From 8519fb30e438f8088b71a94a7d5a660a814d3872 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Tue, 7 Feb 2006 12:58:52 -0800 Subject: [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 Acked-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') 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); \ }) -- cgit v1.2.3-70-g09d2