kern/43840: panic kassert "so->so_head == NULL" failed

[spz%NetBSD.org@localhost]

>Number:         43840
>Category:       kern
>Synopsis:       panic: kassert "so->so_head == NULL" failed: file 
>"/usr/src/sys/kern/uipc_socket.c", line 703
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Sep 04 15:50:00 +0000 2010
>Originator:     S.P.Zeidler
>Release:        netbsd-5 2010-04-27
>Organization:
        TNF
>Environment:
System: NetBSD mollari.netbsd.org 5.1_RC1 NetBSD 5.1_RC1 (MOLLARI) #2: Tue Apr 
27 20:41:27 UTC 2010 
root%franklin.NetBSD.org@localhost:/home/netbsd/5/amd64/kern-compile/MOLLARI 
amd64
Architecture: x86_64
Machine: amd64
>Description:

panic: kernel diagnostic assertion "so->so_head == NULL" failed: file "/usr/src/
sys/kern/uipc_socket.c", line 703
fatal breakpoint trap in supervisor mode
trap type 1 code 0 rip ffffffff803bce95 cs 8 rflags 246 cr2  520120 cpl 4 rsp ff
ff800030eef820
Stopped in pid 0.3 (system) at  netbsd:breakpoint+0x5:  leave

db{0}> bt
breakpoint() at netbsd:breakpoint+0x5
cpu_Debugger() at netbsd:cpu_Debugger+0x9
panic() at netbsd:panic+0x24d
__kernassert() at netbsd:__kernassert+0x2d
soabort() at netbsd:soabort+0xc4
syn_cache_get() at netbsd:syn_cache_get+0x6a3
tcp_input() at netbsd:tcp_input+0x1242
ip_input() at netbsd:ip_input+0x438
ipintr() at netbsd:ipintr+0x6a
softint_dispatch() at netbsd:softint_dispatch+0xc3
db{0}> sh reg
ds          0xf7f0
es          0x3
fs          0x8
gs          0x596e
rdi         0x4
rsi         0x3f8
rbp         0xffff800030eef820
rbx         0xffff800030eef840
rdx         0x8
rcx         0x4
rax         0x1
r8          0xffffffff8057800a  copyright+0x3f26a
r9          0x1
r10         0xffff800030eef750
r11         0x8
r12         0x104
r13         0xffffffff805b3630  copyright+0x7a890
r14         0xffff800030eefb50
r15         0xffff80002edeb022
rip         0xffffffff803bce95  breakpoint+0x5
cs          0x8
rflags      0x246
rsp         0xffff800030eef820
ss          0
netbsd:breakpoint+0x5:  leave

>How-To-Repeat:
        seen only once yet
>Fix: