panic: munhash (cannot happen?)

[David Wiseman]

Problem:
	panic: munhash

Reference:
	4.2bsd
	/sys/sys/vm_mem.c:munhash(dev, bn)

Repeat-by:
	The program gpss is very big and the following procedure has
	been done with breakpoints at locations other than that
	used below; each of these times nothing happened.

	us>	adb ../gpss
	us>	1690a:b0
	us>	:r -out=tt rpt1
	it>	running ../gpss
	it>	panic: munhash
		  .
		  .
		  .

	We have duplicated this twice and are confident that it could
	be duplicated again but our *users* wouldn't be happy if we did.

Configuration:
	VAX 11/750(3Mb) + RA81 + TU80 + DZ11 + DHDM(able)

Question:
	The code itself insists that this panic cannot happen.
	Unfortunately for us, it has. Has anyone out there seen this
	or any related bugs in 4.2bsd? Could this be a hardware
	failure?

	...!utzoo!uwo!deepthot!watmath!...
		   !	 !
		 magi	magi

	David Wiseman @ Department of Computer Science
			The University of Western Ontario
			London Ontario Canada N6A 5B7
			(519) 679-3461