On Fri, 14 Sep 2012 20:00:09 +0900
Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> wrote:

> > @@ -187,9 +184,10 @@ void register_page_bootmem_info_node(struct pglist_data *pgdat)
> >     end_pfn = pfn + pgdat->node_spanned_pages;
> >
> >     /* register_section info */
> > -   for (; pfn < end_pfn; pfn += PAGES_PER_SECTION)
> > -           register_page_bootmem_info_section(pfn);
> > -
> > +   for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
> > +           if (pfn_valid(pfn) && (pfn_to_nid(pfn) == node))
>
> I cannot judge whether your configuration is correct or not.
> Thus if it is correct, I want a comment of why the node check is
> needed. In usual configuration, a node does not span the other one.
> So it is natural that "pfn_to_nid(pfn) is same as "pgdat->node_id".
> Thus we may remove the node check in the future.

 

yup.  How does this look?

--- a/mm/memory_hotplug.c~memory-hotplug-fix-a-double-register-section-info-bug-fix
+++ a/mm/memory_hotplug.c
@@ -185,6 +185,12 @@ void register_page_bootmem_info_node(str

        /* register_section info */

        for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {

+               /*
+                * Some platforms can assign the same pfn to multiple nodes - on
+                * node0 as well as nodeN.  To avoid registering a pfn against
+                * multiple nodes we check that this pfn does not already
+                * reside in some other node.
+                */

                if (pfn_valid(pfn) && (pfn_to_nid(pfn) == node))

                        register_page_bootmem_info_section(pfn);
        }
_