kern/121809: unable to umount

[barbara]

> Synopsis: unable to umount
> 
> State-Changed-From-To: open->feedback
> State-Changed-By: vwe
> State-Changed-When: Tue Mar 18 21:30:16 UTC 2008
> State-Changed-Why: 
> 
> Unfortunately your report does not contain much information to work on.
> Please send us the following information:
> mount
> dmesg
> sysctl vfs
> If this is consistent behaviour with only a specific filesystem, please
> provide additional output of:
> dumpfs (fsinquestion)
> disklabel (slice/deviceinquestion)
> Please try if this is still an issue with or without softupdates enabled and
> if it helps to sync;sync before umount'ing.
> If not, please send us your kernel config or at least a diff to GENERIC.
> Best is to try if you're able to reproduce this using a GENERIC kernel.
> 
> http://www.freebsd.org/cgi/query-pr.cgi?pr=121809
> 

Today, after a reboot, I did the test again and the problem was still existing.
So I've rebuilt world+kernel again after updating the sources.
I still have to reboot to run make installworld but the problem seems gone after that. Is this possible? Maybe I've missed an error during the previous install(world)|(kernel) (?).
I'm going to reboot on the next minutes and repeat the test again.
If it will be all right, do you need other tests/info like booting the old kernel or update the sources at more or less the time they was updated yesterday? If so, please, tell me.