[Midnightbsd-cvs] src [8316] trunk/sys/vm/vm_fault.c: dirty the newly copied anonymous pages after the wired region is forked.

[laffer1 at midnightbsd.org]

Revision: 8316
          http://svnweb.midnightbsd.org/src/?rev=8316
Author:   laffer1
Date:     2016-09-17 18:35:21 -0400 (Sat, 17 Sep 2016)
Log Message:
-----------
dirty the newly copied anonymous pages after the wired region is forked.

Modified Paths:
--------------
    trunk/sys/vm/vm_fault.c

Modified: trunk/sys/vm/vm_fault.c
===================================================================
--- trunk/sys/vm/vm_fault.c	2016-09-17 22:33:45 UTC (rev 8315)
+++ trunk/sys/vm/vm_fault.c	2016-09-17 22:35:21 UTC (rev 8316)
@@ -1308,9 +1308,13 @@
 		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.
+	 * 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;
@@ -1353,6 +1357,7 @@
 		pmap_copy_page(src_m, dst_m);
 		VM_OBJECT_UNLOCK(object);
 		dst_m->valid = VM_PAGE_BITS_ALL;
+		dst_m->dirty = VM_PAGE_BITS_ALL;
 		VM_OBJECT_UNLOCK(dst_object);
 
 		/*