From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f70.google.com (mail-wm0-f70.google.com [74.125.82.70]) by kanga.kvack.org (Postfix) with ESMTP id 7FA0F6B0005 for ; Tue, 30 Jan 2018 04:57:42 -0500 (EST) Received: by mail-wm0-f70.google.com with SMTP id e74so2861134wmg.0 for ; Tue, 30 Jan 2018 01:57:42 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id n15si8469334wmc.126.2018.01.30.01.57.41 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 30 Jan 2018 01:57:41 -0800 (PST) Date: Tue, 30 Jan 2018 10:57:39 +0100 From: Michal Hocko Subject: Re: [netfilter-core] kernel panic: Out of memory and no killable processes... (2) Message-ID: <20180130095739.GV21609@dhcp22.suse.cz> References: <201801290020.w0T0KK8V015938@www262.sakura.ne.jp> <20180129072357.GD5906@breakpoint.cc> <20180129082649.sysf57wlp7i7ltb2@node.shutemov.name> <20180129165722.GF5906@breakpoint.cc> <20180129182811.fze4vrb5zd5cojmr@node.shutemov.name> <20180129223522.GG5906@breakpoint.cc> <20180130075226.GL21609@dhcp22.suse.cz> <20180130081127.GH5906@breakpoint.cc> <20180130082817.cbax5qj4mxancx4b@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Dmitry Vyukov Cc: "Kirill A. Shutemov" , Florian Westphal , Tetsuo Handa , David Miller , netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev , Andrea Arcangeli , Yang Shi , syzkaller-bugs@googlegroups.com, LKML , Ingo Molnar , Linux-MM , David Rientjes , Andrew Morton , guro@fb.com, "Kirill A. Shutemov" On Tue 30-01-18 10:02:34, Dmitry Vyukov wrote: > On Tue, Jan 30, 2018 at 9:28 AM, Kirill A. Shutemov > wrote: > > On Tue, Jan 30, 2018 at 09:11:27AM +0100, Florian Westphal wrote: > >> Michal Hocko wrote: > >> > On Mon 29-01-18 23:35:22, Florian Westphal wrote: > >> > > Kirill A. Shutemov wrote: > >> > [...] > >> > > > I hate what I'm saying, but I guess we need some tunable here. > >> > > > Not sure what exactly. > >> > > > >> > > Would memcg help? > >> > > >> > That really depends. I would have to check whether vmalloc path obeys > >> > __GFP_ACCOUNT (I suspect it does except for page tables allocations but > >> > that shouldn't be a big deal). But then the other potential problem is > >> > the life time of the xt_table_info (or other potentially large) data > >> > structures. Are they bound to any process life time. > >> > >> No. > > > > Well, IIUC they bound to net namespace life time, so killing all > > proccesses in the namespace would help to get memory back. :) > > ... unless the namespace is mounted into file system. > > Let's start with NOWARN as that's what kernel generally uses for > allocations with user-controllable size. ENOMEM is roughly as > informative as the WARNING message in this case. You want __GFP_NORETRY but that is not _fully_ supported by kvmalloc right now. More specifically kvmalloc doesn't guanratee that the request will not trigger the OOM killer (like regular __GFP_NORETRY). This is because of internal vmalloc restrictions. If you are however OK to simply bail out in most cases then __GFP_NORETRY should work reasonably fine. > I think we also need to consider setting up memory cgroup for > syzkaller test processes (we do RLIMIT_AS, but that's weak). Well, this is not about syzkaller, it merely pointed out a potential DoS... And that has to be addressed somehow. -- 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