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=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 EB4EEC46475 for ; Tue, 23 Oct 2018 05:57:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AB1D520671 for ; Tue, 23 Oct 2018 05:57:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AB1D520671 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.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 S1727508AbeJWOSu (ORCPT ); Tue, 23 Oct 2018 10:18:50 -0400 Received: from mx2.suse.de ([195.135.220.15]:37122 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726764AbeJWOSu (ORCPT ); Tue, 23 Oct 2018 10:18:50 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id E5C14ACB5; Tue, 23 Oct 2018 05:56:56 +0000 (UTC) Date: Tue, 23 Oct 2018 07:56:55 +0200 From: Michal Hocko To: David Rientjes Cc: Tetsuo Handa , 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, Andrew Morton , Sergey Senozhatsky , Petr Mladek , Sergey Senozhatsky , Steven Rostedt Subject: Re: [PATCH] mm,oom: Use timeout based back off. Message-ID: <20181023055655.GM18839@dhcp22.suse.cz> 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-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 22-10-18 14:11:10, David Rientjes wrote: [...] > 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. These are some pretty strong words for a code that tends to work for most users out there. I do not remember any bug reports except for artificial stress tests or your quite unspecific claims about absolutely catastrophic impact which is not backed by any specific details. I have shown interest in addressing as many issues as possible but I absolutely detest getting back to the previous state with an indeterministic pile of heuristic which were lockup prone and basically unmaintainable. Going around with timeouts and potentially export them to userspace might sound attractive for the simplicity but this should be absolutely the last resort when a proper solution is too complex (from a code or maintainability POV). I do not believe we have reached that state yet. -- Michal Hocko SUSE Labs