I've successfully reproduced this bug 

I'm on 3.16 kernel, mesa 10.2.5.

I start Qt5 QtCreator (as I know it uses OpenGL acceleration for some QML
elements), then I start any 3D-demanding app (like one of Valve's game titles).
After that I close app. And when I close QtCreator, this bug occurs, total
system hang, ring 0 freezes and does not wake up on soft reset.

Where should I look at to fix it? I assume it hids somewhere in GPUVM? (or is
it needed anymore or is it already fixed?)