Hi Andrew,

So sorry for such a long delay. I missed this one.
Please check the attached patch if you still need it.
All comments are followed.

Thanks. :)

On 11/21/2012 06:29 AM, Andrew Morton wrote:

On Fri, 16 Nov 2012 19:58:10 +0800
Wen Congyang[off-list ref]  wrote:

quoted

From: Lai Jiangshan<redacted>

Now, memory management can handle movable node or nodes which don't have
any normal memory, so we can dynamic configure and add movable node by:
	online a ZONE_MOVABLE memory from a previous offline node
	offline the last normal memory which result a non-normal-memory-node

movable-node is very important for power-saving,
hardware partitioning and high-available-system(hardware fault management).

...

--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c

@@ -589,11 +589,19 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
  	return 0;
  }

+#ifdef CONFIG_MOVABLE_NODE
+/* when CONFIG_MOVABLE_NODE, we allow online node don't have normal memory */

The comment is hard to understand.  Should it read "When
CONFIG_MOVABLE_NODE, we permit onlining of a node which doesn't have
normal memory"?

quoted

+static bool can_online_high_movable(struct zone *zone)
+{
+	return true;
+}
+#else /* #ifdef CONFIG_MOVABLE_NODE */
  /* ensure every online node has NORMAL memory */
  static bool can_online_high_movable(struct zone *zone)
  {
  	return node_state(zone_to_nid(zone), N_NORMAL_MEMORY);
  }
+#endif /* #ifdef CONFIG_MOVABLE_NODE */

  /* check which state of node_states will be changed when online memory */
  static void node_states_check_changes_online(unsigned long nr_pages,

@@ -1097,6 +1105,13 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
  	return offlined;
  }

+#ifdef CONFIG_MOVABLE_NODE
+/* when CONFIG_MOVABLE_NODE, we allow online node don't have normal memory */

Ditto, after replacing "online" with offlining".

quoted

+static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
+{
+	return true;
+}
+#else /* #ifdef CONFIG_MOVABLE_NODE */
  /* ensure the node has NORMAL memory if it is still online */
  static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
  {

@@ -1120,6 +1135,7 @@ static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
  	 */
  	return present_pages == 0;
  }
+#endif /* #ifdef CONFIG_MOVABLE_NODE */

Please, spend more time over the accuracy and completeness of the
changelog and comments?  That will result in better and more
maintainable code.  And it results in *much* more effective code
reviewing.


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