Race in pagevec_strip?

From: Christoph Lameter
Date: Thu Mar 16 2006 - 13:33:38 EST


Seems that we can call try_to_release_page with PagePrivate off and a
valid 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@xxxxxxx>

Index: linux-2.6.16-rc6/mm/swap.c
===================================================================
--- linux-2.6.16-rc6.orig/mm/swap.c 2006-03-11 14:12:55.000000000 -0800
+++ linux-2.6.16-rc6/mm/swap.c 2006-03-16 10:15:23.000000000 -0800
@@ -392,8 +392,9 @@ void pagevec_strip(struct pagevec *pvec)
for (i = 0; i < pagevec_count(pvec); i++) {
struct page *page = pvec->pages[i];

- if (PagePrivate(page) && !TestSetPageLocked(page)) {
- try_to_release_page(page, 0);
+ if (TestSetPageLocked(page)) {
+ if (PagePrivate(page))
+ try_to_release_page(page, 0);
unlock_page(page);
}
}
-
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