From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f200.google.com (mail-qt0-f200.google.com [209.85.216.200]) by kanga.kvack.org (Postfix) with ESMTP id D4EFB6B0253 for ; Fri, 12 Aug 2016 12:05:16 -0400 (EDT) Received: by mail-qt0-f200.google.com with SMTP id 101so1357108qtb.0 for ; Fri, 12 Aug 2016 09:05:16 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id o4si3701568qkf.61.2016.08.12.09.05.16 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 12 Aug 2016 09:05:16 -0700 (PDT) Date: Fri, 12 Aug 2016 18:05:12 +0200 From: Oleg Nesterov Subject: Re: [PATCH 09/10] vhost, mm: make sure that oom_reaper doesn't reap memory read by vhost Message-ID: <20160812160512.GA30930@redhat.com> References: <1469734954-31247-10-git-send-email-mhocko@kernel.org> <20160728233359-mutt-send-email-mst@kernel.org> <20160729060422.GA5504@dhcp22.suse.cz> <20160729161039-mutt-send-email-mst@kernel.org> <20160729133529.GE8031@dhcp22.suse.cz> <20160729205620-mutt-send-email-mst@kernel.org> <20160731094438.GA24353@dhcp22.suse.cz> <20160812094236.GF3639@dhcp22.suse.cz> <20160812132140.GA776@redhat.com> <20160812144157.GL3639@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160812144157.GL3639@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: "Paul E. McKenney" , linux-mm@kvack.org, Andrew Morton , Tetsuo Handa , David Rientjes , Vladimir Davydov , "Michael S. Tsirkin" On 08/12, Michal Hocko wrote: > > On Fri 12-08-16 15:21:41, Oleg Nesterov wrote: > > > Whats really interesting is that I still fail to understand do we really > > need this hack, iiuc you are not sure too, and Michael didn't bother to > > explain why a bogus zero from anon memory is worse than other problems > > caused by SIGKKILL from oom-kill.c. > > Yes, I admit that I am not familiar with the vhost memory usage model so > I can only speculate. But the mere fact that the mm is bound to a device > fd Yes, and I already tried to complain. This doesn't look right in any case. > which can be passed over to a different process makes me worried. > This means that the mm is basically isolated from the original process > until the last fd is closed which is under control of the process which > holds it. The mm can still be access during that time from the vhost > worker. And I guess this is exactly where the problem lies. Agreed. 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