linux-kernel - Re: 3.8-rc2 lockdep complains about console_lock vs. fb_notifier

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Message-ID: <CA+icZUXjmjgFii4bpr6fvfUY9jfu932bCxa088g-wZjOfpYbng@mail.gmail.com>
Date:	Wed, 16 Jan 2013 10:52:11 +0100
From:	Sedat Dilek <sedat.dilek@...il.com>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	Jiri Kosina <jkosina@...e.cz>, linux-fbdev@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>, alan@...rguk.ukuu.org.uk,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.cz>,
	linux-next <linux-next@...r.kernel.org>
Subject: Re: 3.8-rc2 lockdep complains about console_lock vs. fb_notifier_list.rwsem

On Wed, Jan 16, 2013 at 10:35 AM, Takashi Iwai <tiwai@...e.de> wrote:
> At Wed, 16 Jan 2013 10:21:46 +0100,
> Sedat Dilek wrote:
>>
>> On Tue, Jan 15, 2013 at 3:25 PM, Takashi Iwai <tiwai@...e.de> wrote:
>> > At Sat, 5 Jan 2013 13:13:27 +0100,
>> > Sedat Dilek wrote:
>> >>
>> >> Hi Jiri,
>> >>
>> >> ...known issue (see thread in [1]), please feel free to test patches
>> >> from Alan and Andrew (see [1], [2] and [3]) and report.
>> >>
>> >> Regards,
>> >> - Sedat -
>> >>
>> >> [1] http://marc.info/?t=135309396400003&r=1&w=2
>> >> [2] http://ozlabs.org/~akpm/mmots/broken-out/fb-rework-locking-to-fix-lock-ordering-on-takeover.patch
>> >> [3] http://ozlabs.org/~akpm/mmots/broken-out/fb-rework-locking-to-fix-lock-ordering-on-takeover-fix.patch
>> >> [4] http://ozlabs.org/~akpm/mmots/broken-out/fb-rework-locking-to-fix-lock-ordering-on-takeover-fix-2.patch
>> >
>> > I've hit this bug and tried the patch [2] ([3] and [4] are gone).
>> > Unfortunately the deadlock is still reported, as seen below.
>> >
>> > A similar fix for fbcon_unbind(), splitting an unlocked version of
>> > unbind_con_driver() and call it?
>> >
>> > (BTW, the patch [2] contains strange characters in the comments, and
>> >  has a few coding issues easily detected by checkpatch.pl.)
>> >
>>
>> [ CCing Rafael as he asked in another thread if I had sent a patch ]
>>
>> I noticed also some these "strange" chars in the patch from Andrew and
>> a patch of mine was sent as
>> "fb-Rework-locking-to-fix-lock-ordering-on-takeover-fix-comments.patch"
>> to the lists.
>>
>> It is strange to me that Andrew or other maintainers himself did not
>> check with "checkpatch.pl".
>> This should be a common testcase!
>> Hey, noone is perfect :-).
>> ( /me has also not checked with that script - I just saw it. )
>>
>> Just as a note to the issue in general:
>> Andrew took over the patch from Alan which is very honest - he is not
>> the active TTY maintainer!
>> Didn't Greg takeover maintenance from Alan (after a dispute and blaming Alan)?
>> If this is true, why the hell is Greg not CCed?
>
> Let's do it :)
>
> Greg, Jiri, this bug hits already quite a few people.
>
> I can reproduce the bug easily on a machine with a radeon graphics.
> It appears always at boot when lockdep is enabled.
>
>
>> Thanks for the real patch in the followup of this thread!
>> Who will take care of it :-)?
>
> Either tty maintainer, or fb maintainer, or Andrew?
>
> FWIW, Andrew took my patch in mm:
>   http://ozlabs.org/~akpm/mmots/broken-out/fb-rework-locking-to-fix-lock-ordering-on-takeover.patch
>   http://ozlabs.org/~akpm/mmots/broken-out/fb-yet-another-band-aid-for-fixing-lockdep-mess.patch
>

[ CCing linux-next ML ]

Thanks for all your efforts to get this fb-issue nailed down for mainline!

Just as a note being a Linux-Next customer:

"fb-yet-another-band-aid-for-fixing-lockdep-mess.patch" did not hit
next-20130116!
Thanks for the link!

Normally Andrew sents out a mmotm release marking patches from his
tree destinated for Linux-Next with a "*".

To quote from the latest mmotm release-notes:

"This mmotm tree contains the following patches against 3.8-rc3:
(patches marked "*" will be included in linux-next)"

But anyway this stuff is Linux-3.8 material as well.

- Sedat -

>
> thanks,
>
> Takashi
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