[PATCH] pgdat allocation for new node add (call pgdat allocation)

Add node-hot-add support to add_memory().

node hotadd uses this sequence.
1. allocate pgdat.
2. refresh NODE_DATA()
3. call free_area_init_node() to initialize
4. create sysfs entry
5. add memory (old add_memory())
6. set node online
7. run kswapd for new node.
(8). update zonelist after pages are onlined. (This is already merged in -mm
   due to update phase is difference.)

Note:
  To make common function as much as possible,
  there is 2 changes from v2.
    - The old add_memory(), which is defiend by each archs,
      is renamed to arch_add_memory(). New add_memory becomes
      caller of arch dependent function as a common code.

    - This patch changes add_memory()'s interface
        From: add_memory(start, end)
        TO  : add_memory(nid, start, end).
      It was cause of similar code that finding node id from
      physical address is inside of old add_memory() on each arch.

      In addition, acpi memory hotplug driver can find node id easier.
      In v2, it must walk DSDT'S _CRS by matching physical address to
      get the handle of its memory device, then get _PXM and node id.
      Because input is just physical address.
      However, in v3, the acpi driver can use handle to get _PXM and node id
      for the new memory device. It can pass just node id to add_memory().

Fix interface of arch_add_memory() is in next patche.
Signed-off-by: Yasunori Goto     <y-goto@jp.fujitsu.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: "Brown, Len" <len.brown@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

mm/memory_hotplug.c

@@ -164,13 +164,65 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
 	return 0;
 }
 
+static pg_data_t *hotadd_new_pgdat(int nid, u64 start)
+{
+	struct pglist_data *pgdat;
+	unsigned long zones_size[MAX_NR_ZONES] = {0};
+	unsigned long zholes_size[MAX_NR_ZONES] = {0};
+	unsigned long start_pfn = start >> PAGE_SHIFT;
+
+	pgdat = arch_alloc_nodedata(nid);
+	if (!pgdat)
+		return NULL;
+
+	arch_refresh_nodedata(nid, pgdat);
+
+	/* we can use NODE_DATA(nid) from here */
+
+	/* init node's zones as empty zones, we don't have any present pages.*/
+	free_area_init_node(nid, pgdat, zones_size, start_pfn, zholes_size);
+
+	return pgdat;
+}
+
+static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
+{
+	arch_refresh_nodedata(nid, NULL);
+	arch_free_nodedata(pgdat);
+	return;
+}
+
 int add_memory(int nid, u64 start, u64 size)
 {
+	pg_data_t *pgdat = NULL;
+	int new_pgdat = 0;
 	int ret;
 
+	if (!node_online(nid)) {
+		pgdat = hotadd_new_pgdat(nid, start);
+		if (!pgdat)
+			return -ENOMEM;
+		new_pgdat = 1;
+		ret = kswapd_run(nid);
+		if (ret)
+			goto error;
+	}
+
 	/* call arch's memory hotadd */
 	ret = arch_add_memory(nid, start, size);
 
+	if (ret < 0)
+		goto error;
+
+	/* we online node here. we have no error path from here. */
+	node_set_online(nid);
+
+	return ret;
+error:
+	/* rollback pgdat allocation and others */
+	if (new_pgdat)
+		rollback_node_hotadd(nid, pgdat);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(add_memory);