Panic (GPF) on ZFS during make

I ran a simple "make" in /usr/src/bin/cat, and got dropped to debugger  
within a second.

BTW, before I give you a hundred lines of text: is there a good way to  
save the backtrace from the kernel debugger to disk? Dumps/panicking  
appears to ruin the backtrace. I had a nice backtrace on screen, but  
could obviously not copy/paste it from there (and figured it'd be  
saved with the core). In any case, the crash appears to have been  
related to, as can be seen below, zfs_freebsd_getattr and  
_sx_xlock_hard.

FreeBSD chaos.exscape.org 8.0-CURRENT FreeBSD 8.0-CURRENT #0 r193521M:  
Fri Jun  5 21:19:40 CEST 2009     root_at_chaos.exscape.org:/usr/obj/usr/ 
src/sys/DTRACE  amd64

kernel trap 9 with interrupts disabled

Fatal trap 9: general protection fault while in kernel mode
cpuid = 0; apic id = 00
instruction pointer = 0x20:0xffffffff805871a9
stack pointer           = 0x28:0xffffff803e7925b0
frame pointer           = 0x28:0xffffff803e792610
code segment        = base 0x0, limit 0xfffff, type 0x1b
             = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags    = resume, IOPL = 0
current process     = 80128 (make)
panic: from debugger
cpuid = 0
Uptime: 3d2h55m30s
Physical memory: 2028 MB
Dumping 1932 MB: 1917 .........

Reading symbols from /boot/kernel/zfs.ko...Reading symbols from / 
bootdir/boot/kernel/zfs.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/zfs.ko
Reading symbols from /boot/kernel/opensolaris.ko...Reading symbols  
from /bootdir/boot/kernel/opensolaris.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/opensolaris.ko
Reading symbols from /boot/kernel/amdtemp.ko...Reading symbols from / 
bootdir/boot/kernel/amdtemp.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/amdtemp.ko
Reading symbols from /boot/kernel/smbfs.ko...Reading symbols from / 
bootdir/boot/kernel/smbfs.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/smbfs.ko
Reading symbols from /boot/kernel/libiconv.ko...Reading symbols from / 
bootdir/boot/kernel/libiconv.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/libiconv.ko
Reading symbols from /boot/kernel/libmchain.ko...Reading symbols from / 
bootdir/boot/kernel/libmchain.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/libmchain.ko
Reading symbols from /boot/kernel/geom_gate.ko...Reading symbols from / 
bootdir/boot/kernel/geom_gate.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/geom_gate.ko
Reading symbols from /boot/kernel/accf_http.ko...Reading symbols from / 
bootdir/boot/kernel/accf_http.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/accf_http.ko
Reading symbols from /boot/kernel/dtraceall.ko...Reading symbols from / 
bootdir/boot/kernel/dtraceall.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/profile.ko
Reading symbols from /boot/kernel/cyclic.ko...Reading symbols from / 
bootdir/boot/kernel/cyclic.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/cyclic.ko
Reading symbols from /boot/kernel/dtrace.ko...Reading symbols from / 
bootdir/boot/kernel/dtrace.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/dtrace.ko
Reading symbols from /boot/kernel/systrace.ko...Reading symbols from / 
bootdir/boot/kernel/systrace.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/systrace.ko
Reading symbols from /boot/kernel/sdt.ko...Reading symbols from / 
bootdir/boot/kernel/sdt.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/sdt.ko
Reading symbols from /boot/kernel/lockstat.ko...Reading symbols from / 
bootdir/boot/kernel/lockstat.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/lockstat.ko
Reading symbols from /boot/kernel/fbt.ko...Reading symbols from / 
bootdir/boot/kernel/fbt.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/fbt.ko
Reading symbols from /boot/kernel/dtnfsclient.ko...Reading symbols  
from /bootdir/boot/kernel/dtnfsclient.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/dtnfsclient.ko
Reading symbols from /boot/kernel/dtmalloc.ko...Reading symbols from / 
bootdir/boot/kernel/dtmalloc.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/dtmalloc.ko
#0  doadump () at pcpu.h:223
223 pcpu.h: No such file or directory.
     in pcpu.h
(kgdb) #0  doadump () at pcpu.h:223
#1  0xffffffff8057ec59 in boot (howto=260)
     at /usr/src/sys/kern/kern_shutdown.c:419
#2  0xffffffff8057f0ac in panic (fmt=Variable "fmt" is not available.
)
     at /usr/src/sys/kern/kern_shutdown.c:575
#3  0xffffffff801d4fe7 in db_panic (addr=Variable "addr" is not  
available.
)
     at /usr/src/sys/ddb/db_command.c:478
#4  0xffffffff801d53f1 in db_command (last_cmdp=0xffffffff80bdc9a0,  
cmd_table=Variable "cmd_table" is not available.

) at /usr/src/sys/ddb/db_command.c:445
#5  0xffffffff801d5640 in db_command_loop ()
     at /usr/src/sys/ddb/db_command.c:498
#6  0xffffffff801d75d9 in db_trap (type=Variable "type" is not  
available.
) at /usr/src/sys/ddb/db_main.c:229
#7  0xffffffff805b0ab5 in kdb_trap (type=9, code=0,  
tf=0xffffff803e792500)
     at /usr/src/sys/kern/subr_kdb.c:534
#8  0xffffffff808603ed in trap_fatal (frame=0xffffff803e792500,  
eva=Variable "eva" is not available.
)
     at /usr/src/sys/amd64/amd64/trap.c:847
#9  0xffffffff808610ba in trap (frame=0xffffff803e792500)
     at /usr/src/sys/amd64/amd64/trap.c:639
#10 0xffffffff8083ad27 in calltrap ()
     at /usr/src/sys/amd64/amd64/exception.S:223
#11 0xffffffff805871a9 in _sx_xlock_hard (sx=0xffffff0002b8d0f1,
     tid=18446742974242527008, opts=Variable "opts" is not available.
) at /usr/src/sys/kern/kern_sx.c:575
#12 0xffffffff80587b1e in _sx_xlock (sx=Variable "sx" is not available.
) at sx.h:155
#13 0xffffffff80ef3564 in rrw_enter () from /boot/kernel/zfs.ko
#14 0xffffff0002c78100 in ?? ()
#15 0xffffff803e792810 in ?? ()
#16 0xffffffff80ef9545 in zfs_freebsd_getattr () from /boot/kernel/ 
zfs.ko
Previous frame inner to this frame (corrupt stack?)
(kgdb)

More info (core.txt + vmcore) still available.

Regards,
Thomas