[PATCH v3 15/24] mm/balloon_compaction: move internal helpers to balloon_compaction.c

[David Hildenbrand (Red Hat)]

On 1/20/26 00:01, David Hildenbrand (Red Hat) wrote:
> Let's move the helpers that are not required by drivers anymore.
> 
> While at it, drop the doc of balloon_page_device() as it is trivial.
> 
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes at oracle.com>
> Acked-by: Michael S. Tsirkin <mst at redhat.com>
> Signed-off-by: David Hildenbrand (Red Hat) <david at kernel.org>
> ---
>   include/linux/balloon_compaction.h | 44 ------------------------------
>   mm/balloon_compaction.c            | 38 ++++++++++++++++++++++++++
>   2 files changed, 38 insertions(+), 44 deletions(-)
> 
> diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h
> index d1d4739398978..eec8994056a44 100644
> --- a/include/linux/balloon_compaction.h
> +++ b/include/linux/balloon_compaction.h
> @@ -75,48 +75,4 @@ static inline void balloon_devinfo_init(struct balloon_dev_info *balloon)
>   	balloon->migratepage = NULL;
>   	balloon->adjust_managed_page_count = false;
>   }
> -
> -#ifdef CONFIG_BALLOON_COMPACTION
> -/*
> - * balloon_page_device - get the b_dev_info descriptor for the balloon device
> - *			 that enqueues the given page.
> - */
> -static inline struct balloon_dev_info *balloon_page_device(struct page *page)
> -{
> -	return (struct balloon_dev_info *)page_private(page);
> -}
> -#endif /* CONFIG_BALLOON_COMPACTION */
> -
> -/*
> - * balloon_page_insert - insert a page into the balloon's page list and make
> - *			 the page->private assignment accordingly.
> - * @balloon : pointer to balloon device
> - * @page    : page to be assigned as a 'balloon page'
> - *
> - * Caller must ensure the balloon_pages_lock is held.
> - */
> -static inline void balloon_page_insert(struct balloon_dev_info *balloon,
> -				       struct page *page)
> -{
> -	__SetPageOffline(page);
> -	if (IS_ENABLED(CONFIG_BALLOON_COMPACTION)) {
> -		SetPageMovableOps(page);
> -		set_page_private(page, (unsigned long)balloon);
> -	}
> -	list_add(&page->lru, &balloon->pages);
> -}
> -
> -/*
> - * balloon_page_finalize - prepare a balloon page that was removed from the
> - *			   balloon list for release to the page allocator
> - * @page: page to be released to the page allocator
> - *
> - * Caller must ensure the balloon_pages_lock is held.
> - */
> -static inline void balloon_page_finalize(struct page *page)
> -{
> -	if (IS_ENABLED(CONFIG_BALLOON_COMPACTION))
> -		set_page_private(page, 0);
> -	/* PageOffline is sticky until the page is freed to the buddy. */
> -}
>   #endif /* _LINUX_BALLOON_COMPACTION_H */
> diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
> index 1843e168db3ca..e0a4b481c3eda 100644
> --- a/mm/balloon_compaction.c
> +++ b/mm/balloon_compaction.c
> @@ -17,6 +17,44 @@
>    */
>   static DEFINE_SPINLOCK(balloon_pages_lock);
>   
> +static struct balloon_dev_info *balloon_page_device(struct page *page)
> +{
> +	return (struct balloon_dev_info *)page_private(page);
> +}
> +
> +/*
> + * balloon_page_insert - insert a page into the balloon's page list and make
> + *			 the page->private assignment accordingly.
> + * @balloon : pointer to balloon device
> + * @page    : page to be assigned as a 'balloon page'
> + *
> + * Caller must ensure the balloon_pages_lock is held.
> + */
> +static void balloon_page_insert(struct balloon_dev_info *balloon,
> +				       struct page *page)
> +{
> +	__SetPageOffline(page);
> +	if (IS_ENABLED(CONFIG_BALLOON_COMPACTION)) {
> +		SetPageMovableOps(page);
> +		set_page_private(page, (unsigned long)balloon);
> +	}
> +	list_add(&page->lru, &balloon->pages);
> +}
> +
> +/*
> + * balloon_page_finalize - prepare a balloon page that was removed from the
> + *			   balloon list for release to the page allocator
> + * @page: page to be released to the page allocator
> + *
> + * Caller must ensure the balloon_pages_lock is held.
> + */
> +static void balloon_page_finalize(struct page *page)
> +{
> +	if (IS_ENABLED(CONFIG_BALLOON_COMPACTION))
> +		set_page_private(page, 0);
> +	/* PageOffline is sticky until the page is freed to the buddy. */
> +}
> +
>   static void balloon_page_enqueue_one(struct balloon_dev_info *b_dev_info,
>   				     struct page *page)
>   {

The following on top to silence [1]. Results in two contextual conflicts
in later patches which is easy to resolve. As an alternative, we could throw in a
__maybe_unused but this is cleaner.

[1] https://lkml.kernel.org/r/202601201338.4muFmFHV-lkp@intel.com


 From a02a0de0670a6be9a34d06eea3ba41297ce547dc Mon Sep 17 00:00:00 2001
From: "David Hildenbrand (Red Hat)" <david at kernel.org>
Date: Tue, 20 Jan 2026 07:37:39 +0100
Subject: [PATCH] fixup: mm/balloon_compaction: move internal helpers to
  balloon_compaction.c

Move balloon_page_device() under CONFIG_BALLOON_COMPACTION.

Reported-by: kernel test robot <lkp at intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202601201338.4muFmFHV-lkp@intel.com/
Signed-off-by: David Hildenbrand (Red Hat) <david at kernel.org>
---
  mm/balloon_compaction.c | 9 ++++-----
  1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index e0a4b481c3eda..30fa7ee8e1f3a 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -17,11 +17,6 @@
   */
  static DEFINE_SPINLOCK(balloon_pages_lock);
  
-static struct balloon_dev_info *balloon_page_device(struct page *page)
-{
-	return (struct balloon_dev_info *)page_private(page);
-}
-
  /*
   * balloon_page_insert - insert a page into the balloon's page list and make
   *			 the page->private assignment accordingly.
@@ -232,6 +227,10 @@ struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info)
  EXPORT_SYMBOL_GPL(balloon_page_dequeue);
  
  #ifdef CONFIG_BALLOON_COMPACTION
+static struct balloon_dev_info *balloon_page_device(struct page *page)
+{
+	return (struct balloon_dev_info *)page_private(page);
+}
  
  static bool balloon_page_isolate(struct page *page, isolate_mode_t mode)
  
-- 
2.52.0


-- 
Cheers

David