Screensaver unlock screen shown twice after playing video

[Amir]

Observed behaviour: resuming from screensaver, after unlocking the screen with a password, the desktop is shown briefly and is immediately locked again, but with a different look-and-feel lock screen. Entering the password once more will finally show the desktop. This started happening seemingly sporadically, and would continue to happen consistently until end of session (logout or shutdown).

Digging further, it was found that a `gnome-screensaver` process was running in addition to the normal `cinnamon-screensaver`. It was a child process of `systemd --user`, so a `ps -o pid,comm,cgroup` found that it was running as part of `dbus.service`.

Finally, the culprit was found in the journal for that unit (`dbus.service`):
Nov 12 15:03:40 laptop dbus-daemon[1696]: [session uid=1000 pid=1696] Activating service name='org.gnome.ScreenSaver' requested by ':1.206' (uid=1000 pid=3445 comm="/usr/bin/totem --gapplication-service " label="unconfined")

So, the workaround (which I am quite happy with, frankly) is to use VLC instead of Totem. ☺

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: cinnamon-session 3.6.1-1
ProcVersionSignature: Ubuntu 4.15.0-38.41-generic 4.15.18
Uname: Linux 4.15.0-38-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.4
Architecture: amd64
CurrentDesktop: X-Cinnamon
Date: Tue Nov 13 08:56:37 2018
InstallationDate: Installed on 2018-10-31 (12 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
SourcePackage: cinnamon-session
UpgradeStatus: No upgrade log present (probably fresh install)

[Amir (amiryal)]

This is where my technical knowledge is reaching its current boundaries. Based on what I saw in this Arch forum thread[1], it seems possible to block certain services from starting up in `/usr/share/glib-2.0/schemas/org.cinnamon.SessionManager.gschema.xml`. There is an `autostart-blacklist` key, but maybe there is also a way to block Totem from requesting `org.gnome.ScreenSaver` even at a later point?

[1] https://bbs.archlinux.org/viewtopic.php?pid=1706725#p1706725

[Amir (amiryal)]

It may be considered a bug in Totem, actually. Is it OK for it to ask D-Bus to launch the Gnome screensaver in the first place, while not running in a Gnome session?

+Bastien Nocera, what do you think[1]?

[1] https://gitlab.gnome.org/GNOME/totem/commit/336154c47dc415299e54b260c5438def6afd6f8b

[Bastien Nocera (hadess-deactivatedaccount)]

Should be fixed in https://gitlab.gnome.org/GNOME/totem/merge_requests/20

[Fantu (fantonifabio)]

This seems only a totem issue (and now solved), or I'm wrong?

[Bastien Nocera (hadess-deactivatedaccount)]

It was worked around in totem, but ultimately was a bug in mutter, which I also fixed.

It will still affect systems with older versions of mutter, or systems that don't use mutter and use X11 directly.

[Bastien Nocera (hadess-deactivatedaccount)]

Never mind, I confused this bug with another screensaver one.

There was a bug in totem, but there's also a bug in those other implementors of the interface which don't implement the full API. I don't think that those will ever be fixed. The problem won't happen until it happens again...

[Joshua Peisach (itzswirlz)]

Hey Amir, can you still reproduce this?

[Amir (amiryal)]

No, seems like it was fixed (tested on Ubuntu 22.04 LTS).