mm: make do_mmap_pgoff return populate as a size in bytes, not as a bool

do_mmap_pgoff() rounds up the desired size to the next PAGE_SIZE
multiple, however there was no equivalent code in mm_populate(), which
caused issues.

This could be fixed by introduced the same rounding in mm_populate(),
however I think it's preferable to make do_mmap_pgoff() return populate
as a size rather than as a boolean, so we don't have to duplicate the
size rounding logic in mm_populate().

Signed-off-by: Michel Lespinasse <walken@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Tested-by: Andy Lutomirski <luto@amacapital.net>
Cc: Greg Ungerer <gregungerer@westnet.com.au>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/nommu.c b/mm/nommu.c
index 7296a5a..18c1b93 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1251,7 +1251,7 @@
 			    unsigned long prot,
 			    unsigned long flags,
 			    unsigned long pgoff,
-			    bool *populate)
+			    unsigned long *populate)
 {
 	struct vm_area_struct *vma;
 	struct vm_region *region;
@@ -1261,7 +1261,7 @@
 
 	kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
 
-	*populate = false;
+	*populate = 0;
 
 	/* decide whether we should attempt the mapping, and if so what sort of
 	 * mapping */