| From f37a96914d1aea10fed8d9af10251f0b9caea31b Mon Sep 17 00:00:00 2001 |
| From: Michal Hocko <mhocko@suse.cz> |
| Date: Mon, 8 Jul 2013 16:00:29 -0700 |
| Subject: memcg, kmem: fix reference count handling on the error path |
| |
| From: Michal Hocko <mhocko@suse.cz> |
| |
| commit f37a96914d1aea10fed8d9af10251f0b9caea31b upstream. |
| |
| 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> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| mm/memcontrol.c | 8 -------- |
| 1 file changed, 8 deletions(-) |
| |
| --- a/mm/memcontrol.c |
| +++ b/mm/memcontrol.c |
| @@ -6179,14 +6179,6 @@ mem_cgroup_css_online(struct cgroup *con |
| |
| 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; |
| } |
| |
