On Thu, Aug 28, 2025 at 12:01:14AM +0200, David Hildenbrand wrote:
> Let's sanity-check in folio_set_order() whether we would be trying to
> create a folio with an order that would make it exceed MAX_FOLIO_ORDER.
>
> This will enable the check whenever a folio/compound page is initialized
> through prepare_compound_head() / prepare_compound_page().
NIT: with CONFIG_DEBUG_VM set :)
>
> Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
LGTM (apart from nit below), so:
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
> ---
> mm/internal.h | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/mm/internal.h b/mm/internal.h
> index 45da9ff5694f6..9b0129531d004 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -755,6 +755,7 @@ static inline void folio_set_order(struct folio *folio, unsigned int order)
> {
> if (WARN_ON_ONCE(!order || !folio_test_large(folio)))
> return;
> + VM_WARN_ON_ONCE(order > MAX_FOLIO_ORDER);
Given we have 'full-fat' WARN_ON*()'s above, maybe worth making this one too?
>
> folio->_flags_1 = (folio->_flags_1 & ~0xffUL) | order;
> #ifdef NR_PAGES_IN_LARGE_FOLIO
> --
> 2.50.1
>
