mm/hugetlb: refactor __unmap_hugepage_range() to take folio instead of page

The function __unmap_hugepage_range() has two kinds of users:
1) unmap_hugepage_range(), which passes in the head page of a folio.
   Since unmap_hugepage_range() already takes folio and there are no other
   uses of the folio struct in the function, it is natural for
   __unmap_hugepage_range() to take folio also.
2) All other uses, which pass in NULL pointer.

In both cases, we can pass in folio. Refactor __unmap_hugepage_range() to
take folio.

Link: https://lkml.kernel.org/r/20250505182345.506888-5-nifan.cxl@gmail.com
Signed-off-by: Fan Ni <fan.ni@samsung.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
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

include/linux/hugetlb.h

@@ -134,7 +134,7 @@ void unmap_hugepage_range(struct vm_area_struct *,
 void __unmap_hugepage_range(struct mmu_gather *tlb,
 			  struct vm_area_struct *vma,
 			  unsigned long start, unsigned long end,
-			  struct page *ref_page, zap_flags_t zap_flags);
+			  struct folio *, zap_flags_t zap_flags);
 void hugetlb_report_meminfo(struct seq_file *);
 int hugetlb_report_node_meminfo(char *buf, int len, int nid);
 void hugetlb_show_meminfo_node(int nid);
@@ -455,7 +455,7 @@ static inline long hugetlb_change_protection(
 
 static inline void __unmap_hugepage_range(struct mmu_gather *tlb,
 			struct vm_area_struct *vma, unsigned long start,
-			unsigned long end, struct page *ref_page,
+			unsigned long end, struct folio *folio,
 			zap_flags_t zap_flags)
 {
 	BUG();

mm/hugetlb.c

@@ -5840,7 +5840,7 @@ int move_hugetlb_page_tables(struct vm_area_struct *vma,
 
 void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 			    unsigned long start, unsigned long end,
-			    struct page *ref_page, zap_flags_t zap_flags)
+			    struct folio *folio, zap_flags_t zap_flags)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	unsigned long address;
@@ -5913,12 +5913,12 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 
 		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 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 (ref_page) {
-			if (page != ref_page) {
+		if (folio) {
+			if (page_folio(page) != folio) {
 				spin_unlock(ptl);
 				continue;
 			}
@@ -5982,9 +5982,9 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 
 		tlb_remove_page_size(tlb, page, huge_page_size(h));
 		/*
-		 * Bail out after unmapping reference page if supplied
+		 * If we were instructed to unmap a specific folio, we're done.
 		 */
-		if (ref_page)
+		if (folio)
 			break;
 	}
 	tlb_end_vma(tlb, vma);
@@ -6059,7 +6059,7 @@ void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
 	tlb_gather_mmu(&tlb, vma->vm_mm);
 
 	__unmap_hugepage_range(&tlb, vma, start, end,
-			       &folio->page, zap_flags);
+			       folio, zap_flags);
 
 	mmu_notifier_invalidate_range_end(&range);
 	tlb_finish_mmu(&tlb);