From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) by kanga.kvack.org (Postfix) with ESMTP id 8431D6B0003 for ; Wed, 24 Oct 2018 18:54:58 -0400 (EDT) Received: by mail-pg1-f200.google.com with SMTP id x8-v6so4131576pgp.9 for ; Wed, 24 Oct 2018 15:54:58 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id n26-v6si6252062pfe.116.2018.10.24.15.54.56 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 24 Oct 2018 15:54:57 -0700 (PDT) Date: Wed, 24 Oct 2018 15:54:54 -0700 From: Andrew Morton Subject: Re: [PATCH] mm,oom: Use timeout based back off. Message-Id: <20181024155454.4e63191fbfaa0441f2e62f56@linux-foundation.org> In-Reply-To: References: <1540033021-3258-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Tetsuo Handa , Michal Hocko , Johannes Weiner , linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, guro@fb.com, kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org, yang.s@alibaba-inc.com, Sergey Senozhatsky , Petr Mladek , Sergey Senozhatsky , Steven Rostedt On Mon, 22 Oct 2018 14:11:10 -0700 (PDT) David Rientjes wrote: > > Michal has been refusing timeout based approach, but I don't think this > > is something we have to be frayed around the edge about possibility of > > overlooking races/bugs just because Michal does not want to use timeout. > > I believe that timeout based back off is the only approach we can use > > for now. > > > > I've proposed patches that have been running for months in a production > environment that make the oom killer useful without serially killing many > processes unnecessarily. At this point, it is *much* easier to just fork > the oom killer logic rather than continue to invest time into fixing it in > Linux. That's unfortunate because I'm sure you realize how problematic > the current implementation is, how abusive it is, and have seen its > effects yourself. I admire your persistance in trying to fix the issues > surrounding the oom killer, but have come to the conclusion that forking > it is a much better use of time. The oom killer is, I think, fairly standalone and it shouldn't be too hard to add the infrastructure to make the whole thing pluggable. At runtime, not at build time. But it is a last resort - it will result in fragmented effort and difficult decisions for everyone regarding which should be used. There has been a lot of heat and noise and confusion and handwaving in all of this. What we're crying out for is simple testcases which everyone can run. Find a problem, write the testcase, distribute that. Develop a solution for that testcase then move on to the next one.