kern/44144: ifconfig causes assertion failure in vfs_lookup.c

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>Number:         44144
>Category:       kern
>Synopsis:       ifconfig causes assertion failure in vfs_lookup.c
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Nov 24 09:50:00 +0000 2010
>Originator:     Alan Barrett
>Release:        NetBSD 5.99.40
>Organization:
Not much
>Environment:
NetBSD version:      5.99.40 (2010-11-23)
MACHINE:             i386
MACHINE_ARCH:        i386
Build platform:      NetBSD 5.99.27 i386 (2010-04-18)
>Description:
kernel diagnostic assertion "bp->pb_pathcopyuses == 0" failed: file
   .../src/sys/kern/vfs_lookup.c line 232
fatal breakpoint trap in supervisor mode
trap type 1 code 0 eip c0249094 cs 0 eflags 246 cr2 bb98a010 ilevel 6
stopped in pid 158.1 (ifconfig) at netbsd:breakpoint+0x4: popl %ebp
db{0}> bt
breakpoint ...
panic ...
ker_assert ...
pathbuf_destroy ...
firmware_open ...
wpi_init ...
ether_ioctl ...
ieee80211_ioctl ...
wpi_ioctl ...
in6_update_ifa ...
in6_ifattach ...
in6_if_up ...
ifioctl_common ...
wpi_ioctl ...
ifioctl ...
soo_ioctl ...
sys_ioctl ...

>How-To-Repeat:
I was running a new kernel (5.99.40) with an old userland (5.99.27).
I was running a script to configure the wpi0 network interface,
and the machine crashed.  I think that the command that caused the crash
was "ifconfig wpi0 up".

In case it matters, I use init.chroot in such a way that the real root
is on /dev/md0a, but init chroots into the /cgd1a file system, which is
ffs+wapbl on cgd on wd.

>Fix: