From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mike Kravetz <mike.kravetz@oracle.com>
Subject: Re: [PATCH 02/21] mm/hugetlb: correct max_huge_pages accounting on
 demote
Date: Wed, 14 Sep 2022 10:23:05 -0700
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To: Doug Berger <opendmb@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Jonathan Corbet <corbet@lwn.net>, Rob Herring <robh+dt@kernel.org>, Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Frank Rowand <frowand.list@gmail.com>, Muchun Song <songmuchun@bytedance.com>, Mike Rapoport <rppt@kernel.org>, Christoph Hellwig <hch@lst.de>, Marek Szyprowski <m.szyprowski@samsung.com>, Robin Murphy <robin.murphy@arm.com>, Borislav Petkov <bp@suse.de>, "Paul E. McKenney" <paulmck@kernel.org>, Neeraj Upadhyay <quic_neeraju@quicinc.com>, Randy Dunlap <rdunlap@infradead.org>, Damien Le Moal <damien.lemoal@opensource.wdc.com>, Florian Fainelli <f.fainelli@gmail.com>, David Hildenbrand <david@redhat.com>, Zi Yan <ziy@nvidia.com>, Oscar Salvador <osalvador@suse.de>, Hari Bathini <>

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