Subject: + memcg-dont-need-to-get-a-reference-to-the-parent.patch added to -mm tree
To: lizefan@xxxxxxxxxx,glommer@xxxxxxxxxx,hannes@xxxxxxxxxxx,hughd@xxxxxxxxxx,kamezawa.hiroyu@xxxxxxxxxxxxxx,mhocko@xxxxxxx,tj@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Fri, 28 Jun 2013 16:00:32 -0700
The patch titled
Subject: memcg: don't need to get a reference to the parent
has been added to the -mm tree. Its filename is
memcg-dont-need-to-get-a-reference-to-the-parent.patch
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------------------------------------------------------
From: Li Zefan <lizefan@xxxxxxxxxx>
Subject: memcg: don't need to get a reference to the parent
The cgroup core guarantees it's always safe to access the parent.
Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Glauber Costa <glommer@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 19 +++----------------
1 file changed, 3 insertions(+), 16 deletions(-)
diff -puN mm/memcontrol.c~memcg-dont-need-to-get-a-reference-to-the-parent mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-dont-need-to-get-a-reference-to-the-parent
+++ a/mm/memcontrol.c
@@ -503,7 +503,6 @@ 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
@@ -6230,19 +6229,10 @@ static void free_rcu(struct rcu_head *rc
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)
@@ -6345,12 +6335,9 @@ mem_cgroup_css_online(struct cgroup *con
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);
_
Patches currently in -mm which might be from lizefan@xxxxxxxxxx are
origin.patch
linux-next.patch
memcg-update-todo-list-in-documentation.patch
revert-memcg-avoid-dangling-reference-count-in-creation-failure.patch
memcg-kmem-fix-reference-count-handling-on-the-error-path.patch
memcg-use-css_get-in-sock_update_memcg.patch
memcg-dont-use-mem_cgroup_get-when-creating-a-kmemcg-cache.patch
memcg-use-css_get-put-when-charging-uncharging-kmem.patch
memcg-use-css_get-put-when-charging-uncharging-kmem-fix.patch
memcg-use-css_get-put-for-swap-memcg.patch
memcg-dont-need-to-get-a-reference-to-the-parent.patch
memcg-kill-memcg-refcnt.patch
memcg-dont-need-to-free-memcg-via-rcu-or-workqueue.patch
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