(In reply to Julien Isorce from comment #9)
> 
> So I have 4 questions:
>  1: Can an application causes a "ring 0 stalled" ? or is it a driver bug
> (kernel side or mesa/drm or xserver) ?

driver bug.  Probably mesa or kernel.

>  2: About these atombios failures, does it mean that it fails to load the
> gpu microcode/firmware ?

Most likely the GPU reset was not actually successful and the atombios errors
are a symptom of that.

>  3: Does it try to do a gpu softreset because I added R600_DEBUG=check_vm ?
> Or this one just help to flush the traces on vm fault (like mentioned in a
> commit msg related to that env var in mesa) ?

check_vm doesn't not change anything with respect to gpu reset.

>  4: For the deallocation failure / leak above (radeon_ttm_bo_destroy
> warning), does it mean the memory is lost until next reboot or does a gpu
> soft reset allow to recover these leaks ? 

I'm not quite sure what you are referring to, but if the GPU reset is
successful, all fences should be signalled so any memory that is pinned due to
a command buffer being in flight could be freed.