[RndTbl] can't stop md yet lsof is empty?

[Trevor Cordes]

Very weird problem here:

I umounted the filesystem on a md (RAID1) device.

Then:

mdadm --stop /dev/md1
mdadm: Cannot get exclusive access to /dev/md1:Perhaps a running process, 
mounted filesystem or active volume group?

Huh?

lsof /dev/md1
<nothing!>

I remounted the fs and tried lsof <fs> and it was empty too.

I can't seem to find any reason why mdadm --stop should not allow stopping 
this array.  Any ideas?  Anything other than lsof that can help find out 
why?