At 11/20/2012 02:22 PM, Jaegeuk Hanse Wrote:

On 11/01/2012 05:44 PM, Wen Congyang wrote:

quoted

From: Yasuaki Ishimatsu <redacted>

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().

Hi Yasuaki,

In order to review this patch, I should dig sparse memory codes in
advance. But I have some confuse of codes. Why need encode/decode mem
map instead of set mem_map to ms->section_mem_map directly?

The memmap is aligned, and the low bits are zero. We store some information
in these bits. So we need to encode/decode memmap here.

Thanks
Wen Congyang

Regards,
Jaegeuk

quoted

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(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index ca07433..66a79a7 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c

@@ -286,11 +286,14 @@ static int __meminit __add_section(int nid,

struct zone *zone,
  #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)