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Date:   Fri, 16 Apr 2021 17:49:20 +0800
From:   Baoquan He <bhe@redhat.com>
To:     Oscar Salvador <osalvador@suse.de>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        David Hildenbrand <david@redhat.com>,
        Michal Hocko <mhocko@kernel.org>,
        Muchun Song <songmuchun@bytedance.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH v9 5/7] mm: Make alloc_contig_range handle free hugetlb
 pages
Message-ID: <20210416094920.GA8560@MiWiFi-R3L-srv>
References: <20210416070023.4742-1-osalvador@suse.de>
 <20210416070023.4742-6-osalvador@suse.de>
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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);
...