From a1391fe1018932653c124193cd98b66ca36afeca Mon Sep 17 00:00:00 2001
From: Johannes Weiner <jweiner@redhat.com>
Date: Wed, 2 Nov 2011 13:38:29 -0700
Subject: [PATCH] --- yaml --- r: 273245 b: refs/heads/master c:
 a61ed3cec51cfd4877855c24890ab8d3e2b143e3 h: refs/heads/master i:   273243:
 671e651003e84a4e3e4d6ff63b9463de443683bb v: v3

---
 [refs]                |  2 +-
 trunk/mm/memcontrol.c | 21 ++++++++++++++++++++-
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index 902019c57bd9..5286b5b83f21 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 9b272977e3b99a8699361d214b51f98c8a9e0e7b
+refs/heads/master: a61ed3cec51cfd4877855c24890ab8d3e2b143e3
diff --git a/trunk/mm/memcontrol.c b/trunk/mm/memcontrol.c
index ce7b35d024e9..01e0c725de65 100644
--- a/trunk/mm/memcontrol.c
+++ b/trunk/mm/memcontrol.c
@@ -993,6 +993,16 @@ void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
 		return;
 	pc = lookup_page_cgroup(page);
 	VM_BUG_ON(PageCgroupAcctLRU(pc));
+	/*
+	 * putback:				charge:
+	 * SetPageLRU				SetPageCgroupUsed
+	 * smp_mb				smp_mb
+	 * PageCgroupUsed && add to memcg LRU	PageLRU && add to memcg LRU
+	 *
+	 * Ensure that one of the two sides adds the page to the memcg
+	 * LRU during a race.
+	 */
+	smp_mb();
 	if (!PageCgroupUsed(pc))
 		return;
 	/* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
@@ -1044,7 +1054,16 @@ static void mem_cgroup_lru_add_after_commit(struct page *page)
 	unsigned long flags;
 	struct zone *zone = page_zone(page);
 	struct page_cgroup *pc = lookup_page_cgroup(page);
-
+	/*
+	 * putback:				charge:
+	 * SetPageLRU				SetPageCgroupUsed
+	 * smp_mb				smp_mb
+	 * PageCgroupUsed && add to memcg LRU	PageLRU && add to memcg LRU
+	 *
+	 * Ensure that one of the two sides adds the page to the memcg
+	 * LRU during a race.
+	 */
+	smp_mb();
 	/* taking care of that the page is added to LRU while we commit it */
 	if (likely(!PageLRU(page)))
 		return;