[PATCH 10/10] memory-hotplug : remove sysfs file of node

Yasuaki Ishimatsu
2012-10-05T02:38:20Z

From: Wen Congyang <wency@cn.fujitsu.com>

This patch introduces a new function try_offline_node() to
remove sysfs file of node when all memory sections of this
node are removed. If some memory sections of this node are
not removed, this function does nothing.

CC: David Rientjes <rientjes@google.com>
CC: Jiang Liu <liuj97@gmail.com>
CC: Len Brown <len.brown@intel.com>
CC: Christoph Lameter <cl@linux.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
mm/memory_hotplug.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 54 insertions(+)

Index: linux-3.6/mm/memory_hotplug.c
===================================================================
--- linux-3.6.orig/mm/memory_hotplug.c 2012-10-04 18:30:31.767709165 +0900
+++ linux-3.6/mm/memory_hotplug.c 2012-10-04 18:32:46.907842637 +0900
@@ -29,6 +29,7 @@
#include <linux/suspend.h>
#include <linux/mm_inline.h>
#include <linux/firmware-map.h>
+#include <linux/stop_machine.h>

#include <asm/tlbflush.h>

@@ -1276,6 +1277,57 @@ int offline_memory(u64 start, u64 size)
return 0;
}

+static int check_cpu_on_node(void *data)
+{
+ struct pglist_data *pgdat = data;
+ int cpu;
+
+ for_each_online_cpu(cpu) {
+ if (cpu_to_node(cpu) == pgdat->node_id)
+ /*
+ * the cpu on this node is onlined, and we can't
+ * offline this node.
+ */
+ return -EBUSY;
+ }
+
+ return 0;
+}
+
+/* offline the node if all memory sections of this node are removed */
+static void try_offline_node(int nid)
+{
+ unsigned long start_pfn = NODE_DATA(nid)->node_start_pfn;
+ unsigned long end_pfn = start_pfn + NODE_DATA(nid)->node_spanned_pages;
+ unsigned long pfn;
+
+ for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+ unsigned long section_nr = pfn_to_section_nr(pfn);
+
+ if (!present_section_nr(section_nr))
+ continue;
+
+ if (pfn_to_nid(pfn) != nid)
+ continue;
+
+ /*
+ * some memory sections of this node are not removed, and we
+ * can't offline node now.
+ */
+ return;
+ }
+
+ if (stop_machine(check_cpu_on_node, NODE_DATA(nid), NULL))
+ return;
+
+ /*
+ * all memory sections of this node are removed, we can offline this
+ * node now.
+ */
+ node_set_offline(nid);
+ unregister_one_node(nid);
+}
+
int __ref remove_memory(int nid, u64 start, u64 size)
{
int ret = 0;
@@ -1296,6 +1348,8 @@ int __ref remove_memory(int nid, u64 sta
firmware_map_remove(start, start + size, "System RAM");

arch_remove_memory(start, size);
+
+ try_offline_node(nid);
out:
unlock_memory_hotplug();
return ret;