1 files changed, 26 insertions, 86 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index fb19a18892c8..8cf0f9c9599d 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -50,6 +50,7 @@
 #include <trace/events/migrate.h>
 
 #include "internal.h"
+#include "swap.h"
 
 bool isolate_movable_page(struct page *page, isolate_mode_t mode)
 {
@@ -202,7 +203,7 @@ static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw,
 		return false;
 	VM_BUG_ON_PAGE(!PageAnon(page), page);
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
-	VM_BUG_ON_PAGE(pte_present(*pvmw->pte), page);
+	VM_BUG_ON_PAGE(pte_present(ptep_get(pvmw->pte)), page);
 
 	if (folio_test_mlocked(folio) || (pvmw->vma->vm_flags & VM_LOCKED) ||
 	    mm_forbids_zeropage(pvmw->vma->vm_mm))
@@ -328,7 +329,7 @@ static bool remove_migration_pte(struct folio *folio,
 				folio_add_file_rmap_pte(folio, new, vma);
 			set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
 		}
-		if (vma->vm_flags & VM_LOCKED)
+		if (READ_ONCE(vma->vm_flags) & VM_LOCKED)
 			mlock_drain_local();
 
 		trace_remove_migration_pte(pvmw.address, pte_val(pte),
@@ -445,20 +446,6 @@ unlock:
 }
 #endif
 
-static int folio_expected_refs(struct address_space *mapping,
-		struct folio *folio)
-{
-	int refs = 1;
-	if (!mapping)
-		return refs;
-
-	refs += folio_nr_pages(folio);
-	if (folio_test_private(folio))
-		refs++;
-
-	return refs;
-}
-
 /*
  * Replace the folio in the mapping.
  *
@@ -518,15 +505,13 @@ static int __folio_migrate_mapping(struct address_space *mapping,
 	if (folio_test_anon(folio) && folio_test_large(folio))
 		mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON, 1);
 	folio_ref_add(newfolio, nr); /* add cache reference */
-	if (folio_test_swapbacked(folio)) {
+	if (folio_test_swapbacked(folio))
 		__folio_set_swapbacked(newfolio);
-		if (folio_test_swapcache(folio)) {
-			folio_set_swapcache(newfolio);
-			newfolio->private = folio_get_private(folio);
-		}
+	if (folio_test_swapcache(folio)) {
+		folio_set_swapcache(newfolio);
+		newfolio->private = folio_get_private(folio);
 		entries = nr;
 	} else {
-		VM_BUG_ON_FOLIO(folio_test_swapcache(folio), folio);
 		entries = 1;
 	}
 
@@ -603,7 +588,7 @@ static int __folio_migrate_mapping(struct address_space *mapping,
 int folio_migrate_mapping(struct address_space *mapping,
 		struct folio *newfolio, struct folio *folio, int extra_count)
 {
-	int expected_count = folio_expected_refs(mapping, folio) + extra_count;
+	int expected_count = folio_expected_ref_count(folio) + extra_count + 1;
 
 	if (folio_ref_count(folio) != expected_count)
 		return -EAGAIN;
@@ -620,7 +605,7 @@ int migrate_huge_page_move_mapping(struct address_space *mapping,
 				   struct folio *dst, struct folio *src)
 {
 	XA_STATE(xas, &mapping->i_pages, folio_index(src));
-	int rc, expected_count = folio_expected_refs(mapping, src);
+	int rc, expected_count = folio_expected_ref_count(src) + 1;
 
 	if (folio_ref_count(src) != expected_count)
 		return -EAGAIN;
@@ -751,7 +736,7 @@ static int __migrate_folio(struct address_space *mapping, struct folio *dst,
 			   struct folio *src, void *src_private,
 			   enum migrate_mode mode)
 {
-	int rc, expected_count = folio_expected_refs(mapping, src);
+	int rc, expected_count = folio_expected_ref_count(src) + 1;
 
 	/* Check whether src does not have extra refs before we do more work */
 	if (folio_ref_count(src) != expected_count)
@@ -839,7 +824,7 @@ static int __buffer_migrate_folio(struct address_space *mapping,
 		return migrate_folio(mapping, dst, src, mode);
 
 	/* Check whether page does not have extra refs before we do more work */
-	expected_count = folio_expected_refs(mapping, src);
+	expected_count = folio_expected_ref_count(src) + 1;
 	if (folio_ref_count(src) != expected_count)
 		return -EAGAIN;
 
@@ -847,9 +832,11 @@ static int __buffer_migrate_folio(struct address_space *mapping,
 		return -EAGAIN;
 
 	if (check_refs) {
-		bool busy;
+		bool busy, migrating;
 		bool invalidated = false;
 
+		migrating = test_and_set_bit_lock(BH_Migrate, &head->b_state);
+		VM_WARN_ON_ONCE(migrating);
 recheck_buffers:
 		busy = false;
 		spin_lock(&mapping->i_private_lock);
@@ -861,12 +848,12 @@ recheck_buffers:
 			}
 			bh = bh->b_this_page;
 		} while (bh != head);
+		spin_unlock(&mapping->i_private_lock);
 		if (busy) {
 			if (invalidated) {
 				rc = -EAGAIN;
 				goto unlock_buffers;
 			}
-			spin_unlock(&mapping->i_private_lock);
 			invalidate_bh_lrus();
 			invalidated = true;
 			goto recheck_buffers;
@@ -885,7 +872,7 @@ recheck_buffers:
 
 unlock_buffers:
 	if (check_refs)
-		spin_unlock(&mapping->i_private_lock);
+		clear_bit_unlock(BH_Migrate, &head->b_state);
 	bh = head;
 	do {
 		unlock_buffer(bh);
@@ -947,66 +934,20 @@ int filemap_migrate_folio(struct address_space *mapping,
 EXPORT_SYMBOL_GPL(filemap_migrate_folio);
 
 /*
- * Writeback a folio to clean the dirty state
- */
-static int writeout(struct address_space *mapping, struct folio *folio)
-{
-	struct writeback_control wbc = {
-		.sync_mode = WB_SYNC_NONE,
-		.nr_to_write = 1,
-		.range_start = 0,
-		.range_end = LLONG_MAX,
-		.for_reclaim = 1
-	};
-	int rc;
-
-	if (!mapping->a_ops->writepage)
-		/* No write method for the address space */
-		return -EINVAL;
-
-	if (!folio_clear_dirty_for_io(folio))
-		/* Someone else already triggered a write */
-		return -EAGAIN;
-
-	/*
-	 * A dirty folio may imply that the underlying filesystem has
-	 * the folio on some queue. So the folio must be clean for
-	 * migration. Writeout may mean we lose the lock and the
-	 * folio state is no longer what we checked for earlier.
-	 * At this point we know that the migration attempt cannot
-	 * be successful.
-	 */
-	remove_migration_ptes(folio, folio, 0);
-
-	rc = mapping->a_ops->writepage(&folio->page, &wbc);
-
-	if (rc != AOP_WRITEPAGE_ACTIVATE)
-		/* unlocked. Relock */
-		folio_lock(folio);
-
-	return (rc < 0) ? -EIO : -EAGAIN;
-}
-
-/*
  * Default handling if a filesystem does not provide a migration function.
  */
 static int fallback_migrate_folio(struct address_space *mapping,
 		struct folio *dst, struct folio *src, enum migrate_mode mode)
 {
-	if (folio_test_dirty(src)) {
-		/* Only writeback folios in full synchronous migration */
-		switch (mode) {
-		case MIGRATE_SYNC:
-			break;
-		default:
-			return -EBUSY;
-		}
-		return writeout(mapping, src);
-	}
+	WARN_ONCE(mapping->a_ops->writepages,
+			"%ps does not implement migrate_folio\n",
+			mapping->a_ops);
+	if (folio_test_dirty(src))
+		return -EBUSY;
 
 	/*
-	 * Buffers may be managed in a filesystem specific way.
-	 * We must have no buffers or drop them.
+	 * Filesystem may have private data at folio->private that we
+	 * can't migrate automatically.
 	 */
 	if (!filemap_release_folio(src, GFP_KERNEL))
 		return mode == MIGRATE_SYNC ? -EAGAIN : -EBUSY;
@@ -2228,7 +2169,7 @@ static int __add_folio_for_migration(struct folio *folio, int node,
 	if (folio_nid(folio) == node)
 		return 0;
 
-	if (folio_likely_mapped_shared(folio) && !migrate_all)
+	if (folio_maybe_mapped_shared(folio) && !migrate_all)
 		return -EACCES;
 
 	if (folio_test_hugetlb(folio)) {
@@ -2653,11 +2594,10 @@ int migrate_misplaced_folio_prepare(struct folio *folio,
 		 * processes with execute permissions as they are probably
 		 * shared libraries.
 		 *
-		 * See folio_likely_mapped_shared() on possible imprecision
+		 * See folio_maybe_mapped_shared() on possible imprecision
 		 * when we cannot easily detect if a folio is shared.
 		 */
-		if ((vma->vm_flags & VM_EXEC) &&
-		    folio_likely_mapped_shared(folio))
+		if ((vma->vm_flags & VM_EXEC) && folio_maybe_mapped_shared(folio))
 			return -EACCES;
 
 		/*