3.8-rc2: lockdep warning in nouveau driver

[Peter Hurley]

On Wed, 2013-01-09 at 12:45 +0100, Arend van Spriel wrote:
> Maybe this one is already known, but I did not find a post about it. So
> here it is.
> 
> Regards,
> Arend

[snip]

> [    9.589986] =============================================
> [    9.595365] [ INFO: possible recursive locking detected ]
> [    9.600745] 3.8.0-rc2-wl-testing-lockdep-00002-ga524cf0 #1 Not tainted
> [    9.607248] ---------------------------------------------
> [    9.612626] modprobe/163 is trying to acquire lock:
> [    9.617486]  (&subdev->mutex){+.+.+.}, at: [<f8929c12>]
> nv50_fb_vram_new+0x92/0x230 [nouveau]
> [    9.626052]
> [    9.626052] but task is already holding lock:
> [    9.631865]  (&subdev->mutex){+.+.+.}, at: [<f8936505>]
> nv50_disp_data_ctor+0x55/0xc0 [nouveau]
> [    9.640593]
> [    9.640593] other info that might help us debug this:
> [    9.647096]  Possible unsafe locking scenario:
> [    9.647096]
> [    9.652995]        CPU0
> [    9.655430]        ----
> [    9.657867]   lock(&subdev->mutex);
> [    9.661365]   lock(&subdev->mutex);
> [    9.664863]
> [    9.664863]  *** DEADLOCK ***
> [    9.664863]
> [    9.670762]  May be due to missing lock nesting notation

Same.

[    5.995881] =============================================
[    5.995886] [ INFO: possible recursive locking detected ]
[    5.995892] 3.8.0-next-20130125+ttypatch-xeon+lockdep #20130125+ttypatch Not tainted
[    5.995898] ---------------------------------------------
[    5.995904] modprobe/275 is trying to acquire lock:
[    5.995909]  (&subdev->mutex){+.+.+.}, at: [<ffffffffa00d10b8>] nouveau_instobj_create_+0x48/0x90 [nouveau]
[    5.995955] 
[    5.995955] but task is already holding lock:
[    5.995961]  (&subdev->mutex){+.+.+.}, at: [<ffffffffa00da3b5>] nv50_disp_data_ctor+0x65/0xd0 [nouveau]
[    5.995989] 
[    5.995989] other info that might help us debug this:
[    5.995995]  Possible unsafe locking scenario:
[    5.995995] 
[    5.996001]        CPU0
[    5.996004]        ----
[    5.996005]   lock(&subdev->mutex);
[    5.996005]   lock(&subdev->mutex);
[    5.996005] 
[    5.996005]  *** DEADLOCK ***

Regards,
Peter Hurley