mm/zsmalloc: take obj index back from find_alloced_obj

the obj index value should be updated after return from
find_alloced_obj() to avoid CPU burning caused by unnecessary object
scanning.

Link: http://lkml.kernel.org/r/1467882338-4300-2-git-send-email-opensource.ganesh@gmail.com
Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/zsmalloc.c

@@ -1741,10 +1741,11 @@ static void zs_object_copy(struct size_class *class, unsigned long dst,
  * return handle.
  */
 static unsigned long find_alloced_obj(struct size_class *class,
-					struct page *page, int index)
+					struct page *page, int *obj_idx)
 {
 	unsigned long head;
 	int offset = 0;
+	int index = *obj_idx;
 	unsigned long handle = 0;
 	void *addr = kmap_atomic(page);
 
@@ -1765,6 +1766,9 @@ static unsigned long find_alloced_obj(struct size_class *class,
 	}
 
 	kunmap_atomic(addr);
+
+	*obj_idx = index;
+
 	return handle;
 }
 
@@ -1790,7 +1794,7 @@ static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
 	int ret = 0;
 
 	while (1) {
-		handle = find_alloced_obj(class, s_page, obj_idx);
+		handle = find_alloced_obj(class, s_page, &obj_idx);
 		if (!handle) {
 			s_page = get_next_page(s_page);
 			if (!s_page)