Nouveau - Jul 2017 - [regression drm/noveau] suspend to ram -> BOOM: exception RIP: drm_calc_vbltimestamp_from_scanoutpos+335

On Fri, 2017-07-14 at 15:36 +0200, Mike Galbraith wrote:
>  All DRM did was to slip a
> WARN_ON_ONCE() that nouveau triggers into a kernel module where such
> things no longer warn, they blow the box out of the water.
BTW, turn that irksome WARN_ON_ONCE() in drivers/gpu/drm/drm_vblank.c
into a WARN_ONCE(), and all is peachy, you get the warning, box lives.

---
 drivers/gpu/drm/drm_vblank.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -605,7 +605,8 @@ bool drm_calc_vbltimestamp_from_scanoutp
 	 */
 	if (mode->crtc_clock == 0) {
 		DRM_DEBUG("crtc %u: Noop due to uninitialized mode.\n", pipe);
-		WARN_ON_ONCE(drm_drv_uses_atomic_modeset(dev));
+		WARN_ONCE(drm_drv_uses_atomic_modeset(dev), "%s: report me.\n",
+			  dev->driver->name);
 
 		return false;
 	}

Yeah, we shouldn't let the machine die. Are there more WARN_ON_ONCE
usage we could convert to WARN_ONCE?

Reviewed-By: Karol Herbst <karolherbst at gmail.com>

On Fri, Jul 14, 2017 at 5:05 PM, Tobias Klausmann
<tobias.johannes.klausmann at mni.thm.de> wrote:
> On 7/14/17 3:41 PM, Mike Galbraith wrote:
>>
>> On Fri, 2017-07-14 at 15:36 +0200, Mike Galbraith wrote:
>>>
>>>   All DRM did was to slip a
>>> WARN_ON_ONCE() that nouveau triggers into a kernel module where
such
>>> things no longer warn, they blow the box out of the water.
>>
>> BTW, turn that irksome WARN_ON_ONCE() in drivers/gpu/drm/drm_vblank.c
>> into a WARN_ONCE(), and all is peachy, you get the warning, box lives.
>>
>> ---
>>   drivers/gpu/drm/drm_vblank.c |    3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> --- a/drivers/gpu/drm/drm_vblank.c
>> +++ b/drivers/gpu/drm/drm_vblank.c
>> @@ -605,7 +605,8 @@ bool drm_calc_vbltimestamp_from_scanoutp
>>          */
>>         if (mode->crtc_clock == 0) {
>>                 DRM_DEBUG("crtc %u: Noop due to uninitialized
mode.\n",
>> pipe);
>> -               WARN_ON_ONCE(drm_drv_uses_atomic_modeset(dev));
>> +               WARN_ONCE(drm_drv_uses_atomic_modeset(dev), "%s:
report
>> me.\n",
>> +                         dev->driver->name);
>>                 return false;
>>         }
>
>
>
> Hey,
>
> confirmed this helps saving the box, but we still have to find the root
> cause! Backtrace with the above fix applied (and the one which came in with
> the latest drm-fixes merge)!
>
>
> [1] https://hastebin.com/uyoqifijed.http
>
> Thanks,
>
> Tobias
>Reviewed-By: Karol Herbst <karolherbst at gmail.com>
> _______________________________________________
> Nouveau mailing list
> Nouveau at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/nouveau

On Fri, 2017-07-14 at 17:05 +0200, Tobias Klausmann
wrote:
> On 7/14/17 3:41 PM, Mike Galbraith wrote:
> > On Fri, 2017-07-14 at 15:36 +0200, Mike Galbraith wrote:
> >>   All DRM did was to slip a
> >> WARN_ON_ONCE() that nouveau triggers into a kernel module where
such
> >> things no longer warn, they blow the box out of the water.
> > BTW, turn that irksome WARN_ON_ONCE() in drivers/gpu/drm/drm_vblank.c
> > into a WARN_ONCE(), and all is peachy, you get the warning, box lives.
> >
> > ---
> >   drivers/gpu/drm/drm_vblank.c |    3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > --- a/drivers/gpu/drm/drm_vblank.c
> > +++ b/drivers/gpu/drm/drm_vblank.c
> > @@ -605,7 +605,8 @@ bool drm_calc_vbltimestamp_from_scanoutp
> >   	 */
> >   	if (mode->crtc_clock == 0) {
> >   		DRM_DEBUG("crtc %u: Noop due to uninitialized mode.\n",
pipe);
> > -		WARN_ON_ONCE(drm_drv_uses_atomic_modeset(dev));
> > +		WARN_ONCE(drm_drv_uses_atomic_modeset(dev), "%s: report
me.\n",
> > +			  dev->driver->name);
> >   
> >   		return false;
> >   	}
> 
> 
> Hey,
> 
> confirmed this helps saving the box, but we still have to find the root 
> cause! Backtrace with the above fix applied (and the one which came in 
> with the latest drm-fixes merge)!
Yeah, I'll be reporting some extra whining from my 8600 GT backup box.

	-Mike