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| author | Michal Hocko <mhocko@suse.cz> | 2013-07-09 01:00:29 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-07-09 19:33:24 +0200 |
| commit | f37a96914d1aea10fed8d9af10251f0b9caea31b (patch) | |
| tree | 67979668006c0baf66711786ea7c82f8233ad4a5 /mm/memcontrol.c | |
| parent | Revert "memcg: avoid dangling reference count in creation failure" (diff) | |
| download | linux-f37a96914d1aea10fed8d9af10251f0b9caea31b.tar.xz linux-f37a96914d1aea10fed8d9af10251f0b9caea31b.zip | |
memcg, kmem: fix reference count handling on the error path
mem_cgroup_css_online calls mem_cgroup_put if memcg_init_kmem fails.
This is not correct because only memcg_propagate_kmem takes an
additional reference while mem_cgroup_sockets_init is allowed to fail as
well (although no current implementation fails) but it doesn't take any
reference. This all suggests that it should be memcg_propagate_kmem
that should clean up after itself so this patch moves mem_cgroup_put
over there.
Unfortunately this is not that easy (as pointed out by Li Zefan) because
memcg_kmem_mark_dead marks the group dead (KMEM_ACCOUNTED_DEAD) if it is
marked active (KMEM_ACCOUNTED_ACTIVE) which is the case even if
memcg_propagate_kmem fails so the additional reference is dropped in
that case in kmem_cgroup_destroy which means that the reference would be
dropped two times.
The easiest way then would be to simply remove mem_cgrroup_put from
mem_cgroup_css_online and rely on kmem_cgroup_destroy doing the right
thing.
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Glauber Costa <glommer@openvz.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org> [3.8]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
| -rw-r--r-- | mm/memcontrol.c | 8 |
1 files changed, 0 insertions, 8 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 6b73d8657d64..bdeb82ca6c20 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6345,14 +6345,6 @@ mem_cgroup_css_online(struct cgroup *cont) error = memcg_init_kmem(memcg, &mem_cgroup_subsys); mutex_unlock(&memcg_create_mutex); - if (error) { - /* - * We call put now because our (and parent's) refcnts - * are already in place. mem_cgroup_put() will internally - * call __mem_cgroup_free, so return directly - */ - mem_cgroup_put(memcg); - } return error; } |