Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753930Ab2JVMxW (ORCPT ); Mon, 22 Oct 2012 08:53:22 -0400 Received: from mx2.parallels.com ([64.131.90.16]:50307 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753823Ab2JVMxU (ORCPT ); Mon, 22 Oct 2012 08:53:20 -0400 Message-ID: <50854199.9020804@parallels.com> Date: Mon, 22 Oct 2012 16:52:41 +0400 From: Glauber Costa User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121016 Thunderbird/16.0.1 MIME-Version: 1.0 To: Michal Hocko CC: David Rientjes , , , Mel Gorman , Tejun Heo , Andrew Morton , Johannes Weiner , KAMEZAWA Hiroyuki , Christoph Lameter , Pekka Enberg , , , Pekka Enberg Subject: Re: [PATCH v5 06/14] memcg: kmem controller infrastructure References: <1350382611-20579-1-git-send-email-glommer@parallels.com> <1350382611-20579-7-git-send-email-glommer@parallels.com> <507FCA90.8060307@parallels.com> <5081269B.5000603@parallels.com> <50853D47.4030409@parallels.com> <20121022125124.GA8344@dhcp22.suse.cz> In-Reply-To: <20121022125124.GA8344@dhcp22.suse.cz> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2030 Lines: 54 On 10/22/2012 04:51 PM, Michal Hocko wrote: > [Sorry for the late reply] > > On Mon 22-10-12 16:34:15, Glauber Costa wrote: >> On 10/20/2012 12:34 AM, David Rientjes wrote: >>> On Fri, 19 Oct 2012, Glauber Costa wrote: >>> >>>>>>> What about gfp & __GFP_FS? >>>>>>> >>>>>> >>>>>> Do you intend to prevent or allow OOM under that flag? I personally >>>>>> think that anything that accepts to be OOM-killed should have GFP_WAIT >>>>>> set, so that ought to be enough. >>>>>> >>>>> >>>>> The oom killer in the page allocator cannot trigger without __GFP_FS >>>>> because direct reclaim has little chance of being very successful and >>>>> thus we end up needlessly killing processes, and that tends to happen >>>>> quite a bit if we dont check for it. Seems like this would also happen >>>>> with memcg if mem_cgroup_reclaim() has a large probability of failing? >>>>> >>>> >>>> I can indeed see tests for GFP_FS in some key locations in mm/ before >>>> calling the OOM Killer. >>>> >>>> Should I test for GFP_IO as well? >>> >>> It's not really necessary, if __GFP_IO isn't set then it wouldn't make >>> sense for __GFP_FS to be set. >>> >>>> If the idea is preventing OOM to >>>> trigger for allocations that can write their pages back, how would you >>>> feel about the following test: >>>> >>>> may_oom = (gfp & GFP_KERNEL) && !(gfp & __GFP_NORETRY) ? >>>> >>> >>> I would simply copy the logic from the page allocator and only trigger oom >>> for __GFP_FS and !__GFP_NORETRY. >>> >> >> That seems reasonable to me. Michal ? > > Yes it makes sense to be consistent with the global case. While we are > at it, do we need to consider PF_DUMPCORE resp. !__GFP_NOFAIL? > at least from kmem, GFP_NOFAIL will not reach this codepath. We will ditch it to the root in memcontrol.h -- 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/