Comment # 4 on bug 111669 from Pierre-Eric Pelloux-Prayer

Thanks for the test and new trace.

I can reproduce the hang and it seems to go away with AMD_DEBUG=nodma.

Another workaround is to use the following kernel parameter
amdgpu.vm_update_mode=3 (well, except that sometimes this introduces another
problem, see https://bugs.freedesktop.org/show_bug.cgi?id=111682)