https://bugs.freedesktop.org/show_bug.cgi?id=91790
--- Comment #11 from Mathias Tillman master.homer@gmail.com --- (In reply to Alex Deucher from comment #10)
Created attachment 118056 [details] [review] possible fix
I think this patch should fix it.
No luck here I'm afraid - I'm having a hard time reproducing it during normal desktop usage (with or without the patch), but it did lockup while running Unigine Valley.