[Intel-gfx] [PATCH] drm/i915: Gracefully handle obj not bound to GGTT in is_pin_display

[Daniel Vetter]

On Thu, May 15, 2014 at 01:14:54PM +0000, Mateo Lozano, Oscar wrote:
> > > But looking at the code a better way should be:
> > > 1. Create new bo, wrap it in a kms fb.
> > > 2. Slap busy load onto that bo, e.g. reapeatedly fill it with the blitter.
> > > 3. Enable evil interruptor (igt_fork_signal_helper).
> > > 4. Submit pageflip
> > >
> > > -> Boom since the set_cache_level will block, get interrupted and exit
> > > early with -EINTR.
> > >
> > > Given sufficient overkill in 2. this should be 100% reliable to reproduce.
> 
> As soon as I execbuffer to the bo, it gets a vma for the GGTT vm:
> 
> 	vm = ctx->vm;
> 	if (!USES_FULL_PPGTT(dev))
> 		vm = &dev_priv->gtt.base;
> 
> 	...
> 
> 	/* Look up object handles */
> 	ret = eb_lookup_vmas(eb, exec, args, vm, file);
> 	if (ret)
> 		goto err;
> 
> And then it becomes impossible to reproduce the problem :(
> Is there any other trick to make set_cache_level fail?

i915.ppgtt=2 should still make this blow up. The bug kinda doesn't exist
without full ppgtt I think ...
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch