initrd panic with 2.4.8

[Rico Tudor]

Using the included procedure, I can generate this fatal message:

	kernel BUG at inode.c:681!
	...

Bug is present in other 2.4 kernels, and is easily reproduced.

First, configure stock 2.4.8 with ramdisk & initrd.

Then, prepare contents of initrd:

	date >/tmp/initrd

lilo.conf contains an entry like this:

	image = /tmp/bzImage
		read-only
		append = "noinitrd mem=32m init=/bin/bash"
		initrd = /tmp/initrd

The small memory arena (32MB) isn't required, but speeds the failure.
After running `lilo', boot machine, and type

	exec 3</dev/initrd
	cat <&3
	exec 3<&-	# optionally close initrd
	tar cf - . | wc

Crash will occur within seconds.  Root file system should be safe, being
read-only.  Closing /dev/initrd frees memory, and probably corrupts the
kernel -- keeping it open avoids the crash.