From 5bf5f03c271907978489868a4c72aeb42b5127d2 Mon Sep 17 00:00:00 2001 From: Pravin B Shelar Date: Tue, 29 May 2012 15:06:49 -0700 Subject: 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 Signed-off-by: Pravin B Shelar Reviewed-by: Christoph Lameter Acked-by: Andrea Arcangeli Cc: Pekka Enberg Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') 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 } -- cgit v1.2.3