From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754611AbcFPNgS (ORCPT ); Thu, 16 Jun 2016 09:36:18 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:39561 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753861AbcFPNgQ (ORCPT ); Thu, 16 Jun 2016 09:36:16 -0400 To: mhocko@kernel.org Cc: linux-mm@kvack.org, rientjes@google.com, oleg@redhat.com, vdavydov@parallels.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, penguin-kernel@I-love.SAKURA.ne.jp Subject: Re: [PATCH 10/10] mm, oom: hide mm which is shared with kthread or global init From: Tetsuo Handa 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> <20160609154156.GG24777@dhcp22.suse.cz> <201606162215.IIE64528.FFFLHOJQtSOOVM@I-love.SAKURA.ne.jp> In-Reply-To: <201606162215.IIE64528.FFFLHOJQtSOOVM@I-love.SAKURA.ne.jp> Message-Id: <201606162236.DDG82865.OFOtSLMJFVQHOF@I-love.SAKURA.ne.jp> X-Mailer: Winbiff [Version 2.51 PL2] X-Accept-Language: ja,en,zh Date: Thu, 16 Jun 2016 22:36:09 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Tetsuo Handa wrote: > But this is not safe for CONFIG_MMU=y kernels as well. > can_oom_reap == false means that oom_reap_task() will not be called. > It is possible that the TIF_MEMDIE thread falls into > > atomic_read(&task->signal->oom_victims) > 0 && find_lock_task_mm(task) == NULL > > situation. We are still risking OOM livelock. We must somehow clear (or ignore) > TIF_MEMDIE even if oom_reap_task() is not called. Oops. mmput() from exit_mm() does not block in that case. So, we won't livelock here. > > Can't we apply http://lkml.kernel.org/r/201606102323.BCC73478.FtOJHFQMSVFLOO@I-love.SAKURA.ne.jp now? > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f71.google.com (mail-it0-f71.google.com [209.85.214.71]) by kanga.kvack.org (Postfix) with ESMTP id DA11B6B0005 for ; Thu, 16 Jun 2016 09:37:27 -0400 (EDT) Received: by mail-it0-f71.google.com with SMTP id d71so88578805ith.1 for ; Thu, 16 Jun 2016 06:37:27 -0700 (PDT) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [2001:e42:101:1:202:181:97:72]) by mx.google.com with ESMTPS id l67si12997456oib.95.2016.06.16.06.37.26 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 16 Jun 2016 06:37:27 -0700 (PDT) Subject: Re: [PATCH 10/10] mm, oom: hide mm which is shared with kthread or global init From: Tetsuo Handa 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> <20160609154156.GG24777@dhcp22.suse.cz> <201606162215.IIE64528.FFFLHOJQtSOOVM@I-love.SAKURA.ne.jp> In-Reply-To: <201606162215.IIE64528.FFFLHOJQtSOOVM@I-love.SAKURA.ne.jp> Message-Id: <201606162236.DDG82865.OFOtSLMJFVQHOF@I-love.SAKURA.ne.jp> Date: Thu, 16 Jun 2016 22:36:09 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: mhocko@kernel.org Cc: linux-mm@kvack.org, rientjes@google.com, oleg@redhat.com, vdavydov@parallels.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, penguin-kernel@I-love.SAKURA.ne.jp Tetsuo Handa wrote: > But this is not safe for CONFIG_MMU=y kernels as well. > can_oom_reap == false means that oom_reap_task() will not be called. > It is possible that the TIF_MEMDIE thread falls into > > atomic_read(&task->signal->oom_victims) > 0 && find_lock_task_mm(task) == NULL > > situation. We are still risking OOM livelock. We must somehow clear (or ignore) > TIF_MEMDIE even if oom_reap_task() is not called. Oops. mmput() from exit_mm() does not block in that case. So, we won't livelock here. > > Can't we apply http://lkml.kernel.org/r/201606102323.BCC73478.FtOJHFQMSVFLOO@I-love.SAKURA.ne.jp now? > -- 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