kern/38475: bogus mbuf chain

[martin%duskware.de@localhost]

>Number:         38475
>Category:       kern
>Synopsis:       bogus mbuf chain
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Apr 21 12:30:00 +0000 2008
>Originator:     Martin Husemann
>Release:        NetBSD 4.99.60
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD nelly.aprisoft.de 4.99.60 NetBSD 4.99.60 (NELLY.MP) #2: Mon Apr 
21 10:04:16 CEST 2008 
martin%emmas.aprisoft.de@localhost:/nelly/usr/src/sys/arch/sparc64/compile/NELLY.MP
 sparc64
Architecture: sparc64
Machine: sparc64
>Description:

Under NFS load, I see several signs of mbuf chain corruption. First encounter
was a in4_cksum panic, most other variants were like this:

panic: m_copym: m == 0, off =1236

with backtrace:
m_copym0
ip_fragment
ip_output
udp_output
udp_usrreq
nfs_timer

>How-To-Repeat:

Usually config + make depend + make -j 4 with source on NFS is enough for
me.

>Fix:
n/a