From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932536AbcFIPmF (ORCPT ); Thu, 9 Jun 2016 11:42:05 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:34795 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752464AbcFIPmC (ORCPT ); Thu, 9 Jun 2016 11:42:02 -0400 Date: Thu, 9 Jun 2016 17:41:57 +0200 From: Michal Hocko To: Tetsuo Handa Cc: linux-mm@kvack.org, rientjes@google.com, oleg@redhat.com, vdavydov@parallels.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 10/10] mm, oom: hide mm which is shared with kthread or global init Message-ID: <20160609154156.GG24777@dhcp22.suse.cz> References: <1465473137-22531-1-git-send-email-mhocko@kernel.org> <1465473137-22531-11-git-send-email-mhocko@kernel.org> <201606100015.HBB65678.LSOFFJOFMQHOVt@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201606100015.HBB65678.LSOFFJOFMQHOVt@I-love.SAKURA.ne.jp> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 10-06-16 00:15:18, Tetsuo Handa wrote: [...] > Nobody will set MMF_OOM_REAPED flag if can_oom_reap == true on > CONFIG_MMU=n kernel. If a TIF_MEMDIE thread in CONFIG_MMU=n kernel > is blocked before exit_oom_victim() in exit_mm() from do_exit() is > called, the system will lock up. This is not handled in the patch > nor explained in the changelog. I have made it clear several times that !CONFIG_MMU is not a target of this patch series nor other OOM changes because I am not convinced issues which we are trying to solve are real on those platforms. I am not really sure what you are trying to achieve now with these !CONFIG_MMU remarks but if you see _real_ regressions for those configurations please describe them. This generic statements when CONFIG_MMU implications are put into !CONFIG_MMU context are not really useful. If there are possible OOM killer deadlocks without this series then adding these patches shouldn't make them worse. E.g. this particular patch is basically a noop for !CONFIG_MMU because use_mm() is MMU specific. It is also highly improbable that a task would share mm with init... -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f70.google.com (mail-lf0-f70.google.com [209.85.215.70]) by kanga.kvack.org (Postfix) with ESMTP id F2DA96B007E for ; Thu, 9 Jun 2016 11:42:00 -0400 (EDT) Received: by mail-lf0-f70.google.com with SMTP id u74so19475540lff.0 for ; Thu, 09 Jun 2016 08:42:00 -0700 (PDT) Received: from mail-wm0-f68.google.com (mail-wm0-f68.google.com. [74.125.82.68]) by mx.google.com with ESMTPS id n129si9178734wmn.117.2016.06.09.08.41.59 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 09 Jun 2016 08:41:59 -0700 (PDT) Received: by mail-wm0-f68.google.com with SMTP id m124so11636959wme.3 for ; Thu, 09 Jun 2016 08:41:59 -0700 (PDT) Date: Thu, 9 Jun 2016 17:41:57 +0200 From: Michal Hocko Subject: Re: [PATCH 10/10] mm, oom: hide mm which is shared with kthread or global init Message-ID: <20160609154156.GG24777@dhcp22.suse.cz> References: <1465473137-22531-1-git-send-email-mhocko@kernel.org> <1465473137-22531-11-git-send-email-mhocko@kernel.org> <201606100015.HBB65678.LSOFFJOFMQHOVt@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201606100015.HBB65678.LSOFFJOFMQHOVt@I-love.SAKURA.ne.jp> Sender: owner-linux-mm@kvack.org List-ID: To: Tetsuo Handa Cc: linux-mm@kvack.org, rientjes@google.com, oleg@redhat.com, vdavydov@parallels.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org On Fri 10-06-16 00:15:18, Tetsuo Handa wrote: [...] > Nobody will set MMF_OOM_REAPED flag if can_oom_reap == true on > CONFIG_MMU=n kernel. If a TIF_MEMDIE thread in CONFIG_MMU=n kernel > is blocked before exit_oom_victim() in exit_mm() from do_exit() is > called, the system will lock up. This is not handled in the patch > nor explained in the changelog. I have made it clear several times that !CONFIG_MMU is not a target of this patch series nor other OOM changes because I am not convinced issues which we are trying to solve are real on those platforms. I am not really sure what you are trying to achieve now with these !CONFIG_MMU remarks but if you see _real_ regressions for those configurations please describe them. This generic statements when CONFIG_MMU implications are put into !CONFIG_MMU context are not really useful. If there are possible OOM killer deadlocks without this series then adding these patches shouldn't make them worse. E.g. this particular patch is basically a noop for !CONFIG_MMU because use_mm() is MMU specific. It is also highly improbable that a task would share mm with init... -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org