linux-kernel - [PATCH 4/5] cpu-hotplug,memory-hotplug: clear cpu_to

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Date:	Mon, 26 Nov 2012 18:20:26 +0800
From:	Wen Congyang <wency@...fujitsu.com>
To:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	linux-pm@...r.kernel.org, linux-acpi@...r.kernel.org,
	x86@...nel.org
Cc:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	David Rientjes <rientjes@...gle.com>,
	Jiang Liu <liuj97@...il.com>,
	Minchan Kim <minchan.kim@...il.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mel@....ul.ie>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Tang Chen <tangchen@...fujitsu.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Len Brown <len.brown@...el.com>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Wen Congyang <wency@...fujitsu.com>
Subject: [PATCH 4/5] cpu-hotplug,memory-hotplug: clear cpu_to_node() when offlining the node

When the node is offlined, there is no memory/cpu on the node. If a
sleep task runs on a cpu of this node, it will be migrated to the
cpu on the other node. So we can clear cpu-to-node mapping.

Cc: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Cc: David Rientjes <rientjes@...gle.com>
Cc: Jiang Liu <liuj97@...il.com>
Cc: Minchan Kim <minchan.kim@...il.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Mel Gorman <mel@....ul.ie>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Tang Chen <tangchen@...fujitsu.com>
Signed-off-by: Wen Congyang <wency@...fujitsu.com>
---
 mm/memory_hotplug.c | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index b7c30bb..5ae86d7 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1669,6 +1669,34 @@ static int check_cpu_on_node(void *data)
 	return 0;
 }
 
+static void unmap_cpu_on_node(void *data)
+{
+#ifdef CONFIG_ACPI_NUMA
+	struct pglist_data *pgdat = data;
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		if (cpu_to_node(cpu) == pgdat->node_id)
+			numa_clear_node(cpu);
+#endif
+}
+
+static int check_and_unmap_cpu_on_node(void *data)
+{
+	int ret = check_cpu_on_node(data);
+
+	if (ret)
+		return ret;
+
+	/*
+	 * the node will be offlined when we come here, so we can clear
+	 * the cpu_to_node() now.
+	 */
+
+	unmap_cpu_on_node(data);
+	return 0;
+}
+
 /* offline the node if all memory sections of this node are removed */
 void try_offline_node(int nid)
 {
@@ -1695,7 +1723,7 @@ void try_offline_node(int nid)
 		return;
 	}
 
-	if (stop_machine(check_cpu_on_node, NODE_DATA(nid), NULL))
+	if (stop_machine(check_and_unmap_cpu_on_node, NODE_DATA(nid), NULL))
 		return;
 
 	/*
-- 
1.8.0

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