From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0CBDBECDE44 for ; Wed, 24 Oct 2018 22:55:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9D4052075D for ; Wed, 24 Oct 2018 22:54:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9D4052075D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726686AbeJYHY4 (ORCPT ); Thu, 25 Oct 2018 03:24:56 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:47420 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725829AbeJYHY4 (ORCPT ); Thu, 25 Oct 2018 03:24:56 -0400 Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 145651814; Wed, 24 Oct 2018 22:54:56 +0000 (UTC) Date: Wed, 24 Oct 2018 15:54:54 -0700 From: Andrew Morton 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 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> X-Mailer: Sylpheed 3.6.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.