Comment # 6 on bug 955096 from Takashi Iwai

(In reply to Antoine Belvire from comment #5)
> (In reply to Takashi Iwai from comment #4)
> > Looks like so...  But the log attached doesn't contain the timeout messages
> > you pasted, so it's hard to judge.
> 
> Sorry, I don't understand��� What I pasted is extracted from the shutdown.log
> attached. I can see the timeout messages there, beginning at line 364.
> 
> ?

Oh, yes, sorry somehow overlooked.

> > To simply a bit, could you try to boot in the single user mode and shutdown
> > for confirming that the problem is still present?
> 
> I will try that. For now, I've juste noticed that if I log out before
> shutdown, it shutdowns properly.

This is interesting.  So some remaining process might block unmounting?
Can you trigger alt-sysrq-t to get the current tasks while hanging?
You may need to enable magic sysrq beforehand like
  sysctl kernel.sysrq=1
or modify /etc/sysctl.d/* for permanent change.