I had planned to test reverting those commits, but after reading through the
thread it seems those commits simply further exposed symptoms of a larger issue
that I believe was fixed in
http://lists.freedesktop.org/archives/dri-devel/2016-January/097880.html.

I am running a 4.4.0 kernel with that patch applied and so far have not seen
the issues I described. Although, ironically, on my first boot I had the stuck
login screen as described in the thread.