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authorPravin B Shelar <pshelar@nicira.com>2012-05-29 15:06:49 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-29 16:22:24 -0700
commit5bf5f03c271907978489868a4c72aeb42b5127d2 (patch)
tree2d6b283fa5ee83b723fd4b4a8f070ae53c60ebe9 /include
parentdbda591d920b4c7692725b13e3f68ecb251e9080 (diff)
downloadlinux-5bf5f03c271907978489868a4c72aeb42b5127d2.tar.bz2
mm: fix slab->page flags corruption
Transparent huge pages can change page->flags (PG_compound_lock) without taking Slab lock. Since THP can not break slab pages we can safely access compound page without taking compound lock. Specifically this patch fixes a race between compound_unlock() and slab functions which perform page-flags updates. This can occur when get_page()/put_page() is called on a page from slab. [akpm@linux-foundation.org: tweak comment text, fix comment layout, fix label indenting] Reported-by: Amey Bhide <abhide@nicira.com> Signed-off-by: Pravin B Shelar <pshelar@nicira.com> Reviewed-by: Christoph Lameter <cl@linux.com> Acked-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/mm.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index aa20bafa40f6..ce26716238c3 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -321,6 +321,7 @@ static inline int is_vmalloc_or_module_addr(const void *x)
static inline void compound_lock(struct page *page)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ VM_BUG_ON(PageSlab(page));
bit_spin_lock(PG_compound_lock, &page->flags);
#endif
}
@@ -328,6 +329,7 @@ static inline void compound_lock(struct page *page)
static inline void compound_unlock(struct page *page)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ VM_BUG_ON(PageSlab(page));
bit_spin_unlock(PG_compound_lock, &page->flags);
#endif
}