Currently __remove_section for SPARSEMEM_VMEMMAP does nothing. But even if
we use SPARSEMEM_VMEMMAP, we can unregister the memory_section.

So the patch add unregister_memory_section() into __remove_section().

CC: David Rientjes <rientjes@google.com>
CC: Jiang Liu <redacted>
CC: Len Brown <redacted>
CC: Christoph Lameter <redacted>
Cc: Minchan Kim <redacted>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: KOSAKI Motohiro <redacted> 
CC: Wen Congyang <redacted>
Signed-off-by: Yasuaki Ishimatsu <redacted>
---
 mm/memory_hotplug.c |   13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

Index: linux-3.6/mm/memory_hotplug.c
=================================--- linux-3.6.orig/mm/memory_hotplug.c	2012-10-04 18:29:50.577668254 +0900

+++ linux-3.6/mm/memory_hotplug.c	2012-10-04 18:29:58.284676075 +0900

@@ -279,11 +279,14 @@ static int __meminit __add_section(int n
 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 static int __remove_section(struct zone *zone, struct mem_section *ms)
 {
-	/*
-	 * XXX: Freeing memmap with vmemmap is not implement yet.
-	 *      This should be removed later.
-	 */
-	return -EBUSY;
+	int ret = -EINVAL;
+
+	if (!valid_section(ms))
+		return ret;
+
+	ret = unregister_memory_section(ms);
+
+	return ret;
 }
 #else
 static int __remove_section(struct zone *zone, struct mem_section *ms)