https://bugs.freedesktop.org/show_bug.cgi?id=58667
--- Comment #4 from Thomas Rohloff v10lator@myway.de --- !Is this a regression? Does it happen with older versions of mesa or kernel?! Not that I know about. "May also be related to bug 58354." Do you have the path noted there ("drm/radeon: use DMA engine for VM page table updates on cayman/TN") ? I would loce to try to revert this patch and test it, but I'm unable to google it.