[PATCH v1 18/29] mm: remove __folio_test_movable()

David Hildenbrand
2025-06-30T13:01:13Z

Convert to page_has_movable_ops(). While at it, cleanup relevant code
a bit.

The data_race() in migrate_folio_unmap() is questionable: we already
hold a page reference, and concurrent modifications can no longer
happen (iow: __ClearPageMovable() no longer exists). Drop it for now,
we'll rework page_has_movable_ops() soon either way to no longer
rely on page->mapping.

Wherever we cast from folio to page now is a clear sign that this
code has to be decoupled.

Reviewed-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
include/linux/page-flags.h | 6 ------
mm/migrate.c | 43 ++++++++++++--------------------------
mm/vmscan.c | 6 ++++--
3 files changed, 17 insertions(+), 38 deletions(-)

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index c67163b73c5ec..4c27ebb689e3c 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -744,12 +744,6 @@ static __always_inline bool PageAnon(const struct page *page)
return folio_test_anon(page_folio(page));
}

-static __always_inline bool __folio_test_movable(const struct folio *folio)
-{
- return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
- PAGE_MAPPING_MOVABLE;
-}
-
static __always_inline bool page_has_movable_ops(const struct page *page)
{
return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
diff --git a/mm/migrate.c b/mm/migrate.c
index 587af35b7390d..15d3c1031530c 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -219,12 +219,7 @@ void putback_movable_pages(struct list_head *l)
continue;
}
list_del(&folio->lru);
- /*
- * We isolated non-lru movable folio so here we can use
- * __folio_test_movable because LRU folio's mapping cannot
- * have PAGE_MAPPING_MOVABLE.
- */
- if (unlikely(__folio_test_movable(folio))) {
+ if (unlikely(page_has_movable_ops(&folio->page))) {
putback_movable_ops_page(&folio->page);
} else {
node_stat_mod_folio(folio, NR_ISOLATED_ANON +
@@ -237,26 +232,20 @@ void putback_movable_pages(struct list_head *l)
/* Must be called with an elevated refcount on the non-hugetlb folio */
bool isolate_folio_to_list(struct folio *folio, struct list_head *list)
{
- bool isolated, lru;
-
if (folio_test_hugetlb(folio))
return folio_isolate_hugetlb(folio, list);

- lru = !__folio_test_movable(folio);
- if (lru)
- isolated = folio_isolate_lru(folio);
- else
- isolated = isolate_movable_ops_page(&folio->page,
- ISOLATE_UNEVICTABLE);
-
- if (!isolated)
- return false;
-
- list_add(&folio->lru, list);
- if (lru)
+ if (page_has_movable_ops(&folio->page)) {
+ if (!isolate_movable_ops_page(&folio->page,
+ ISOLATE_UNEVICTABLE))
+ return false;
+ } else {
+ if (!folio_isolate_lru(folio))
+ return false;
node_stat_add_folio(folio, NR_ISOLATED_ANON +
folio_is_file_lru(folio));
-
+ }
+ list_add(&folio->lru, list);
return true;
}

@@ -1140,12 +1129,7 @@ static void migrate_folio_undo_dst(struct folio *dst, bool locked,
static void migrate_folio_done(struct folio *src,
enum migrate_reason reason)
{
- /*
- * Compaction can migrate also non-LRU pages which are
- * not accounted to NR_ISOLATED_*. They can be recognized
- * as __folio_test_movable
- */
- if (likely(!__folio_test_movable(src)) && reason != MR_DEMOTION)
+ if (likely(!page_has_movable_ops(&src->page)) && reason != MR_DEMOTION)
mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON +
folio_is_file_lru(src), -folio_nr_pages(src));

@@ -1164,7 +1148,6 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
int rc = -EAGAIN;
int old_page_state = 0;
struct anon_vma *anon_vma = NULL;
- bool is_lru = data_race(!__folio_test_movable(src));
bool locked = false;
bool dst_locked = false;

@@ -1265,7 +1248,7 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
goto out;
dst_locked = true;

- if (unlikely(!is_lru)) {
+ if (unlikely(page_has_movable_ops(&src->page))) {
__migrate_folio_record(dst, old_page_state, anon_vma);
return MIGRATEPAGE_UNMAP;
}
@@ -1330,7 +1313,7 @@ static int migrate_folio_move(free_folio_t put_new_folio, unsigned long private,
prev = dst->lru.prev;
list_del(&dst->lru);

- if (unlikely(__folio_test_movable(src))) {
+ if (unlikely(page_has_movable_ops(&src->page))) {
rc = migrate_movable_ops_page(&dst->page, &src->page, mode);
if (rc)
goto out;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 098bcc821fc74..103dfc729a823 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1658,9 +1658,11 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone,
unsigned int noreclaim_flag;

list_for_each_entry_safe(folio, next, folio_list, lru) {
+ /* TODO: these pages should not even appear in this list. */
+ if (page_has_movable_ops(&folio->page))
+ continue;
if (!folio_test_hugetlb(folio) && folio_is_file_lru(folio) &&
- !folio_test_dirty(folio) && !__folio_test_movable(folio) &&
- !folio_test_unevictable(folio)) {
+ !folio_test_dirty(folio) && !folio_test_unevictable(folio)) {
folio_clear_active(folio);
list_move(&folio->lru, &clean_folios);
}
--
2.49.0