From df9d6985be2a7e7683c46e4c6ea608fc69f02b45 Mon Sep 17 00:00:00 2001
From: Christoph Lameter <cl@gentwo.org>
Date: Mon, 31 Oct 2011 17:09:35 -0700
Subject: [PATCH] mm: do not drain pagevecs for mlockall(MCL_FUTURE)

MCL_FUTURE does not move pages between lru list and draining the LRU per
cpu pagevecs is a nasty activity.  Avoid doing it unecessarily.

Signed-off-by: Christoph Lameter <cl@gentwo.org>
Cc: David Rientjes <rientjes@google.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/mlock.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/mlock.c b/mm/mlock.c
index 048260c4e02e..7debb4fdf79b 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -549,7 +549,8 @@ SYSCALL_DEFINE1(mlockall, int, flags)
 	if (!can_do_mlock())
 		goto out;
 
-	lru_add_drain_all();	/* flush pagevec */
+	if (flags & MCL_CURRENT)
+		lru_add_drain_all();	/* flush pagevec */
 
 	down_write(&current->mm->mmap_sem);
 
-- 
2.20.1