Hi!

I've got a rather nasty, totally reproducible problem with some stacked
file systems.  (This is on port-mac68k, in case it matters.)

	/usr/src		 is mounted via nfs
	/usr/src/sys/arch/mac68k is nullfs mounted as /home/paul/original
	/home/paul/changes	 is unionfs mounted below /usr/.../mac68k

Then, when I try to compare files between /home/paul/original/* and
/home/paul/changes/* (with the output of diff redirected to another
subdirectory in /home/paul), I get a kernel panic:

	panic: lockmgr: locking against myself

Traceback:

	_Debugger + 6
	_panic + 52
	_lockmgr + 402
	_layer_lock + b8
	_vn_lock + 64
	_vrele + 72
	_lookup + 3f4
	_namei + 2de
	_sys___stat13 + 2a
	_syscall + 148
	_trap0 + e

This is with sources -current as of Thursday 7/29, but it also happens
with sources from about two weeks ago (around 7/15).

Any ideas?

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| Paul Goyette      | PGP DSS Key fingerprint:   | E-mail addresses:     |
| Network Engineer  |   BCD7 5301 9513 58A6 0DBC |  paul@whooppee.com    |
| and kernel hacker |   91EB ADB1 A280 3B79 9221 |  pgoyette@juniper.net |
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