[Bug 1841915] Re: black screen, unresponsive, after logout from gnome Wayland session

[Iain Lane]

I have tried to reproduce this but I can't, not in a VM or on my real
system (i915). I tried with and without automatic login, with the
vanilla GNOME session and with the Ubuntu session, with and without the
same user logged in over SSH (to keep the systemd --user instance
alive), and every log in/out cycle worked. Sorry :/

I'll note that VT switching works for me on all machines, and I see no
lingering processes after logging out.

One thing I did manage to reproduce, using the attached program (a
daemon which doesn't quit when SIGTERMed, which I was trying to use to
recreate your situation. Run it from xterm *not* gnome-terminal), is a
30 second *delay* on logout. Did you wait longer than that? If I edit
`/usr/lib/systemd/user/gnome-session-wayland.service` and add
TimeoutStopSec=5 at the end (then reboot), then the delay reduces to 5
seconds. I'll ask upstream about whether that's a good idea but this
might not be your problem.

If you go to `/usr/share/wayland-sessions/`, you can remove `--systemd`
from the `Exec=` line of the session you're using, to revert to the
previous method of launching the session. If that fixes it, then (in the
broken situation), please enable GDM debug output
(/etc/gdm3/custom.conf), and while the system is hanging fetch the
output of 'loginctl', then for each session listed there, 'loginctl
show-session <session id>' and 'loginctl session-status <session-id>',
as well as 'journalctl -b' and attach them here.

Thanks.

** Attachment added: "daemon.c"
   https://bugs.launchpad.net/ubuntu/+source/gdm3/+bug/1841915/+attachment/5286400/+files/daemon.c

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https://bugs.launchpad.net/bugs/1841915

Title:
  black screen, unresponsive, after logout from gnome Wayland session

Status in gdm3 package in Ubuntu:
  Confirmed
Status in gnome-shell package in Ubuntu:
  Confirmed
Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  on logout the screen is black, the system is unresponsive and has to
  be restarted. (Untested by me yet, but I expect ssh-ing in and
  restarting gdm would work.)

  I believe this may be already reported upstream here:
  https://bugzilla.redhat.com/show_bug.cgi?id=1745554 That's why I've
  reported this against gdm3 even though I honestly don't know if it
  might be a gnome-shell, gnome-session or mutter based error. (FWIW
  without the upstream bug to link to I'd maybe suspect gnome-shell
  first.)

  NB: This machine's conf has AutomaticLogin enabled, but another
  machine also on 19.10 does not, and it's showing the same thing. On
  *this* machine I found that the *first* time I logged out, it was OK,
  but not the second time. On the other machine, it fails first time
  too. It's as if the gdm login screen can appear exactly once. That
  (and being on gnome 3.33) is why I don't think this is a dupe of
  #1824588.

  Nothing appears in /var/crash as a result of this.

  ProblemType: Bug
  DistroRelease: Ubuntu 19.10
  Package: gdm3 3.33.90-1ubuntu1
  ProcVersionSignature: Ubuntu 5.2.0-13.14-generic 5.2.8
  Uname: Linux 5.2.0-13-generic x86_64
  ApportVersion: 2.20.11-0ubuntu7
  Architecture: amd64
  CurrentDesktop: ubuntu:GNOME
  Date: Thu Aug 29 10:51:22 2019
  InstallationDate: Installed on 2018-09-11 (351 days ago)
  InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Alpha amd64 (20180214)
  SourcePackage: gdm3
  UpgradeStatus: Upgraded to eoan on 2019-07-16 (43 days ago)
  mtime.conffile..etc.gdm3.custom.conf: 2019-07-17T00:07:04.528641

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