From: Wu Fengguang <fengguang.wu@intel.com>
Date: Mon, 26 Oct 2009 23:49:53 +0000 (-0700)
Subject: vmscan: limit VM_EXEC protection to file pages
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=41e20983fe553b39bc2b00e07c7a379f0c86a4bc;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

vmscan: limit VM_EXEC protection to file pages

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>
---

diff --git a/mm/vmscan.c b/mm/vmscan.c
index fbb9f6bdad6e..fbcac3bdcf19 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1356,7 +1356,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 			 * 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;
 			}