From 7c11cce3648ebf166f02eb86acdd67f3b72746d0 Mon Sep 17 00:00:00 2001
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Date: Wed, 21 Mar 2012 16:34:26 -0700
Subject: [PATCH] --- yaml --- r: 292690 b: refs/heads/master c:
 4331f7d339ee0b54603344b9d13662a9c022540c h: refs/heads/master v: v3

---
 [refs]                           | 2 +-
 trunk/include/linux/memcontrol.h | 5 ++++-
 trunk/mm/memcontrol.c            | 9 ++++++++-
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/[refs] b/[refs]
index ffd5d8f22f28..3fe29f14fb26 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 2ff76f1193f8481f7e6c29304eea4006e8e51569
+refs/heads/master: 4331f7d339ee0b54603344b9d13662a9c022540c
diff --git a/trunk/include/linux/memcontrol.h b/trunk/include/linux/memcontrol.h
index bf7ae01fc93b..f94efd2f6c27 100644
--- a/trunk/include/linux/memcontrol.h
+++ b/trunk/include/linux/memcontrol.h
@@ -144,6 +144,8 @@ static inline bool mem_cgroup_disabled(void)
 void __mem_cgroup_begin_update_page_stat(struct page *page, bool *locked,
 					 unsigned long *flags);
 
+extern atomic_t memcg_moving;
+
 static inline void mem_cgroup_begin_update_page_stat(struct page *page,
 					bool *locked, unsigned long *flags)
 {
@@ -151,7 +153,8 @@ static inline void mem_cgroup_begin_update_page_stat(struct page *page,
 		return;
 	rcu_read_lock();
 	*locked = false;
-	return __mem_cgroup_begin_update_page_stat(page, locked, flags);
+	if (atomic_read(&memcg_moving))
+		__mem_cgroup_begin_update_page_stat(page, locked, flags);
 }
 
 void __mem_cgroup_end_update_page_stat(struct page *page,
diff --git a/trunk/mm/memcontrol.c b/trunk/mm/memcontrol.c
index 0e13b2aeea61..eb1004f207b3 100644
--- a/trunk/mm/memcontrol.c
+++ b/trunk/mm/memcontrol.c
@@ -1306,8 +1306,13 @@ int mem_cgroup_swappiness(struct mem_cgroup *memcg)
  *                                              rcu_read_unlock()
  *         start move here.
  */
+
+/* for quick checking without looking up memcg */
+atomic_t memcg_moving __read_mostly;
+
 static void mem_cgroup_start_move(struct mem_cgroup *memcg)
 {
+	atomic_inc(&memcg_moving);
 	atomic_inc(&memcg->moving_account);
 	synchronize_rcu();
 }
@@ -1318,8 +1323,10 @@ static void mem_cgroup_end_move(struct mem_cgroup *memcg)
 	 * Now, mem_cgroup_clear_mc() may call this function with NULL.
 	 * We check NULL in callee rather than caller.
 	 */
-	if (memcg)
+	if (memcg) {
+		atomic_dec(&memcg_moving);
 		atomic_dec(&memcg->moving_account);
+	}
 }
 
 /*