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From: Alan Cox <alc@FreeBSD.org>
Date: Sun, 17 May 2009 20:40:41 +0000 (UTC)
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Subject: svn commit: r192261 - head/sys/vm
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Author: alc
Date: Sun May 17 20:40:41 2009
New Revision: 192261
URL: http://svn.freebsd.org/changeset/base/192261

Log:
  Eliminate a pointless call to pmap_clear_reference() from vm_pageout_scan().
  If the page belongs to an object with a reference count of zero, then it
  can't have any managed mappings on which to clear a reference bit.

Modified:
  head/sys/vm/vm_pageout.c

Modified: head/sys/vm/vm_pageout.c
==============================================================================
--- head/sys/vm/vm_pageout.c	Sun May 17 20:26:00 2009	(r192260)
+++ head/sys/vm/vm_pageout.c	Sun May 17 20:40:41 2009	(r192261)
@@ -786,7 +786,8 @@ rescan0:
 		 */
 		if (object->ref_count == 0) {
 			vm_page_flag_clear(m, PG_REFERENCED);
-			pmap_clear_reference(m);
+			KASSERT(!pmap_page_is_mapped(m),
+			    ("vm_pageout_scan: page %p is mapped", m));
 
 		/*
 		 * Otherwise, if the page has been referenced while in the