On Sun, Nov 08, 2020 at 01:09:40PM +0000, Anthony Richardby wrote:
> 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
I've managed to use ports clang and lldb to build and inspect a powerpc
drm_vblank.o and it points to src/sys/dev/pci/drm/include/linux/atomic.h:165:2
which is the ilp32 version of atomic64_read().
The following patch makes sure the lock involved is initialised.
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 13:51:27 -0000
@@ -481,7 +481,8 @@ 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);
+ atomic64_set(&vblank->count, 0);
}
DRM_INFO("Supports vblank timestamp caching Rev 2 (21.10.2013).\n");
