[PATCH] fix race in pagevec_strip?

We can call try_to_release_page() with PagePrivate off and a valid
page->mapping This may cause all sorts of trouble for the filesystem
*_releasepage() handlers.  XFS bombs out in that case.

Lock the page before checking for page private.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/mm/swap.c b/mm/swap.c
index e9ec06d845e8..b524ea90bddb 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -393,7 +393,8 @@ void pagevec_strip(struct pagevec *pvec)
                 struct page *page = pvec->pages[i];
 
                 if (PagePrivate(page) && !TestSetPageLocked(page)) {
-                        try_to_release_page(page, 0);
+                        if (PagePrivate(page))
+                                try_to_release_page(page, 0);
                         unlock_page(page);
                 }
         }