kern/47815: Reader / writer lock error: rw_vector_enter: locking against myself

[obergsgbg-comp%yahoo.se@localhost]

>Number:         47815
>Category:       kern
>Synopsis:       Reader / writer lock error: rw_vector_enter: locking against 
>myself
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue May 14 18:55:00 +0000 2013
>Originator:     Emil Öberg
>Release:        NetBSD 6.1_RC3
>Organization:
>Environment:
NetBSD m350 6.1_RC3 NetBSD 6.1_RC3 (BRASAN) #14: Mon May  6 20:45:44 CEST 2013  
emil@m350:/usr/src/sys/arch/amd64/compile/BRASAN amd64
>Description:
System is idle, no one logged on, no extra services started beside what is on a 
normal, minimal installation, no X11.

Periodic reboots (2-3 times aday) from following crash:

Reader / writer lock error: rw_vector_enter: locking against myself

lock address : 0xfffffe813d16dfa0
current cpu  :                  1
current lwp  : 0xfffffe8139a6c340
owner/count  : 0xfffffe8139a6c340 flags    : 0x0000000000000004

panic: lock error
cpu1: Begin traceback...
printf_nolog() at netbsd:printf_nolog
lockdebug_abort() at netbsd:lockdebug_abort+0x3a
rw_vector_enter() at netbsd:rw_vector_enter+0x281
genfs_lock() at netbsd:genfs_lock+0x7b
VOP_LOCK() at netbsd:VOP_LOCK+0x32
vn_lock() at netbsd:vn_lock+0x70
ufs_lookup() at netbsd:ufs_lookup+0x9e0
VOP_LOOKUP() at netbsd:VOP_LOOKUP+0x34
lookup_once() at netbsd:lookup_once+0xab
namei_tryemulroot() at netbsd:namei_tryemulroot+0x2b2
namei() at netbsd:namei+0x42
vn_open() at netbsd:vn_open+0x92
do_open() at netbsd:do_open+0xcd
sys_open() at netbsd:sys_open+0x59
syscall() at netbsd:syscall+0xc4

Crash is in filesystem routines, here's what's mounted:

NOTE: Root is on USB memory stick!

/dev/sd0a on / type ffs (log, noatime, nodevmtime, local)
tmpfs on /var/run type tmpfs (local)
tmpfs on /tmp type tmpfs (local)
tmpfs on /var/tmp type tmpfs (local)
kernfs on /kern type kernfs (local)
ptyfs on /dev/pts type ptyfs (local)
procfs on /proc type procfs (local)
nora:/home/export/src on /usr/src type nfs


System activities when system is left to it's own:
PID TTY   STAT    TIME COMMAND
  0 ?     OKl  0:01.31 [system]
  1 ?     Is   0:00.01 init 
 45 ?     S    0:00.01 sshd: emil@pts/0 (sshd)
168 ?     Is   0:00.00 dhclient re0 
223 ?     Ss   0:00.01 /usr/sbin/syslogd -s 
242 ?     Ss   0:00.00 /usr/sbin/rpcbind -l 
308 ?     Is   0:00.00 /usr/sbin/powerd 
391 ?     Is   0:00.00 /usr/sbin/sshd 
410 ?     Is   0:00.05 sshd: emil [priv] 
526 ?     I    0:00.02 qmgr -l -t unix -u 
527 ?     S    0:00.02 pickup -l -t fifo -u 
595 ?     Ss   0:00.02 /usr/libexec/postfix/master 
604 ?     Is   0:00.00 /usr/sbin/inetd -l 
637 ?     Is   0:00.00 /usr/sbin/cron 
 44 ttyp0 Ss   0:00.01 -sh 
646 ttyp0 O+   0:00.00 ps -xa 
581 tty00 Is+  0:00.00 /usr/libexec/getty std.9600 console 

>How-To-Repeat:
Just leave the system running
>Fix: