kern/38100: Kernel panic while unmounting automounted NFS filesystem

[tron%zhadum.org.uk@localhost]

>Number:         38100
>Category:       kern
>Synopsis:       Kernel panic while unmounting automounted NFS filesystem
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Feb 24 23:35:00 +0000 2008
>Originator:     Matthias Scheler
>Release:        NetBSD 4.99.54 (2008-02-24 sources, already present in 4.99.52)
>Organization:
Matthias Scheler                                  http://zhadum.org.uk/
>Environment:
System: NetBSD sheridan.zhadum.org.uk 4.99.54 NetBSD 4.99.54 (SHERIDAN) #0: Sun 
Feb 24 12:16:44 GMT 2008 
tron%colwyn.zhadum.org.uk@localhost:/src/sys/compile/SHERIDAN sparc64
Architecture: sparc64
Machine: sparc64
>Description:
My ULTRA60 running NetBSD-current panics everytime when amd(8) unmounts an
NFS filesystem with a message like this:

panic: kernel diagnostic assertion "np->n_dirgens == NULL" failed: file 
"/src/NetBSD-current/src/sys/nfs/nfs_node.c", line 321

>How-To-Repeat:
ls -l /automounted/nfs/volume/.
amq -u /automounted/nfs/volume/.

[Waiting instead of running "amq" also triggers the panic.]

>Fix:
None provided.