From 9e851a53daeff2c33cf1a72f693780163c8dfa3f Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.cz>
Date: Tue, 26 Jul 2011 16:08:29 -0700
Subject: [PATCH] --- yaml --- r: 260406 b: refs/heads/master c:
 8521fc50d433507a7cdc96bec280f9e5888a54cc h: refs/heads/master v: v3

---
 [refs]                |  2 +-
 trunk/mm/memcontrol.c | 12 ++----------
 2 files changed, 3 insertions(+), 11 deletions(-)

diff --git a/[refs] b/[refs]
index 7baeab3df37d..4e1cd72d3bcc 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 3e92041d68b40c47faa34c7dc08fc650a6c36adc
+refs/heads/master: 8521fc50d433507a7cdc96bec280f9e5888a54cc
diff --git a/trunk/mm/memcontrol.c b/trunk/mm/memcontrol.c
index 79f23a189941..5f84d2351ddb 100644
--- a/trunk/mm/memcontrol.c
+++ b/trunk/mm/memcontrol.c
@@ -2092,7 +2092,6 @@ struct memcg_stock_pcp {
 #define FLUSHING_CACHED_CHARGE	(0)
 };
 static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
-static DEFINE_MUTEX(percpu_charge_mutex);
 
 /*
  * Try to consume stocked charge on this cpu. If success, one page is consumed
@@ -2199,7 +2198,8 @@ static void drain_all_stock(struct mem_cgroup *root_mem, bool sync)
 
 	for_each_online_cpu(cpu) {
 		struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
-		if (test_bit(FLUSHING_CACHED_CHARGE, &stock->flags))
+		if (mem_cgroup_same_or_subtree(root_mem, stock->cached) &&
+				test_bit(FLUSHING_CACHED_CHARGE, &stock->flags))
 			flush_work(&stock->work);
 	}
 out:
@@ -2214,22 +2214,14 @@ static void drain_all_stock(struct mem_cgroup *root_mem, bool sync)
  */
 static void drain_all_stock_async(struct mem_cgroup *root_mem)
 {
-	/*
-	 * If someone calls draining, avoid adding more kworker runs.
-	 */
-	if (!mutex_trylock(&percpu_charge_mutex))
-		return;
 	drain_all_stock(root_mem, false);
-	mutex_unlock(&percpu_charge_mutex);
 }
 
 /* This is a synchronous drain interface. */
 static void drain_all_stock_sync(struct mem_cgroup *root_mem)
 {
 	/* called when force_empty is called */
-	mutex_lock(&percpu_charge_mutex);
 	drain_all_stock(root_mem, true);
-	mutex_unlock(&percpu_charge_mutex);
 }
 
 /*