From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f43.google.com (mail-pa0-f43.google.com [209.85.220.43]) by kanga.kvack.org (Postfix) with ESMTP id C6DB36B0253 for ; Mon, 24 Aug 2015 17:10:12 -0400 (EDT) Received: by pacti10 with SMTP id ti10so32274684pac.0 for ; Mon, 24 Aug 2015 14:10:12 -0700 (PDT) Received: from mail-pa0-x22e.google.com (mail-pa0-x22e.google.com. [2607:f8b0:400e:c03::22e]) by mx.google.com with ESMTPS id s3si29386737pdh.219.2015.08.24.14.10.11 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 24 Aug 2015 14:10:12 -0700 (PDT) Received: by pacti10 with SMTP id ti10so32274384pac.0 for ; Mon, 24 Aug 2015 14:10:11 -0700 (PDT) Date: Mon, 24 Aug 2015 14:10:10 -0700 (PDT) From: David Rientjes Subject: Re: [patch -mm] mm, oom: add global access to memory reserves on livelock In-Reply-To: <201508212229.GIC00036.tVFMQLOOFJOFSH@I-love.SAKURA.ne.jp> Message-ID: References: <20150821081745.GG23723@dhcp22.suse.cz> <201508212229.GIC00036.tVFMQLOOFJOFSH@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Tetsuo Handa Cc: mhocko@kernel.org, akpm@linux-foundation.org, mgorman@suse.de, hannes@cmpxchg.org, oleg@redhat.com, vbabka@suse.cz, linux-kernel@vger.kernel.org, linux-mm@kvack.org On Fri, 21 Aug 2015, Tetsuo Handa wrote: > Why can't we think about choosing more OOM victims instead of granting access > to memory reserves? > We have no indication of which thread is holding a mutex that would need to be killed, so we'd be randomly killing processes waiting for forward progress. A worst-case scenario would be the thread is OOM_DISABLE and we kill every process on the system needlessly. This problem obviously occurs often enough that killing all userspace isnt going to be a viable solution. > Also, SysRq might not be usable under OOM because workqueues can get stuck. > The panic_on_oom_timeout was first proposed using a workqueue but was > updated to use a timer because there is no guarantee that workqueues work > as expected under OOM. > I don't know anything about a panic_on_oom_timeout, but panicking would only be a reasonable action if memory reserves were fully depleted. That could easily be dealt with in the page allocator so there's no timeout involved. -- 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