From: Li Zefan <lizefan@huawei.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>, Glauber Costa <glommer@parallels.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Johannes Weiner <hannes@cmpxchg.org>,
LKML <linux-kernel@vger.kernel.org>,
Cgroups <cgroups@vger.kernel.org>,
linux-mm@kvack.org
Subject: [PATCH 10/12] memcg: don't need to get a reference to the parent
Date: Mon, 8 Apr 2013 14:35:34 +0800 [thread overview]
Message-ID: <51626536.3040901@huawei.com> (raw)
In-Reply-To: <5162648B.9070802@huawei.com>
The cgroup core guarantees it's always safe to access the parent.
v2:
- added a comment in mem_cgroup_put() as suggested by Michal
- removed mem_cgroup_get(), otherwise gcc will warn that it's not used
Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
mm/memcontrol.c | 19 +++----------------
1 file changed, 3 insertions(+), 16 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 7fdd69d..9ca5a99 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -501,7 +501,6 @@ enum res_type {
*/
static DEFINE_MUTEX(memcg_create_mutex);
-static void mem_cgroup_get(struct mem_cgroup *memcg);
static void mem_cgroup_put(struct mem_cgroup *memcg);
static inline
@@ -6125,19 +6124,10 @@ static void free_rcu(struct rcu_head *rcu_head)
schedule_work(&memcg->work_freeing);
}
-static void mem_cgroup_get(struct mem_cgroup *memcg)
-{
- atomic_inc(&memcg->refcnt);
-}
-
static void __mem_cgroup_put(struct mem_cgroup *memcg, int count)
{
- if (atomic_sub_and_test(count, &memcg->refcnt)) {
- struct mem_cgroup *parent = parent_mem_cgroup(memcg);
+ if (atomic_sub_and_test(count, &memcg->refcnt))
call_rcu(&memcg->rcu_freeing, free_rcu);
- if (parent)
- mem_cgroup_put(parent);
- }
}
static void mem_cgroup_put(struct mem_cgroup *memcg)
@@ -6239,12 +6229,9 @@ mem_cgroup_css_online(struct cgroup *cont)
res_counter_init(&memcg->kmem, &parent->kmem);
/*
- * We increment refcnt of the parent to ensure that we can
- * safely access it on res_counter_charge/uncharge.
- * This refcnt will be decremented when freeing this
- * mem_cgroup(see mem_cgroup_put).
+ * No need to take a reference to the parent because cgroup
+ * core guarantees its existence.
*/
- mem_cgroup_get(parent);
} else {
res_counter_init(&memcg->res, NULL);
res_counter_init(&memcg->memsw, NULL);
--
1.8.0.2
--
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next prev parent reply other threads:[~2013-04-08 6:36 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-08 6:32 [PATCH 0/12][V2] memcg: make memcg's life cycle the same as cgroup Li Zefan
2013-04-08 6:33 ` [PATCH 01/12] memcg: take reference before releasing rcu_read_lock Li Zefan
2013-04-08 6:33 ` [PATCH 02/12] memcg: avoid accessing memcg after releasing reference Li Zefan
2013-04-08 6:33 ` [PATCH 03/12] Revert "memcg: avoid dangling reference count in creation failure." Li Zefan
2013-04-09 2:50 ` Kamezawa Hiroyuki
2013-04-08 6:33 ` [PATCH 04/12] memcg, kmem: fix reference count handling on the error path Li Zefan
2013-04-09 2:51 ` Kamezawa Hiroyuki
2013-04-08 6:34 ` [PATCH 05/12] memcg: use css_get() in sock_update_memcg() Li Zefan
2013-04-08 6:34 ` [PATCH 06/12] memcg: don't use mem_cgroup_get() when creating a kmemcg cache Li Zefan
2013-04-09 2:53 ` Kamezawa Hiroyuki
2013-04-08 6:34 ` [PATCH 07/12] memcg: use css_get/put when charging/uncharging kmem Li Zefan
2013-04-08 14:14 ` Michal Hocko
2013-04-09 2:55 ` Kamezawa Hiroyuki
2013-04-08 6:34 ` [PATCH 08/12] memcg: use css_get/put for swap memcg Li Zefan
2013-04-08 6:35 ` [PATCH 09/12] cgroup: make sure parent won't be destroyed before its children Li Zefan
2013-04-08 15:36 ` Tejun Heo
2013-04-08 6:35 ` Li Zefan [this message]
2013-04-08 6:36 ` [PATCH 11/12] memcg: kill memcg refcnt Li Zefan
2013-04-08 6:36 ` [PATCH 12/12] memcg: don't need to free memcg via RCU or workqueue Li Zefan
2013-04-08 14:15 ` Michal Hocko
2013-04-09 2:57 ` Kamezawa Hiroyuki
2013-04-08 6:36 ` [PATCH 13/12] memcg: don't need memcg->memcg_name Li Zefan
2013-04-08 14:25 ` Michal Hocko
2013-04-09 1:28 ` Li Zefan
2013-04-09 3:10 ` Kamezawa Hiroyuki
2013-04-09 3:18 ` Li Zefan
2013-04-09 3:46 ` Kamezawa Hiroyuki
2013-04-09 7:55 ` Glauber Costa
2013-04-09 3:59 ` Tejun Heo
2013-04-09 7:53 ` Glauber Costa
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