kern/42057: smbfs umount panic in 5.0.1

[jansen.gotis%gmail.com@localhost]

>Number:         42057
>Category:       kern
>Synopsis:       smbfs umount panic in 5.0.1
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Sep 13 14:55:00 +0000 2009
>Originator:     Jansen Gotis
>Release:        NetBSD 5.0.1
>Organization:
>Environment:
NetBSD rosalyn.jansen.homenet 5.0.1 NetBSD 5.0.1 (GENERIC) #0: Thu Jul 30 
01:39:11 UTC 2009  
builds%b8.netbsd.org@localhost:/home/builds/ab/netbsd-5-0-1-RELEASE/i386/200907292356Z-obj/home/builds/ab/netbsd-5-0-1-RELEASE/src/sys/arch/i386/compile/GENERIC
 i386

>Description:
I mounted an smbfs share then changed my working directory to somewhere inside 
it. I accidentally tried to unmount it while cwd'd inside the mountpoint. 
Subsequent access resulted in a panic.
>How-To-Repeat:
# mount_smbfs -N //host/share /mnt
# cd /mnt
# umount /mnt
# cd
# cd /mnt
>Fix:
There are patches to HEAD sources on this page: 
http://mail-index.netbsd.org/tech-kern/2009/07/01/msg005395.html

It just requires a bit of massaging to apply to netbsd-5-0 sources.