[PATCH RFC 11/35] mm: sanity-check maximum folio size in folio_set_order()

David Hildenbrand
2025-08-21T20:08:06Z

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().

Signed-off-by: David Hildenbrand <david@redhat.com>
---
mm/internal.h | 1 +
1 file changed, 1 insertion(+)

diff --git a/mm/internal.h b/mm/internal.h
index 45b725c3dc030..946ce97036d67 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);

folio->_flags_1 = (folio->_flags_1 & ~0xffUL) | order;
#ifdef NR_PAGES_IN_LARGE_FOLIO
--
2.50.1