Unix Technical Digest V1 #14

[Ron Heiby (The Moderator)]

Unix Technical Digest       Wed, 13 Feb 85       Volume  1 : Issue  14

Today's Topics:
                       Panic: munhash (2 msgs)
                 Panic: munhash (and bugs in general)
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Date: 11 Feb 85 17:53:21 GMT
From: system at asuvax.UUCP (Marc Lesure)
Subject: Panic: munhash

I need an explanation of what "Panic: munhash" means.  We are running
4.2bsd and seem to crash daily with this panic.  Also, is there any
sort of documentation which explains what the different panics are
and what they mean.
---
Marc Lesure, System Manager, Engineering Computer Center
Arizona State University, Tempe, Arizona
UUCP:	...!ucbvax!arizona!asuvax!lesure
CSNET:  lesure at asu

------------------------------

Date: 12 Feb 85 17:48:30 GMT
From: rick at seismo.UUCP (Rick Adams)
Subject: Panic: munhash

>From mccallum at opus.ARPA Wed Dec 21 15:14:15 1983
Date: 20 Dec 83 6:38:33-PST (Tue)
Subject: Re: panic: munhash (4.2BSD crash)

The bug fix for the panic: munhash in 4.2/4.1c has been posted.
The posted fix did not explain under what conditions the panic occurs.
The problem shows up when you have a LARGE file system and use a debugger
on program that resides in the part of the file system that makes the block
number field use all 20 bits.  The fix is as follows:


 From: RWS%mit-xx at sri-unix.UUCP
 Subject: sundry 4.2 bugs
 Message-ID: <13280 at sri-arpa.UUCP>
 Date: Wed, 2-Nov-83 15:15:00 MST
 Lines: 64

 Despite claims to the contrary, the block number sign extension problem still
 exists.  Berkeley put in a fix that should have worked, but a C compiler bug
 apparently keeps it from working.  In /sys/sys/vm_mem.c in memall() the code
       swapdev : mount[c->c_mdev].m_dev, (daddr_t)(u_long)c->c_blkno
 should be changed to
       swapdev : mount[c->c_mdev].m_dev, c->c_blkno
 and in /sys/vax/vm_machdep.c in chgprot() the code
           munhash(mount[c->c_mdev].m_dev, (daddr_t)(u_long)c->c_blkno);
 should be changed to
           munhash(mount[c->c_mdev].m_dev, c->c_blkno);
 because the C compiler apparently incorrectly folds the (daddr_t) and (u_long)
 together and sign extends anyway.  Simply taking out the (daddr_t)(u_long)
 works, although lint will probably complain about it.

------------------------------

Date: 15 Feb 85 07:57:24 GMT
From: ed at mtxinu.UUCP (Ed Gould)
Subject: Panic: munhash (and bugs in general)

> I need an explanation of what "Panic: munhash" means.  We are running
> 4.2bsd and seem to crash daily with this panic.

I've seen several questions lately about this and other well-known 4.2
bugs, so I'm posting this note about the Bug List.

As a service to the 4.2 community, mt Xinu makes available the
colection of bug reports that have been mailed to Berkeley.  A tape is
availatle to holders of AT&T licenses that are 32/V of newer who also
have a 4.2 license from UC.  To obtain a tape, send copies of the
relevant pages (3 from the AT&T license, 2 from UC) and a check for
$110.00 (or a purchase order for $150.00) to

	mt Xinu
	739 Allston Way
	Berkeley, CA  94710
	Attn: Buglist

A paper copy (or a tape for the above price) that does not contain any
AT&T licensed source is also available to anyone who requests it,
either by US Mail to the above address or {ucbvax,decvax}!mtxinu!buglist.
Please *do not* phone for information.

NOTE:  This list is a raw compilation of reports from members of the
4.2 community.  Mt Xinu has not edited or verified *any* of the reports
of proposed fixes, with the exception that duplicates may be merged,
and flames without content have been removed.

-- 
Ed Gould		    mt Xinu, 739 Allston Way, Berkeley, CA  94710  USA
{ucbvax,decvax}!mtxinu!ed   +1 415 644 0146

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End of Unix Technical Digest
******************************
-- 
Ronald W. Heiby / ihnp4!{wnuxa!heiby|wnuxb!netnews}
AT&T Information Systems, Inc.
Lisle, IL  (CU-D21)