Comment 7 for bug 719388

I am not sure if anyone from Ubuntu will even respond here, but I checked upstream code and provided logs (btw thanks for them, very usefull here).

What happens here is:
- system is fully udev managed, both userspace and kernel are recent enough
- according to logs, something during "udev event" acknowledge fails and libdevmapper takes old compatible path
(trying to create/remove link in /dev/ itself) and also decrementing cookie semaphore.
- unfortunately, the event _was_ triggerred and dmsetup udevcomplete called and because both udev and libdevmapper decrements the semaphore, the second call fails with the message above.

I think the reason is in kernel (kernel do not annonce for some that uvent was sent) but I was not able to reproduce this. If you have some way how to reproduce it reliably, please let me know...

(The bug is not critical, the operation itself finishes correctly.)