Date: Fri, 30 Jul 1999 10:50:01 +0200
To: "Julian Stacey" <jhs@
From: gnats-admin@_ERASE_FreeBSD.org
Subject: Re: kern/12884: panic: lockmgr: locking against myself - from amd with nfs

Thank you very much for your problem report.
It has the internal identification `kern/12884'.
The individual assigned to look at your
report is: freebsd-bugs. 

>Category:       kern
>Responsible:    freebsd-bugs
>Synopsis:       Hot to panic FreeBSD-3.2-Release
>Arrival-Date:   Fri Jul 30 01:50:01 PDT 1999

29.07.1999

SEND-PR: -*- send-pr -*-
SEND-PR: Lines starting with `SEND-PR' will be removed automatically, as
SEND-PR: will all comments (text enclosed in `<' and `>').
SEND-PR: 
SEND-PR: Please consult the send-pr man page `send-pr(1)' or the Texinfo
SEND-PR: manual if you are not sure how to fill out a problem report.
SEND-PR:
SEND-PR: Note that the Synopsis field is mandatory.  The Subject (for
SEND-PR: the mail) will be made the same as Synopsis unless explicitly
SEND-PR: changed.
SEND-PR:
SEND-PR: Choose from the following categories:
SEND-PR:
SEND-PR: bin   conf  docs  gnu   i386  kern  misc  ports 
SEND-PR:
To: FreeBSD-gnats-submit@_ERASE_freebsd.org
From: "Julian Stacey" <jhs@
Reply-To: "Julian Stacey" <jhs@
Subject: panic: lockmgr: locking against myself - from amd with nfs
X-send-pr-version: 3.2

>Submitter-Id:   current-users
>Originator:     Julian H. Stacey jhs@
>Confidential:   no
>Synopsis:       How to panic FreeBSD-3.2-Release
>Severity:       serious
>Priority:       medium 
>Category:       kern
>Release:        FreeBSD 3.2-RELEASE i386
>Class:          sw-bug
>Environment: 

	3.2-Rel, nfs & amd

>Description: 

	How to panic the kernel:

>How-To-Repeat: 
	amd -p -k i386 -l syslog -a /a /host /etc/amd.map # from rc.conf
	grep `hostname -s` /etc/exports # note removing hostname 
					# does not prevent a crash
	ln -s .. /a/`hostname -s`
	wall warn all users we are about to crash
	echo now see	panic: lockmgr: locking against myself
	ls /host/`hostname -s`	# panic occurs

	OK, it's silly to do
	 	ln -s .. /a/`hostname -s`
	but it's unfortunate that it panics.
		(I did the ln on a spare box while experimenting to try to
		find some way to have /host/* mount the other hosts,
		but /host/`hostname -s` just be root (or better "..")
		as I use sitewide addresses like /host/some_host/usr3/.....
		& I want the access to be a more efficient ufs direct
		in the one case where the  host happens to be local -
		I haven't found a solution to that yet BTW)

>Fix: 
	
	Maybe AMD should at startup do
		chmod a-w o-w /a ; chown 0 /a