
frontswap.c | ||
highmem.c | ||
huge_memory.c | ||
hugetlb.c | ||
hugetlb_cgroup.c | ||
hwpoison-inject.c | ||
init-mm.c | ||
internal.h | ||
interval_tree.c | ||
Kconfig | ||
Kconfig.debug | ||
kmemcheck.c | ||
kmemleak-test.c | ||
kmemleak.c | ||
ksm.c | ||
maccess.c | ||
madvise.c | ||
Makefile | ||
memblock.c | ||
memcontrol.c | ||
memory-failure.c | ||
memory.c | ||
memory_hotplug.c | ||
mempolicy.c | ||
mempool.c | ||
memtest.c | ||
migrate.c | ||
mincore.c | ||
mlock.c | ||
mm_init.c | ||
mmap.c | ||
mmu_context.c | ||
mmu_notifier.c | ||
mmzone.c | ||
mprotect.c | ||
mremap.c | ||
msync.c | ||
nobootmem.c | ||
nommu.c | ||
oom_kill.c | ||
page-writeback.c | ||
page_alloc.c | ||
page_cgroup.c | ||
page_io.c | ||
page_isolation.c | ||
pageowner.c | ||
pagewalk.c | ||
percpu-km.c | ||
percpu-vm.c | ||
percpu.c | ||
pgtable-generic.c | ||
process_reclaim.c | ||
process_vm_access.c | ||
quicklist.c | ||
readahead.c | ||
rmap.c | ||
shmem.c | ||
showmem.c | ||
slab.c | ||
slab.h | ||
slab_common.c | ||
slob.c | ||
slub.c | ||
sparse-vmemmap.c | ||
sparse.c | ||
swap.c | ||
swap_state.c | ||
swapfile.c | ||
truncate.c | ||
util.c | ||
vmalloc.c | ||
vmpressure.c | ||
vmscan.c | ||
vmstat.c | ||
zbud.c | ||
zpool.c | ||
zsmalloc.c | ||
zswap.c |