[PATCH RFC 11/29] mm/migrate: move movable_ops page handling out of move_to_new_folio()
From: David Hildenbrand <hidden>
Date: 2025-06-18 17:40:50
Also in:
linux-doc, linux-fsdevel, linux-mm, linuxppc-dev, lkml
Subsystem:
memory management, memory management - memory policy and migration, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
Let's move that handling directly into migrate_folio_move(), so we can simplify move_to_new_folio(). While at it, fixup the documentation a bit. Note that unmap_and_move_huge_page() does not care, because it only deals with actual folios. (we only support migration of individual movable_ops pages) Signed-off-by: David Hildenbrand <redacted> --- mm/migrate.c | 61 ++++++++++++++++++++++++---------------------------- 1 file changed, 28 insertions(+), 33 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 456e41dad83a2..db807f9bbf975 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c@@ -1024,11 +1024,12 @@ static int fallback_migrate_folio(struct address_space *mapping, } /* - * Move a page to a newly allocated page - * The page is locked and all ptes have been successfully removed. + * Move a src folio to a newly allocated dst folio. * - * The new page will have replaced the old page if this function - * is successful. + * The src and dst folios are locked and the src folios was unmapped from + * the page tables. + * + * On success, the src folio was replaced by the dst folio. * * Return value: * < 0 - error code
@@ -1037,34 +1038,30 @@ static int fallback_migrate_folio(struct address_space *mapping, static int move_to_new_folio(struct folio *dst, struct folio *src, enum migrate_mode mode) { + struct address_space *mapping = folio_mapping(src); int rc = -EAGAIN; - bool is_lru = !__folio_test_movable(src); VM_BUG_ON_FOLIO(!folio_test_locked(src), src); VM_BUG_ON_FOLIO(!folio_test_locked(dst), dst); - if (likely(is_lru)) { - struct address_space *mapping = folio_mapping(src); - - if (!mapping) - rc = migrate_folio(mapping, dst, src, mode); - else if (mapping_inaccessible(mapping)) - rc = -EOPNOTSUPP; - else if (mapping->a_ops->migrate_folio) - /* - * Most folios have a mapping and most filesystems - * provide a migrate_folio callback. Anonymous folios - * are part of swap space which also has its own - * migrate_folio callback. This is the most common path - * for page migration. - */ - rc = mapping->a_ops->migrate_folio(mapping, dst, src, - mode); - else - rc = fallback_migrate_folio(mapping, dst, src, mode); + if (!mapping) + rc = migrate_folio(mapping, dst, src, mode); + else if (mapping_inaccessible(mapping)) + rc = -EOPNOTSUPP; + else if (mapping->a_ops->migrate_folio) + /* + * Most folios have a mapping and most filesystems + * provide a migrate_folio callback. Anonymous folios + * are part of swap space which also has its own + * migrate_folio callback. This is the most common path + * for page migration. + */ + rc = mapping->a_ops->migrate_folio(mapping, dst, src, + mode); + else + rc = fallback_migrate_folio(mapping, dst, src, mode); - if (rc != MIGRATEPAGE_SUCCESS) - goto out; + if (rc == MIGRATEPAGE_SUCCESS) { /* * For pagecache folios, src->mapping must be cleared before src * is freed. Anonymous folios must stay anonymous until freed.
@@ -1074,10 +1071,7 @@ static int move_to_new_folio(struct folio *dst, struct folio *src, if (likely(!folio_is_zone_device(dst))) flush_dcache_folio(dst); - } else { - rc = migrate_movable_ops_page(&dst->page, &src->page, mode); } -out: return rc; }
@@ -1328,20 +1322,21 @@ static int migrate_folio_move(free_folio_t put_new_folio, unsigned long private, int rc; int old_page_state = 0; struct anon_vma *anon_vma = NULL; - bool is_lru = !__folio_test_movable(src); struct list_head *prev; __migrate_folio_extract(dst, &old_page_state, &anon_vma); prev = dst->lru.prev; list_del(&dst->lru); + if (unlikely(__folio_test_movable(src))) { + rc = migrate_movable_ops_page(&dst->page, &src->page, mode); + goto out_unlock_both; + } + rc = move_to_new_folio(dst, src, mode); if (rc) goto out; - if (unlikely(!is_lru)) - goto out_unlock_both; - /* * When successful, push dst to LRU immediately: so that if it * turns out to be an mlocked page, remove_migration_ptes() will
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2.49.0