Bug 23935

	This is the information I've managed to collect. Excuse me, but
this was my first DDB and kgdb experience.

Script started on Fri Dec 29 04:57:17 2000
# gdb -k
GNU gdb 4.18
Copyright 1998 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i386-unknown-freebsd".
(kgdb) symbol-file /boot/kernel/kernel
Reading symbols from /boot/kernel/kernel...(no debugging symbols found)...done.
(kgdb) exec-file /var/crash/kernel.0
(kgdb) core-file /var/crash/vmcore.0
IdlePTD 3416064
initial pcb at 2a0240
panicstr: from debugger
panic messages:
---
panic: blockable mtx_enter() of lockmgr interlock when not legal @ ../../kern/kern_lock.c:247
panic: from debugger
Uptime: 16m49s

dumping to dev ad0s2b, offset 81920
dump ata0: resetting devices .. done
24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 
---
#0  0xc016c572 in dumpsys ()
(kgdb) where
#0  0xc016c572 in dumpsys ()
#1  0xc016c358 in boot ()
#2  0xc016c72d in panic ()
#3  0xc011bb3d in db_panic ()
#4  0xc011badb in db_command ()
#5  0xc011bba2 in db_command_loop ()
#6  0xc011de0f in db_trap ()
#7  0xc0207116 in kdb_trap ()
#8  0xc0212944 in trap ()
#9  0xc0207385 in Debugger ()
#10 0xc016c724 in panic ()
#11 0xc01664c6 in witness_enter ()
#12 0xc0162a9e in lockmgr ()
#13 0xc016de9c in psignal ()
#14 0xc016d9d9 in pgsignal ()
#15 0xc018826f in ttyinput ()
#16 0xc0200725 in sckbdevent ()
#17 0xc01f870f in atkbd_intr ()
#18 0xc021d08c in atkbd_isa_intr ()
#19 0xc02182d1 in ithd_loop ()
(kgdb) # ^D
Script done on Fri Dec 29 04:58:05 2000

I'll provide any information needed because I can reliably reproduce the panic
situation.

How-To-Repeat: 	Make a ppp dial-up connection using user-level ppp(8). ftp to an
ftp server. Drop the connection by `killall ppp' or by issuing `down'
at ppp(8) command prompt.  Press Ctrl-Z in ftp to suspend it. The
box panics.