[PATCH v2 15/23] mm/balloon_compaction: assert that the balloon_pages_lock is held

[Lorenzo Stoakes]

On Thu, Jan 15, 2026 at 10:20:05AM +0100, David Hildenbrand (Red Hat) wrote:
> Let's add some sanity checks for holding the balloon_pages_lock when
> we're effectively inflating/deflating a page.
>
> Signed-off-by: David Hildenbrand (Red Hat) <david at kernel.org>

Seems reasonable to me, so:

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

> ---
>  mm/balloon_compaction.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
> index 717bc43732d09..f6e0582bd7ffe 100644
> --- a/mm/balloon_compaction.c
> +++ b/mm/balloon_compaction.c
> @@ -33,6 +33,7 @@ static inline struct balloon_dev_info *balloon_page_device(struct page *page)
>  static inline void balloon_page_insert(struct balloon_dev_info *balloon,
>  				       struct page *page)
>  {
> +	lockdep_assert_held(&balloon_pages_lock);
>  	__SetPageOffline(page);
>  	if (IS_ENABLED(CONFIG_BALLOON_COMPACTION)) {
>  		SetPageMovableOps(page);
> @@ -50,6 +51,7 @@ static inline void balloon_page_insert(struct balloon_dev_info *balloon,
>   */
>  static inline void balloon_page_finalize(struct page *page)
>  {
> +	lockdep_assert_held(&balloon_pages_lock);
>  	if (IS_ENABLED(CONFIG_BALLOON_COMPACTION))
>  		set_page_private(page, 0);
>  	/* PageOffline is sticky until the page is freed to the buddy. */
> --
> 2.52.0
>