From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx129.postini.com [74.125.245.129]) by kanga.kvack.org (Postfix) with SMTP id 86EE18D001E for ; Wed, 12 Jun 2013 16:49:50 -0400 (EDT) Received: by mail-pd0-f170.google.com with SMTP id x11so4743990pdj.29 for ; Wed, 12 Jun 2013 13:49:49 -0700 (PDT) Date: Wed, 12 Jun 2013 13:49:47 -0700 (PDT) From: David Rientjes Subject: Re: [patch 2/2] memcg: do not sleep on OOM waitqueue with full charge context In-Reply-To: <20130612203705.GB17282@dhcp22.suse.cz> Message-ID: References: <20130606053315.GB9406@cmpxchg.org> <20130606173355.GB27226@cmpxchg.org> <20130606215425.GM15721@cmpxchg.org> <20130607000222.GT15576@cmpxchg.org> <20130612082817.GA6706@dhcp22.suse.cz> <20130612203705.GB17282@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Johannes Weiner , Andrew Morton , KAMEZAWA Hiroyuki , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org On Wed, 12 Jun 2013, Michal Hocko wrote: > The patch is a big improvement with a minimum code overhead. Blocking > any task which sits on top of an unpredictable amount of locks is just > broken. So regardless how many users are affected we should merge it and > backport to stable trees. The problem is there since ever. We seem to > be surprisingly lucky to not hit this more often. > Right now it appears that that number of users is 0 and we're talking about a problem that was reported in 3.2 that was released a year and a half ago. The rules of inclusion in stable also prohibit such a change from being backported, specifically "It must fix a real bug that bothers people (not a, "This could be a problem..." type thing)". We have deployed memcg on a very large number of machines and I can run a query over all software watchdog timeouts that have occurred by deadlocking on i_mutex during memcg oom. It returns 0 results. > I am not quite sure I understand your reservation about the patch to be > honest. Andrew still hasn't merged this one although 1/2 is in. Perhaps he is as unconvinced? The patch adds 100 lines of code, including fields to task_struct for memcg, for a problem that nobody can reproduce. My question still stands: can anybody, even with an instrumented kernel to make it more probable, reproduce the issue this is addressing? -- 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