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Subject[87/99] vmscan: limit VM_EXEC protection to file pages
2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Wu Fengguang <fengguang.wu@intel.com>
commit 41e20983fe553b39bc2b00e07c7a379f0c86a4bc upstream.

It is possible to have !Anon but SwapBacked pages, and some apps could
create huge number of such pages with MAP_SHARED|MAP_ANONYMOUS. These
pages go into the ANON lru list, and hence shall not be protected: we only
care mapped executable files. Failing to do so may trigger OOM.
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
mm/vmscan.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1298,7 +1298,7 @@ static void shrink_active_list(unsigned
* IO, plus JVM can create lots of anon VM_EXEC pages,
* so we ignore them here.
*/
- if ((vm_flags & VM_EXEC) && !PageAnon(page)) {
+ if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) {
list_add(&page->lru, &l_active);
continue;
}



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