misc/131113: mount hangs on attempt to remount as rw

[Elmar Stellnberger]

>Number:         131113
>Category:       misc
>Synopsis:       mount hangs on attempt to remount as rw
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Jan 29 10:20:01 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator:     Elmar Stellnberger
>Release:        7.1
>Organization:
>Environment:
FreeBSD scaleo.studiob 7.1-RELEASE FreeBSD 7.1-RELEASE #0: Thu Jan  1 14:37:25 UTC 2009     root at logan.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386

>Description:
> mount -o rw /Users
hangs and can not be terminated by kill or kill -9.
sucessive 
> umount /Users
umount: unmount of /Users failed: Device busy
operations fail.
> ps ax|grep mount
 1713  p0- D      0:00.00 mount -o rw /Users
 1733  p4  S+     0:00.00 grep mount

> mount -d -o rw /Users
mount -t ext2fs -o ro -o rw /dev/ad4s5 /Users
> mount -d -o remount,rw /Users
mount -t ext2fs -o ro -o remount -o rw /dev/ad4s5 /Users

p.s.: under Linux it is possible to change mount parameters of already mounted file systems with remount.
>How-To-Repeat:

>Fix:


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