kern/44206: reproducable (for me) NFS panic

[martin%NetBSD.org@localhost]

>Number:         44206
>Category:       kern
>Synopsis:       reproducable (for me) NFS panic
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Dec 08 09:05:01 +0000 2010
>Originator:     Martin Husemann
>Release:        NetBSD 5.99.41
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD after-hours.aprisoft.de 5.99.41 NetBSD 5.99.41 (GENERIC) #25: 
Tue Dec 7 12:41:46 CET 2010 
martin%emmas.aprisoft.de@localhost:/nelly/usr/src/sys/arch/sparc64/compile/GENERIC
 sparc64
Architecture: sparc64
Machine: sparc64
>Description:

This machine uses pkgsrc (including pkgsrc/distfiles) over NFS. Whenever
I make pkgsrc download a distfile, I get this panic:

panic: kernel diagnostic assertion "mb->m_next != NULL" failed: file 
"../../../../nfs/nfs_vnops.c", line 1377
Stopped in pid 0.50 (system) at netbsd:cpu_Debugger+0x4:        nop
db{1}> bt
kern_assert(1726ec0, 176c488, 561, 176c588, 1, f2c57d0) at 
netbsd:kern_assert+0x2c
nfs_writerpc(0, e9d5d08, 1, e9d5bf0, e9d5be0, ede8a20) at 
netbsd:nfs_writerpc+0xe84
nfs_doio(8000, e909400, e9d5cc8, e9d5d08, ede8b30, f802cb0) at 
netbsd:nfs_doio+0x510
nfssvc_iod(e909400, e909400, 0, d210e00, 10b9e80, 189b000) at 
netbsd:nfssvc_iod+0x150
db{1}> mach cpu 0
db{0}> bt
intr_biglock_wrapper(400aa80, 0, e0017ed0, 6, 120dd80, 1c14000) at 
netbsd:intr_biglock_wrapper+0x4
sparc_interrupt(0, d22f400, 0, d210e00, 175f400, d213c50) at 
netbsd:sparc_interrupt+0x1e8
kernel_lock(0, 0, 592, 17958b0, 0, 60) at netbsd:_kernel_lock+0xc0
sleepq_block(0, 0, d22f400, 1, 0, d22f400) at netbsd:sleepq_block+0x1e4
cv_timedwait(ede8a30, ede8a20, 0, 4590d70, 0, 0) at netbsd:cv_timedwait+0x108
nfs_rcvlock(0, eec67e0, 4590d70, eec67e0, 0, 45d8da8) at netbsd:nfs_rcvlock+0xc8
nfs_request(0, ede8a20, 2034, d22f400, d20ef00, 189d000) at 
netbsd:nfs_request+0x320
nfs_writerpc(1b, e085d08, 1, e085bf0, e085be0, ede8a20) at 
netbsd:nfs_writerpc+0x3ec
nfs_doio(0, d22f400, e085cc8, e085d08, ede8b30, f802cb0) at 
netbsd:nfs_doio+0x510
nfssvc_iod(d22f400, d22f400, 0, d210e00, 10b9e80, 189b000) at 
netbsd:nfssvc_iod+0x150


>How-To-Repeat:
s/a

>Fix:
any hints welcome