From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id 2477C6B0005 for ; Thu, 29 Mar 2018 10:50:58 -0400 (EDT) Received: by mail-wr0-f200.google.com with SMTP id q10so2902136wre.6 for ; Thu, 29 Mar 2018 07:50:58 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id u44si5018666wrf.112.2018.03.29.07.50.56 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 29 Mar 2018 07:50:56 -0700 (PDT) Date: Thu, 29 Mar 2018 16:50:55 +0200 From: Michal Hocko Subject: Re: [PATCH] mm,oom: Do not unfreeze OOM victim thread. Message-ID: <20180329145055.GH31039@dhcp22.suse.cz> References: <1522334218-4268-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1522334218-4268-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> Sender: owner-linux-mm@kvack.org List-ID: To: Tetsuo Handa Cc: linux-pm@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Pavel Machek , "Rafael J. Wysocki" On Thu 29-03-18 23:36:58, Tetsuo Handa wrote: > Currently, mark_oom_victim() calls __thaw_task() on the OOM victim > threads and freezing_slow_path() unfreezes the OOM victim thread. > But I think this exceptional behavior makes little sense nowadays. Well, I would like to see this happen because it would allow more changes on top. E.g. get rid of TIF_MEMDIE finally. But I am not really sure we are there yet. OOM reaper is useful tool but it still cannot help in some cases (shared memory, a lot of metadata allocated on behalf of the process etc...). Considering that the freezing can be an unprivileged operation (think cgroup freezer) then I am worried that one container can cause the global oom killer and hide oom victims to the fridge and spill over to other containers. Maybe I am overly paranoid and this scenario is not even all that interesting but I would like to hear a better justification which explains all these cases rather than "we have oom reaper so we are good to go" rationale. -- Michal Hocko SUSE Labs