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Subject[PATCH Bug fix 4/5] cpu-hotplug,memory-hotplug: clear cpu_to_node() when offlining the node
Date
From: Wen Congyang <wency@cn.fujitsu.com>

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@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
---
mm/memory_hotplug.c | 30 +++++++++++++++++++++++++++++-
1 files changed, 29 insertions(+), 1 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index edd1773..022583b 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1702,6 +1702,34 @@ 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)
{
@@ -1728,7 +1756,7 @@ void try_offline_node(int nid)
return;
}

- if (stop_machine(check_cpu_on_node, pgdat, NULL))
+ if (stop_machine(check_and_unmap_cpu_on_node, pgdat, NULL))
return;

/*
--
1.7.1


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