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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1F9BC433F5 for ; Tue, 5 Oct 2021 14:01:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB66E614C8 for ; Tue, 5 Oct 2021 14:01:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235579AbhJEOCr (ORCPT ); Tue, 5 Oct 2021 10:02:47 -0400 Received: from relay.sw.ru ([185.231.240.75]:33224 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235734AbhJEOB6 (ORCPT ); Tue, 5 Oct 2021 10:01:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=virtuozzo.com; s=relay; h=Content-Type:MIME-Version:Date:Message-ID:From: Subject; bh=Ed1xsp8lTrCrW27f1J4vH57YUUHw0q5d5pOknhx3OhI=; b=dlg9oxUUL9ON2P7NI FPotPplwDm0pN9yRtW6uR6cImMJygenILBxuPbXKwHqwkrR4Xsm7PM70jOo1HQjb2RHaPSRAf8sNN 43yHyfSpf5DwKO2Vlo3GxDZ1spky8JiojDNWL2JimTvGua0MPzIGIEIvEsmMJTyevyQJZawJhUsLI =; Received: from [10.93.0.56] by relay.sw.ru with esmtp (Exim 4.94.2) (envelope-from ) id 1mXkzF-0054Yv-SG; Tue, 05 Oct 2021 17:00:05 +0300 Subject: Re: [PATCH mm v2] vmalloc: back off when the current task is OOM-killed From: Vasily Averin To: Michal Hocko Cc: Johannes Weiner , Vladimir Davydov , Andrew Morton , Tetsuo Handa , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel@openvz.org References: <83efc664-3a65-2adb-d7c4-2885784cf109@virtuozzo.com> Message-ID: Date: Tue, 5 Oct 2021 17:00:05 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <83efc664-3a65-2adb-d7c4-2885784cf109@virtuozzo.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/5/21 4:52 PM, Vasily Averin wrote: > Huge vmalloc allocation on heavy loaded node can lead to a global > memory shortage. Task called vmalloc can have worst badness and > be selected by OOM-killer, however taken fatal signal does not > interrupt allocation cycle. Vmalloc repeat page allocaions > again and again, exacerbating the crisis and consuming the memory > freed up by another killed tasks. > > After a successful completion of the allocation procedure, a fatal > signal will be processed and task will be destroyed finally. > However it may not release the consumed memory, since the allocated > object may have a lifetime unrelated to the completed task. > In the worst case, this can lead to the host will panic > due to "Out of memory and no killable processes..." > > This patch allows OOM-killer to break vmalloc cycle, makes OOM more > effective and avoid host panic. It does not check oom condition directly, > however, and breaks page allocation cycle when fatal signal was received. > > This may trigger some hidden problems, when caller does not handle > vmalloc failures, or when rollaback after failed vmalloc calls own > vmallocs inside. However all of these scenarios are incorrect: > vmalloc does not guarantee successful allocation, it has never been called > with __GFP_NOFAIL and threfore either should not be used for any rollbacks > or should handle such errors correctly and not lead to critical > failures. I briefly checked this patch together with v3 memcg: prohibit unconditional exceeding the limit of dying tasks over v5.15-rc4. I executed LTP on host, all oom, cgroup and memcg tests was successfully finished. and then experimented with memcg limited LXC containers. I did not noticed any troubles on my test node. Thank you, Vasily Averin