Commit 0bd85420 authored Nov 13, 2014 by Tang Chen Committed by Linus Torvalds Nov 13, 2014

mem-hotplug: reset node present pages when hot-adding a new pgdat



When memory is hot-added, all the memory is in offline state.  So clear
all zones' present_pages because they will be updated in online_pages()
and offline_pages().  Otherwise, /proc/zoneinfo will corrupt:

When the memory of node2 is offline:

  # cat /proc/zoneinfo
  ......
  Node 2, zone   Movable
  ......
        spanned  8388608
        present  8388608
        managed  0

When we online memory on node2:

  # cat /proc/zoneinfo
  ......
  Node 2, zone   Movable
  ......
        spanned  8388608
        present  16777216
        managed  8388608

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: <stable@vger.kernel.org>	[3.16+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent f784a3f1

mm/memory_hotplug.c

+17 −0

Original line number	Diff line number	Diff line
		@@ -1067,6 +1067,16 @@ out:
		}
		#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */

		static void reset_node_present_pages(pg_data_t *pgdat)
		{
		struct zone *z;

		for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
		z->present_pages = 0;

		pgdat->node_present_pages = 0;
		}

		/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
		static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
		{
		@@ -1105,6 +1115,13 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
		*/
		reset_node_managed_pages(pgdat);

		/*
		* When memory is hot-added, all the memory is in offline state. So
		* clear all zones' present_pages because they will be updated in
		* online_pages() and offline_pages().
		*/
		reset_node_present_pages(pgdat);

		return pgdat;
		}

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