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From: Dmitry Vyukov <dvyukov@google.com>
To: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: syzbot <syzbot+bf78a74f82c1cf19069e@syzkaller.appspotmail.com>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	David Miller <davem@davemloft.net>,
	David Ahern <dsahern@gmail.com>, Florian Westphal <fw@strlen.de>,
	Jiri Benc <jbenc@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
	Xin Long <lucien.xin@gmail.com>,
	mschiffer@universe-factory.net, netdev <netdev@vger.kernel.org>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	Vladislav Yasevich <vyasevich@gmail.com>
Subject: Re: INFO: task hung in ip6gre_exit_batch_net
Date: Tue, 5 Jun 2018 11:36:30 +0200	[thread overview]
Message-ID: <CACT4Y+bPrdK7xSeUk=pgVVyaseDZUAvArBA4bEWPsUi7CE3EVw@mail.gmail.com> (raw)
In-Reply-To: <cf729ce5-7948-d475-1b20-f31fb313df88@virtuozzo.com>

On Tue, Jun 5, 2018 at 11:03 AM, Kirill Tkhai <ktkhai@virtuozzo.com> wrote:
> Hi, Dmirty!
>
> On 04.06.2018 18:22, Dmitry Vyukov wrote:
>> On Mon, Jun 4, 2018 at 5:03 PM, syzbot
>> <syzbot+bf78a74f82c1cf19069e@syzkaller.appspotmail.com> wrote:
>>> Hello,
>>>
>>> syzbot found the following crash on:
>>>
>>> HEAD commit:    bc2dbc5420e8 Merge branch 'akpm' (patches from Andrew)
>>> git tree:       upstream
>>> console output: https://syzkaller.appspot.com/x/log.txt?x=164e42b7800000
>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=982e2df1b9e60b02
>>> dashboard link: https://syzkaller.appspot.com/bug?extid=bf78a74f82c1cf19069e
>>> compiler:       gcc (GCC) 8.0.1 20180413 (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+bf78a74f82c1cf19069e@syzkaller.appspotmail.com
>>
>> Another hang on rtnl lock:
>>
>> #syz dup: INFO: task hung in netdev_run_todo
>>
>> May be related to "unregister_netdevice: waiting for DEV to become free":
>> https://syzkaller.appspot.com/bug?id=1a97a5bd119fd97995f752819fd87840ab9479a9

netdev_wait_allrefs does not hold rtnl lock during waiting, so it must
be something different.


>> Any other explanations for massive hangs on rtnl lock for minutes?
>
> To exclude the situation, when a task exists with rtnl_mutex held:
>
> would the pr_warn() from print_held_locks_bug() be included in the console output
> if they appear?

Yes, everything containing "WARNING:" is detected as bug.

  reply	other threads:[~2018-06-05  9:36 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-04 15:03 syzbot
2018-06-04 15:22 ` Dmitry Vyukov
2018-06-05  9:03   ` Kirill Tkhai
2018-06-05  9:36     ` Dmitry Vyukov [this message]
2018-06-05 13:55       ` Kirill Tkhai
2018-06-07 18:23         ` Dmitry Vyukov
2018-06-07 18:54           ` Kirill Tkhai
2018-06-07 19:03             ` Dmitry Vyukov
2018-06-07 19:59               ` Kirill Tkhai
2018-06-08  8:18                 ` Dmitry Vyukov
2018-06-08  8:31                   ` Kirill Tkhai
2018-06-08  8:38                     ` Dmitry Vyukov
2018-06-08  8:43                       ` Kirill Tkhai

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