From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753656AbZBCFgK (ORCPT ); Tue, 3 Feb 2009 00:36:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751797AbZBCFf5 (ORCPT ); Tue, 3 Feb 2009 00:35:57 -0500 Received: from e28smtp03.in.ibm.com ([59.145.155.3]:40402 "EHLO e28smtp03.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751485AbZBCFf4 (ORCPT ); Tue, 3 Feb 2009 00:35:56 -0500 Date: Tue, 3 Feb 2009 11:05:51 +0530 From: Balbir Singh To: Li Zefan Cc: David Rientjes , KAMEZAWA Hiroyuki , Andrew Morton , "linux-kernel@vger.kernel.org" , "nishimura@mxp.nes.nec.co.jp" , "linux-mm@kvack.org" Subject: Re: [-mm patch] Show memcg information during OOM Message-ID: <20090203053551.GP918@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20090202125240.GA918@balbir.in.ibm.com> <20090202140849.GB918@balbir.in.ibm.com> <49879DE5.8030505@cn.fujitsu.com> <20090203044143.GM918@balbir.in.ibm.com> <4987D512.90001@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <4987D512.90001@cn.fujitsu.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Li Zefan [2009-02-03 13:24:34]: > David Rientjes wrote: > > On Tue, 3 Feb 2009, Balbir Singh wrote: > > > >>>> diff --git a/mm/oom_kill.c b/mm/oom_kill.c > >>>> index d3b9bac..b8e53ae 100644 > >>>> --- a/mm/oom_kill.c > >>>> +++ b/mm/oom_kill.c > >>>> @@ -392,6 +392,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, > >>>> current->comm, gfp_mask, order, current->oomkilladj); > >>>> task_lock(current); > >>>> cpuset_print_task_mems_allowed(current); > >>>> + mem_cgroup_print_mem_info(mem); > >>> I think this can be put outside the task lock. The lock is used to call task_cs() safely in > >>> cpuset_print_task_mems_allowed(). > >>> > >> Thanks, I'll work on that in the next version. > >> > > > > I was also wondering about this and assumed that it was necessary to > > prevent the cgroup from disappearing during the oom. If task_lock() isn't > > held, is the memcg->css.cgroup->dentry->d_name.name dereference always > > safe without rcu? > > > > The cgroup won't disappear, since mem_cgroup_out_of_memory() is called with memcg's css refcnt > increased. :) > And this as well, yes! -- Balbir