panic: already on hash list

[YONETANI Tomokazu]

Hi.
Caught this panic while playing with my build box.  I don't know the exact
moment when it panicked, as the monitor was connected to another box, but
here's what I was doing before the panic anyway:

- login to the build box from the console, and slogin to the router box
  (running DragonFly 1.8), and rebooted it.
- switch the monitor/keyboard to the router box, wait for it to boot,
  and login to the console.  slogin to the build machine, start GNU screen,
  start w3m (a text-based web browser, similar to lynx), tried to visit
  Google but it didn't work (this was expected, because for some reason mpd
  starts up earlier than ipnat and I always have to restart before I can
  connect to the Internet from behind the router).
- split the screen inside GNU screen, and typed ctrl+C on w3m.  A few seconds
  later I realized that the build box was unresponsive, and then I heard
  the machine rebooted.

Probably this panic only occurs on SMP machines, but I'd like to make sure
it won't happen on the router box before upgrading it.

The kernel dump is uploaded as ~y0netan1/crash/{kernel,vmcore}.11 on my
leaf account, in case someone is interested.

Thanks.

Unread portion of the kernel message buffer:
panic: already on hash list
mp_lock = 00000000; cpuid = 0
boot() called on cpu#0

syncing disks... 3 
done
Uptime: 1h31m54s

dumping to dev #ad/0x20001, blockno 640
[snipped]
(kgdb) bt
#0  dumpsys () at ./machine/thread.h:83
#1  0xc0198cbd in boot (howto=256)
    at /home/source/dragonfly/R2_0/src/sys/kern/kern_shutdown.c:375
#2  0xc0198f80 in panic (fmt=0xc02e2386 "already on hash list")
    at /home/source/dragonfly/R2_0/src/sys/kern/kern_shutdown.c:800
#3  0xc01ff460 in in_pcbinsconnhash (inp=0xd316c260)
    at /home/source/dragonfly/R2_0/src/sys/netinet/in_pcb.c:1053
#4  0xc02124d7 in tcp_connect_oncpu (tp=0xd316c320, sin=0xd7ef3d80, 
    if_sin=0xd316c260)
    at /home/source/dragonfly/R2_0/src/sys/netinet/tcp_usrreq.c:917
#5  0xc02126e1 in tcp_connect (tp=0xd316c320, nam=<value optimized out>, 
    td=<value optimized out>)
    at /home/source/dragonfly/R2_0/src/sys/netinet/tcp_usrreq.c:1036
#6  0xc02138b1 in tcp_usr_connect (so=0xd2c80fc0, nam=0xd7ef3d80, 
    td=0xd4102590)
    at /home/source/dragonfly/R2_0/src/sys/netinet/tcp_usrreq.c:479
#7  0xc01c9972 in netmsg_pru_connect (msg=0xd62d0bd0)
    at /home/source/dragonfly/R2_0/src/sys/kern/uipc_msg.c:450
#8  0xc020f0bc in tcpmsg_service_loop (dummy=0x0)
    at /home/source/dragonfly/R2_0/src/sys/netinet/tcp_subr.c:385
#9  0xc01a0961 in lwkt_deschedule_self (td=Cannot access memory at address 0x8
)
    at /home/source/dragonfly/R2_0/src/sys/kern/lwkt_thread.c:223