Comment 91 for bug 332270

Yeah, Fishor if TJ is correct then what's happening is this.

Udev adds watches on any of these devices which you have...
disk/partition
lvm
crypto
raid
(any other device-mapper things)

Only, unfortunately, two or more of those are the same real device. A race condition (which would probably be aggravated by SMP systems) can then occur where a potentially infinite loop of self-chaining change events starts. I would presume that at some point it either overflows or bogs down to the point where so many instances are spawned that it causes the lag and then lets you past.