https://bugs.freedesktop.org/show_bug.cgi?id=82162
--- Comment #5 from mmstickman@gmail.com --- I've been having the same problem on Arch Linux for a while now with my Radeon HD 7950 too. My Kabini laptop, which is also radeonsi, isn't affected. Dmesg spams the following messages repeatedly:
[ 3069.134039] [TTM] Illegal buffer object size [ 3069.134046] [drm:radeon_gem_object_create] *ERROR* Failed to allocate GEM object (0, 6, 4096, -22)