From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f46.google.com (mail-oi0-f46.google.com [209.85.218.46]) by kanga.kvack.org (Postfix) with ESMTP id D9A876B0069 for ; Thu, 9 Oct 2014 00:42:44 -0400 (EDT) Received: by mail-oi0-f46.google.com with SMTP id h136so1051059oig.19 for ; Wed, 08 Oct 2014 21:42:44 -0700 (PDT) Received: from mail-oi0-x236.google.com (mail-oi0-x236.google.com [2607:f8b0:4003:c06::236]) by mx.google.com with ESMTPS id v7si1212659oep.101.2014.10.08.21.42.43 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 08 Oct 2014 21:42:43 -0700 (PDT) Received: by mail-oi0-f54.google.com with SMTP id v63so1016131oia.41 for ; Wed, 08 Oct 2014 21:42:43 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1412777266-8251-1-git-send-email-mhocko@suse.cz> References: <1412777266-8251-1-git-send-email-mhocko@suse.cz> Date: Wed, 8 Oct 2014 21:42:43 -0700 Message-ID: Subject: Re: [PATCH 0/3] OOM vs. freezer interaction fixes From: Cong Wang Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Andrew Morton , "\\Rafael J. Wysocki\\" , David Rientjes , Tejun Heo , LKML , linux-mm@kvack.org Hi, Michal On Wed, Oct 8, 2014 at 7:07 AM, Michal Hocko wrote: > Hi Andrew, Rafael, > > this has been originally discussed here [1] but didn't lead anywhere AFAICS > so I would like to resurrect them. > Thanks a lot for taking them for me! I was busy with some networking stuffs and also actually waiting for Rafael's response to your patch. > The first and third patch are regression fixes and they are a stable > material IMO. The second patch is a simple cleanup. > > The 1st patch is fixing a regression introduced in 3.3 since when OOM > killer is not able to kill any frozen task and live lock as a result. > The fix gets us back to the 3.2. As it turned out during the discussion [2] > this was still not 100% sufficient and that's why we need the 3rd patch. > > I was thinking about the proper 1st vs. 3rd patch ordering because > the 1st patch basically opens a race window fixed by the later patch. > Original patch from Cong Wang has covered this by cgroup_freezing(current) > check in should_thaw_current(). But this approach still suffers from OOM > vs. PM freezer interaction (OOM killer would still live lock waiting for a > PM frozen task this time). It should be very rare OOM happens during PM frozen. > > So I think the most straight forward way is to address only OOM vs. > frozen task interaction in the first patch, mark it for stable 3.3+ and > leave the race to a separate follow up patch which is applicable to > stable 3.2+ (before a3201227f803 made it inefficient). > > Switching 1st and 3rd patches would make some sense as well but then > it might end up even more confusing because we would be fixing a > non-existent issue in upstream first... > Agreed. Up to you, I have no strong opinions here. :) Again, thanks! -- 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