From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f48.google.com (mail-pa0-f48.google.com [209.85.220.48]) by kanga.kvack.org (Postfix) with ESMTP id 5F9506B0009 for ; Thu, 28 Jan 2016 17:26:54 -0500 (EST) Received: by mail-pa0-f48.google.com with SMTP id yy13so29788418pab.3 for ; Thu, 28 Jan 2016 14:26:54 -0800 (PST) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [2001:e42:101:1:202:181:97:72]) by mx.google.com with ESMTPS id 130si19463929pfb.3.2016.01.28.14.26.53 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 28 Jan 2016 14:26:53 -0800 (PST) Subject: Re: [PATCH 3/2] oom: clear TIF_MEMDIE after oom_reaper managed to unmap the address space From: Tetsuo Handa References: <1452516120-5535-1-git-send-email-mhocko@kernel.org> <201601181335.JJD69226.JHVQSMFOFOFtOL@I-love.SAKURA.ne.jp> <20160126163823.GG27563@dhcp22.suse.cz> <201601282024.JBG90615.JLFQOSFFVOMHtO@I-love.SAKURA.ne.jp> <20160128215121.GE621@dhcp22.suse.cz> In-Reply-To: <20160128215121.GE621@dhcp22.suse.cz> Message-Id: <201601290726.GGC12497.OSQJVtMFFOHOLF@I-love.SAKURA.ne.jp> Date: Fri, 29 Jan 2016 07:26:39 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: mhocko@kernel.org Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, mgorman@suse.de, rientjes@google.com, torvalds@linux-foundation.org, oleg@redhat.com, hughd@google.com, andrea@kernel.org, riel@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Michal Hocko wrote: > On Thu 28-01-16 20:24:36, Tetsuo Handa wrote: > [...] > > I like the OOM reaper approach but I can't agree on merging the OOM reaper > > without providing a guaranteed last resort at the same time. If you do want > > to start the OOM reaper as simple as possible (without being bothered by > > a lot of possible corner cases), please pursue a guaranteed last resort > > at the same time. > > I am getting tired of this level of argumentation. oom_reaper in its > current form is a step forward. I have acknowledged there are possible > improvements doable on top but I do not see them necessary for the core > part being merged. I am not trying to rush this in because I am very > well aware of how subtle and complex all the interactions might be. > So please stop your "we must have it all at once" attitude. This is > nothing we have to rush in. We are not talking about a regression which > has to be absolutely fixed in few days. I'm not asking you to merge a perfect version of oom_reaper from the beginning. I know it is too difficult. Instead, I'm asking you to allow using timeout based approaches (shown below) as temporarily workaround because there are environments which cannot wait for oom_reaper to become enough reliable. Would you please reply to the thread which proposed a guaranteed last resort (shown below)? Tetsuo Handa wrote: > I consider phases for managing system-wide OOM events as follows. > > (1) Design and use a system with appropriate memory capacity in mind. > > (2) When (1) failed, the OOM killer is invoked. The OOM killer selects > an OOM victim and allow that victim access to memory reserves by > setting TIF_MEMDIE to it. > > (3) When (2) did not solve the OOM condition, start allowing all tasks > access to memory reserves by your approach. > > (4) When (3) did not solve the OOM condition, start selecting more OOM > victims by my approach. > > (5) When (4) did not solve the OOM condition, trigger the kernel panic. > -- 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