[wlug] “*ERROR* pipe is still busy with an old pageflip”

I’ve been hitting an occasional display freeze that matches this description <http://forums.gentoo.org/viewtopic-p-7675146.html>. Looks like a known problem with the 3.16 kernel. I thought things had got better with a system update I did 11 days ago, but this afternoon the freeze recurred. Unlike the previous times, killing all my user processes succeeded in unfreezing the display, so I was able to log in again without rebooting.