CCing the systemd list; folks on that list may have ideas or advice about this bug.
On Wed, 13 Jan 2016 15:07:06 -0800 Josh Triplett <[email protected]> wrote: > Recently (not sure when this changed), running "systemctl stop gdm3" no > longer stops all gdm3-related processes; it leaves portions of the > greeter session running under "user-113.slice", running as the > Debian-gdm user. > > This breaks "systemctl restart gdm3" and similar mechanisms. Currently, > to fully restart gdm3, I have to stop gdm3, stop user-113.slice, and > then start gdm3 again.

