https://bugs.freedesktop.org/show_bug.cgi?id=82162
--- Comment #26 from mmstickman@gmail.com --- After compiling the latest version of mesa from git, I'm still getting this bug with my Radeon HD 7950 spamming the system log.
[ 372.835016] [TTM] Illegal buffer object size [ 372.835019] [TTM] Illegal buffer object size [ 372.835021] [drm:radeon_gem_object_create] *ERROR* Failed to allocate GEM object (0, 6, 4096, -22)
So it doesn't seem to be fixed for me at least.