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From: Randy Dunlap <rdunlap@infradead.org>
To: paulmck@kernel.org, Dmitry Vyukov <dvyukov@google.com>
Cc: syzbot <syzbot+792dec47d693ccdc05a0@syzkaller.appspotmail.com>,
	Josh Triplett <josh@joshtriplett.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	rcu@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: linux-next build error (8)
Date: Fri, 20 Mar 2020 09:34:13 -0700
Message-ID: <ef4ec876-8b78-3f4a-a3fb-6dbc038e92df@infradead.org> (raw)
In-Reply-To: <20200320162650.GP3199@paulmck-ThinkPad-P72>

On 3/20/20 9:26 AM, Paul E. McKenney wrote:
> On Fri, Mar 20, 2020 at 04:38:54PM +0100, Dmitry Vyukov wrote:
>> On Thu, Mar 19, 2020 at 4:04 PM Paul E. McKenney <paulmck@kernel.org> wrote:
>>> On Thu, Mar 19, 2020 at 08:13:35AM +0100, Dmitry Vyukov wrote:
>>>> On Wed, Mar 18, 2020 at 10:41 PM Paul E. McKenney <paulmck@kernel.org> wrote:
>>>>> On Wed, Mar 18, 2020 at 09:54:07PM +0100, Dmitry Vyukov wrote:
>>>>>> On Wed, Mar 18, 2020 at 5:57 PM syzbot
>>>>>> <syzbot+792dec47d693ccdc05a0@syzkaller.appspotmail.com> wrote:
>>>>>>> Hello,
>>>>>>> syzbot found the following crash on:
>>>>>>> HEAD commit:    47780d78 Add linux-next specific files for 20200318
>>>>>>> git tree:       linux-next
>>>>>>> console output: https://syzkaller.appspot.com/x/log.txt?x=14228745e00000
>>>>>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=b68b7b89ad96c62a
>>>>>>> dashboard link: https://syzkaller.appspot.com/bug?extid=792dec47d693ccdc05a0
>>>>>>> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
>>>>>>> Unfortunately, I don't have any reproducer for this crash yet.
>>>>>>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>>>>>>> Reported-by: syzbot+792dec47d693ccdc05a0@syzkaller.appspotmail.com
>>>>>>> kernel/rcu/tasks.h:1070:37: error: 'rcu_tasks_rude' undeclared (first use in this function); did you mean 'rcu_tasks_qs'?
>>>>>> +rcu maintainers
>>>>> The kbuild test robot beat you to it, and apologies for the hassle.
>>>>> Fixed in -rcu on current "dev" branch.
>>>> If the kernel dev process would only have a way to avoid dups from all
>>>> test systems...
>>> I do significant testing before pushing to -next, but triggering this
>>> one requires a combination of Kconfig options that are incompatible
>>> with rcutorture.  :-/
>>> I suppose one strategy would be to give kbuild test robot some time before
>>> passing to -next, but they seem to sometimes get too far behind for me to
>>> be willing to wait that long.  So my current approach is to push my "dev"
>>> branch, run moderate rcutorture testing (three hours per scenario other
>>> than TREE10, which gets only one hour), and if that passes, push to -next.
>>> I suppose that I could push to -next only commits that are at least three
>>> days old or some such.  But I get in trouble pushing to -next too slowly
>>> as often as I get in trouble pushing too quickly, so I suspect that my
>>> current approach is in roughly the right place.
>>>> Now we need to spend time and deal with it. What has fixed it?
>>> It is fixed by commit c6ef38e4d595 ("rcu-tasks: Add RCU tasks to
>>> rcutorture writer stall output") and some of its predecessors.
>>> Perhaps more useful to you, this commit is included in next-20200319
>>> from the -next tree.  ;-)
>> Let's tell syzbot about the fix:
>> #syz fix: rcu-tasks: Add RCU tasks to rcutorture writer stall output
>> I think what you are doing is the best possible option in the current situation.
>> I don't think requiring all human maintainers to do more manual
>> repetitive work, which is not well defined and even without a way to
>> really require something from them is scalable nor reliable nor the
>> right approach.
> Thank you, and I do greatly appreciate the automation!
>> We would consume something like LKGR [1] if it existed for the kernel.
>> But it would require tighter integration of testing systems with
>> kernel dev processes, or of course throwing more manual labor at it to
>> track all uncoordinated testing systems and publishing LKGR tags.
>> [1] https://chromium.googlesource.com/chromiumos/docs/+/master/glossary.md
> At my end, it is pretty quick and easy to detect duplicate notifications
> of the same bug, so the current situation isn't causing me undue distress.

Yeah, I saw the same build error and did-not-report it since it was
already reported.  :)


  reply index

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <000000000000ae2ab305a123f146@google.com>
2020-03-18 20:54 ` Dmitry Vyukov
2020-03-18 21:41   ` Paul E. McKenney
2020-03-19  7:13     ` Dmitry Vyukov
2020-03-19 15:04       ` Paul E. McKenney
2020-03-20 15:38         ` Dmitry Vyukov
2020-03-20 16:26           ` Paul E. McKenney
2020-03-20 16:34             ` Randy Dunlap [this message]
2020-03-20 17:04               ` Paul E. McKenney
2020-03-20 13:08       ` Dan Carpenter
2020-03-20 15:42         ` Dmitry Vyukov

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