svn commit: r242012 - head/sys/vm

[Konstantin Belousov]

Author: kib
Date: Wed Oct 24 18:32:37 2012
New Revision: 242012
URL: http://svn.freebsd.org/changeset/base/242012

Log:
  Commit the actual text provided by Alan, instead of the wrong update
  in r242011.
  
  MFC after:	1 week

Modified:
  head/sys/vm/vm_fault.c

Modified: head/sys/vm/vm_fault.c
==============================================================================
--- head/sys/vm/vm_fault.c	Wed Oct 24 18:21:59 2012	(r242011)
+++ head/sys/vm/vm_fault.c	Wed Oct 24 18:32:37 2012	(r242012)
@@ -1287,11 +1287,13 @@ vm_fault_copy_entry(vm_map_t dst_map, vm
 		access &= ~VM_PROT_WRITE;
 
 	/*
-	 * Loop through all of the pages in the entry's range, copying
-	 * each one from the source object (it should be there) to the
-	 * destination object.  Note that copied pages are not wired
-	 * and marked dirty to prevent reclamation without saving the
-	 * content into the swap file on pageout.
+	 * Loop through all of the virtual pages within the entry's
+	 * range, copying each page from the source object to the
+	 * destination object.  Since the source is wired, those pages
+	 * must exist.  In contrast, the destination is pageable.
+	 * Since the destination object does share any backing storage
+	 * with the source object, all of its pages must be dirtied,
+	 * regardless of whether they can be written.
 	 */
 	for (vaddr = dst_entry->start, dst_pindex = 0;
 	    vaddr < dst_entry->end;