Control: clone -1 -2 -3 Control: retitle -2 cinnamon-session: Should not upload XDG_SESSION_ID to systemd --user Control: reassign -2 cinnamon-session 4.8.0-2 Control: retitle -3 mate-session-manager: Should not upload XDG_SESSION_ID to systemd --user Control: reassign -3 mate-session-manager 1.24.1-1 Control: retitle -1 gnome-session: Should work around session managers that upload XDG_SESSION_ID to systemd --user Control: reassign -1 gnome-session 3.38.0-3 Control: forwarded -1 https://gitlab.gnome.org/GNOME/gnome-session/-/issues/86
A summary of this bug for MATE and Cinnamon maintainers: Steps to reproduce: * Install a bullseye system with GNOME and Cinnamon, or GNOME and MATE, or all three. I used GNOME and Cinnamon (only) in a VM to diagnose what was happening, and then installed MATE on the same VM to verify whether it has the same bug as Cinnamon (it does). * Configure gdm to be the display manager (I don't know whether this is actually important, but it's what I had) * Have Debian's default systemd-logind configuration with KillUserProcesses=no (contrary to the systemd upstream default of KillUserProcesses=yes) * Log in as a test user. Before entering the password, set the requested desktop session to Cinnamon or MATE using the cogwheel icon in the lower right corner. * Log out, returning to the gdm greeter. * Quickly log back in as the same user, but before entering the password, set the requested desktop session to something GNOME-based. I tested "GNOME" and "GNOME on Xorg", but GNOME Classic would probably behave the same. * Lock the screen (Super+L, where Super is usually the Windows logo key) * Try to unlock the screen with the password Expected result: * Screen successfully unlocks Actual result: * An error message like this appears during GNOME startup: gnome-shell[2218]: JS ERROR: Could not get a proxy for the current session: Gio.IOErrorEnum: GDBus.Error:org.freedesktop.login1.NoSuchSession: No session '2' known where 2 is the session ID that was allocated to Cinnamon or MATE (and not the numerically larger session ID that was allocated to GNOME). * Screen does not unlock, password prompt immediately reappears. Logs with extra debugging (see below) are available in <https://people.debian.org/~smcv/bug973474/>. The root cause is that in GNOME 3.38, GNOME Shell is run as a `systemd --user` service, which inherits the activation environment variables that are uploaded to `systemd --user` by user processes such as gnome-session, cinnamon-session, mate-session-manager, and (if installed) /etc/X11/Xsession.d/95dbus_update-activation-env. gnome-session and 95dbus_update-activation-env are careful to avoid sending variables that should be specific to one particular login session - particularly XDG_SEAT, XDG_SESSION_ID and XDG_VTNR - to `systemd --user`. However, cinnamon-session and mate-session-manager do not have the same special case for those variables and will indiscriminately upload everything. For example, looking for "New session" in journal-cinnamon.txt.gz, we can see Cinnamon session 2 start at 12:16:07, and XDG_SESSION_ID=2 is uploaded to `dbus-daemon --session` and copied from there to `system --user` at 12:16:09. After we log out and back in, GNOME session 6 starts at 12:17:08. If everything worked correctly, we should see messages like this: gnome-shell[1234]: Unset XDG_SESSION_ID, getCurrentSessionProxy() called outside a user session. Asking logind directly. gnome-shell[1234]: Will monitor session 6 but instead gnome-shell inherits XDG_SESSION_ID=2 from the activation environment, and tries (and fails) to monitor that. The MATE log shows similar symptoms. Helpful steps to debug: * Boot with systemd.log_level=debug on the kernel command-line so you can see more of what is going on * Put this unit in /etc/systemd/system/dbus-monitor.service with a symlink to ../dbus-monitor.service in /etc/systemd/system/multi-user.target.wants: [Unit] Description=System bus monitor Before=gdm.service Wants=dbus.socket After=dbus.socket [Service] User=root ExecStart=/usr/bin/dbus-monitor --system * Put this unit in /etc/systemd/user/dbus-monitor.service with a symlink to ../dbus-monitor.service in /etc/systemd/user/default.target.wants: [Unit] Description=Session bus monitor Before=org.gnome.Shell@wayland.service org.gnome.Shell@x11.service Wants=dbus.socket After=dbus.socket [Service] ExecStart=/usr/bin/dbus-monitor --session * Before logging out from Cinnamon or MATE, use logger(1) to record a message in the system log * Before locking the screen in GNOME, use logger(1) again I think this is really a bug in cinnamon-session and mate-session-manager: they should not be adding highly login-session-specific variables like XDG_SESSION_ID to the activation environment. However, when there's a bad interaction between two components it's often better to fix both ends, so I'm testing a patch for gnome-session that will make it work around this. smcv
