A related bug:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/600453
See also
https://bugs.freedesktop.org/show_bug.cgi?id=29278
A related bug:
https:/ /bugs.launchpad .net/ubuntu/ +source/ linux/+ bug/600453
See also
https:/ /bugs.freedeskt op.org/ show_bug. cgi?id= 29278