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From: Sasha Levin <levinsasha928@gmail.com>
To: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
	linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
	Jiri Slaby <jirislaby@gmail.com>
Subject: Re: [PATCH 3/3] tty_lock: Localise the lock
Date: Tue, 8 May 2012 20:12:37 +0200	[thread overview]
Message-ID: <CA+1xoqdi1Jdkrjtj9bmnDfs4Ok=o=AsmpP=MY0V8cDXjcSNm1w@mail.gmail.com> (raw)
In-Reply-To: <4FA838D2.9000908@suse.cz>

On Mon, May 7, 2012 at 11:04 PM, Jiri Slaby <jslaby@suse.cz> wrote:
> On 05/07/2012 07:00 PM, Sasha Levin wrote:
>>> So whatever your trace is showing, that's not the bug. Something more
>>> complicated would appear to be afoot.
>>
>> Oddly enough, tty != tty->link, but the lockdep warning triggers.
>>
>> Any idea why it might happen?
>
> I think so, both locks are the same lockdep class. So lockdep thinks it
> is the same lock. However this is a false positive. I guess we need
> mutex_lock_nested...

It looks like it causes an actual deadlock, and hung_tasks screams if
left alone for a bit, so it doesn't look like a lockdep issue.

  reply	other threads:[~2012-05-08 18:13 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-05-03 21:21 [PATCH 1/3] tty_lock: undo the old tty_lock use on the ctty Alan Cox
2012-05-03 21:22 ` [PATCH 2/3] pty: Lock the devpts bits privately Alan Cox
2012-05-08 18:18   ` H. Peter Anvin
2012-05-08 20:43     ` Alan Cox
2012-05-08 20:41       ` H. Peter Anvin
2012-05-03 21:24 ` [PATCH 3/3] tty_lock: Localise the lock Alan Cox
2012-05-04 20:48   ` Arnd Bergmann
2012-05-04 23:54   ` Greg KH
2012-05-04 23:55     ` Greg KH
2012-05-07 16:03   ` Sasha Levin
2012-05-07 16:03     ` Sasha Levin
2012-05-07 16:11     ` Alan Cox
2012-05-07 16:30       ` Sasha Levin
2012-05-07 16:42         ` Alan Cox
2012-05-07 17:00           ` Sasha Levin
2012-05-07 21:04             ` Jiri Slaby
2012-05-08 18:12               ` Sasha Levin [this message]
2012-05-11 10:40                 ` Sasha Levin
2012-05-11 14:52                   ` Greg KH
2012-05-11 15:09                     ` Sasha Levin
2012-05-11 15:09                       ` Sasha Levin

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