[PATCH v2 10/37] mm: sanity-check maximum folio size in folio_set_order()

[David Hildenbrand]

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() with
CONFIG_DEBUG_VM set.

Reviewed-by: Zi Yan <ziy at nvidia.com>
Reviewed-by: Wei Yang <richard.weiyang at gmail.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes at oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett at oracle.com>
Signed-off-by: David Hildenbrand <david at redhat.com>
---
 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);
 
 	folio->_flags_1 = (folio->_flags_1 & ~0xffUL) | order;
 #ifdef NR_PAGES_IN_LARGE_FOLIO
-- 
2.50.1