(In reply to Michel Dänzer from comment #2)
> (In reply to Andy Furniss from comment #0)
> > Haven't seen on drm-next-3.18-wip
> 
> Can you bisect the kernel?

May be a bit early, but I will sit on the one before for a while to confirm.

Looks like the head commit -

commit bb9a49819ed30f3f5782b2504066547a8507a591
Author: Christian König <christian.koenig@amd.com>
Date:   Mon Oct 13 12:41:47 2014 +0200

    drm/radeon: update the VM after setting BO address

    This way the necessary VM update is kicked off immediately
    if all BOs involved are in GPU accessible memory.

I haven't managed to lock or get Valley to GPU fault on the one before so far.

FWIW I noticed even on head the valley fault doesn't always happen - it seems
that I need to have set my CPUs to perf (which I nearly always do when testing
things like this). With cpufreq ondemand I didn't see the fault.