Embora geralmente o desligamento demore menos de um minuto, às vezes leva 2 ou 3. Podem ser meus 7 btrfs Os HDDs são os culpados (eles demoram 3 minutos para montar), mas o problema é inconsistente. A tela fica preta com o sublinhado piscando e, eventualmente, desliga.
Esta, eu acho, é a parte relevante de journalctl -b -1
Mar 05 14:16:47 Shamaniak systemd[444]: Stopped target Basic System.
Mar 05 14:16:47 Shamaniak systemd[444]: Stopped target Timers.
Mar 05 14:16:47 Shamaniak systemd[444]: Stopped target Sockets.
Mar 05 14:16:47 Shamaniak systemd[444]: Closed Sound System.
Mar 05 14:16:47 Shamaniak systemd[444]: Stopped target Paths.
Mar 05 14:16:47 Shamaniak systemd[444]: Closed D-Bus User Message Bus Socket.
Mar 05 14:16:47 Shamaniak systemd[444]: Reached target Shutdown.
Mar 05 14:16:47 Shamaniak systemd[444]: Starting Exit the Session...
Mar 05 14:16:47 Shamaniak systemd[1]: Stopped Light Display Manager.
Mar 05 14:16:47 Shamaniak systemd[1]: lightdm.service: Unit entered failed state.
Mar 05 14:16:47 Shamaniak systemd[1]: lightdm.service: Failed with result 'exit-code'.
Mar 05 14:16:47 Shamaniak systemd[444]: Received SIGRTMIN+24 from PID 12539 (kill).
Mar 05 14:16:47 Shamaniak systemd[445]: pam_unix(systemd-user:session): session closed for user barafu
Mar 05 14:16:47 Shamaniak systemd[1]: Stopped User Manager for UID 1000.
Mar 05 14:18:15 Shamaniak systemd[1]: session-c1.scope: Stopping timed out. Killing.
Mar 05 14:18:15 Shamaniak systemd[1]: Stopped Session c1 of user barafu.
Mar 05 14:18:15 Shamaniak systemd[1]: session-c1.scope: Unit entered failed state.
Mar 05 14:18:15 Shamaniak systemd[1]: Removed slice User Slice of barafu.
Mar 05 14:18:15 Shamaniak systemd[1]: Stopping Permit User Sessions...
Mar 05 14:18:15 Shamaniak systemd[1]: Stopping Login Service...
Mar 05 14:18:15 Shamaniak systemd[1]: Stopped Permit User Sessions.
Mar 05 14:18:16 Shamaniak systemd[1]: Stopped target Remote File Systems.
Mar 05 14:18:16 Shamaniak systemd[1]: Stopped Login Service.
Mar 05 14:18:16 Shamaniak systemd[1]: Stopped target Basic System.
Mar 05 14:18:16 Shamaniak systemd[1]: Stopped target Slices.
Mar 05 14:18:16 Shamaniak systemd[1]: Stopped target Paths.
Estou usando canela com LightDM, caso seja relevante.