login only works on 2nd try

[junghans]

This is a stock Fedora 37 install with xfce. After a reboot the first login will always fail and then 2nd try will work.
(see https://bugzilla.redhat.com/show_bug.cgi?id=2167386)

Looking at the difference in lightdm.log (success) vs light.log.old (failed), the only real different is:

--- lightdm.log 2023-02-08 18:46:09.056295101 -0700
+++ lightdm.log.old     2023-02-08 18:46:09.057295116 -0700
@@ -59,20 +61,25 @@
 DEBUG: Authenticate result for user user: Success
 DEBUG: User user authorized
 DEBUG: Greeter sets language en_US.utf8
-DEBUG: Greeter requests session xfce
-DEBUG: Seat seat0: Stopping greeter; display server will be re-used for user session
-DEBUG: Terminating login1 session c2
-DEBUG: Session pid=1234: Sending SIGTERM
 DEBUG: Greeter closed communication channel
+DEBUG: Session pid=1234: Exited with return value 1
+DEBUG: Seat seat0: Session stopped
+DEBUG: Seat seat0: Stopping; failed to start a greeter
+DEBUG: Seat seat0: Stopping
+DEBUG: Seat seat0: Stopping display server
+DEBUG: Sending signal 15 to process 3321
+DEBUG: Seat seat0: Stopping session
 DEBUG: Session pid=1234: Exited with return value 0
 DEBUG: Seat seat0: Session stopped

Any ideas what is going wrong here?

[leigh123linux]

Maybe the greeter app is broken.

[+15.54s] DEBUG: Authenticate result for user leigh: Success
[+15.54s] DEBUG: User leigh authorized
[+15.54s] DEBUG: Greeter requests session cinnamon
[+15.54s] DEBUG: Seat seat0: Stopping greeter; display server will be re-used for user session
[+15.54s] DEBUG: Terminating login1 session c1
[+15.54s] DEBUG: Session pid=916: Sending SIGTERM
[+15.56s] DEBUG: Greeter closed communication channel
[+15.56s] DEBUG: Session pid=916: Exited with return value 0
[+15.56s] DEBUG: Seat seat0: Session stopped
[+15.56s] DEBUG: Seat seat0: Greeter stopped, running session
[+15.56s] DEBUG: Registering session with bus path /org/freedesktop/DisplayManager/Session0
[+15.56s] DEBUG: Session pid=984: Running command /etc/X11/xinit/Xsession cinnamon-session-cinnamon
[+15.56s] DEBUG: Creating shared data directory /var/lib/lightdm-data/leigh
[+15.56s] DEBUG: Session pid=984: Logging to .xsession-errors
[+16.07s] DEBUG: Activating VT 1
[+16.07s] DEBUG: Activating login1 session 2
[+16.07s] DEBUG: Seat seat0 changes active session to 
[+16.07s] DEBUG: Seat seat0 changes active session to 2
[+16.07s] DEBUG: Session 2 is already active

I use slick-greeter

[knob-creek]

The same happens here, but only on one PC (with slick-greeter), every other PC around just works as expected, with the gtk greeter as well as with the slick greeter. It still happens with Fedora 38.
Analysing the logs shows that the X11 and xfce scripts cannot communicate with the X server (or there is no X server). This is why starting the xfce session fails with exit code 1.

Adding a loop into one of the X11 scripts never succeeds, so no X server ever shows up while the session tries to start.

After logout, the next login immediately succeeds.

The issue is independent from gtk-greeter or slick greeter; switching back to gtk-greeter by simply deleting 90-slick-greeter.conf does not change this.

[leigh123linux]

IMO it's the session that should start X or Wayland, it isn't lightdm's job to start it.

[knob-creek]

lightdm is the first one who needs the X server, and it is the one starting it. (Try ps afx.) That already started X server is then re-used by the session.
What i have seen so far: after the first failed login attempt, a new X server is started, seemingly with the same parameters, but obviously something is different.

[knob-creek]

This might be an explanation and a solution:

• On the machine in question, the host name changes after lightdm is started.
• This might have X reject connections from processes started with a different host name than the one X itself was started with.
• Solution would be: don't change the host name after lightdm was started, or, start lightdm only after the host name is settled.

What i did:

• Enter a matching host name into /etc/hostname.
• Start lightdm after systemd-hostnamed.service by adding an appropriate line to /lib/systemd/system/lightdm.service.

The latter might be adopted by the distributions.

[junghans]

I can confirm entering a hostname in /etc/hostname works!

[raveit65]

I really like to see an upstream PR or commit before we add this to fedora.

[junghans]

@raveit65 The lightdm.service files are distribution specific, but #336 has the fix suggested by @knob-creek in #291 (comment) for Debian at least.

[raveit65]

@raveit65 The lightdm.service files are distribution specific, but #336 has the fix suggested by @knob-creek in #291 (comment) for Debian at least.

Well, the file is inside the debian folder because of the structure of debian packaging for debian and his derivatives.
But it is definitely the same file for all distros which use systemd. For me this is an upstream task.