Ram Pai [off-list ref] writes:
 +

+#define mm_set_pkey_is_allocated(mm, pkey)	\
+	(mm_pkey_allocation_map(mm) & pkey_alloc_mask(pkey))
+

 static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
 {
-	return (pkey == 0);
+	/* a reserved key is never considered as 'explicitly allocated' */
+	return ((pkey < arch_max_pkey()) &&
+		!mm_set_pkey_is_reserved(mm, pkey) &&
+		mm_set_pkey_is_allocated(mm, pkey));
 }

that is confusing naming. what is mm_set_pkey_is_allocated()? . 'set' in
that name is confusing.

-aneesh