(In reply to comment #40)
> in /etc/environment I have R600_DEBUG=nodma ever since discovering that
> setting, i.e.: also now the R6))_DEBUG is set to nodma.
> 
> I did not apply any of your patches over the 3.9.0-rc7 kernel.

Your log looks to the one in bug 58354, which is also related to DMA, or bug
59089, which is related to htile/VM.

The best thing would be to bisect the kernel between a good known version and
the first bad one. Do you have a previous kernel version that was working OK as
a good reference?