Yes, but that was experimental code, not meant to be used by the general populace just yet and hence not enabled by default in kernel builds. The whole radeon-CP, TTM, DRI2, KMS stuff is all brand new, after all. Some distros have been enabling it by default, granted, but that's their security failing. :)
Note that the new checker is about video memory, not general process memory, so the security implications are a bit limited (although still serious enough to warrant fixing on multi-user systems, of course).