Comment # 5 on bug 1011053 from Thiago Macieira

> Does the problem happen every time when you shutdown or reboot? Or only 
> occurred when the system is happening to run "dmeventd" deamon?

The two are the same thing because dmeventd is always running. My system is
configured to snapshot /home every hour, so unless I start the system, do
something and shut down before it runs, it'll happen.(In reply to zhen ren from
comment #4)

> What we need to known is what the lvm is doing there? We can imagine that
> snapper (hourly according to you) tell lvm to take snapshot, after that, the
> cleanup algorithm will also let lvm to cleanup the old snapshot. I don't
> know how long each of the operations lvm will take, which decides how busy
> lvm is, and the time window the shutdown meets a working lvm. It is
> reasonable if shutdown happens during lvm is busy. Anyway, I will look into
> more when I get time;-)

As far as I can tell:
* hourly, snapper wakes up and tells lvm to take a snapshot
* lvm starts dmeventd because of that
* dmeventd NEVER exits
* since dmeventd never exits, the D-Bus service fails to shut down in systemd,
requiring a timeout before SIGKILL