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authorAndrea Arcangeli <aarcange@redhat.com>2011-01-13 15:46:33 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-13 17:32:39 -0800
commita95a82e96c48270980dd248ccd5546f1b49e6f8a (patch)
tree35f10c2a8d2cd0e1aa9d33f7a4f55332c0733ee6
parent9180706344487700b40da9eca5dedd3d11cb33b4 (diff)
thp: put_page: recheck PageHead after releasing the compound_lock
After releasing the compound_lock split_huge_page can still run and release the page before put_page_testzero runs. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/swap.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/mm/swap.c b/mm/swap.c
index 33f5292fe13..e0eeef94088 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -131,8 +131,12 @@ static void put_compound_page(struct page *page)
atomic_dec(&page->_count);
VM_BUG_ON(atomic_read(&page_head->_count) <= 0);
compound_unlock_irqrestore(page_head, flags);
- if (put_page_testzero(page_head))
- __put_compound_page(page_head);
+ if (put_page_testzero(page_head)) {
+ if (PageHead(page_head))
+ __put_compound_page(page_head);
+ else
+ __put_single_page(page_head);
+ }
} else {
/* page_head is a dangling pointer */
VM_BUG_ON(PageTail(page));