svn commit: r320202 - head/sys/vm

[Konstantin Belousov]

Author: kib
Date: Wed Jun 21 18:54:28 2017
New Revision: 320202
URL: https://svnweb.freebsd.org/changeset/base/320202

Log:
  Call pmap_copy() only for map entries which have the backing object
  instantiated.
  
  Calling pmap_copy() on non-faulted anonymous memory entries is useless.
  
  Noted and reviewed by:	alc
  Sponsored by:	The FreeBSD Foundation
  MFC after:	1 week

Modified:
  head/sys/vm/vm_map.c

Modified: head/sys/vm/vm_map.c
==============================================================================
--- head/sys/vm/vm_map.c	Wed Jun 21 18:51:30 2017	(r320201)
+++ head/sys/vm/vm_map.c	Wed Jun 21 18:54:28 2017	(r320202)
@@ -3239,6 +3239,10 @@ vm_map_copy_entry(
 				fake_entry->next = curthread->td_map_def_user;
 				curthread->td_map_def_user = fake_entry;
 			}
+
+			pmap_copy(dst_map->pmap, src_map->pmap,
+			    dst_entry->start, dst_entry->end - dst_entry->start,
+			    src_entry->start);
 		} else {
 			dst_entry->object.vm_object = NULL;
 			dst_entry->offset = 0;
@@ -3248,9 +3252,6 @@ vm_map_copy_entry(
 				*fork_charge += size;
 			}
 		}
-
-		pmap_copy(dst_map->pmap, src_map->pmap, dst_entry->start,
-		    dst_entry->end - dst_entry->start, src_entry->start);
 	} else {
 		/*
 		 * We don't want to make writeable wired pages copy-on-write.