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, URIBL_BLOCKED,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 9E07EC43441 for ; Wed, 14 Nov 2018 10:16:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6D5E32145D for ; Wed, 14 Nov 2018 10:16:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6D5E32145D 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 S1732631AbeKNUSo (ORCPT ); Wed, 14 Nov 2018 15:18:44 -0500 Received: from mx2.suse.de ([195.135.220.15]:43244 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727704AbeKNUSn (ORCPT ); Wed, 14 Nov 2018 15:18:43 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id EF621AED4; Wed, 14 Nov 2018 10:16:05 +0000 (UTC) Date: Wed, 14 Nov 2018 11:16:04 +0100 From: Michal Hocko To: Tetsuo Handa Cc: David Rientjes , Roman Gushchin , linux-mm@kvack.org, Andrew Morton , LKML Subject: Re: [RFC PATCH v2 0/3] oom: rework oom_reaper vs. exit_mmap handoff Message-ID: <20181114101604.GM23419@dhcp22.suse.cz> References: <20181025082403.3806-1-mhocko@kernel.org> <20181108093224.GS27423@dhcp22.suse.cz> <9dfd5c87-ae48-8ffb-fbc6-706d627658ff@i-love.sakura.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9dfd5c87-ae48-8ffb-fbc6-706d627658ff@i-love.sakura.ne.jp> 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 Wed 14-11-18 18:46:13, Tetsuo Handa wrote: [...] > There is always an invisible lock called "scheduling priority". You can't > leave the MMF_OOM_SKIP to the exit path. Your approach is not ready for > handling the worst case. And that problem is all over the memory reclaim. You can get starved to death and block other resources. And the memory reclaim is not the only one. This is a fundamental issue of the locking without priority inheritance and other real time techniques. > Nacked-by: Tetsuo Handa OK, if your whole point is to block any changes into this area unless it is your solution to be merged then I guess I will just push patches through with your explicit Nack on them. Your feedback was far fetched at many times has distracted the discussion way too often. This is especially sad because your testing and review was really helpful at times. I do not really have energy to argue the same set of arguments over and over again. You have expressed unwillingness to understand the overall picture several times. You do not care about a long term maintenance burden of this code which is quite tricky already and refuse to understand the cost/benefit part. If this series works for the workload reported by David I will simply push it through and let Andrew decide. If there is a lack of feedback I will just keep it around because it seems that most users do not care about these corner cases anyway. -- Michal Hocko SUSE Labs