mm, page_ext: periodically reschedule during page_ext_init()

page_ext_init() can take long on large machines, so add a cond_resched()
point after each section is processed.  This will allow moving the init
to a later point at boot without triggering lockup reports.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Vlastimil Babka <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: Laura Abbott <[email protected]>
Cc: Vinayak Menon <[email protected]>
Cc: zhong jiang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: tehcaster

mm/page_ext.c

@@ -406,6 +406,7 @@ void __init page_ext_init(void)
 				continue;
 			if (init_section_page_ext(pfn, nid))
 				goto oom;
+			cond_resched();
 		}
 	}
 	hotplug_memory_notifier(page_ext_callback, 0);