mm/page_isolation.c: change the prototype of undo_isolate_page_range()

undo_isolate_page_range() never fails, so no need to return value.

Link: http://lkml.kernel.org/r/1562075604-8979-1-git-send-email-kernelfans@gmail.com
Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/page-isolation.h

@@ -50,7 +50,7 @@ start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
  * Changes MIGRATE_ISOLATE to MIGRATE_MOVABLE.
  * target range is [start_pfn, end_pfn)
  */
-int
+void
 undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 			unsigned migratetype);
 

mm/page_isolation.c

@@ -230,7 +230,7 @@ undo:
 /*
  * Make isolated pages available again.
  */
-int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
+void undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 			    unsigned migratetype)
 {
 	unsigned long pfn;
@@ -247,7 +247,6 @@ int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 			continue;
 		unset_migratetype_isolate(page, migratetype);
 	}
-	return 0;
 }
 /*
  * Test all pages in the range is free(means isolated) or not.