panic: nfssvc_nfsd(): debug.mpsafenet=1 && Giant

Howdy!

I was testing out the BSDInstaller NetBoot Installation Services
feature (PXE Boot) and ran into this panic:

[hand scribed]

panic: nfssvc_nfsd(): debug.mpsafenet=1 && Giant
cpuid =0
KDB: enter: panic
[thread pid 1003 tid 100090 ]
Stopped at      db_enter+0x2b: nop
db> show locks
exclusive sleep mutex nfsd_mtx r = 0 (0xc0b8fc20) locked _at_
/usr/src/sys/nfsserver/nfs_syscalls.c:511
exclusive sleep mutex Giant r = 0 (0xc0b309c0) locked _at_
/usr/src/sys/nfsserver/nfs_serv.c:526
db> bt
Tracing pid 1003 tid 100090 td 0xc2c3da80
kdb_enter
panic
nfssvc
nfssvc
syscall
Xint0x80_syscall() at Xint0x80_syscall+31

This panic is reproducable every time.  Let me know if can gather more
information and or test patches.

Thanks!!