From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f200.google.com (mail-qk0-f200.google.com [209.85.220.200]) by kanga.kvack.org (Postfix) with ESMTP id 4A2756B0005 for ; Tue, 31 May 2016 17:48:27 -0400 (EDT) Received: by mail-qk0-f200.google.com with SMTP id q79so2494164qke.3 for ; Tue, 31 May 2016 14:48:27 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id x10si32560449qtc.54.2016.05.31.14.48.26 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 31 May 2016 14:48:26 -0700 (PDT) Date: Tue, 31 May 2016 23:48:23 +0200 From: Oleg Nesterov Subject: Re: [PATCH 5/6] mm, oom: kill all tasks sharing the mm Message-ID: <20160531214823.GC26582@redhat.com> References: <1464613556-16708-1-git-send-email-mhocko@kernel.org> <1464613556-16708-6-git-send-email-mhocko@kernel.org> <20160530181816.GA25480@redhat.com> <20160531074318.GD26128@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160531074318.GD26128@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: linux-mm@kvack.org, Tetsuo Handa , David Rientjes , Vladimir Davydov , Andrew Morton , LKML On 05/31, Michal Hocko wrote: > > On Mon 30-05-16 20:18:16, Oleg Nesterov wrote: > > > > perhaps the is_global_init() == T case needs a warning too? the previous changes > > take care about vfork() from /sbin/init, so the only reason we can see it true > > is that /sbin/init shares the memory with a memory hog... Nevermind, forget. > > I have another two patches waiting for this to settle and one of them > adds a warning to that path. Good, > > This is a bit off-topic, but perhaps we can also change the PF_KTHREAD check later. > > Of course we should not try to kill this kthread, but can_oom_reap can be true in > > this case. A kernel thread which does use_mm() should handle the errors correctly > > if (say) get_user() fails because we unmap the memory. > > I was worried that the kernel thread would see a zero page so this could > lead to a data corruption. We can't avoid this anyway. use_mm(victim->mm) can be called after we decide to kill the victim. So I think that we should always ignore kthreads, and in task_will_free_mem() too. But let me repeat, I agree we should discuss this later, I am not trying to suggest this change right now. Oleg. -- 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