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From: bostic@OKEEFFE.BERKELEY.EDU (Keith Bostic)
Newsgroups: comp.bugs.4bsd.ucb-fixes
Subject: V1.40 (fodkluster() and pagein() fixes)
Message-ID: <8711122252.AA00954@okeeffe.Berkeley.EDU>
Date: Thu, 12-Nov-87 17:52:34 EST
Article-I.D.: okeeffe.8711122252.AA00954
Posted: Thu Nov 12 17:52:34 1987
Date-Received: Sat, 14-Nov-87 21:55:21 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 71
Approved: ucb-fixes@okeeffe.berkeley.edu

Subject: fodkluster() and pagein() fixes
Index: sys/sys/vm_page.c 4.3BSD

Description:
	Fodkluster() can walk backwards past the 0 page, and
	pagein() doesn't correctly flush the buffer cache when
	it wants to page data in.
Repeat-By:
	These aren't real repeatable.  The first can happen, although
	very rarely; the second never fails on 4.3BSD due to the way
	the buffer cache works.
Fix:
	Apply the following patch to vm_page.c.

*** vm_page.c.orig	Thu Nov 12 13:16:22 1987
--- vm_page.c	Thu Nov 12 13:16:29 1987
***************
*** 3,9 ****
   * All rights reserved.  The Berkeley software License Agreement
   * specifies the terms and conditions for redistribution.
   *
!  *	@(#)vm_page.c	7.1 (Berkeley) 6/5/86
   */
  
  #include "../machine/reg.h"
--- 3,9 ----
   * All rights reserved.  The Berkeley software License Agreement
   * specifies the terms and conditions for redistribution.
   *
!  *	@(#)vm_page.c	7.2 (Berkeley) 7/27/86
   */
  
  #include "../machine/reg.h"
***************
*** 365,371 ****
  		 * cache, so we explicitly flush them out to disk
  		 * so that the proper data will be paged in.
  		 */
! 		blkflush(dev, bn, (long)CLSIZE*NBPG);
  #ifdef TRACE
  		if (type != CTEXT)
  			trace(TR_XFODMISS, dev, bn);
--- 365,371 ----
  		 * cache, so we explicitly flush them out to disk
  		 * so that the proper data will be paged in.
  		 */
! 		blkflush(dev, bn, (long)klsize*CLSIZE*NBPG);
  #ifdef TRACE
  		if (type != CTEXT)
  			trace(TR_XFODMISS, dev, bn);
***************
*** 1263,1271 ****
  	bn = *pbn;
  	v = v0;
  	for (klsize = 1; klsize < KLMAX; klsize++) {
! 		v -= CLSIZE;
! 		if (v < vmin)
  			break;
  		fpte -= CLSIZE;
  		if (fpte->pg_fod == 0)
  			break;
--- 1263,1271 ----
  	bn = *pbn;
  	v = v0;
  	for (klsize = 1; klsize < KLMAX; klsize++) {
! 		if (v <= vmin)
  			break;
+ 		v -= CLSIZE;
  		fpte -= CLSIZE;
  		if (fpte->pg_fod == 0)
  			break;