kern/42531: system panic when unmounting a smb shared folder during poweroff

[baiyang%gmail.com@localhost]

>Number:         42531
>Category:       kern
>Synopsis:       system panic when unmounting a smb shared folder during 
>poweroff
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Dec 27 15:55:00 +0000 2009
>Originator:     BaiYang
>Release:        5.0.1 / i386
>Organization:
BaiY
>Environment:
NetBSD  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 have installed NetBSD on a VMWare guest and the host is running a win2k3 
server. 

There are some C/C++ projects stored in the host system. I need compile this 
projects under NetBSD. So I mount several SMB share every time I want to 
compile something, and do the 'make'.

After everything is done, I shutdown the guest machine by using 'poweroff' 
command, At this time, if a "big" (contains thousands of source file) project 
just compiled, then the system will panic with something like this:

====================================================================
syncing disk ... done
unmounting file systems ... uvm_fault...
....
....
panic: trap
...
...
====================================================================

For a full screen shot, please check here: 
http://baiy.cn/image/netbsd_poweroff_panic.png
>How-To-Repeat:
Read and write many files on a smb folder, then poweroff.
>Fix: