Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932143Ab3DBO23 (ORCPT ); Tue, 2 Apr 2013 10:28:29 -0400 Received: from cantor2.suse.de ([195.135.220.15]:47008 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761319Ab3DBO20 (ORCPT ); Tue, 2 Apr 2013 10:28:26 -0400 Date: Tue, 2 Apr 2013 16:28:25 +0200 From: Michal Hocko To: Glauber Costa Cc: Li Zefan , 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: <20130402142825.GA32520@dhcp22.suse.cz> References: <515A8A40.6020406@huawei.com> <20130402121600.GK24345@dhcp22.suse.cz> <20130402141646.GQ24345@dhcp22.suse.cz> <515AE948.1000704@parallels.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <515AE948.1000704@parallels.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: 1701 Lines: 55 On Tue 02-04-13 18:20:56, Glauber Costa wrote: > On 04/02/2013 06:16 PM, Michal Hocko wrote: > > mem_cgroup_css_online > > memcg_init_kmem > > mem_cgroup_get # refcnt = 2 > > memcg_update_all_caches > > memcg_update_cache_size # fails with ENOMEM > > Here is the thing: this one in kmem only happens for kmem enabled > memcgs. For those, we tend to do a get once, and put only when the last > kmem reference is gone. > > For non-kmem memcgs, refcnt will be 1 here, and will be balanced out by > the mem_cgroup_put() in css_free. So we need this, right? --- diff --git a/mm/memcontrol.c b/mm/memcontrol.c index f608546..2ef875d 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5306,6 +5306,8 @@ static int memcg_propagate_kmem(struct mem_cgroup *memcg) ret = memcg_update_cache_sizes(memcg); mutex_unlock(&set_limit_mutex); out: + if (ret) + mem_cgroup_put(memcg); return ret; } #endif /* CONFIG_MEMCG_KMEM */ @@ -6417,16 +6419,6 @@ 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); - if (parent->use_hierarchy) - mem_cgroup_put(parent); - } return error; } -- 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/