https://bugzilla.kernel.org/show_bug.cgi?id=70411
--- Comment #4 from Alex Deucher alexdeucher@gmail.com --- (In reply to Christoph Haag from comment #3)
Still, this lockup is not nice since currently only a reboot makes the radeon gpu usable again.
Welcome to GPUs. Unfortunately, there's not really a whole lot we can do other than disabling hyperz or fixing the hyperz setup in mesa that's causing the problem. Either way this isn't really a kernel bug.