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[2620:137:e000::1:20]) by mx.google.com with ESMTP id r2-20020a50c002000000b00418c2b5be00si895996edb.226.2022.04.08.08.29.59; Fri, 08 Apr 2022 08:30:24 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@suse.com header.s=susede1 header.b=Uh8D+SNC; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=suse.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231368AbiDHJip (ORCPT + 99 others); Fri, 8 Apr 2022 05:38:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47294 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229825AbiDHJio (ORCPT ); Fri, 8 Apr 2022 05:38:44 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 740301CB02 for ; Fri, 8 Apr 2022 02:36:38 -0700 (PDT) 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-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_PASS,T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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