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Date:   Wed, 14 Sep 2022 10:23:05 -0700
From:   Mike Kravetz <mike.kravetz@oracle.com>
To:     Doug Berger <opendmb@gmail.com>
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Subject: Re: [PATCH 02/21] mm/hugetlb: correct max_huge_pages accounting on
 demote
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On 09/13/22 12:54, Doug Berger wrote:
> When demoting a hugepage to a smaller order, the number of pages
> added to the target hstate will be the size of the large page
> divided by the size of the smaller page.
> 
> Fixes: 8531fc6f52f5 ("hugetlb: add hugetlb demote page support")
> Signed-off-by: Doug Berger <opendmb@gmail.com>
> ---
>  mm/hugetlb.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index e070b8593b37..79949893ac12 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -3472,7 +3472,8 @@ static int demote_free_huge_page(struct hstate *h, struct page *page)
>  	 * based on pool changes for the demoted page.
>  	 */
>  	h->max_huge_pages--;
> -	target_hstate->max_huge_pages += pages_per_huge_page(h);
> +	target_hstate->max_huge_pages += pages_per_huge_page(h) /
> +					 pages_per_huge_page(target_hstate);
>  
>  	return rc;
>  }

This has already been fixed here,

https://lore.kernel.org/linux-mm/20220823030209.57434-2-linmiaohe@huawei.com/

-- 
Mike Kravetz