Portupgrade, -CURRENT & SMP

I have three machines which I just upgraded from 5.4 to -CURRENT.  They 
are two SMP desktops and a UP laptop.

After building world and installing, I started to run portupgrade on my 
systems.  On the laptop, everything has been running smoothly..  On both 
SMP systems, portupgrade hangs.  top shows the ruby18 process stuck in 
the *vnode state.  On one machine, which I can't physically access, it's 
been this way for hours.  I can't ssh into this machine, and only have 
access to sessions that were connected before the hang.  On my home 
machine (which I can physically access), I've been able to log in on the 
virtual consoles and reboot when this happens (though it's not ever able 
to sync all buffers and cleanly unmount /).  It's now happened with 5 or 
6 consecutive attempts at portupgrade on this machine.  The most recent 
time this happened, on a hunch, I built a UP kernel, rebooted, and tried 
portupgrade again.  It's now been running for two hours without hanging 
(previous record was less than five minutes).

I've googled around a bit for this problem, but haven't come across 
anythign yet.  Has anyone seen this before?  I'll gladly submit a pr, 
but I'm just looking for more idea, or maybe some confirmation from 
others who have seen this.

Adam