follow: no put_page() if FOLL_GET not specified.

Seems that one of the side effects of the dirty pages patch in
2.6.17-rc4-mm3 is that follow_pages does a page_put if FOLL_GET is
not set in the flags passed to it. This breaks sys_move_pages()
page status determination.

Only put_page if we did a get_page() before.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Index: linux-2.6.17-rc4-mm3/mm/memory.c
===================================================================
--- linux-2.6.17-rc4-mm3.orig/mm/memory.c	2006-05-22 18:03:32.280767264 -0700
+++ linux-2.6.17-rc4-mm3/mm/memory.c	2006-05-23 10:01:48.917295988 -0700
@@ -964,7 +964,7 @@ struct page *follow_page(struct vm_area_
 			set_page_dirty(page);
 		mark_page_accessed(page);
 	}
-	if (!(flags & FOLL_GET))
+	if (!(flags & FOLL_GET) && (flags & FOLL_TOUCH))
 		put_page(page);
 	goto out;