From: Konstantin Khlebnikov <khlebnikov@openvz.org>
Date: Wed, 24 Aug 2011 23:47:12 +0000 (+1000)
Subject: Logic added in commit 8cab4754d24a0 ("vmscan: make mapped executable pages
X-Git-Tag: next-20110927~1^2~61
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=03c84c9e6419ab12456c0964e4418b33a6733513;p=karo-tx-linux.git

Logic added in commit 8cab4754d24a0 ("vmscan: make mapped executable pages
the first class citizen") was noticeably weakened in commit
645747462435d84 ("vmscan: detect mapped file pages used only once").

Currently these pages can become "first class citizens" only after second
usage.  After this patch page_check_references() will activate they after
first usage, and executable code gets yet better chance to stay in memory.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 017ae9674a0a..f8fd50144f7c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -717,6 +717,12 @@ static enum page_references page_check_references(struct page *page,
 		if (referenced_page || referenced_ptes > 1)
 			return PAGEREF_ACTIVATE;
 
+		/*
+		 * Activate file-backed executable pages after first usage.
+		 */
+		if (vm_flags & VM_EXEC)
+			return PAGEREF_ACTIVATE;
+
 		return PAGEREF_KEEP;
 	}