Re: Race in pagevec_strip?

[Christoph Lameter <clameter@sgi.com>]

Sigh. TestSetPackLocked works just opposite of spin_trylock. So add an !


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@sgi.com>

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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