From owner-freebsd-hackers  Thu May 10  0:40:31 2001
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To: hackers@freebsd.org
Cc: phk@freebsd.org
Subject: Who's cleaning up after disk_clone?
Date: Thu, 10 May 2001 00:40:28 -0700
From: Dima Dorfman <dima@unixfreak.org>
Message-Id: <20010510074028.847EE3E28@bazooka.unixfreak.org>
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disk_clone is set as the dev_clone handler by the disk minilayer to
create /dev/disk0sXY devices; however, as far as I can tell, those
devices are never destroyed.  For example (/dev is devfs here):

	dima@spike# mdconfig -a -t swap -s 32m
	md0
	dima@spike# disklabel -r -w md0 auto
	dima@spike# ll /dev/md*
	crw-r-----  1 root  operator   95, 0x00010002 May 10 00:12 /dev/md0
	crw-r-----  1 root  operator   95,   2 May 10 00:30 /dev/md0c
	crw-------  1 root  wheel      95, 0xffff00ff May 10 00:12 /dev/mdctl
	dima@spike# mdconfig -du0
	dima@spike# ll /dev/md*
	crw-r-----  1 root  operator   95,   2 May 10 00:30 /dev/md0c
	crw-------  1 root  wheel      95, 0xffff00ff May 10 00:12 /dev/mdctl

Why is md0c still there?  It was created as part of the disklabel
operation.  Furthermore,

	dima@spike# kldunload md
	dima@spike# ls /dev/md0c

will cause a page fault in kernel mode in this situation.  I can't get
a crash dump, but vn_isdisk() was called from vn_stat() which was
called from stat() (ls called this), and I'm guessing it crashed
because there is a stale (now unloaded) cdevsw associated with /dev/md0c.

So, my questions are:

	- is this a bug?  At least the page fault is; and
	- what should be destroying /dev/md0c?

Thanks for any insight,

					Dima Dorfman
					dima@unixfreak.org

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