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[PATCH v3 4/4] mm/hugetlb: Convert use of struct page to folio in __unmap_hugepage_range()

nifan.cxl@gmail.com posted 4 patches 7 months, 3 weeks ago
[PATCH v3 4/4] mm/hugetlb: Convert use of struct page to folio in __unmap_hugepage_range()
Posted by nifan.cxl@gmail.com 7 months, 3 weeks ago 
From: Fan Ni <fan.ni@samsung.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@samsung.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;
 
 	WARN_ON(!is_vm_hugetlb_page(vma));
 	BUG_ON(start & ~huge_page_mask(h));
@@ -5879,14 +5879,13 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 			continue;
 		}
 
-		page = pte_page(pte);
 		/*
 		 * If a reference page is supplied, it is because a specific
 		 * page is being unmapped, not a range. Ensure the page we
 		 * are about to unmap is the actual page of interest.
 		 */
-		if (folio) {
-			if (page_folio(page) != folio) {
+		if (folio_provided) {
+			if (folio != page_folio(pte_page(pte))) {
 				spin_unlock(ptl);
 				continue;
 			}
@@ -5896,12 +5895,14 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 			 * looking like data was lost
 			 */
 			set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
+		} else {
+			folio = page_folio(pte_page(pte));
 		}
 
 		pte = huge_ptep_get_and_clear(mm, address, ptep, sz);
 		tlb_remove_huge_tlb_entry(h, tlb, ptep, address);
 		if (huge_pte_dirty(pte))
-			set_page_dirty(page);
+			folio_mark_dirty(folio);
 		/* Leave a uffd-wp pte marker if needed */
 		if (huge_pte_uffd_wp(pte) &&
 		    !(zap_flags & ZAP_FLAG_DROP_MARKER))
@@ -5909,7 +5910,7 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 					make_pte_marker(PTE_MARKER_UFFD_WP),
 					sz);
 		hugetlb_count_sub(pages_per_huge_page(h), mm);
-		hugetlb_remove_rmap(page_folio(page));
+		hugetlb_remove_rmap(folio);
 
 		/*
 		 * Restore the reservation for anonymous page, otherwise the
@@ -5918,8 +5919,8 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		 * reservation bit.
 		 */
 		if (!h->surplus_huge_pages && __vma_private_lock(vma) &&
-		    folio_test_anon(page_folio(page))) {
-			folio_set_hugetlb_restore_reserve(page_folio(page));
+		    folio_test_anon(folio)) {
+			folio_set_hugetlb_restore_reserve(folio);
 			/* Reservation to be adjusted after the spin lock */
 			adjust_reservation = true;
 		}
@@ -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
 		 */
-		if (folio)
+		if (folio_provided)
 			break;
 	}
 	tlb_end_vma(tlb, vma);
-- 
2.47.2
Re: [PATCH v3 4/4] mm/hugetlb: Convert use of struct page to folio in __unmap_hugepage_range()
Posted by Oscar Salvador 7 months, 3 weeks ago 
On Mon, Apr 28, 2025 at 10:11:47AM -0700, nifan.cxl@gmail.com wrote:
> From: Fan Ni <fan.ni@samsung.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@samsung.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;

This might be me just nitpicking but:

Why not rename folio to ref_folio o provided_folio and do

        struct folio *folio = ref_folio;

I think it is more natural than the boolean.

Also you need to update the comment that references the 'reference page' and the one
David mentioned.

Anyway,

Reviewed-by: Oscar Salvador <osalvador@suse.de>


-- 
Oscar Salvador
SUSE Labs
Re: [PATCH v3 4/4] mm/hugetlb: Convert use of struct page to folio in __unmap_hugepage_range()
Posted by David Hildenbrand 7 months, 3 weeks ago 
On 28.04.25 19:11, nifan.cxl@gmail.com wrote:
> From: Fan Ni <fan.ni@samsung.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@samsung.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@redhat.com>

-- 
Cheers,

David / dhildenb

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