I am using Ubuntu Gutsy, which is the in-development branch heading for... = 0
their next stable release.
I have noticed that since some kernel release post-2.6.20 I have been
unable to mount my /boot partition:
$ sudo strace -f mount /dev/hda1 /mnt/foo
execve("/bin/mount", ["mount", "/dev/hda1", "/mnt/foo"], [/* 41 vars*/])= 0
mount("/dev/hda1", "/mnt/foo", "ext3", MS_MGC_VAL, NULL) = -1 EBUSY (Device or resource busy)...
rt_sigprocmask(SIG_UNBLOCK, ~[TRAP SEGV RTMIN RT_1], NULL, 8) = 0
write(2, "mount: /dev/hda1 already mounted"..., 50mount: /dev/hda1 already mounted or /mnt/foo busy) = 50
All other block devices (all LVM LVs) seem to mount with no problems.