vmscan: activate executable pages after first usage

commit c909e99364c8b6ca07864d752950b6b4ecf6bef4 upstream.

Stable note: Not tracked in Bugzilla. There were reports of shared
	mapped pages being unfairly reclaimed in comparison to older kernels.
	This is being addressed over time.

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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 4391b5f49e28bdb78ddf67495abb2f767474216d)

Signed-off-by: Jerry Snitselaar <jerry.snitselaar@oracle.com>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 8fac23d710c5e3e540a2ff8f5c2255bc66d7f8c1..e57d9b2ee58a1f44dde6f2bd7d9098b9bd3304c2 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -726,6 +726,12 @@ 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;
        }