Re: 3.8-rc2 lockdep complains about console_lock vs. fb_notifier_list.rwsem

On Wed, Jan 16, 2013 at 12:07 PM, Sedat Dilek [off-list ref] wrote:

On Wed, Jan 16, 2013 at 10:59 AM, Sedat Dilek [off-list ref] wrote:

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On Wed, Jan 16, 2013 at 10:52 AM, Sedat Dilek [off-list ref] wrote:

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On Wed, Jan 16, 2013 at 10:35 AM, Takashi Iwai [off-list ref] wrote:

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At Wed, 16 Jan 2013 10:21:46 +0100,
Sedat Dilek wrote:

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On Tue, Jan 15, 2013 at 3:25 PM, Takashi Iwai [off-list ref] wrote:

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At Sat, 5 Jan 2013 13:13:27 +0100,
Sedat Dilek wrote:

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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.

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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.

JYI: [1] now does NOT have anymore those "strange" chars, Thanks Takashi san.

I will test next-20130116 with both fb-fixes as -2 kernel.
( Running LTP-lite on my "naked" -1 kernel only with my kbuild/deb-pkg-fixes. )

Thanks to everyone involved.

I have reverted the three fb-fixes from akpm-tree in next-20130116...
...and applied the two fb-fixes from mmotm-tree (see attached patches file).

FYI: The 1st patch from mmotm-tree is a (proper) replacement for the 3
patches in Linux-Next.

Furthermore, I made some quick testing:
Booting into the system is fine.
Suspend + resume looks good (see dmesg.diff).

See also attached files!

En plus, I have run successfully LTP-lite.

$ egrep -i 'error|fail'
runltplite-results_3.8.0-rc3-next20130116-2-iniza-generic.txt | egrep
-v -i 'expected' | wc -l
208

I do not want to flood the MLs, so people wanting full LTP-lite report
(~600KiB) can contact me.

- Sedat -

- Sedat -

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- Sedat -

[1] http://ozlabs.org/~akpm/mmots/broken-out/fb-rework-locking-to-fix-lock-ordering-on-takeover.patch
[2] http://ozlabs.org/~akpm/mmots/broken-out/fb-yet-another-band-aid-for-fixing-lockdep-mess.patch

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- Sedat -

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thanks,

Takashi