[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20130402121600.GK24345@dhcp22.suse.cz>
Date: Tue, 2 Apr 2013 14:16:00 +0200
From: Michal Hocko <mhocko@...e.cz>
To: Li Zefan <lizefan@...wei.com>
Cc: Glauber Costa <glommer@...allels.com>,
Johannes Weiner <hannes@...xchg.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
LKML <linux-kernel@...r.kernel.org>,
Cgroups <cgroups@...r.kernel.org>, linux-mm@...ck.org
Subject: Re: [PATCH] memcg: don't do cleanup manually if
mem_cgroup_css_online() fails
On Tue 02-04-13 15:35:28, Li Zefan wrote:
[...]
> @@ -6247,16 +6247,7 @@ 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);
> - if (parent->use_hierarchy)
> - mem_cgroup_put(parent);
> - }
> +
> return error;
> }
The mem_cgroup_put(parent) part is incorrect because mem_cgroup_put goes
up the hierarchy already but I do not think mem_cgroup_put(memcg) should
go away as well. Who is going to free the last reference then?
Maybe I am missing something but we have:
cgroup_create
css = ss->css_alloc(cgrp)
mem_cgroup_css_alloc
atomic_set(&memcg->refcnt, 1)
online_css(ss, cgrp)
mem_cgroup_css_online
error = memcg_init_kmem # fails
goto err_destroy
err_destroy:
cgroup_destroy_locked(cgrp)
offline_css
mem_cgroup_css_offline
no mem_cgroup_put on the way.
--
Michal Hocko
SUSE Labs
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists