Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759218Ab3DBMQG (ORCPT ); Tue, 2 Apr 2013 08:16:06 -0400 Received: from cantor2.suse.de ([195.135.220.15]:39850 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754734Ab3DBMQD (ORCPT ); Tue, 2 Apr 2013 08:16:03 -0400 Date: Tue, 2 Apr 2013 14:16:00 +0200 From: Michal Hocko To: Li Zefan Cc: Glauber Costa , Johannes Weiner , KAMEZAWA Hiroyuki , LKML , Cgroups , linux-mm@kvack.org Subject: Re: [PATCH] memcg: don't do cleanup manually if mem_cgroup_css_online() fails Message-ID: <20130402121600.GK24345@dhcp22.suse.cz> References: <515A8A40.6020406@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <515A8A40.6020406@huawei.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1400 Lines: 48 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/