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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 0C011C433F5 for ; Mon, 13 Sep 2021 08:53:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EA33260FBF for ; Mon, 13 Sep 2021 08:53:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238190AbhIMIyx (ORCPT ); Mon, 13 Sep 2021 04:54:53 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:52178 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237801AbhIMIyw (ORCPT ); Mon, 13 Sep 2021 04:54:52 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 2BD0B1FFAB; Mon, 13 Sep 2021 08:53:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1631523216; 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=kchB+aw0FiEHbBgAGvT8V7qxriNJ47RlDUOFmHHFsR8=; b=kGFs+4yihN3fLKCge3xceliBWYVrbZxUw+0zsqAVcpn5mgLH/8I1UfL/abne0cLcIy5BfQ yKP5rIR4r7OfrZo/Xkn8Xzn3z6WA/qAVONP+h+kArUvhUxk8NrP4LW4K8CNZ0VD72+YMAX HXBEC49PkTTooA+LPItgSLJerNg1ol0= 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 DBC99A3B93; Mon, 13 Sep 2021 08:53:35 +0000 (UTC) Date: Mon, 13 Sep 2021 10:53:35 +0200 From: Michal Hocko To: Vasily Averin Cc: Johannes Weiner , Vladimir Davydov , Andrew Morton , Tetsuo Handa , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH memcg] memcg: prohibit unconditional exceeding the limit of dying tasks Message-ID: References: <5b06a490-55bc-a6a0-6c85-690254f86fad@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5b06a490-55bc-a6a0-6c85-690254f86fad@virtuozzo.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 10-09-21 15:39:28, Vasily Averin wrote: > The kernel currently allows dying tasks to exceed the memcg limits. > The allocation is expected to be the last one and the occupied memory > will be freed soon. > This is not always true because it can be part of the huge vmalloc > allocation. Allowed once, they will repeat over and over again. > Moreover lifetime of the allocated object can differ from > In addition the lifetime of the dying task. > Multiple such allocations running concurrently can not only overuse > the memcg limit, but can lead to a global out of memory and, > in the worst case, cause the host to panic. > > Signed-off-by: Vasily Averin > --- > mm/memcontrol.c | 23 +++++------------------ > 1 file changed, 5 insertions(+), 18 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 389b5766e74f..67195fcfbddf 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1834,6 +1834,9 @@ static enum oom_status mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int > return OOM_ASYNC; > } > > + if (should_force_charge()) > + return OOM_SKIPPED; mem_cgroup_out_of_memory already check for the bypass, now you are duplicating that check with a different answer to the caller. This is really messy. One of the two has to go away. -- Michal Hocko SUSE Labs