From: Sasha Levin <levinsasha928@gmail.com>
To: Jiri Slaby <jslaby@suse.cz>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: tty_ldisc_hangup: waiting (init) for ttyS0 took too long, but we keep waiting...
Date: Tue, 13 Nov 2012 15:16:35 -0500 [thread overview]
Message-ID: <50A2AAA3.7080303@gmail.com> (raw)
In-Reply-To: <50A2A6DE.4030305@suse.cz>
On 11/13/2012 03:00 PM, Jiri Slaby wrote:
> On 11/10/2012 05:46 AM, Sasha Levin wrote:
>> Hi all,
>>
>> I'm seeing lots of cases when my fuzzing session hangs with a message that
>> starts with:
>>
>> [ 104.670841] tty_ldisc_hangup: waiting (init) for ttyS0 took too long, but we keep waiting...
>>
>> And continues with a hung task spew, such as:
>>
>> [ 242.990329] INFO: task init:1 blocked for more than 120 seconds.
>> [ 242.990955] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> [ 242.991527] init D ffff8800132c0000 3408 1 0 0x00000002
>> [ 242.992156] ffff88001327dc18 0000000000000002 ffff88001327dbd8 ffffffff81152f95
>> [ 242.992784] ffff880013280000 ffff88001327dfd8 ffff88001327dfd8 ffff88001327dfd8
>> [ 242.994200] ffff8800132c0000 ffff880013280000 ffff880013280910 7fffffffffffffff
>> [ 242.995780] Call Trace:
>> [ 242.996429] [<ffffffff81152f95>] ? sched_clock_local+0x25/0xa0
>> [ 242.997704] [<ffffffff83bdf065>] schedule+0x55/0x60
>> [ 242.999864] [<ffffffff83bdcea5>] schedule_timeout+0x45/0x360
>> [ 243.008415] [<ffffffff83be077d>] ? _raw_spin_unlock_irqrestore+0x5d/0xb0
>> [ 243.008980] [<ffffffff8117ff8d>] ? trace_hardirqs_on+0xd/0x10
>> [ 243.009756] [<ffffffff83be07a4>] ? _raw_spin_unlock_irqrestore+0x84/0xb0
>> [ 243.010662] [<ffffffff81139e17>] ? prepare_to_wait+0x77/0x90
>> [ 243.011452] [<ffffffff81bb7a56>] tty_ldisc_wait_idle.isra.6+0x76/0xb0
>> [ 243.012314] [<ffffffff81139ff0>] ? abort_exclusive_wait+0xb0/0xb0
>> [ 243.013157] [<ffffffff81bb83bb>] tty_ldisc_hangup+0x1cb/0x320
>> [ 243.013927] [<ffffffff81baf712>] ? __tty_hangup+0x122/0x430
>> [ 243.014687] [<ffffffff81baf71a>] __tty_hangup+0x12a/0x430
>> [ 243.015410] [<ffffffff83be07a4>] ? _raw_spin_unlock_irqrestore+0x84/0xb0
>> [ 243.016321] [<ffffffff81bb187a>] disassociate_ctty+0x6a/0x230
>> [ 243.017112] [<ffffffff811107fa>] do_exit+0x4ea/0xbd0
>> [ 243.017793] [<ffffffff811ccc65>] ? rcu_user_exit+0xc5/0xf0
>> [ 243.018549] [<ffffffff8117ff8d>] ? trace_hardirqs_on+0xd/0x10
>> [ 243.019339] [<ffffffff81110fa4>] do_group_exit+0x84/0xd0
>> [ 243.020109] [<ffffffff81111002>] sys_exit_group+0x12/0x20
>> [ 243.020815] [<ffffffff83be2298>] tracesys+0xe1/0xe6
>> [ 243.021607] 1 lock held by init/1:
>> [ 243.022079] #0: (&tty->ldisc_mutex){+.+...}, at: [<ffffffff81bb8312>] tty_ldisc_hangup+0x122/0x320
>>
>> All of this on latest -next, inside a KVM tools guest.
>>
>> Help appreciated.
>
> Hi, for me this looks like a false positive. The TTY layer just waits
> for the process sitting on the TTY to vanish. Maybe we should touch the
> watchdogs?
Doesn't it happen only when the process is terminating though? Why would
it take more than 2 minutes to die?
Thanks,
Sasha
prev parent reply other threads:[~2012-11-13 20:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-10 4:46 tty_ldisc_hangup: waiting (init) for ttyS0 took too long, but we keep waiting Sasha Levin
2012-11-13 20:00 ` Jiri Slaby
2012-11-13 20:16 ` Sasha Levin [this message]
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