From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f199.google.com (mail-wr0-f199.google.com [209.85.128.199]) by kanga.kvack.org (Postfix) with ESMTP id CA9C46B0006 for ; Tue, 30 Jan 2018 09:01:07 -0500 (EST) Received: by mail-wr0-f199.google.com with SMTP id d17so2017820wrc.9 for ; Tue, 30 Jan 2018 06:01:07 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id e123si9559474wma.186.2018.01.30.06.01.06 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 30 Jan 2018 06:01:06 -0800 (PST) Date: Tue, 30 Jan 2018 15:01:04 +0100 From: Michal Hocko Subject: Re: [netfilter-core] kernel panic: Out of memory and no killable processes... (2) Message-ID: <20180130140104.GE21609@dhcp22.suse.cz> References: <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> <20180130095739.GV21609@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180130095739.GV21609@dhcp22.suse.cz> 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 10:57:39, Michal Hocko wrote: > 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. So how about this? ---