Re: [linux-next / tty] possible circular locking dependency detected

Path	csiph.com!eternal-september.org!feeder.eternal-september.org!aioe.org!bofh.it!news.nic.it!robomod
From	Vegard Nossum <vegard.nossum@oracle.com>
Newsgroups	linux.kernel
Subject	Re: [linux-next / tty] possible circular locking dependency detected
Date	Mon, 22 May 2017 12:40:03 +0200
Message-ID	<tJSUP-4wq-47@gated-at.bofh.it> (permalink)
References	<tJQgh-2Cc-3@gated-at.bofh.it> <tJSL7-4td-3@gated-at.bofh.it>
User-Agent	Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1
MIME-Version	1.0
Content-Type	text/plain; charset=utf-8; format=flowed
Content-Language	en-US
Content-Transfer-Encoding	7bit
X-Source-IP	userv0021.oracle.com [156.151.31.71]
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	28
Organization	linux.* mail to news gateway
X-Original-Cc	Jiri Slaby <jslaby@suse.com>, linux-kernel@vger.kernel.org, Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
X-Original-Date	Mon, 22 May 2017 12:27:31 +0200
X-Original-Message-ID	<50cc6717-c709-873c-b434-07da13365977@oracle.com>
X-Original-References	<20170522073943.GA469@jagdpanzerIV.localdomain> <20170522102454.GA30331@kroah.com>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1646721

Show key headers only | View raw

On 05/22/17 12:24, Greg Kroah-Hartman wrote:
> On Mon, May 22, 2017 at 04:39:43PM +0900, Sergey Senozhatsky wrote:
>> Hello,
>>
>> [ 1274.378287] ======================================================
>> [ 1274.378289] WARNING: possible circular locking dependency detected
>> [ 1274.378290] 4.12.0-rc1-next-20170522-dbg-00007-gc09b2ab28b74-dirty #1317 Not tainted
>> [ 1274.378291] ------------------------------------------------------
>> [ 1274.378293] kworker/u8:5/111 is trying to acquire lock:
>> [ 1274.378294]  (&buf->lock){+.+...}, at: [<ffffffff812f2831>] tty_buffer_flush+0x34/0x88
>> [ 1274.378300]
>>                 but task is already holding lock:
>> [ 1274.378301]  (&o_tty->termios_rwsem/1){++++..}, at: [<ffffffff812ee5c7>] isig+0x47/0xd2
>> [ 1274.378307]
>>                 which lock already depends on the new lock.
>>

> Any hint as to what you were doing when this happened?
> 
> Does this also show up in 4.11?

It's my patch "tty: fix port buffer locking" :-/

At a glance, looks related to pty taking the lock on the other side in a
different order. I'll have a closer look.


Vegard

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[linux-next / tty] possible circular locking dependency detected Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-05-22 09:50 +0200
  Re: [linux-next / tty] possible circular locking dependency detected Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-22 12:30 +0200
    Re: [linux-next / tty] possible circular locking dependency detected Jiri Slaby <jslaby@suse.cz> - 2017-05-22 12:30 +0200
    Re: [linux-next / tty] possible circular locking dependency detected Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-05-22 12:40 +0200
    Re: [linux-next / tty] possible circular locking dependency detected Vegard Nossum <vegard.nossum@oracle.com> - 2017-05-22 12:40 +0200

csiph-web