https://bugs.freedesktop.org/show_bug.cgi?id=66963
--- Comment #223 from lockheed qwrules@gmail.com ---
It's part of the radeon kernel driver. It doesn't matter what userspace drivers (mesa, xf86-video-ati) you use.
Ok, thanks for enlightening me. I had things confused. So this is a kernel bug list? I thought it is X-related.