https://bugs.freedesktop.org/show_bug.cgi?id=99138

--- Comment #2 from Arthur Marsh arthur.marsh@internode.on.net --- While bisecting an unrelated kernel bug I found that some kernels between 4.9.0 and 4.10-rc1 allowed:

service lxdm stop

to work as expected and cleanly stop the X server.

Otherwise either a kill -9 of the lxdm and Xorg process or a reboot is needed to start the X server again.

If it would be helpful I could try bisecting to find the commit that stopped X shutting down cleanly.