kern/161956: filesystem lock with mount nullfs in random cases

[subbsd]

>Number:         161956
>Category:       kern
>Synopsis:       filesystem lock with mount nullfs in random cases
>Confidential:   no
>Severity:       non-critical
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Oct 24 08:40:03 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator:     subbsd
>Release:        9.0-RC1
>Organization:
>Environment:
FreeBSD fbsd.my.domain 9.0-RC1 FreeBSD 9.0-RC1 #0: Wed Oct 19 23:11:33 MSK 2011     root at fbsd.my.domain:/usr/obj/usr/src/sys/GENERIC  amd64
>Description:
filesystem (zfs or ufs) is freezing in random time when mount nullfs is work.

more information: http://docs.freebsd.org/cgi/getmsg.cgi?fetch=270240+0+archive/2011/freebsd-fs/20111023.freebsd-fs
>How-To-Repeat:
making it easy to reproduce when do 'svn cleanup' for mounted directory, see

http://docs.freebsd.org/cgi/getmsg.cgi?fetch=270240+0+archive/2011/freebsd-fs/20111023.freebsd-fs
>Fix:


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