Comment 3 for bug 846061

Here's a handy script to reproduce the error. This uses dd to create an image file, so it doesn't require any real volumes.

And here's the key part of the log:

#libdm-deptree.c:865 Removing demo_vg-foo_lv (252:0)
#libdm-common.c:1153 Udev cookie 0xd4d4fb5 (semid 720897) created
#libdm-common.c:1166 Udev cookie 0xd4d4fb5 (semid 720897) incremented
#libdm-common.c:1054 Udev cookie 0xd4d4fb5 (semid 720897) incremented
#libdm-common.c:1226 Udev cookie 0xd4d4fb5 (semid 720897) assigned to dm_task type 2 with flags 0x0
#ioctl/libdm-iface.c:1821 dm remove (252:0) NF [16384]
#libdm-common.c:1081 Udev cookie 0xd4d4fb5 (semid 720897) decremented
#libdm-common.c:815 demo_vg-foo_lv: Stacking NODE_DEL (replaces other stacked ops)
#libdm-common.c:1069 semid 720897: semop failed for cookie 0xd4d4fb5: incorrect semaphore state
#libdm-common.c:1270 Failed to set a proper state for notification semaphore identified by cookie value 223170485 (0xd4d4fb5) to initialize waiting for incoming notifications.
#libdm-common.c:1096 Udev cookie 0xd4d4fb5 (semid 720897) destroyed

This is on Ubuntu 11.10. The warning does not occur on Ubuntu 11.04.