X server crash from autologin session returns to greeter, not autologin session

[Robert Ancell]

hi all,

I find that LightDM cannot autologin my user when X crashes or when I kill X process, even if I configure /etc/lightdm/lightdm.conf with autologin options.

My /etc/lightdm/lightdm.conf is as follows:
[SeatDefaults]
allow-guest=false
autologin-guest=false
autologin-user=mytestuser
autologin-user-timeout=0
autologin-session=lightdm-autologin

There are only 2 users in my system: root, mytestuser.

When I "sudo kill xxxx" to kill X process, LightDM just shows a dialog to ask for username and password, while I expect an autologin.

/var/log/lightdm/lightdm.log says:
[+0.03s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.04s] DEBUG: Starting Light Display Manager 1.10.0, UID=0 PID=3505
[+0.04s] DEBUG: Loading configuration dirs from /usr/share/lightdm/lightdm.conf.d
[+0.04s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-greeter-wrapper.conf
[+0.04s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-guest-wrapper.conf
[+0.04s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-xserver-command.conf
[+0.04s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/60-lightdm-gtk-greeter.conf
[+0.04s] DEBUG: Loading configuration dirs from /usr/local/share/lightdm/lightdm.conf.d
[+0.04s] DEBUG: Loading configuration dirs from /etc/xdg/lightdm/lightdm.conf.d
[+0.04s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf.d/10-xfce.conf
[+0.04s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf
[+0.04s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.04s] DEBUG: Registered seat module xlocal
[+0.04s] DEBUG: Registered seat module xremote
[+0.04s] DEBUG: Registered seat module unity
[+0.04s] DEBUG: Registered seat module surfaceflinger
[+0.34s] DEBUG: Adding default seat
[+0.34s] DEBUG: Seat: Starting
[+0.34s] DEBUG: Seat: Creating user session
[+0.99s] DEBUG: Loading users from org.freedesktop.Accounts
[+1.08s] DEBUG: Seat: Creating display server of type x
[+1.08s] DEBUG: Deactivating Plymouth
[+1.11s] DEBUG: Using VT 7
[+1.11s] DEBUG: Seat: Starting local X display on VT 7
[+1.11s] DEBUG: DisplayServer x-0: Logging to /var/log/lightdm/x-0.log
[+1.11s] DEBUG: DisplayServer x-0: Writing X server authority to /var/run/lightdm/root/:0
[+1.11s] DEBUG: DisplayServer x-0: Launching X Server
[+1.11s] DEBUG: Launching process 3713: /usr/bin/X -core :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+1.11s] DEBUG: DisplayServer x-0: Waiting for ready signal from X server :0
[+1.11s] DEBUG: User /org/freedesktop/Accounts/User999 added
[+1.23s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+1.23s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0
[+6.88s] DEBUG: Got signal 10 from process 3713
[+6.88s] DEBUG: DisplayServer x-0: Got signal from X server :0
[+6.88s] DEBUG: DisplayServer x-0: Connecting to XServer :0
[+6.88s] DEBUG: Quitting Plymouth; retaining splash
[+6.91s] DEBUG: Seat: Display server ready, starting session authentication
[+6.91s] DEBUG: Session pid=4246: Started with service 'lightdm-autologin', username 'mytestuser'
[+6.93s] DEBUG: Session pid=4246: Authentication complete with return value 0: Success
[+6.93s] DEBUG: Seat: Session authenticated, running command
[+6.93s] DEBUG: Registering session with bus path /org/freedesktop/DisplayManager/Session0
[+6.94s] DEBUG: Session pid=4246: Running command /usr/sbin/lightdm-session startxfce4
[+6.94s] DEBUG: Creating shared data directory /var/lib/lightdm-data/mytestuser
[+6.94s] DEBUG: Session pid=4246: Logging to .xsession-errors
[+6.94s] DEBUG: Activating VT 7
[+6.94s] DEBUG: Activating login1 session /org/freedesktop/login1/session/c6
[+191.16s] DEBUG: Session pid=4246: Exited with return value 0
[+191.16s] DEBUG: Seat: Session stopped
[+191.16s] DEBUG: Seat: Stopping display server, no sessions require it
[+191.16s] DEBUG: Sending signal 15 to process 3713
[+191.36s] DEBUG: Process 3713 exited with return value 0
[+191.36s] DEBUG: DisplayServer x-0: X server stopped
[+191.36s] DEBUG: Releasing VT 7
[+191.36s] DEBUG: DisplayServer x-0: Removing X server authority /var/run/lightdm/root/:0
[+191.36s] DEBUG: Seat: Display server stopped
[+191.36s] DEBUG: Seat: Active display server stopped, starting greeter
[+191.36s] DEBUG: Seat: Creating greeter session
[+191.37s] DEBUG: Seat: Creating display server of type x
[+191.37s] DEBUG: Using VT 7
[+191.37s] DEBUG: Seat: Starting local X display on VT 7
[+191.37s] DEBUG: DisplayServer x-0: Logging to /var/log/lightdm/x-0.log
[+191.37s] DEBUG: DisplayServer x-0: Writing X server authority to /var/run/lightdm/root/:0
[+191.37s] DEBUG: DisplayServer x-0: Launching X Server
[+191.37s] DEBUG: Launching process 9629: /usr/bin/X -core :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+191.37s] DEBUG: DisplayServer x-0: Waiting for ready signal from X server :0
[+191.43s] DEBUG: Got signal 10 from process 9629
[+191.43s] DEBUG: DisplayServer x-0: Got signal from X server :0
[+191.43s] DEBUG: DisplayServer x-0: Connecting to XServer :0
[+191.43s] DEBUG: Seat: Display server ready, starting session authentication
[+191.43s] DEBUG: Session pid=9646: Started with service 'lightdm-greeter', username 'lightdm'
[+191.45s] DEBUG: Session pid=9646: Authentication complete with return value 0: Success
[+191.45s] DEBUG: Seat: Session authenticated, running command
[+191.45s] DEBUG: Session pid=9646: Running command /usr/lib/lightdm/lightdm-greeter-session /usr/sbin/lightdm-gtk-greeter
[+191.45s] DEBUG: Creating shared data directory /var/lib/lightdm-data/lightdm
[+191.45s] DEBUG: Session pid=9646: Logging to /var/log/lightdm/x-0-greeter.log
[+191.53s] DEBUG: Activating VT 7
[+191.53s] DEBUG: Activating login1 session /org/freedesktop/login1/session/c8
[+191.69s] DEBUG: Session pid=9646: Greeter connected version=1.10.0
[+193.10s] DEBUG: Session pid=9646: Greeter start authentication
[+193.10s] DEBUG: Session pid=9701: Started with service 'lightdm', username '(null)'
[+193.11s] DEBUG: Session pid=9701: Got 1 message(s) from PAM
[+193.11s] DEBUG: Session pid=9646: Prompt greeter with 1 message(s)
[+195.42s] DEBUG: Session pid=9646: Greeter start authentication for mytestuser
[+195.42s] DEBUG: Session pid=9701: Sending SIGTERM
[+195.42s] DEBUG: Session pid=9716: Started with service 'lightdm', username 'mytestuser'
[+195.42s] DEBUG: Session pid=9701: Terminated with signal 15
[+195.42s] DEBUG: Session: Failed during authentication
[+195.42s] DEBUG: Seat: Session stopped
[+195.43s] DEBUG: Session pid=9716: Got 1 message(s) from PAM
[+195.43s] DEBUG: Session pid=9646: Prompt greeter with 1 message(s)
[+298.05s] DEBUG: Session pid=9646: Continue authentication
[+298.06s] DEBUG: Session pid=9716: Authentication complete with return value 0: Success
[+298.06s] DEBUG: Session pid=9646: Authenticate result for user mytestuser: Success
[+298.06s] DEBUG: Session pid=9646: User mytestuser authorized
[+298.06s] DEBUG: Session pid=9646: Greeter sets language zh_CN
[+298.07s] CRITICAL: g_dbus_connection_call_sync_internal: assertion 'object_path != NULL && g_variant_is_object_path (object_path)' failed
[+298.07s] DEBUG: Writing /home/mytestuser/.dmrc
[+298.12s] DEBUG: Session pid=9646: Greeter requests session xfce
[+298.12s] CRITICAL: g_dbus_connection_call_sync_internal: assertion 'object_path != NULL && g_variant_is_object_path (object_path)' failed
[+298.12s] DEBUG: Writing /home/mytestuser/.dmrc
[+298.27s] DEBUG: Seat: Stopping greeter; display server will be re-used for user session
[+298.27s] DEBUG: Session pid=9646: Sending SIGTERM
[+298.32s] DEBUG: Session pid=9646: Greeter closed communication channel
[+298.32s] DEBUG: Session pid=9646: Exited with return value 0
[+298.32s] DEBUG: Seat: Session stopped
[+298.32s] DEBUG: Seat: Greeter stopped, running session
[+298.32s] DEBUG: Registering session with bus path /org/freedesktop/DisplayManager/Session1
[+298.33s] DEBUG: Session pid=9716: Running command /usr/sbin/lightdm-session startxfce4
[+298.33s] DEBUG: Creating shared data directory /var/lib/lightdm-data/mytestuser
[+298.33s] DEBUG: Session pid=9716: Logging to .xsession-errors
[+298.38s] DEBUG: Activating VT 7
[+298.38s] DEBUG: Activating login1 session /org/freedesktop/login1/session/c9

Let me explain this log.
1. [+0.03s]: On system boot, the first LightDM login: it's an autologin action as configured by lightdm.conf.
2. [+6.94s]: End of the first LightDM login, starts a session on VT 7.
3. [+191.16s]: I killed X process to emulate X crashing. LightDM detected this, and restarted a new greeter. Now a dialog showed and asked for username and password. I did not input username nor password now.
4. [+298.05s]: I input username and password, and hitted Login button.

So my question is: how to do autologin when X crashes?

Thx!

[Robert Ancell (robert-ancell)]

I converted this to a bug. LightDM is implemented to return to the greeter after an X server crash inside an autologin session. However I think you're correct it makes more sense to return to the autologin session.

[Clément Désiles (cde-)]

Hi Robert,
any update on this? I know this is kind of old, but I think this is still useful for some users.

I'm figuring out an issue, there are rare cases when my Linux devices have an Xorg crash (occurs once in a month), and lightdm does not autologin back again. The user do not know the login password, not even can type it on screen... I'm looking for a resilient dm, which goes back to normal when I do `pkill -9 Xorg`.

In any way, Lightdm should not care about Xorg repeated crashes: Xorg crash => lightdm => Xorg crash => Xorg crash etc... Lightdm should fail, then systemd should restart it. The restart protection mechanism is handled by systemd, if too many restarts occurs, then the service will be stopped.

What do you think?

[Clément Désiles (cde-)]

I found out a way to do that, in my lightdm configuration:

```
display-stopped-script=pkill lightdm
```