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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B9C9CC433EF for ; Fri, 8 Apr 2022 09:59:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234040AbiDHKBb (ORCPT ); Fri, 8 Apr 2022 06:01:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43626 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231820AbiDHKBa (ORCPT ); Fri, 8 Apr 2022 06:01:30 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3EFF7280 for ; Fri, 8 Apr 2022 02:59:27 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id B55C01F861; Fri, 8 Apr 2022 09:59:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1649411965; 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=y0PsAMl4/noPyoCGgn90zWHMgOGH/EHQX9wluEN2ZzE=; b=qvI+nJfthhLgm4/0Bg/SPiYcBdNPjZoWaTOy7+IuAL+tqk+N4AJf3/eggurasamK3fRgH3 PdtmguuffZ/riaOvGEqgmhSQnzGF1/c36IlZ+YqfZxtAG8yDZWdH30qTm68LzpNkwdbK9l hB2XMMR1OSUE8fYBtEO5ZWN8HxR90Y0= 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 5B2E5A3B96; Fri, 8 Apr 2022 09:59:25 +0000 (UTC) Date: Fri, 8 Apr 2022 11:59:25 +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> <676fb197-d045-c537-c1f7-e18320a6d15f@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <676fb197-d045-c537-c1f7-e18320a6d15f@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 08-04-22 05:40:09, Nico Pache wrote: > > > On 4/8/22 05:36, Michal Hocko wrote: > > 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. > Is it not the case that if we delay an OOM, the amount of available memory stays > limited and other processes that are allocating memory can become OOM candidates? No. Have a look at oom_evaluate_task (tsk_is_oom_victim check). -- Michal Hocko SUSE Labs