mm/hugetlb: convert use of struct page to folio in __unmap_hugepage_range()

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.

Link: https://lkml.kernel.org/r/20250505182345.506888-6-nifan.cxl@gmail.com
Signed-off-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: "Vishal Moola (Oracle)" <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: fancxl

mm/hugetlb.c

@@ -5843,11 +5843,11 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 			    struct folio *folio, zap_flags_t zap_flags)
 {
 	struct mm_struct *mm = vma->vm_mm;
+	const bool folio_provided = !!folio;
 	unsigned long address;
 	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;
@@ -5911,14 +5911,13 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 			continue;
 		}
 
-		page = pte_page(pte);
 		/*
 		 * If a folio is supplied, it is because a specific
 		 * folio is being unmapped, not a range. Ensure the folio we
 		 * are about to unmap is the actual folio of interest.
 		 */
-		if (folio) {
-			if (page_folio(page) != folio) {
+		if (folio_provided) {
+			if (folio != page_folio(pte_page(pte))) {
 				spin_unlock(ptl);
 				continue;
 			}
@@ -5928,20 +5927,22 @@ 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))
 			set_huge_pte_at(mm, address, ptep,
 					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
@@ -5950,8 +5951,8 @@ 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;
 		}
@@ -5975,16 +5976,17 @@ 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));
 		/*
 		 * If we were instructed to unmap a specific folio, we're done.
 		 */
-		if (folio)
+		if (folio_provided)
 			break;
 	}
 	tlb_end_vma(tlb, vma);