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authorNick Piggin <npiggin@suse.de>2006-02-07 12:58:52 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-07 16:12:33 -0800
commit8519fb30e438f8088b71a94a7d5a660a814d3872 (patch)
tree8d29a7b1fa33e5f65e649d363cfa10e83c4fab97 /include
parent99f6d61bda82d09b2d94414d413d39f66a0b7da2 (diff)
[PATCH] mm: compound release fix
Compound pages on SMP systems can now often be freed from pagetables via the release_pages path. This uses put_page_testzero which does not handle compound pages at all. Releasing constituent pages from process mappings decrements their count to a large negative number and leaks the reference at the head page - net result is a memory leak. The problem was hidden because the debug check in put_page_testzero itself actually did take compound pages into consideration. Fix the bug and the debug check. Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/mm.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 85854b86746..75e9f072499 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -303,7 +303,7 @@ struct page {
*/
#define put_page_testzero(p) \
({ \
- BUG_ON(page_count(p) == 0); \
+ BUG_ON(atomic_read(&(p)->_count) == -1);\
atomic_add_negative(-1, &(p)->_count); \
})