From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EEB64C4321D for ; Fri, 17 Aug 2018 18:38:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9B27121A31 for ; Fri, 17 Aug 2018 18:38:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9B27121A31 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=fieldses.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728085AbeHQVnI (ORCPT ); Fri, 17 Aug 2018 17:43:08 -0400 Received: from fieldses.org ([173.255.197.46]:37232 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726888AbeHQVnH (ORCPT ); Fri, 17 Aug 2018 17:43:07 -0400 Received: by fieldses.org (Postfix, from userid 2815) id C5601BD9; Fri, 17 Aug 2018 14:38:40 -0400 (EDT) Date: Fri, 17 Aug 2018 14:38:40 -0400 From: "J. Bruce Fields" To: "Eric W. Biederman" Cc: Dmitry Vyukov , Stephen Rothwell , syzbot , jlayton@kernel.org, linux-fsdevel , LKML , syzkaller-bugs , Al Viro Subject: Re: general protection fault in send_sigurg_to_task Message-ID: <20180817183840.GA12582@fieldses.org> References: <0000000000007f59610573509684@google.com> <000000000000f4136d0573512103@google.com> <20180814191129.GN7906@fieldses.org> <87o9e3gdtg.fsf@xmission.com> <87d0ugc0pk.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87d0ugc0pk.fsf@xmission.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 17, 2018 at 01:22:31PM -0500, Eric W. Biederman wrote: > Dmitry Vyukov writes: > > > On Wed, Aug 15, 2018 at 9:01 PM, Eric W. Biederman > > wrote: > >> Dmitry Vyukov writes: > >> > >>> On Tue, Aug 14, 2018 at 12:11 PM, J. Bruce Fields wrote: > >>>> On Mon, Aug 13, 2018 at 06:33:02AM -0700, syzbot wrote: > >>>>> syzbot has found a reproducer for the following crash on: > >>>>> > >>>>> HEAD commit: 5ed5da74de9e Add linux-next specific files for 20180813 > >>>>> git tree: linux-next > >>>> > >>>> I fetched linux-next but don't have 5ed5da74de9e. > >>> > >>> Hi Bruce, > >>> > >>> +Stephen for the disappeared linux-next commit. > >>> > >>> On the dashboard link you can see that it also happened on a more > >>> recent commit 4e8b38549b50459a22573d756dd1f4e1963c2a8d that I do see > >>> now in linux-next. > >>> > >>>> I'm also not sure why I'm on the cc for this. > >>> > >>> You've been pointed to by "./scripts/get_maintainer.pl -f fs/fcntl.c" > >>> as maintainer of the file, which is the file where the crash happened. > >> > >> You need to use your reproducer to bisect and find the commit that > >> caused this. Otherwise you will continue to confuse people. > >> > >> get_maintainer.pl is not a good target for automated reporting > >> especially against linux-next. > > > > Hi Eric, > > > > We will do bisection. > > But I afraid it will not give perfect attribution for a number of reasons: > > - broken build/boot which happens sometimes for prolonged periods and > > prohibits bisection > > - elusive races that can't be reproduced reliably and thus bisection > > can give wrong results > > - bugs introduced too long ago (e.g. author email is not even valid today) > > - reproducers triggering more than 1 bug, so base bisection commit > > can actually be for another bug, or bisection can switch from one bug > > to another > > - last but not least, bugs without reproducers > > Bisection will add useful information to the bug report, but it will > > not necessary make attribution better than it is now. > > > > Do you have more examples where bugs were misreported? From what I see > > current attrition works well. There are episodic fallouts, but well, > > nothing is perfect in this world. Humans don't bisect frequently and > > misreport sometimes. I think we just need to re-route bugs in such > > cases. > > I have yet to see syzbot make a good report. Especially against > linux-next. It did result in a fix (thanks!): https://lkml.org/lkml/2018/8/16/47 So I'd call that a better-than-nothing report if not a great report? There's some value just in timeliness; it's a lot easier for me to fix a bug that I introduced in the last few days, with the change still fresh in my mind.... --b.