busdma/scsi trm(4) related panic

Hi,

I've been getting what appears to be a busdma / scsi related panic for
the past couple of days.  This is based solely on what little info I get
when it drops to the debugger - I haven't been able to get a core dump. 
It panics during the boot process immediately after it tries to probe my
scsi devices (just a cdrom) attached to my Tekram DC-315U adapter.  If I
remove trm(4) from my kernel, I can boot without a panic, but if I load
the trm module, and then issue `camcontrol rescan all` it will panic. 
Reverting /usr/src/sys/i386/i386/busdma_machdep.c to version 1.52 lets
me boot and use my scsi devices without panics. Version 1.53 will panic
too.

This is with -current sources as of 5:57am MST (12:47UTC) on Aug. 5.  
FreeBSD jonnyv.kwsn.lan 5.1-CURRENT FreeBSD 5.1-CURRENT #3: Tue Aug  5
21:09:50 MST 2003    
jonnyv_at_jonnyv.kwsn.lan:/usr/obj/usr/src/sys/JONNYV  i386


Here's what little info I have (apologies for typos, I had to transcribe
this by hand):

Fatal trap 12: page fault while in kernel mode
fault virtual address 	= 0x0
fault code		= supervisor write, page not present
instruction pointer	= 0x8:0xc35682f
stack pointer		= 0x10:0xd68fbb94
frame pointer		= 0x10:0xd68fbbd8
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, def32 1, gran 1
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 12 (swi7: tty:sio clock)
kernel: type 12 trap, code = 0
Stopped at _bus_dmamap_load_buffer+0x3ff: movl %ecx,0(%edx,%eax,8)

$ nm -n /boot/kernel/kernel | grep c03568
c03568e0 T bus_dmamap_load

If there's anything you'd like me to type at the "db>" prompt, just ask
and I'll send the output.

Thanks,
Jon