Comment # 3 on bug 1138984 from Franck Bui

(In reply to Alynx Zhou from comment #1)
> Maybe you'd better use `poweroff` instead `halt`, because it seems that
> `halt` may not send ACPI instruction but poweroff do send, which leads
> hangs, because halt terminates system but does not tell computer to
> shutdown, so your screen is still on and it looks like hangs.

Indeed so the fact that the shutdown process hangs forever with halt is
expected. If you don't want this behavior, uses something like "reboot",
"poweroff"...

Regarding the umount failures, the one regarding /var is a known issue as
journald is still writing logs in the journal until very lately.

For the other ones... I don't know, but it's a different issue which should be
reported in a new bug. So please open a new bug if you want us to look at them
but make sure to provide the debug logs.

For providing the debug logs:

 - make sure to use persistent journals:
   # mkdir /var/log/journal
   # reboot

 - before rebooting turn the debug logs on:
   # systemd-analyze log-level debug

 - reboot

 - provide the debug logs from the previous boot:
   # journalctl -b -1 -o short-monotonic