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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7BB66C433F5 for ; Fri, 8 Apr 2022 09:36:40 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F1EC66B0071; Fri, 8 Apr 2022 05:36:39 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id ECE676B0072; Fri, 8 Apr 2022 05:36:39 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D95D26B0074; Fri, 8 Apr 2022 05:36:39 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0052.hostedemail.com [216.40.44.52]) by kanga.kvack.org (Postfix) with ESMTP id C6B836B0071 for ; Fri, 8 Apr 2022 05:36:39 -0400 (EDT) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 6AF8B1846F77C for ; Fri, 8 Apr 2022 09:36:39 +0000 (UTC) X-FDA: 79333206918.23.19D55A4 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by imf24.hostedemail.com (Postfix) with ESMTP id D9E98180002 for ; Fri, 8 Apr 2022 09:36:38 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 86642210FC; Fri, 8 Apr 2022 09:36:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1649410597; h=from:from:reply-to: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=95tOhAK/1hRdesCKfizRfrMyglbamAOnmgAf+q60Zdk=; b=Uh8D+SNCT/P3uEEpbfCfYvbhA48dAm/GoQe8WQZF1/MqmX0o9K18NBdwtvif2B5QcF/vlw jXy0BhEiwyvuumPF1hQrc3tNtStwM0GUGUGckmd8QomBlJSDvnSfauD1Q6+dGdP9hhe02k IOlKP64NREeSCTqNGvPnpwL/Fn2OkMY= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 18681A3B82; Fri, 8 Apr 2022 09:36:37 +0000 (UTC) Date: Fri, 8 Apr 2022 11:36:36 +0200 From: Michal Hocko To: Nico Pache Cc: Thomas Gleixner , Peter Zijlstra , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Rafael Aquini , Waiman Long , Baoquan He , Christoph von Recklinghausen , Don Dutile , "Herton R . Krzesinski" , David Rientjes , Andrea Arcangeli , Andrew Morton , Davidlohr Bueso , Ingo Molnar , Joel Savitz , Darren Hart , stable@kernel.org Subject: Re: [PATCH v8] oom_kill.c: futex: Don't OOM reap the VMA containing the robust_list_head Message-ID: References: <20220408032809.3696798-1-npache@redhat.com> <20220408081549.GM2731@worktop.programming.kicks-ass.net> <87tub4j7hg.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: 5tt54i7hs4rngwzct415xfokxhqdo6jc Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=Uh8D+SNC; spf=pass (imf24.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.28 as permitted sender) smtp.mailfrom=mhocko@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: D9E98180002 X-HE-Tag: 1649410598-912480 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000119, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri 08-04-22 04:52:33, Nico Pache wrote: [...] > In a heavily contended CPU with high memory pressure the delay may also > lead to other processes unnecessarily OOMing. Let me just comment on this part because there is likely a confusion inlved. Delaying the oom_reaper _cannot_ lead to additional OOM killing because the the oom killing is throttled by existence of a preexisting OOM victim. In other words as long as there is an alive victim no further victims are not selected and the oom killer backs off. The oom_repaer will hide the alive oom victim after it is processed. The longer the delay will be the longer an oom victim can block a further progress but it cannot really cause unnecessary OOMing. -- Michal Hocko SUSE Labs