memory_hotplug: use pgdat_resize_lock() in __offline_pages()

mmzone.h documents node_size_lock (which pgdat_resize_lock() locks) as
follows:

        * Must be held any time you expect node_start_pfn, node_present_pages
        * or node_spanned_pages stay constant.  [...]

So actually hold it when we update node_present_pages in __offline_pages().

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index fd37d64e7af875fa741821ded02f1df632371fb9..e55bc6d9eed82f1b911df5e3fec46c39a014a545 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1585,7 +1585,11 @@ repeat:
        /* removal success */
        zone->managed_pages -= offlined_pages;
        zone->present_pages -= offlined_pages;
+
+       pgdat_resize_lock(zone->zone_pgdat, &flags);
        zone->zone_pgdat->node_present_pages -= offlined_pages;
+       pgdat_resize_unlock(zone->zone_pgdat, &flags);
+
        totalram_pages -= offlined_pages;
 
        init_per_zone_wmark_min();