Processes in "ufs" state (PR kern/104406)

Hello list!

I've stumbled across this (probable) bug when doing some
number-crunching. Processes which try to access the filesystem hang at
some point when another process has been gobbling up CPU time for a
sufficiently long time. Interestingly, processes which have already
opened some files before the `hang' can apparently read/write them
without hindrance (iostat shows some disk activity). Interactive
processes run well too. When the number-cruncher is `kill -STOP'ped and
`kill -CONT'ed, everything runs well for another while. It's reliably
and frequently reproducible here both on recent and late August CURRENT,
the kernel is GENERIC, the hardware is basic (no RAID, etc.).

Could anyone experienced enough try to look into this and/or give advice
for debugging the problem? I have ddb available, but I'm not sure about
where to look.

http://www.freebsd.org/cgi/query-pr.cgi?pr=104406

Thanks in advance,

-- 
DoubleF
No virus detected in this message. Ehrm, wait a minute...
/kernel: pid 56921 (antivirus), uid 32000: exited on signal 9
Oh yes, no virus:)