udev races with snaphots?

Binary package hint: lvm2

Current dual-core amd64 hardy system:
# dpkg -l lvm2 dmsetup | grep ^ii
ii dmsetup 2:1.02.20-2ubuntu2 The Linux Kernel Device Mapper userspace library
ii lvm2 2.02.26-1ubuntu9 The Linux Logical Volume Manager

The system makes 10 LVM snaphots for backups every other hour. Occasionally I get messages like these in the syslog:

Jun 7 10:23:40 new kernel: [3666376.279740] device-mapper: ioctl: unable to remove open device linux-srv_mysql-real
...
Jun 13 02:23:35 new udevd-event[24254]: unlink_secure: chmod(/dev/mapper/linux-backup_var_spool-cow, 0000) failed: No such file or directory
...
Jun 17 00:23:44 new udevd-event[12412]: unlink_secure: chown(/dev/mapper/linux-backup_srv_mysql-cow, 0, 0) failed: No such file or directory
Jun 17 00:23:44 new udevd-event[12412]: unlink_secure: chmod(/dev/mapper/linux-backup_srv_mysql-cow, 0000) failed: No such file or directory

The messages *seem* to be harmless. Snapshot creation, mounting, unmounting, deletion seem to work okay and the backups were fine so far. But we are talking about backups, even a bogus error message means that I have to check the backups each time this happens.

The problem shows up both with vanilla and Ubuntu kernels.