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SubjectRe: [PATCH v2 3/5] mm/memory_hotplug: use nth_page() in place of direct struct page manipulation.
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On 06.09.23 17:03, Zi Yan wrote:
> From: Zi Yan <ziy@nvidia.com>

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@vger.kernel.org>
> Signed-off-by: Zi Yan <ziy@nvidia.com>
> Reviewed-by: Muchun Song <songmuchun@bytedance.com>
> ---
> 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@redhat.com>

--
Cheers,

David / dhildenb

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