From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: ebiederm@xmission.com (Eric W. Biederman) To: Dmitry Vyukov Cc: "J. Bruce Fields" , Stephen Rothwell , syzbot , jlayton@kernel.org, linux-fsdevel , LKML , syzkaller-bugs , Al Viro References: <0000000000007f59610573509684@google.com> <000000000000f4136d0573512103@google.com> <20180814191129.GN7906@fieldses.org> <87o9e3gdtg.fsf@xmission.com> Date: Fri, 17 Aug 2018 13:22:31 -0500 In-Reply-To: (Dmitry Vyukov's message of "Fri, 17 Aug 2018 10:26:58 -0700") Message-ID: <87d0ugc0pk.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: general protection fault in send_sigurg_to_task Sender: linux-kernel-owner@vger.kernel.org List-ID: 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. Eric