mm: convert mm_counter() to take a folio

Now all callers of mm_counter() have a folio, convert mm_counter() to take
a folio.  Saves a call to compound_head() hidden inside PageAnon().

Link: https://lkml.kernel.org/r/20240111152429.3374566-10-willy@infradead.org
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Kefeng Wang

arch/s390/mm/pgtable.c

@@ -723,7 +723,7 @@ static void ptep_zap_swap_entry(struct mm_struct *mm, swp_entry_t entry)
 	else if (is_migration_entry(entry)) {
 		struct folio *folio = pfn_swap_entry_folio(entry);
 
-		dec_mm_counter(mm, mm_counter(&folio->page));
+		dec_mm_counter(mm, mm_counter(folio));
 	}
 	free_swap_and_cache(entry);
 }

include/linux/mm.h

@@ -2603,11 +2603,11 @@ static inline int mm_counter_file(struct page *page)
 	return MM_FILEPAGES;
 }
 
-static inline int mm_counter(struct page *page)
+static inline int mm_counter(struct folio *folio)
 {
-	if (PageAnon(page))
+	if (folio_test_anon(folio))
 		return MM_ANONPAGES;
-	return mm_counter_file(page);
+	return mm_counter_file(&folio->page);
 }
 
 static inline unsigned long get_mm_rss(struct mm_struct *mm)

mm/memory.c

@@ -808,7 +808,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 	} else if (is_migration_entry(entry)) {
 		folio = pfn_swap_entry_folio(entry);
 
-		rss[mm_counter(&folio->page)]++;
+		rss[mm_counter(folio)]++;
 
 		if (!is_readable_migration_entry(entry) &&
 				is_cow_mapping(vm_flags)) {
@@ -840,7 +840,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 		 * keep things as they are.
 		 */
 		folio_get(folio);
-		rss[mm_counter(page)]++;
+		rss[mm_counter(folio)]++;
 		/* Cannot fail as these pages cannot get pinned. */
 		folio_try_dup_anon_rmap_pte(folio, page, src_vma);
 
@@ -1476,7 +1476,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 				if (pte_young(ptent) && likely(vma_has_recency(vma)))
 					folio_mark_accessed(folio);
 			}
-			rss[mm_counter(page)]--;
+			rss[mm_counter(folio)]--;
 			if (!delay_rmap) {
 				folio_remove_rmap_pte(folio, page, vma);
 				if (unlikely(page_mapcount(page) < 0))
@@ -1504,7 +1504,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 			 * see zap_install_uffd_wp_if_needed().
 			 */
 			WARN_ON_ONCE(!vma_is_anonymous(vma));
-			rss[mm_counter(page)]--;
+			rss[mm_counter(folio)]--;
 			if (is_device_private_entry(entry))
 				folio_remove_rmap_pte(folio, page, vma);
 			folio_put(folio);
@@ -1519,7 +1519,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 			folio = pfn_swap_entry_folio(entry);
 			if (!should_zap_folio(details, folio))
 				continue;
-			rss[mm_counter(&folio->page)]--;
+			rss[mm_counter(folio)]--;
 		} else if (pte_marker_entry_uffd_wp(entry)) {
 			/*
 			 * For anon: always drop the marker; for file: only

mm/rmap.c

@@ -1780,7 +1780,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 				set_huge_pte_at(mm, address, pvmw.pte, pteval,
 						hsz);
 			} else {
-				dec_mm_counter(mm, mm_counter(&folio->page));
+				dec_mm_counter(mm, mm_counter(folio));
 				set_pte_at(mm, address, pvmw.pte, pteval);
 			}
 
@@ -1795,7 +1795,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 			 * migration) will not expect userfaults on already
 			 * copied pages.
 			 */
-			dec_mm_counter(mm, mm_counter(&folio->page));
+			dec_mm_counter(mm, mm_counter(folio));
 		} else if (folio_test_anon(folio)) {
 			swp_entry_t entry = page_swap_entry(subpage);
 			pte_t swp_pte;
@@ -2181,7 +2181,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 				set_huge_pte_at(mm, address, pvmw.pte, pteval,
 						hsz);
 			} else {
-				dec_mm_counter(mm, mm_counter(&folio->page));
+				dec_mm_counter(mm, mm_counter(folio));
 				set_pte_at(mm, address, pvmw.pte, pteval);
 			}
 
@@ -2196,7 +2196,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 			 * migration) will not expect userfaults on already
 			 * copied pages.
 			 */
-			dec_mm_counter(mm, mm_counter(&folio->page));
+			dec_mm_counter(mm, mm_counter(folio));
 		} else {
 			swp_entry_t entry;
 			pte_t swp_pte;

mm/userfaultfd.c

@@ -124,7 +124,7 @@ int mfill_atomic_install_pte(pmd_t *dst_pmd,
 	 * Must happen after rmap, as mm_counter() checks mapping (via
 	 * PageAnon()), which is set by __page_set_anon_rmap().
 	 */
-	inc_mm_counter(dst_mm, mm_counter(page));
+	inc_mm_counter(dst_mm, mm_counter(folio));
 
 	set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);