mm: zone_reclaim: make isolate_lru_page() filter-aware

commit f80c0673610e36ae29d63e3297175e22f70dde5f upstream.

Stable note: Not tracked in Bugzilla. THP and compaction disrupt the LRU list
	leading to poor reclaim decisions which has a variable
	performance impact.

In __zone_reclaim case, we don't want to shrink mapped page.  Nonetheless,
we have isolated mapped page and re-add it into LRU's head.  It's
unnecessary CPU overhead and makes LRU churning.

Of course, when we isolate the page, the page might be mapped but when we
try to migrate the page, the page would be not mapped.  So it could be
migrated.  But race is rare and although it happens, it's no big deal.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@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>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 0ed9149..80acfbc 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -164,6 +164,8 @@ static inline int is_unevictable_lru(enum lru_list l)
 #define ISOLATE_ACTIVE		((__force isolate_mode_t)0x2)
 /* Isolate clean file */
 #define ISOLATE_CLEAN		((__force isolate_mode_t)0x4)
+/* Isolate unmapped file */
+#define ISOLATE_UNMAPPED	((__force isolate_mode_t)0x8)
 
 /* LRU Isolation modes. */
 typedef unsigned __bitwise__ isolate_mode_t;