memory hotremove: unset migrate type "ISOLATE" after removal

We should unset migrate type "ISOLATE" when we successfully removed memory.
 But current code has BUG and cannot works well.

This patch also includes bugfix?  to change get_pageblock_flags to
get_pageblock_migratetype().

Thanks to Badari Pulavarty for finding this.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memory_hotplug.c

@@ -574,8 +574,8 @@ repeat:
 	/* Ok, all of our target is islaoted.
 	   We cannot do rollback at this point. */
 	offline_isolated_pages(start_pfn, end_pfn);
-	/* reset pagetype flags */
-	start_isolate_page_range(start_pfn, end_pfn);
+	/* reset pagetype flags and makes migrate type to be MOVABLE */
+	undo_isolate_page_range(start_pfn, end_pfn);
 	/* removal success */
 	zone->present_pages -= offlined_pages;
 	zone->zone_pgdat->node_present_pages -= offlined_pages;

mm/page_isolation.c

@@ -55,7 +55,7 @@ start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn)
 	return 0;
 undo:
 	for (pfn = start_pfn;
-	     pfn <= undo_pfn;
+	     pfn < undo_pfn;
 	     pfn += pageblock_nr_pages)
 		unset_migratetype_isolate(pfn_to_page(pfn));
 
@@ -76,7 +76,7 @@ undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn)
 	     pfn < end_pfn;
 	     pfn += pageblock_nr_pages) {
 		page = __first_valid_page(pfn, pageblock_nr_pages);
-		if (!page || get_pageblock_flags(page) != MIGRATE_ISOLATE)
+		if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
 			continue;
 		unset_migratetype_isolate(page);
 	}
@@ -126,7 +126,7 @@ int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 	 */
 	for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
 		page = __first_valid_page(pfn, pageblock_nr_pages);
-		if (page && get_pageblock_flags(page) != MIGRATE_ISOLATE)
+		if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
 			break;
 	}
 	if (pfn < end_pfn)