1 files changed, 69 insertions, 67 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index 9e5ef39ce73a..e3065c9edb55 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -231,18 +231,17 @@ static void putback_movable_ops_page(struct page *page)
  * src and dst are also released by migration core. These pages will not be
  * folios in the future, so that must be reworked.
  *
- * Returns MIGRATEPAGE_SUCCESS on success, otherwise a negative error
- * code.
+ * Returns 0 on success, otherwise a negative error code.
  */
 static int migrate_movable_ops_page(struct page *dst, struct page *src,
 		enum migrate_mode mode)
 {
-	int rc = MIGRATEPAGE_SUCCESS;
+	int rc;
 
 	VM_WARN_ON_ONCE_PAGE(!page_has_movable_ops(src), src);
 	VM_WARN_ON_ONCE_PAGE(!PageMovableOpsIsolated(src), src);
 	rc = page_movable_ops(src)->migrate_page(dst, src, mode);
-	if (rc == MIGRATEPAGE_SUCCESS)
+	if (!rc)
 		ClearPageMovableOpsIsolated(src);
 	return rc;
 }
@@ -297,19 +296,16 @@ bool isolate_folio_to_list(struct folio *folio, struct list_head *list)
 }
 
 static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw,
-					  struct folio *folio,
-					  unsigned long idx)
+		struct folio *folio, pte_t old_pte, unsigned long idx)
 {
 	struct page *page = folio_page(folio, idx);
-	bool contains_data;
 	pte_t newpte;
-	void *addr;
 
 	if (PageCompound(page))
 		return false;
 	VM_BUG_ON_PAGE(!PageAnon(page), page);
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
-	VM_BUG_ON_PAGE(pte_present(ptep_get(pvmw->pte)), page);
+	VM_BUG_ON_PAGE(pte_present(old_pte), page);
 
 	if (folio_test_mlocked(folio) || (pvmw->vma->vm_flags & VM_LOCKED) ||
 	    mm_forbids_zeropage(pvmw->vma->vm_mm))
@@ -320,15 +316,17 @@ static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw,
 	 * this subpage has been non present. If the subpage is only zero-filled
 	 * then map it to the shared zeropage.
 	 */
-	addr = kmap_local_page(page);
-	contains_data = memchr_inv(addr, 0, PAGE_SIZE);
-	kunmap_local(addr);
-
-	if (contains_data)
+	if (!pages_identical(page, ZERO_PAGE(0)))
 		return false;
 
 	newpte = pte_mkspecial(pfn_pte(my_zero_pfn(pvmw->address),
 					pvmw->vma->vm_page_prot));
+
+	if (pte_swp_soft_dirty(old_pte))
+		newpte = pte_mksoft_dirty(newpte);
+	if (pte_swp_uffd_wp(old_pte))
+		newpte = pte_mkuffd_wp(newpte);
+
 	set_pte_at(pvmw->vma->vm_mm, pvmw->address, pvmw->pte, newpte);
 
 	dec_mm_counter(pvmw->vma->vm_mm, mm_counter(folio));
@@ -371,13 +369,13 @@ static bool remove_migration_pte(struct folio *folio,
 			continue;
 		}
 #endif
+		old_pte = ptep_get(pvmw.pte);
 		if (rmap_walk_arg->map_unused_to_zeropage &&
-		    try_to_map_unused_to_zeropage(&pvmw, folio, idx))
+		    try_to_map_unused_to_zeropage(&pvmw, folio, old_pte, idx))
 			continue;
 
 		folio_get(folio);
 		pte = mk_pte(new, READ_ONCE(vma->vm_page_prot));
-		old_pte = ptep_get(pvmw.pte);
 
 		entry = pte_to_swp_entry(old_pte);
 		if (!is_migration_entry_young(entry))
@@ -564,10 +562,10 @@ static int __folio_migrate_mapping(struct address_space *mapping,
 		struct folio *newfolio, struct folio *folio, int expected_count)
 {
 	XA_STATE(xas, &mapping->i_pages, folio_index(folio));
+	struct swap_cluster_info *ci = NULL;
 	struct zone *oldzone, *newzone;
 	int dirty;
 	long nr = folio_nr_pages(folio);
-	long entries, i;
 
 	if (!mapping) {
 		/* Take off deferred split queue while frozen and memcg set */
@@ -587,15 +585,22 @@ static int __folio_migrate_mapping(struct address_space *mapping,
 		if (folio_test_swapbacked(folio))
 			__folio_set_swapbacked(newfolio);
 
-		return MIGRATEPAGE_SUCCESS;
+		return 0;
 	}
 
 	oldzone = folio_zone(folio);
 	newzone = folio_zone(newfolio);
 
-	xas_lock_irq(&xas);
+	if (folio_test_swapcache(folio))
+		ci = swap_cluster_get_and_lock_irq(folio);
+	else
+		xas_lock_irq(&xas);
+
 	if (!folio_ref_freeze(folio, expected_count)) {
-		xas_unlock_irq(&xas);
+		if (ci)
+			swap_cluster_unlock_irq(ci);
+		else
+			xas_unlock_irq(&xas);
 		return -EAGAIN;
 	}
 
@@ -616,9 +621,6 @@ static int __folio_migrate_mapping(struct address_space *mapping,
 	if (folio_test_swapcache(folio)) {
 		folio_set_swapcache(newfolio);
 		newfolio->private = folio_get_private(folio);
-		entries = nr;
-	} else {
-		entries = 1;
 	}
 
 	/* Move dirty while folio refs frozen and newfolio not yet exposed */
@@ -628,11 +630,10 @@ static int __folio_migrate_mapping(struct address_space *mapping,
 		folio_set_dirty(newfolio);
 	}
 
-	/* Swap cache still stores N entries instead of a high-order entry */
-	for (i = 0; i < entries; i++) {
+	if (folio_test_swapcache(folio))
+		__swap_cache_replace_folio(ci, folio, newfolio);
+	else
 		xas_store(&xas, newfolio);
-		xas_next(&xas);
-	}
 
 	/*
 	 * Drop cache reference from old folio by unfreezing
@@ -641,8 +642,11 @@ static int __folio_migrate_mapping(struct address_space *mapping,
 	 */
 	folio_ref_unfreeze(folio, expected_count - nr);
 
-	xas_unlock(&xas);
 	/* Leave irq disabled to prevent preemption while updating stats */
+	if (ci)
+		swap_cluster_unlock(ci);
+	else
+		xas_unlock(&xas);
 
 	/*
 	 * If moved to a different zone then also account
@@ -688,7 +692,7 @@ static int __folio_migrate_mapping(struct address_space *mapping,
 	}
 	local_irq_enable();
 
-	return MIGRATEPAGE_SUCCESS;
+	return 0;
 }
 
 int folio_migrate_mapping(struct address_space *mapping,
@@ -737,7 +741,7 @@ int migrate_huge_page_move_mapping(struct address_space *mapping,
 
 	xas_unlock_irq(&xas);
 
-	return MIGRATEPAGE_SUCCESS;
+	return 0;
 }
 
 /*
@@ -853,14 +857,14 @@ static int __migrate_folio(struct address_space *mapping, struct folio *dst,
 		return rc;
 
 	rc = __folio_migrate_mapping(mapping, dst, src, expected_count);
-	if (rc != MIGRATEPAGE_SUCCESS)
+	if (rc)
 		return rc;
 
 	if (src_private)
 		folio_attach_private(dst, folio_detach_private(src));
 
 	folio_migrate_flags(dst, src);
-	return MIGRATEPAGE_SUCCESS;
+	return 0;
 }
 
 /**
@@ -967,7 +971,7 @@ recheck_buffers:
 	}
 
 	rc = filemap_migrate_folio(mapping, dst, src, mode);
-	if (rc != MIGRATEPAGE_SUCCESS)
+	if (rc)
 		goto unlock_buffers;
 
 	bh = head;
@@ -1071,7 +1075,7 @@ static int fallback_migrate_folio(struct address_space *mapping,
  *
  * Return value:
  *   < 0 - error code
- *  MIGRATEPAGE_SUCCESS - success
+ *     0 - success
  */
 static int move_to_new_folio(struct folio *dst, struct folio *src,
 				enum migrate_mode mode)
@@ -1099,7 +1103,7 @@ static int move_to_new_folio(struct folio *dst, struct folio *src,
 	else
 		rc = fallback_migrate_folio(mapping, dst, src, mode);
 
-	if (rc == MIGRATEPAGE_SUCCESS) {
+	if (!rc) {
 		/*
 		 * For pagecache folios, src->mapping must be cleared before src
 		 * is freed. Anonymous folios must stay anonymous until freed.
@@ -1189,7 +1193,7 @@ static void migrate_folio_done(struct folio *src,
 static int migrate_folio_unmap(new_folio_t get_new_folio,
 		free_folio_t put_new_folio, unsigned long private,
 		struct folio *src, struct folio **dstp, enum migrate_mode mode,
-		enum migrate_reason reason, struct list_head *ret)
+		struct list_head *ret)
 {
 	struct folio *dst;
 	int rc = -EAGAIN;
@@ -1198,16 +1202,6 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
 	bool locked = false;
 	bool dst_locked = false;
 
-	if (folio_ref_count(src) == 1) {
-		/* Folio was freed from under us. So we are done. */
-		folio_clear_active(src);
-		folio_clear_unevictable(src);
-		/* free_pages_prepare() will clear PG_isolated. */
-		list_del(&src->lru);
-		migrate_folio_done(src, reason);
-		return MIGRATEPAGE_SUCCESS;
-	}
-
 	dst = get_new_folio(src, private);
 	if (!dst)
 		return -ENOMEM;
@@ -1297,7 +1291,7 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
 
 	if (unlikely(page_has_movable_ops(&src->page))) {
 		__migrate_folio_record(dst, old_page_state, anon_vma);
-		return MIGRATEPAGE_UNMAP;
+		return 0;
 	}
 
 	/*
@@ -1327,7 +1321,7 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
 
 	if (!folio_mapped(src)) {
 		__migrate_folio_record(dst, old_page_state, anon_vma);
-		return MIGRATEPAGE_UNMAP;
+		return 0;
 	}
 
 out:
@@ -1459,7 +1453,7 @@ static int unmap_and_move_huge_page(new_folio_t get_new_folio,
 	if (folio_ref_count(src) == 1) {
 		/* page was freed from under us. So we are done. */
 		folio_putback_hugetlb(src);
-		return MIGRATEPAGE_SUCCESS;
+		return 0;
 	}
 
 	dst = get_new_folio(src, private);
@@ -1522,8 +1516,7 @@ static int unmap_and_move_huge_page(new_folio_t get_new_folio,
 		rc = move_to_new_folio(dst, src, mode);
 
 	if (page_was_mapped)
-		remove_migration_ptes(src,
-			rc == MIGRATEPAGE_SUCCESS ? dst : src, 0);
+		remove_migration_ptes(src, !rc ? dst : src, 0);
 
 unlock_put_anon:
 	folio_unlock(dst);
@@ -1532,7 +1525,7 @@ put_anon:
 	if (anon_vma)
 		put_anon_vma(anon_vma);
 
-	if (rc == MIGRATEPAGE_SUCCESS) {
+	if (!rc) {
 		move_hugetlb_state(src, dst, reason);
 		put_new_folio = NULL;
 	}
@@ -1540,7 +1533,7 @@ put_anon:
 out_unlock:
 	folio_unlock(src);
 out:
-	if (rc == MIGRATEPAGE_SUCCESS)
+	if (!rc)
 		folio_putback_hugetlb(src);
 	else if (rc != -EAGAIN)
 		list_move_tail(&src->lru, ret);
@@ -1650,7 +1643,7 @@ static int migrate_hugetlbs(struct list_head *from, new_folio_t get_new_folio,
 						      reason, ret_folios);
 			/*
 			 * The rules are:
-			 *	Success: hugetlb folio will be put back
+			 *	0: hugetlb folio will be put back
 			 *	-EAGAIN: stay on the from list
 			 *	-ENOMEM: stay on the from list
 			 *	Other errno: put on ret_folios list
@@ -1667,7 +1660,7 @@ static int migrate_hugetlbs(struct list_head *from, new_folio_t get_new_folio,
 				retry++;
 				nr_retry_pages += nr_pages;
 				break;
-			case MIGRATEPAGE_SUCCESS:
+			case 0:
 				stats->nr_succeeded += nr_pages;
 				break;
 			default:
@@ -1721,7 +1714,7 @@ static void migrate_folios_move(struct list_head *src_folios,
 				reason, ret_folios);
 		/*
 		 * The rules are:
-		 *	Success: folio will be freed
+		 *	0: folio will be freed
 		 *	-EAGAIN: stay on the unmap_folios list
 		 *	Other errno: put on ret_folios list
 		 */
@@ -1731,7 +1724,7 @@ static void migrate_folios_move(struct list_head *src_folios,
 			*thp_retry += is_thp;
 			*nr_retry_pages += nr_pages;
 			break;
-		case MIGRATEPAGE_SUCCESS:
+		case 0:
 			stats->nr_succeeded += nr_pages;
 			stats->nr_thp_succeeded += is_thp;
 			break;
@@ -1870,14 +1863,27 @@ static int migrate_pages_batch(struct list_head *from,
 				continue;
 			}
 
+			/*
+			 * If we are holding the last folio reference, the folio
+			 * was freed from under us, so just drop our reference.
+			 */
+			if (likely(!page_has_movable_ops(&folio->page)) &&
+			    folio_ref_count(folio) == 1) {
+				folio_clear_active(folio);
+				folio_clear_unevictable(folio);
+				list_del(&folio->lru);
+				migrate_folio_done(folio, reason);
+				stats->nr_succeeded += nr_pages;
+				stats->nr_thp_succeeded += is_thp;
+				continue;
+			}
+
 			rc = migrate_folio_unmap(get_new_folio, put_new_folio,
-					private, folio, &dst, mode, reason,
-					ret_folios);
+					private, folio, &dst, mode, ret_folios);
 			/*
 			 * The rules are:
-			 *	Success: folio will be freed
-			 *	Unmap: folio will be put on unmap_folios list,
-			 *	       dst folio put on dst_folios list
+			 *	0: folio will be put on unmap_folios list,
+			 *	   dst folio put on dst_folios list
 			 *	-EAGAIN: stay on the from list
 			 *	-ENOMEM: stay on the from list
 			 *	Other errno: put on ret_folios list
@@ -1927,11 +1933,7 @@ static int migrate_pages_batch(struct list_head *from,
 				thp_retry += is_thp;
 				nr_retry_pages += nr_pages;
 				break;
-			case MIGRATEPAGE_SUCCESS:
-				stats->nr_succeeded += nr_pages;
-				stats->nr_thp_succeeded += is_thp;
-				break;
-			case MIGRATEPAGE_UNMAP:
+			case 0:
 				list_move_tail(&folio->lru, &unmap_folios);
 				list_add_tail(&dst->lru, &dst_folios);
 				break;