On 6 Sep 2023, at 13:17, David Hildenbrand wrote:
> On 06.09.23 17:03, Zi Yan wrote:
>> From: Zi Yan <ziy@xxxxxxxxxx>
>
> Subject talks about "nth_page()" but that's not what this patch does.
>
>>
>> When dealing with hugetlb pages, manipulating struct page pointers
>> directly can get to wrong struct page, since struct page is not guaranteed
>> to be contiguous on SPARSEMEM without VMEMMAP. Use nth_page() to handle
>> it properly.
>
> ^ dito
>
>>
>> Fixes: eeb0efd071d8 ("mm,memory_hotplug: fix scan_movable_pages() for gigantic hugepages")
>> Cc: <stable@xxxxxxxxxxxxxxx>
>> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
>> Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
>> ---
>> mm/memory_hotplug.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index 1b03f4ec6fd2..3b301c4023ff 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -1689,7 +1689,7 @@ static int scan_movable_pages(unsigned long start, unsigned long end,
>> */
>> if (HPageMigratable(head))
>> goto found;
>> - skip = compound_nr(head) - (page - head);
>> + skip = compound_nr(head) - (pfn - page_to_pfn(head));
>> pfn += skip - 1;
>> }
>> return -ENOENT;
>
> I suspect systems without VMEMMAP also don't usually support gigantic pages AND hotunplug :)
>
> With the subject+description fixed
>
> Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Sure. Thanks.
--
Best Regards,
Yan, Zi
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