From: Cody P Schafer <cody@linux.vnet.ibm.com>
Date: Wed, 19 Jun 2013 00:06:04 +0000 (+1000)
Subject: memory_hotplug: use pgdat_resize_lock() in __offline_pages()
X-Git-Tag: next-20130619~2^2~519
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=547a11abe2df9644e26ca311a06d3ac0bba1e713;p=karo-tx-linux.git

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 a870d8071a3c..330b2c982633 100644
--- 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();