Panic unloading rl0

I rebuilt my kernel so that I could load/unload rl0.  When I ran
"kldunload if_rl", I received this panic:

Fatal trap 9: general protection fault while in kernel mode
cpuid = 0; apic id = 00
instruction pointer	= 0x8:0xffffffff80397a66
stack pointer	        = 0x10:0xfffffffe97c1b920
frame pointer	        = 0x10:0xfffffffe97c1b960
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 2231 (kldunload)
exclusive sleep mutex in_multi_mtx (in_multi_mtx) r = 0
(0xffffffff80bfc300) locked _at_ /usr/src/8x-zfs/sys/netinet/in.c:1033
exclusive sleep mutex Giant (Giant) r = 0 (0xffffffff80a388c0) locked
_at_ /usr/src/8x-zfs/sys/dev/kbdmux/kbdmux.c:1044
exclusive sx kernel linker (kernel linker) r = 0 (0xffffffff80a36a00)
locked _at_ /usr/src/8x-zfs/sys/kern/kern_linker.c:1059
exclusive sleep mutex in_multi_mtx (in_multi_mtx) r = 0
(0xffffffff80bfc300) locked _at_ /usr/src/8x-zfs/sys/netinet/in.c:1033
exclusive sleep mutex Giant (Giant) r = 0 (0xffffffff80a388c0) locked
_at_ /usr/src/8x-zfs/sys/dev/kbdmux/kbdmux.c:1044
exclusive sx kernel linker (kernel linker) r = 0 (0xffffffff80a36a00)
locked _at_ /usr/src/8x-zfs/sys/kern/kern_linker.c:1059
shared sx filedesc structure (filedesc structure) r = 0
(0xffffff0013157248) locked _at_
/usr/src/8x-zfs/sys/kern/sys_generic.c:1033

db> run lockinfo

db:0:lockinfo> show locks
db:0:locks>  show alllocks
Process 2231 (kldunload) thread 0xffffff00570eb3b0 (100224)
Process 1293 (syslogd) thread 0xffffff0002898000 (100069)
db:0:alllocks>  show lockedvnods
Locked vnodes
db> show pcpu

cpuid        = 0
curthread    = 0xffffff00570eb3b0: pid 2231 "kldunload"
curpcb       = 0xfffffffe97c1bd40
fpcurthread  = none
idlethread   = 0xffffff00023f4760: pid 11 "idle: cpu0"
spin locks held:
db> bt

Tracing pid 2231 tid 100224 td 0xffffff00570eb3b0
in_ifdetach() at in_ifdetach+0x106
if_detach() at if_detach+0xfa
rl_detach() at rl_detach+0x19e
device_detach() at device_detach+0xa4
devclass_delete_driver() at devclass_delete_driver+0xc0
driver_module_handler() at driver_module_handler+0xfe
module_unload() at module_unload+0x35
linker_file_unload() at linker_file_unload+0x16b
kern_kldunload() at kern_kldunload+0xf3
syscall() at syscall+0x1bf
Xfast_syscall() at Xfast_syscall+0xab
--- syscall (444, FreeBSD ELF64, kldunloadf), rip = 0x800692e1c, rsp =
0x7fffffffe3c8, rbp = 0x5 ---

Can anyone reproduce this problem?

Let me know if you need more information.

Scot