Re: 6.8 powerbook g4 radeon driver kernel panic

On 2020-11-08 11:14:50 +0000 Jonathan Gray <[email protected]> wrote:

> On Sun, Nov 08, 2020 at 10:51:11AM +0000, Anthony Richardby wrote:
>> On 2020-11-08 02:40:26 +0000 Jonathan Gray <[email protected]> wrote:
>
>>> On Sat, Nov 07, 2020 at 04:01:34PM +0000, Anthony Richardby wrote:
>>> > Hey,
>>> > I'm experiencing a kernel panic whenever I run glxgears, or it
>>> would
>>> > seem when I try to run other gpu-related tasks. I first noticed
>>> this
>>> > when playing video via the application 'mpv', after a couple of
>>> > seconds of video the system freezes!! I've got the trace output
>>> for
>>> > that as the time delay allows me to switch out of X11 to a console
>>> > before the system crashes. Anyway after this I tried 'glxgears'
>>> and
>>> > that crashes immediately (so I'm unable to get the trace, but it
>>> > sounds like it's related?).
>>> > > Just wondering if anyone else is able to reproduce this on their
>>> > powerbooks / other g4 macs, does glxgears work for you?
>>> > > Pic of the trace output: https://postimg.cc/wRLGLKdF
>>> > What is the actual panic message?
>>> > For the archives the trace was:
>>> > panic(b6ae0c) at panic+0x154
>>> mtx_enter(0) at mtx_enter+0x8c
>>> drm_update_vblank_count(2a0fcdf8,e000a000,b6ae78) at
>>> drm_update_vblank_count+0x4b8
>>> drm_handle_vblank(2000611,82720e) at drm_handle_vblank+0xd8
>>> r100_irq_process(a19ca0) at r100_irq_process+0x110
>>> radeon_driver_irq_handler_kms(0) at
>>> radeon_driver_irq_handler_kms+0x28
>>> openpic_ext_intr() at openpic_ext_intr+0x274
>>> extint_call() at extint_call
>>> --- interrupt ---
>>> at 0xe7055e1c
>>> drm_wait_vblank_ioctl(e0732f00,e06b9b84,e7055c60) at
>>> drm_wait_vblank_ioctl+0xb2
>>> drm_do_ioctl(251571d0) at drm_do_ioctl+0x298
>>> drmioctl(25157100,e7055ca8,990000,c010643a,3a033428) at
>>> drmioctl+0xbc
>>> > >
>> The panic message is:
>> panic: mtx 0xe024cc50: locking against myself
>
>> I forgot to mention that this is new in 6.8, I can run glxgears/play
>> video with mpv fine using 6.7.
>
> The seqlock is used from an interrupt context
> drm_update_vblank_count() -> store_vblank()
>
> Can you try a kernel with the following diff?
> Patch against 6.8 branch.
>
> Index: sys/dev/pci/drm/drm_vblank.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/pci/drm/drm_vblank.c,v
> retrieving revision 1.6
> diff -u -p -r1.6 drm_vblank.c
> --- sys/dev/pci/drm/drm_vblank.c	29 Jul 2020 09:52:21 -0000	1.6
> +++ sys/dev/pci/drm/drm_vblank.c	8 Nov 2020 11:04:58 -0000
> @@ -481,7 +481,7 @@ int drm_vblank_init(struct drm_device *d
> 		init_waitqueue_head(&vblank->queue);
> 		setup_timer(&vblank->disable_timer, vblank_disable_fn,
> 		    (unsigned long)vblank);
> -		seqlock_init(&vblank->seqlock, IPL_NONE);
> +		seqlock_init(&vblank->seqlock, IPL_TTY);
> 	}
>
> 	DRM_INFO("Supports vblank timestamp caching Rev 2 (21.10.2013).\n");
>
>

Thanks for the time taken to look into this and offer this diff!
Unfortunately its still crashing, the trace and panic message look to
be the same:

https://postimg.cc/G4KNQ9c6