Re: [PATCH v5 21/21] mm/hugetlb: Disable freeing vmemmap if struct page size is not power of two

[David Hildenbrand <david@xxxxxxxxxx>]

On 20.11.20 07:43, Muchun Song wrote:
> We only can free the unused vmemmap to the buddy system when the
> size of struct page is a power of two.
>
> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> ---
>   mm/hugetlb_vmemmap.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
> index c3b3fc041903..7bb749a3eea2 100644
> --- a/mm/hugetlb_vmemmap.c
> +++ b/mm/hugetlb_vmemmap.c
> @@ -671,7 +671,8 @@ void __init hugetlb_vmemmap_init(struct hstate *h)
>   	unsigned int order = huge_page_order(h);
>   	unsigned int vmemmap_pages;
>   
> -	if (hugetlb_free_vmemmap_disabled) {
> +	if (hugetlb_free_vmemmap_disabled ||
> +	    !is_power_of_2(sizeof(struct page))) {
>   		pr_info("disable free vmemmap pages for %s\n", h->name);
>   		return;
>   	}

This patch should be merged into the original patch that introduced 
vmemmap freeing.

--
Thanks,

David / dhildenb