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 AA268C433EF for ; Thu, 7 Oct 2021 10:48:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 94730610C7 for ; Thu, 7 Oct 2021 10:48:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240985AbhJGKty (ORCPT ); Thu, 7 Oct 2021 06:49:54 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:39134 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241030AbhJGKtw (ORCPT ); Thu, 7 Oct 2021 06:49:52 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 6E67F225E5; Thu, 7 Oct 2021 10:47:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1633603677; 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=mcWJYTrnWNl9H+OH2VlIp+D8YPfOLYhVh6/tuPxFG6E=; b=XLa1+jaF+yRNiuxXt1smb033r6qPpmsLlMjdHa2HtGvwNEuK5fBVKAPThwB7m1bk/Vi7dT BZszrjex1rujp9HJ6R4DaGydGClIQPMBl2Dv4sFPEbaM6g9lRavt9Cywa9zVGxqqlQogRE vEL107lCkhZivdYEgi/rxv64AAdFOmU= 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 EDCE8A3B85; Thu, 7 Oct 2021 10:47:56 +0000 (UTC) Date: Thu, 7 Oct 2021 12:47:53 +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, kernel@openvz.org Subject: Re: [PATCH mm v2] vmalloc: back off when the current task is OOM-killed Message-ID: References: <83efc664-3a65-2adb-d7c4-2885784cf109@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <83efc664-3a65-2adb-d7c4-2885784cf109@virtuozzo.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 05-10-21 16:52:40, 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 will allow also interrupting a user space requist which happens to trigger a large vmalloc, hence the reason for going for fatal_signal_pending rather than oom specific condition. > 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. __GFP_NOFAIL semantic is explicitly not supported for vmalloc. > Signed-off-by: Vasily Averin Acked-by: Michal Hocko I would keep it sitting in the linux-next for some time to sort out potential fallouts and have them fixed before this one gets merged. Thanks! > --- > v2: tsk_is_oom_victim() check replaced by fatal_signal_pending(current), > removed check inside __alloc_pages_bulk(), > according to feedback from mhocko@. > Updated patch description. > --- > mm/vmalloc.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index d77830ff604c..71706f5447f0 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -2860,6 +2860,9 @@ vm_area_alloc_pages(gfp_t gfp, int nid, > struct page *page; > int i; > > + if (fatal_signal_pending(current)) > + break; > + > page = alloc_pages_node(nid, gfp, order); > if (unlikely(!page)) > break; > -- > 2.31.1 -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: [PATCH mm v2] vmalloc: back off when the current task is OOM-killed Date: Thu, 7 Oct 2021 12:47:53 +0200 Message-ID: References: <83efc664-3a65-2adb-d7c4-2885784cf109@virtuozzo.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1633603677; 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=mcWJYTrnWNl9H+OH2VlIp+D8YPfOLYhVh6/tuPxFG6E=; b=XLa1+jaF+yRNiuxXt1smb033r6qPpmsLlMjdHa2HtGvwNEuK5fBVKAPThwB7m1bk/Vi7dT BZszrjex1rujp9HJ6R4DaGydGClIQPMBl2Dv4sFPEbaM6g9lRavt9Cywa9zVGxqqlQogRE vEL107lCkhZivdYEgi/rxv64AAdFOmU= Content-Disposition: inline In-Reply-To: <83efc664-3a65-2adb-d7c4-2885784cf109-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org> List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Vasily Averin Cc: Johannes Weiner , Vladimir Davydov , Andrew Morton , Tetsuo Handa , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kernel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org On Tue 05-10-21 16:52:40, 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 will allow also interrupting a user space requist which happens to trigger a large vmalloc, hence the reason for going for fatal_signal_pending rather than oom specific condition. > 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. __GFP_NOFAIL semantic is explicitly not supported for vmalloc. > Signed-off-by: Vasily Averin Acked-by: Michal Hocko I would keep it sitting in the linux-next for some time to sort out potential fallouts and have them fixed before this one gets merged. Thanks! > --- > v2: tsk_is_oom_victim() check replaced by fatal_signal_pending(current), > removed check inside __alloc_pages_bulk(), > according to feedback from mhocko@. > Updated patch description. > --- > mm/vmalloc.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index d77830ff604c..71706f5447f0 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -2860,6 +2860,9 @@ vm_area_alloc_pages(gfp_t gfp, int nid, > struct page *page; > int i; > > + if (fatal_signal_pending(current)) > + break; > + > page = alloc_pages_node(nid, gfp, order); > if (unlikely(!page)) > break; > -- > 2.31.1 -- Michal Hocko SUSE Labs