linux-kernel - Re: [BUG 3.7-rc1] nouveau cli->mutex possible recursive locking detected

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Date:	Thu, 25 Oct 2012 12:14:46 +0200
From:	"Arend van Spriel" <arend@...adcom.com>
To:	"Ben Skeggs" <bskeggs@...hat.com>
cc:	"Stanislaw Gruszka" <sgruszka@...hat.com>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [BUG 3.7-rc1] nouveau cli->mutex possible recursive locking
 detected

On 10/24/2012 02:45 PM, Arend van Spriel wrote:
> On 10/24/2012 01:14 PM, Arend van Spriel wrote:
>> On 10/16/2012 02:43 PM, Stanislaw Gruszka wrote:
>>> I have this lockdep warning on wireless-testing tree based
>>> on 3.7-rc1 (no other patches except wireless bits).
>>>
>>> =============================================
>>> Restarting tasks ... done.
>>> [ INFO: possible recursive locking detected ]
>>> 3.7.0-rc1-wl+ #2 Not tainted
>>> ---------------------------------------------
>>> Xorg/2269 is trying to acquire lock:
>>>   (&cli->mutex){+.+.+.}, at: [<ffffffffa012a27f>]
>>> nouveau_bo_move_m2mf+0x5f/0x170 [nouveau]
>>>
>>> but task is already holding lock:
>>>   (&cli->mutex){+.+.+.}, at: [<ffffffffa012f3c4>]
>>> nouveau_abi16_get+0x34/0x100 [nouveau]
>>>
>>
>> I have observed the same bug so I built and tested v3.7-rc2 tag with
>> lockdep enabled. It has the same problem and it results in a failure to
>> resume after suspend. See below.
>>
>> Gr. AvS
>
> digging into the trace:
>
>
> nouveau_gem_ioctl_pushbuf() calls nouveau_abi16_get() which grabs the
> mutex. Assume this should protect the chan variable passed to
> nouveau_gem_pushbuf_validate(), which does a bit more that validate as
> it ends up in nouveau_bo_move_m2mf() which uses the drm->chan. However,
> it deadlocks before that.
>
> Gr. AvS

I reverted the two drm merges:

ceb736c Merge branch 'drm-nouveau-fixes' of 
git://anongit.freedesktop.org/git/no
612a9aa Merge branch 'drm-next' of 
git://people.freedesktop.org/~airlied/linux

It is not surprising that it solved the deadlock (doing pm_test). 
Unfortunately, suspend/resume still does not work. System goes to sleep 
just fine, but when trying to resume the BIOS kicks in and system boots 
instead of waking up.

Gr. AvS


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