linux-kernel - Re: [PATCH mm-unstable 3/8] mm/hugetlb: convert dequeue_hugetlb_page

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Message-ID: <Y7SXXF4sGEjR1um5@casper.infradead.org>
Date:   Tue, 3 Jan 2023 21:00:12 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     Sidhartha Kumar <sidhartha.kumar@...cle.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org, songmuchun@...edance.com,
        mike.kravetz@...cle.com, tsahu@...ux.ibm.com, jhubbard@...dia.com
Subject: Re: [PATCH mm-unstable 3/8] mm/hugetlb: convert
 dequeue_hugetlb_page_node functions to folios

On Tue, Jan 03, 2023 at 01:13:35PM -0600, Sidhartha Kumar wrote:
> +static struct folio *dequeue_hugetlb_folio_node_exact(struct hstate *h,
> +								int nid)
>  {
>  	struct page *page;
> +	struct folio *folio;
>  	bool pin = !!(current->flags & PF_MEMALLOC_PIN);
>  
>  	lockdep_assert_held(&hugetlb_lock);
>  	list_for_each_entry(page, &h->hugepage_freelists[nid], lru) {
> -		if (pin && !is_longterm_pinnable_page(page))
> +		folio = page_folio(page);

I'd argue that you can pull folios directly off the hugepage_freelists.
Since they're attached through the 'lru', you know they're not tail
pages, because lru.prev aliases with compound_head.

The rest looks good.