From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751436AbeA2H1H (ORCPT ); Mon, 29 Jan 2018 02:27:07 -0500 Received: from Chamillionaire.breakpoint.cc ([146.0.238.67]:36660 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751330AbeA2H1G (ORCPT ); Mon, 29 Jan 2018 02:27:06 -0500 Date: Mon, 29 Jan 2018 08:23:57 +0100 From: Florian Westphal To: Tetsuo Handa Cc: davem@davemloft.net, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, aarcange@redhat.com, yang.s@alibaba-inc.com, mhocko@suse.com, syzkaller-bugs@googlegroups.com, linux-kernel@vger.kernel.org, mingo@kernel.org, linux-mm@kvack.org, rientjes@google.com, akpm@linux-foundation.org, guro@fb.com, kirill.shutemov@linux.intel.com Subject: Re: [netfilter-core] kernel panic: Out of memory and no killable processes... (2) Message-ID: <20180129072357.GD5906@breakpoint.cc> References: <001a1144b0caee2e8c0563d9de0a@google.com> <201801290020.w0T0KK8V015938@www262.sakura.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201801290020.w0T0KK8V015938@www262.sakura.ne.jp> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Tetsuo Handa wrote: > syzbot wrote: > > syzbot hit the following crash on net-next commit > > 6bb46bc57c8e9ce947cc605e555b7204b44d2b10 (Fri Jan 26 16:00:23 2018 +0000) > > Merge branch 'cxgb4-fix-dump-collection-when-firmware-crashed' > > > > C reproducer is attached. > > syzkaller reproducer is attached. > > Raw console output is attached. > > compiler: gcc (GCC) 7.1.1 20170620 > > .config is attached. > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+8630e35fc7287b392aac@syzkaller.appspotmail.com > > It will help syzbot understand when the bug is fixed. See footer for > > details. > > If you forward the report, please keep this part and the footer. > > > > [ 3685] 0 3685 17821 1 184320 0 0 sshd > > [ 3692] 0 3692 4376 0 32768 0 0 > > syzkaller025682 > > [ 3695] 0 3695 4376 0 36864 0 0 > > syzkaller025682 > > Kernel panic - not syncing: Out of memory and no killable processes... > > > > This sounds like too huge vmalloc() request where size is controlled by userspace. Right. Before eacd86ca3b036e55e172b7279f101cef4a6ff3a4 this used info = __vmalloc(sz, GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY, would it help to re-add that? > vmalloc() once became killable by commit 5d17a73a2ebeb8d1 ("vmalloc: back > off when the current task is killed") but then became unkillable by commit > b8c8a338f75e052d ("Revert "vmalloc: back off when the current task is > killed""). Therefore, we can't handle this problem from MM side. > Please consider adding some limit from networking side. I don't know what "some limit" would be. I would prefer if there was a way to supress OOM Killer in first place so we can just -ENOMEM user. AFAIU NOWARN|NORETRY does that, so I would propose to just read-add it?