Re: [PATCH] mm/hugetlb: fix set_max_huge_pages() when there are surplus pages

[David Hildenbrand <david@redhat.com>]

On 25.02.25 15:19, Jinjiang Tu wrote:
> In set_max_huge_pages(), min_count should mean the acquired persistent
> huge pages, but it contains surplus huge pages. It will leads to failing

s/leads/lead/

> to freeing free huge pages for a Node.
> 
> Steps to reproduce:
> 1) create 5 huge pages in Node 0
> 2) run a program to use all the huge pages
> 3) create 5 huge pages in Node 1
> 4) echo 0 > nr_hugepages for Node 1 to free the huge pages
> 
> The result:
>          Node 0    Node 1
> Total     5         5
> Free      0         5
> Surp      5         5

Can you also share the results after your change?


> 
> Fixes: 9a30523066cd ("hugetlb: add per node hstate attributes")
> Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
> ---
>   mm/hugetlb.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 163190e89ea1..783faec7360b 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -3758,7 +3758,7 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
>   	 * and won't grow the pool anywhere else. Not until one of the
>   	 * sysctls are changed, or the surplus pages go out of use.
>   	 */
> -	min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
> +	min_count = h->resv_huge_pages + persistent_huge_pages(h) - h->free_huge_pages;
>   	min_count = max(count, min_count);
>   	try_to_free_low(h, min_count, nodes_allowed);
>   


-- 
Cheers,

David / dhildenb