From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vk0-f70.google.com (mail-vk0-f70.google.com [209.85.213.70]) by kanga.kvack.org (Postfix) with ESMTP id 1A40C6B0005 for ; Sun, 3 Jul 2016 17:18:02 -0400 (EDT) Received: by mail-vk0-f70.google.com with SMTP id v6so415369171vkb.2 for ; Sun, 03 Jul 2016 14:18:02 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id q72si66272qka.110.2016.07.03.14.18.01 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 03 Jul 2016 14:18:01 -0700 (PDT) Date: Mon, 4 Jul 2016 00:17:55 +0300 From: "Michael S. Tsirkin" Subject: Re: [RFC PATCH 5/6] vhost, mm: make sure that oom_reaper doesn't reap memory read by vhost Message-ID: <20160703215250-mutt-send-email-mst@redhat.com> References: <1467365190-24640-1-git-send-email-mhocko@kernel.org> <1467365190-24640-6-git-send-email-mhocko@kernel.org> <20160703134719.GA28492@redhat.com> <20160703140904.GA26908@redhat.com> <20160703151829.GA28667@redhat.com> <20160703182254-mutt-send-email-mst@redhat.com> <20160703164723.GA30151@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160703164723.GA30151@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Oleg Nesterov Cc: Michal Hocko , linux-mm@kvack.org, Andrew Morton , Tetsuo Handa , David Rientjes , Vladimir Davydov , Michal Hocko On Sun, Jul 03, 2016 at 06:47:23PM +0200, Oleg Nesterov wrote: > On 07/03, Michael S. Tsirkin wrote: > > > > On Sun, Jul 03, 2016 at 05:18:29PM +0200, Oleg Nesterov wrote: > > > > > > Well, we are going to kill all tasks which share this memory. I mean, ->mm. > > > If "sharing memory with another task" means, say, a file, then this memory > > > won't be unmapped (if shared). > > > > > > So let me ask again... Suppose, say, QEMU does VHOST_SET_OWNER and then we > > > unmap its (anonymous/non-shared) memory. Who else's memory can be corrupted? > > > > As you say, I mean anyone who shares memory with QEMU through a file. > > And in this case vhost_worker() reads the anonymous memory of QEMU process, > not the memory which can be shared with another task, correct? > > And if QEMU simply crashes, this can't affect anyone who shares memory with > QEMU through a file, yes? > > Oleg. Well no - the VM memory is not always anonymous memory. It can be an mmaped file. -- MST -- 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