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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 038D5C5517A for ; Mon, 9 Nov 2020 07:37:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 97FC9206CB for ; Mon, 9 Nov 2020 07:37:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="oIVN8Jyb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729557AbgKIHhL (ORCPT ); Mon, 9 Nov 2020 02:37:11 -0500 Received: from mx2.suse.de ([195.135.220.15]:57480 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728038AbgKIHhK (ORCPT ); Mon, 9 Nov 2020 02:37:10 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1604907428; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=g/PynSuV8B/34816mCj4wqI5WVsbyHQQr0XxJVvTNIo=; b=oIVN8JybJ7CZI+XPTUH5xh4Sj04Ey0hAzBc33gWEdd4MyEAYPWjESz/sTnXsvi+J1sl+gw rpmRgH1ZF+qMLV9l/+xfTPDYmR7IUGRokWdRDH73Xng6h/qOELhPnyetYNj1PbbA4UbvKP 494+FKvPnHfBw2BlPSplltmBKF5qbc4= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C985AABAE; Mon, 9 Nov 2020 07:37:08 +0000 (UTC) Date: Mon, 9 Nov 2020 08:37:06 +0100 From: Michal Hocko To: Minchan Kim Cc: Andrew Morton , LKML , linux-mm Subject: Re: [PATCH] mm: introduce oom_kill_disable sysctl knob Message-ID: <20201109073706.GA12240@dhcp22.suse.cz> References: <20201106203238.1375577-1-minchan@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201106203238.1375577-1-minchan@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 06-11-20 12:32:38, Minchan Kim wrote: > It's hard to have some tests to be supposed to work under heavy > memory pressure(e.g., injecting some memory hogger) because > out-of-memory killer easily kicks out one of processes so system > is broken or system loses the memory pressure state since it has > plenty of free memory soon so. I do not follow the reasoning here. So you want to test for a close to no memory available situation and the oom killer stands in the way because it puts a relief? > Even though we could mark existing process's oom_adj to -1000, > it couldn't cover upcoming processes to be forked for the job. Why? > This knob is handy to keep system memory pressure. This sounds like a very dubious reason to introduce a knob to cripple the system. I can see some reason to control the oom handling policy because the effect of the oom killer is really disruptive but a global on/off switch sounds like a too coarse interface. Really what kind of production environment would ever go with oom killer disabled completely? -- Michal Hocko SUSE Labs