Re: [PATCH v9 5/7] mm: Make alloc_contig_range handle free hugetlb pages

[Baoquan He]

On 04/16/21 at 09:00am, Oscar Salvador wrote:
...  
> +/*
> + * alloc_and_dissolve_huge_page - Allocate a new page and dissolve the old one
> + * @h: struct hstate old page belongs to
> + * @old_page: Old page to dissolve
> + * Returns 0 on success, otherwise negated error.
> + */
> +static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page)
> +{
> +	gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
> +	int nid = page_to_nid(old_page);
> +	struct page *new_page;
> +	int ret = 0;
> +
> +	/*
> +	 * Before dissolving the page, we need to allocate a new one for the
> +	 * pool to remain stable. Using alloc_buddy_huge_page() allows us to
> +	 * not having to deal with prep_new_page() and avoids dealing of any
				   ~ prep_new_huge_page() ?
> +	 * counters. This simplifies and let us do the whole thing under the
> +	 * lock.
> +	 */
> +	new_page = alloc_buddy_huge_page(h, gfp_mask, nid, NULL, NULL);
> +	if (!new_page)
> +		return -ENOMEM;
> +
> +retry:
> +	spin_lock_irq(&hugetlb_lock);
...