From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f50.google.com (mail-la0-f50.google.com [209.85.215.50]) by kanga.kvack.org (Postfix) with ESMTP id 1C1926B0069 for ; Wed, 8 Oct 2014 17:51:25 -0400 (EDT) Received: by mail-la0-f50.google.com with SMTP id s18so9363949lam.37 for ; Wed, 08 Oct 2014 14:51:25 -0700 (PDT) Received: from v094114.home.net.pl (v094114.home.net.pl. [79.96.170.134]) by mx.google.com with SMTP id pi7si1889052lbb.15.2014.10.08.14.51.24 for ; Wed, 08 Oct 2014 14:51:25 -0700 (PDT) From: "Rafael J. Wysocki" Subject: Re: [PATCH 0/3] OOM vs. freezer interaction fixes Date: Thu, 09 Oct 2014 00:11:33 +0200 Message-ID: <2107592.sy6uXko7kW@vostro.rjw.lan> In-Reply-To: <1412777266-8251-1-git-send-email-mhocko@suse.cz> References: <1412777266-8251-1-git-send-email-mhocko@suse.cz> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Andrew Morton , Cong Wang , David Rientjes , Tejun Heo , LKML , linux-mm@kvack.org, Linux PM list On Wednesday, October 08, 2014 04:07:43 PM 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. OK So any chance to CC linux-pm too next time? There are people on that list who may be interested as well and are not in the CC directly either. > 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). > > 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... > > --- > [1] http://marc.info/?l=linux-kernel&m=140986986423092 > [2] http://marc.info/?l=linux-kernel&m=141074263721166 > I'm fine with the approach in general, but I need to stare at patch 3 for a little bit longer before I ACK it. Which may not happen really soon as I'll be rather busy on Thu/Fri and then I'll be traveling to the LPC/LCEU next week. -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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