From owner-svn-src-all@FreeBSD.ORG  Mon Aug 17 13:27:56 2009
Return-Path: <owner-svn-src-all@FreeBSD.ORG>
Delivered-To: svn-src-all@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 3D7FE106568D;
	Mon, 17 Aug 2009 13:27:56 +0000 (UTC) (envelope-from kib@FreeBSD.org)
Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c])
	by mx1.freebsd.org (Postfix) with ESMTP id 2C9A68FC68;
	Mon, 17 Aug 2009 13:27:56 +0000 (UTC)
Received: from svn.freebsd.org (localhost [127.0.0.1])
	by svn.freebsd.org (8.14.3/8.14.3) with ESMTP id n7HDRuM0078879;
	Mon, 17 Aug 2009 13:27:56 GMT (envelope-from kib@svn.freebsd.org)
Received: (from kib@localhost)
	by svn.freebsd.org (8.14.3/8.14.3/Submit) id n7HDRuxs078877;
	Mon, 17 Aug 2009 13:27:56 GMT (envelope-from kib@svn.freebsd.org)
Message-Id: <200908171327.n7HDRuxs078877@svn.freebsd.org>
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Mon, 17 Aug 2009 13:27:56 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
	svn-src-head@freebsd.org
X-SVN-Group: head
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Cc: 
Subject: svn commit: r196318 - head/sys/amd64/amd64
X-BeenThere: svn-src-all@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: "SVN commit messages for the entire src tree \(except for &quot;
	user&quot; and &quot; projects&quot; \)" <svn-src-all.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
	<mailto:svn-src-all-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-all>
List-Post: <mailto:svn-src-all@freebsd.org>
List-Help: <mailto:svn-src-all-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
	<mailto:svn-src-all-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 17 Aug 2009 13:27:56 -0000

Author: kib
Date: Mon Aug 17 13:27:55 2009
New Revision: 196318
URL: http://svn.freebsd.org/changeset/base/196318

Log:
  Correct a critical accounting error in pmap_demote_pde().  Specifically,
  when pmap_demote_pde() allocates a page table page to implement a
  user-space demotion, it must increment the pmap's resident page count.
  Not doing so, can lead to an underflow during address space termination
  that causes pmap_remove() to exit prematurely, before it has destroyed
  all of the mappings within the specified range.  The ultimate effect or
  symptom of this error is an assertion failure in vm_page_free_toq()
  because the page being freed is still mapped.
  
  This error is only possible when superpage promotion is enabled.  Thus,
  it only affects FreeBSD  versions greater than 7.2.
  
  Tested by:	pho, alc
  Reviewed by:	alc
  Approved by:	re (rwatson)
  MFC after:	1 week

Modified:
  head/sys/amd64/amd64/pmap.c

Modified: head/sys/amd64/amd64/pmap.c
==============================================================================
--- head/sys/amd64/amd64/pmap.c	Mon Aug 17 13:00:32 2009	(r196317)
+++ head/sys/amd64/amd64/pmap.c	Mon Aug 17 13:27:55 2009	(r196318)
@@ -2261,6 +2261,8 @@ pmap_demote_pde(pmap_t pmap, pd_entry_t 
 			    " in pmap %p", va, pmap);
 			return (FALSE);
 		}
+		if (va < VM_MAXUSER_ADDRESS)
+			pmap->pm_stats.resident_count++;
 	}
 	mptepa = VM_PAGE_TO_PHYS(mpte);
 	firstpte = (pt_entry_t *)PHYS_TO_DMAP(mptepa);