kern/54534: unionfs && mfs|md crashing machine

[neologism at hysteria.sk]

>Number:         54534
>Category:       kern
>Synopsis:       unionfs && mfs|md crashing machine
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Jul 16 01:30:16 PDT 2003
>Closed-Date:
>Last-Modified:
>Originator:     neologism
>Release:        FreeBSD 4.8-STABLE i386
>Organization:
home user
>Environment:
System: FreeBSD k4-316a 4.8-STABLE FreeBSD 4.8-STABLE #0: Tue Jul 15 15:45:23 CEST 2003 root at k4-316a:/usr/obj/usr/src/sys/VALIA i386


	
>Description:

When I try to use unionfs && mfs|md together it crashes the machine.

>How-To-Repeat:
I did this:

kldload union && kldload md && kldload mfs
disklabel -r -w md0 auto
newfs /dev/md0c
mount -t mfs -s 1000 /tmp/a
mount /cdrom	
mount -t union /tmp/a /cdrom
mount -t union /tmp/a /proc	# this
mount -t union /tmp/a /dist 	# and this might not be necessary -I don't know
vi /cdrom/anyfile
umount /dist
umount /proc
umount /cdrom
umount /tmp/a			# this doesn't work
umount /dev/md0c		# this after while crashes machine

It seems like a unionfs bug.. I haven't investigated it but I'd say unionfs
messes some vfs stuff so it crashes...

>Fix:

I don't know.

>Release-Note:
>Audit-Trail:
>Unformatted: