From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751657AbcDUD1L (ORCPT ); Wed, 20 Apr 2016 23:27:11 -0400 Received: from mail-wm0-f49.google.com ([74.125.82.49]:37170 "EHLO mail-wm0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751375AbcDUD1J (ORCPT ); Wed, 20 Apr 2016 23:27:09 -0400 Date: Wed, 20 Apr 2016 23:27:05 -0400 From: Michal Hocko To: Tejun Heo Cc: Johannes Weiner , Petr Mladek , cgroups@vger.kernel.org, Cyril Hrubis , linux-kernel@vger.kernel.org Subject: Re: [PATCH for-4.6-fixes] memcg: remove lru_add_drain_all() invocation from mem_cgroup_move_charge() Message-ID: <20160421032704.GA15585@dhcp22.suse.cz> References: <20160413094216.GC5774@pathway.suse.cz> <20160413183309.GG3676@htj.duckdns.org> <20160413192313.GA30260@dhcp22.suse.cz> <20160414175055.GA6794@cmpxchg.org> <20160415191719.GK12583@htj.duckdns.org> <20160417120747.GC21757@dhcp22.suse.cz> <20160420212922.GH4775@htj.duckdns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160420212922.GH4775@htj.duckdns.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 20-04-16 17:29:22, Tejun Heo wrote: > Hello, Michal. > > On Sun, Apr 17, 2016 at 08:07:48AM -0400, Michal Hocko wrote: [...] > > I liked your proposal when mem_cgroup_move_charge would be called from a > > context which doesn't hold the problematic rwsem much more. Would that > > be too intrusive for the stable backport? > > Yeah, I'm working on the fix but let's plug this one first as it seems > really easy to trigger. I got a couple off-list reports (in and > outside fb) of this triggering. Sure, I think we can use this for an immediate workaround. Nevertheless we want to have a full fix and do not rely on this being the only problem. I would eventually like to reintroduce the draining later when we have a better fix because even though this is not a correctness problem I think we should try hard to not leave anything behind. That being said: Acked-by: Michal Hocko -- Michal Hocko SUSE Labs