[PATCH v1 15/29] mm/migration: remove PageMovable()

David Hildenbrand
2025-06-30T13:01:02Z

As __ClearPageMovable() is gone that would have only made
PageMovable()==false but still __PageMovable()==true, now
PageMovable() == __PageMovable().

So we can replace PageMovable() checks by __PageMovable(). In fact,
__PageMovable() cannot change until a page is freed, so we can turn
some PageMovable() into sanity checks for __PageMovable().

Reviewed-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
include/linux/migrate.h | 2 --
mm/compaction.c | 15 ---------------
mm/migrate.c | 18 ++++++++++--------
3 files changed, 10 insertions(+), 25 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 6eeda8eb1e0d8..25659a685e2aa 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -104,10 +104,8 @@ static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
#endif /* CONFIG_MIGRATION */

#ifdef CONFIG_COMPACTION
-bool PageMovable(struct page *page);
void __SetPageMovable(struct page *page, const struct movable_operations *ops);
#else
-static inline bool PageMovable(struct page *page) { return false; }
static inline void __SetPageMovable(struct page *page,
const struct movable_operations *ops)
{
diff --git a/mm/compaction.c b/mm/compaction.c
index 889ec696ba96a..5c37373017014 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -114,21 +114,6 @@ static unsigned long release_free_list(struct list_head *freepages)
}

#ifdef CONFIG_COMPACTION
-bool PageMovable(struct page *page)
-{
- const struct movable_operations *mops;
-
- VM_BUG_ON_PAGE(!PageLocked(page), page);
- if (!__PageMovable(page))
- return false;
-
- mops = page_movable_ops(page);
- if (mops)
- return true;
-
- return false;
-}
-
void __SetPageMovable(struct page *page, const struct movable_operations *mops)
{
VM_BUG_ON_PAGE(!PageLocked(page), page);
diff --git a/mm/migrate.c b/mm/migrate.c
index 22c115710d0e2..040484230aebc 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -87,9 +87,12 @@ bool isolate_movable_ops_page(struct page *page, isolate_mode_t mode)
goto out;

/*
- * Check movable flag before taking the page lock because
+ * Check for movable_ops pages before taking the page lock because
* we use non-atomic bitops on newly allocated page flags so
* unconditionally grabbing the lock ruins page's owner side.
+ *
+ * Note that once a page has movable_ops, it will stay that way
+ * until the page was freed.
*/
if (unlikely(!__PageMovable(page)))
goto out_putfolio;
@@ -108,7 +111,8 @@ bool isolate_movable_ops_page(struct page *page, isolate_mode_t mode)
if (unlikely(!folio_trylock(folio)))
goto out_putfolio;

- if (!PageMovable(page) || PageIsolated(page))
+ VM_WARN_ON_ONCE_PAGE(!__PageMovable(page), page);
+ if (PageIsolated(page))
goto out_no_isolated;

mops = page_movable_ops(page);
@@ -149,11 +153,10 @@ static void putback_movable_ops_page(struct page *page)
*/
struct folio *folio = page_folio(page);

+ VM_WARN_ON_ONCE_PAGE(!__PageMovable(page), page);
VM_WARN_ON_ONCE_PAGE(!PageIsolated(page), page);
folio_lock(folio);
- /* If the page was released by it's owner, there is nothing to do. */
- if (PageMovable(page))
- page_movable_ops(page)->putback_page(page);
+ page_movable_ops(page)->putback_page(page);
ClearPageIsolated(page);
folio_unlock(folio);
folio_put(folio);
@@ -189,10 +192,9 @@ static int migrate_movable_ops_page(struct page *dst, struct page *src,
{
int rc = MIGRATEPAGE_SUCCESS;

+ VM_WARN_ON_ONCE_PAGE(!__PageMovable(src), src);
VM_WARN_ON_ONCE_PAGE(!PageIsolated(src), src);
- /* If the page was released by it's owner, there is nothing to do. */
- if (PageMovable(src))
- rc = page_movable_ops(src)->migrate_page(dst, src, mode);
+ rc = page_movable_ops(src)->migrate_page(dst, src, mode);
if (rc == MIGRATEPAGE_SUCCESS)
ClearPageIsolated(src);
return rc;
--
2.49.0