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

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Date:	Wed, 24 Oct 2012 14:45:12 +0200
From:	"Arend van Spriel" <arend@...adcom.com>
To:	"Stanislaw Gruszka" <sgruszka@...hat.com>
cc:	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	"Ben Skeggs" <bskeggs@...hat.com>
Subject: Re: [BUG 3.7-rc1] nouveau cli->mutex possible recursive locking
 detected

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

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