Re: [PATCH v1 14/29] mm/migrate: remove __ClearPageMovable()

Lorenzo Stoakes
2025-07-01T10:45:20Z

On Mon, Jun 30, 2025 at 02:59:55PM +0200, David Hildenbrand wrote:
> Unused, let's remove it.
>
> The Chinese docs in Documentation/translations/zh_CN/mm/page_migration.rst
> still mention it, but that whole docs is destined to get outdated and
> updated by somebody that actually speaks that language.

Yeah I've noticed these getting out of sync before, perhaps somebody fluent in
Simplified Chinese can assist at some point :) mine is rather rusty...

>
> Reviewed-by: Zi Yan <ziy@nvidia.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>

Lovely! The best code is no code :>)

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

> ---
> include/linux/migrate.h | 8 ++------
> mm/compaction.c | 11 -----------
> 2 files changed, 2 insertions(+), 17 deletions(-)
>
> diff --git a/include/linux/migrate.h b/include/linux/migrate.h
> index c99a00d4ca27d..6eeda8eb1e0d8 100644
> --- a/include/linux/migrate.h
> +++ b/include/linux/migrate.h
> @@ -35,8 +35,8 @@ struct migration_target_control;
> * @src page. The driver should copy the contents of the
> * @src page to the @dst page and set up the fields of @dst page.
> * Both pages are locked.
> - * If page migration is successful, the driver should call
> - * __ClearPageMovable(@src) and return MIGRATEPAGE_SUCCESS.
> + * If page migration is successful, the driver should
> + * return MIGRATEPAGE_SUCCESS.
> * If the driver cannot migrate the page at the moment, it can return
> * -EAGAIN. The VM interprets this as a temporary migration failure and
> * will retry it later. Any other error value is a permanent migration
> @@ -106,16 +106,12 @@ static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
> #ifdef CONFIG_COMPACTION
> bool PageMovable(struct page *page);
> void __SetPageMovable(struct page *page, const struct movable_operations *ops);
> -void __ClearPageMovable(struct page *page);
> #else
> static inline bool PageMovable(struct page *page) { return false; }
> static inline void __SetPageMovable(struct page *page,
> const struct movable_operations *ops)
> {
> }
> -static inline void __ClearPageMovable(struct page *page)
> -{
> -}
> #endif
>
> static inline
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 17455c5a4be05..889ec696ba96a 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -137,17 +137,6 @@ void __SetPageMovable(struct page *page, const struct movable_operations *mops)
> }
> EXPORT_SYMBOL(__SetPageMovable);
>
> -void __ClearPageMovable(struct page *page)
> -{
> - VM_BUG_ON_PAGE(!PageMovable(page), page);
> - /*
> - * This page still has the type of a movable page, but it's
> - * actually not movable any more.
> - */
> - page->mapping = (void *)PAGE_MAPPING_MOVABLE;
> -}
> -EXPORT_SYMBOL(__ClearPageMovable);
> -
> /* Do not skip compaction more than 64 times */
> #define COMPACT_MAX_DEFER_SHIFT 6
>
> --
> 2.49.0
>