panic: ffs_valloc: dup alloc

Hello,

I'm getting this panic 'panic: ffs_valloc: dup alloc'.
It happens on -CURRENT, since quite some time.
It happens when doing an rsync from a remote server to my secondary disk.  
(ad2,master on ata1), there is no slave on this controller.
And it always happens, so it is very repeatable.
Is this probably a hardware failure? Or software?

$ uname -a
FreeBSD henk.thuis.klop.ws 5.2-CURRENT FreeBSD 5.2-CURRENT #24: Mon Jun 14  
00:25:19 CEST 2004     root_at_henk.thuis.klop.ws:/usr/obj/usr/src/sys/HENK   
i386

A backtrace of the kernel core dump is in the attached gdb.txt.
My dmesg is also attached.

Can I provide more info?

Greetings,

Ronald.

PS: Searched the archives and google, but didn't find anything usefull yet.

-- 
  Ronald Klop
  Amsterdam, The Netherlands