https://bugs.freedesktop.org/show_bug.cgi?id=91278
--- Comment #36 from Mathias Tillman master.homer@gmail.com --- I have run the valley test the entire day (10 hours or so) without a single VM fault or hang with the GPU scheduler enabled on 4.4.
Re-ran the test with your (Grazvydas) patch and it's showing the same symptoms as before when not using the schedluer - that is, a bunch of VM faults, which lead to a hang after around 30 minutes or so.