linux-kernel - Re: [PATCH RFC 16/29] mm: rename __PageMovable() to page_has_movable

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Message-ID: <DAA0D876-D5A4-4E54-9BD3-363E34D8B3F3@nvidia.com>
Date: Fri, 20 Jun 2025 16:37:07 -0400
From: Zi Yan <ziy@...dia.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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 Shakeel Butt <shakeel.butt@...ux.dev>
Subject: Re: [PATCH RFC 16/29] mm: rename __PageMovable() to
 page_has_movable_ops()

On 18 Jun 2025, at 13:39, David Hildenbrand wrote:

> Let's make it clearer that we are talking about movable_ops pages.
>
> Signed-off-by: David Hildenbrand <david@...hat.com>
> ---
>  include/linux/migrate.h    |  2 +-
>  include/linux/page-flags.h |  2 +-
>  mm/compaction.c            |  7 ++-----
>  mm/memory-failure.c        |  4 ++--
>  mm/memory_hotplug.c        |  8 +++-----
>  mm/migrate.c               |  8 ++++----
>  mm/page_alloc.c            |  2 +-
>  mm/page_isolation.c        | 10 +++++-----
>  8 files changed, 19 insertions(+), 24 deletions(-)
>
> diff --git a/include/linux/migrate.h b/include/linux/migrate.h
> index 204e89eac998f..c575778456f97 100644
> --- a/include/linux/migrate.h
> +++ b/include/linux/migrate.h
> @@ -115,7 +115,7 @@ static inline void __SetPageMovable(struct page *page,
>  static inline
>  const struct movable_operations *page_movable_ops(struct page *page)
>  {
> -	VM_BUG_ON(!__PageMovable(page));
> +	VM_BUG_ON(!page_has_movable_ops(page));
>
>  	return (const struct movable_operations *)
>  		((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE);
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index 4fe5ee67535b2..c67163b73c5ec 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -750,7 +750,7 @@ static __always_inline bool __folio_test_movable(const struct folio *folio)
>  			PAGE_MAPPING_MOVABLE;
>  }
>
> -static __always_inline bool __PageMovable(const struct page *page)
> +static __always_inline bool page_has_movable_ops(const struct page *page)
>  {
>  	return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
>  				PAGE_MAPPING_MOVABLE;
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 5c37373017014..f8b7c09e2e48c 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -1056,11 +1056,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
>  		 * Skip any other type of page
>  		 */
>  		if (!PageLRU(page)) {
> -			/*
> -			 * __PageMovable can return false positive so we need
> -			 * to verify it under page_lock.
> -			 */
> -			if (unlikely(__PageMovable(page)) &&
> +			/* Isolation will grab the page lock. */

I feel that the removed comment should stay, since the current comment
makes no sense when I read it alone.

In addition, why is __PageMovable() is renamed to page_has_movable_ops() but
__SetPageMovable() stays the same? page_has_movable_ops() and __SetPageMovable()
are functions for checking and setting PAGE_MAPPING_MOVABLE. The naming just
does not look symmetric.

--
Best Regards,
Yan, Zi