linux-kernel - [PATCH v2 3/4] memory_hotplug: use pgdat_resize_lock() in online

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Date:	Wed,  1 May 2013 16:32:00 -0700
From:	Cody P Schafer <cody@...ux.vnet.ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	David Rientjes <rientjes@...gle.com>,
	Linux MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Cody P Schafer <cody@...ux.vnet.ibm.com>
Subject: [PATCH v2 3/4] memory_hotplug: use pgdat_resize_lock() in online_pages()

mmzone.h documents node_size_lock (which pgdat_resize_lock() locks) as
guarding against changes to node_present_pages, so actually lock it when
we update node_present_pages to keep that promise.

Signed-off-by: Cody P Schafer <cody@...ux.vnet.ibm.com>
---
 mm/memory_hotplug.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index a221fac..0bdca10 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -915,6 +915,7 @@ static void node_states_set_node(int node, struct memory_notify *arg)
 
 int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_type)
 {
+	unsigned long flags;
 	unsigned long onlined_pages = 0;
 	struct zone *zone;
 	int need_zonelists_rebuild = 0;
@@ -993,7 +994,11 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
 
 	zone->managed_pages += onlined_pages;
 	zone->present_pages += onlined_pages;
+
+	pgdat_resize_lock(zone->zone_pgdat, &flags);
 	zone->zone_pgdat->node_present_pages += onlined_pages;
+	pgdat_resize_unlock(zone->zone_pgdat, &flags);
+
 	if (onlined_pages) {
 		node_states_set_node(zone_to_nid(zone), &arg);
 		if (need_zonelists_rebuild)
-- 
1.8.2.2

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