mm: make rmap_walk() return void

There is no user of the return value from rmap_walk() and friends so
this patch makes them void-returning functions.

Link: http://lkml.kernel.org/r/1489555493-14659-9-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
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 6028c38..1d7d457c 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -264,8 +264,8 @@ struct rmap_walk_control {
 	bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
 };
 
-int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
-int rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc);
+void rmap_walk(struct page *page, struct rmap_walk_control *rwc);
+void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc);
 
 #else	/* !CONFIG_MMU */