From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx148.postini.com [74.125.245.148]) by kanga.kvack.org (Postfix) with SMTP id 98C936B0006 for ; Tue, 2 Apr 2013 10:32:50 -0400 (EDT) Message-ID: <515AEC3A.2030401@parallels.com> Date: Tue, 2 Apr 2013 18:33:30 +0400 From: Glauber Costa MIME-Version: 1.0 Subject: Re: [PATCH] memcg: don't do cleanup manually if mem_cgroup_css_online() fails References: <515A8A40.6020406@huawei.com> <20130402121600.GK24345@dhcp22.suse.cz> <20130402141646.GQ24345@dhcp22.suse.cz> <515AE948.1000704@parallels.com> <20130402142825.GA32520@dhcp22.suse.cz> In-Reply-To: <20130402142825.GA32520@dhcp22.suse.cz> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Li Zefan , Johannes Weiner , KAMEZAWA Hiroyuki , LKML , Cgroups , linux-mm@kvack.org On 04/02/2013 06:28 PM, Michal Hocko wrote: > 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; > } > > Yes, indeed you are very right - and thanks for looking at such depth. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org