Bug#973474: gnome: Unable to log back in in after screen lock

[Marcin Owsiany]

Just a quick note because I think I have a lead, but won't be able to go
through all your suggestions today.

First of all, I'm also unable to reproduce the issue if I go straight to
logging into the Gnome session after booting my VM.

However I am able to reproduce it if I first log into and log out of a few
other session types.
I'm still trying to figure out the minimal set which triggers the issue
consistently, but so far I can see the issue if I:
- boot the VM
- log into LXDE session and log out
- log into Cinnamon session and log out
- log into "System X11 default" session which I think is LXQT in this case,
and log out
- log into Gnome session
- lock the screen through the menu in upper right-hand corner
- try to unlock

FWIW, the message which "journalctl -f" shows (in an ssh session running in
parallel) when I enter the unlock password is:

lut 28 21:48:52 debian gdm-password][38277]: gkr-pam: unlocked login keyring

A few replies to some of your points below, I'll keep digging whenever I
have some free time in the coming week.

sob., 27 lut 2021 o 22:28 Simon McVittie <smcv at debian.org> napisał(a):

> On Sat, 27 Feb 2021 at 19:21:46 +0100, Marcin Owsiany wrote:
> > Regarding the messages I see in syslog, see the screenshot I had
> attached to my
> > previous message.
>
> On a freshly-installed, up to date test VM, you should find that the gdm
> login screen has a grey background, but the gnome-shell lock screen has a
> dark blue background (it's a blurred version of your desktop background,
> for which the default in Debian 11 is going to be dark blue).


Right, I'm pretty sure the weird behaviour is in the lock screen, not the
gdm login screen.


> It would
> be useful if you could describe the steps you use to reproduce this bug,
> and at each step that involves a login screen, say whether the background
> is grey or blue.
>
> Here is a sequence of screenshots illustrating my
> attempt to reproduce this, together with my system log:
> <https://people.debian.org/~smcv/973474/> (and then after pressing Enter
> for my test user's password, I'm back to my unlocked session, equivalent
> to <https://people.debian.org/~smcv/973474/5.png>). At what point does
> what you see diverge from that?
>
> I'm surprised you see messages from Xorg: those should only appear when
> you start a completely new session, not when you just lock and unlock
> the screen. This suggests that maybe the session is crashing, and instead
> of the gnome-shell lock screen on tty7, you are going back to the gdm
> login screen on tty1.
>

As far as I can tell it's not crashing. Could they have been triggered by
switching between virtual consoles?
Going forward I'll try to use a parallel SSH login rather than messing
around with CTRL+ALT+Fx to keep things simpler.


> Given that you see messages from Xorg, I would also expect to see more
> messages than just those. Before locking the screen, please run
>
>     logger "before locking"
>
> to leave a marker in the system log; and then please look back through
> the system log at least as far as that marker.
>
> If you look at the systemd journal (as root) instead of syslog, you'll
> also see "auth" messages, which could be relevant: for instance, when
> you enter a wrong password, that should be logged as an "auth" message
> from PAM.
>
> Please describe the steps you took to install your test VM, including
> any non-default settings used? For example, I wonder whether this is
> locale-sensitive - I'm using en_GB.UTF-8 but you seem to be using a
> non-English locale.
>
> If your test VM does not contain any personal or confidential data,
> and you can can transfer files off it with ssh, a shared filesystem or
> paste.debian.net, it would be useful to see the entire systemd journal
> (starting from boot) for this procedure:
>
> - boot the VM
> - log in as a user
> - lock the screen
> - unlock with a correct password
>
> and compare it with
> <https://people.debian.org/~smcv/973474/journalctl_-b.log.gz>.
>
> Or if your test VM contains personal/confidential things, please could
> you try to set up a similar VM without those and reproduce the bug there?
>
> > Is there perhaps some setting I could tweak to convince gnome-shell to
> produce
> > some debug output when I attempt unlocking?
>
> Try these:
>
> systemctl --user edit gnome-shell at x11.service
> systemctl --user edit gnome-shell at wayland.service
> sudo systemctl edit gdm.service
>
> and in each case, add this:
>
> [Service]
> Environment=G_MESSAGES_DEBUG=all
>
> Thanks,
>     smcv
>
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