linux-kernel - Re: [PATCH v1 14/29] mm/migrate: remove _

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Message-ID: <24d2b984-857d-4a11-b016-dc0227d81c88@lucifer.local>
Date: Tue, 1 Jul 2025 11:43:45 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: David Hildenbrand <david@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-doc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
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Subject: Re: [PATCH v1 14/29] mm/migrate: remove __ClearPageMovable()

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 still mention it, but that whole docs is destined to get outdated and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@...dia.com>
> Signed-off-by: David Hildenbrand <david@...hat.com>

Lovely! The best code is no code :>)

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