panic: sbappendaddr

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

Today I get the following panic frequently on hp300.
I wonder if it's MD issue or not, but is there any clue
around that code?

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Checking for core dump...
savecore: /dev/sd0b: Device busy
Mar 31 01:21:21 delica savecore: /dev/sd0b: Device busy
Setting date via ntp.
panic: sbappendaddr
Stopped in pid 157.1 (ntpdate) at       netbsd:cpu_Debugger+0x6:        unlk    
a6
db> tr
cpu_Debugger(0,1701e00,1701e00,4178d84,4178da0) + 6
panic(26391c,1,14,1c,1701e00) + 172
sbappendaddr(170cbc4,4178e5c,1701e00,0,1701e00,1c) + 21a
udp4_sendup(1701e00,1c,4178e5c,170cb2c,11) + 80
udp_input(1701e00,14,11) + 386
ip_input(1701e00) + 5bc
ipintr(0,0,1a,0,4178f40) + 58
softint_overlay(2db1b8,4145000,2f6d1b0,4178fb4,4178f70) + 17a
lwp_userret(4145000) + 11e
machine_userret(4145000,4178fb4,0,1a,85,4145000,4178fb4) + e2
syscall(85) + 6a
trap0() + e
db> 
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Izumi Tsutsui