rmap: add exclusive page to private anon_vma on swapin

On swapin it is fairly common for a page to be owned exclusively by one
process.  In that case we want to add the page to the anon_vma of that
process's VMA, instead of to the root anon_vma.

This will reduce the amount of rmap searching that the swapout code needs
to do.

Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index dc9b3c0..d6661de 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -162,6 +162,8 @@
  */
 void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
+void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
+			   unsigned long, int);
 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
 void page_add_file_rmap(struct page *);
 void page_remove_rmap(struct page *);