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SubjectRe: [PATCH RESEND] memory hotplug: fix a double register section info bug
2012/09/15 5:14, Andrew Morton wrote:
> 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?

Looks good to me.

Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>

>
> --- 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);
> }
> _
>
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