linux-kernel - Re: [PATCH v3 4/4] mm/hugetlb: Convert use of struct page to folio in __unmap_hugepage

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Message-ID: <ba576520-3bec-45e6-8ae8-d36ea0a0e00d@redhat.com>
Date: Mon, 28 Apr 2025 22:53:39 +0200
From: David Hildenbrand <david@...hat.com>
To: nifan.cxl@...il.com, muchun.song@...ux.dev, willy@...radead.org
Cc: mcgrof@...nel.org, a.manzanares@...sung.com, dave@...olabs.net,
 akpm@...ux-foundation.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 Fan Ni <fan.ni@...sung.com>
Subject: Re: [PATCH v3 4/4] mm/hugetlb: Convert use of struct page to folio in
 __unmap_hugepage_range()

On 28.04.25 19:11, nifan.cxl@...il.com wrote:
> From: Fan Ni <fan.ni@...sung.com>
> 
> In __unmap_hugepage_range(), the "page" pointer always points to the
> first page of a huge page, which guarantees there is a folio associating
> with it.  Convert the "page" pointer to use folio.
> 
> Signed-off-by: Fan Ni <fan.ni@...sung.com>
> ---
>   mm/hugetlb.c | 24 +++++++++++++-----------
>   1 file changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 6696206d556e..293c2afa724b 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -5815,12 +5815,12 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
>   	pte_t *ptep;
>   	pte_t pte;
>   	spinlock_t *ptl;
> -	struct page *page;
>   	struct hstate *h = hstate_vma(vma);
>   	unsigned long sz = huge_page_size(h);
>   	bool adjust_reservation = false;
>   	unsigned long last_addr_mask;
>   	bool force_flush = false;
> +	const bool folio_provided = !!folio;

I would but that all the way to the top.

>   		}
> @@ -5943,16 +5944,17 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
>   				 * count will not be incremented by free_huge_folio.
>   				 * Act as if we consumed the reservation.
>   				 */
> -				folio_clear_hugetlb_restore_reserve(page_folio(page));
> +				folio_clear_hugetlb_restore_reserve(folio);
>   			else if (rc)
>   				vma_add_reservation(h, vma, address);
>   		}
>   
> -		tlb_remove_page_size(tlb, page, huge_page_size(h));
> +		tlb_remove_page_size(tlb, folio_page(folio, 0),
> +				     folio_size(folio));
>   		/*
>   		 * Bail out after unmapping reference page if supplied
>   		 */


I wonder if we want to adjust that comment while at it.

/* If we were instructed to unmap a specific folio, we're done. */


Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers,

David / dhildenb