-#define __swp_type(x) (((x).val >> 1) & 0x3f)
-#define __swp_offset(x) ((x).val >> 8)
-#define __swp_entry(type, offset) ((swp_entry_t) { ((type) << 1) | \
- ((offset) << 8) })
+#if _PAGE_BIT_FILE < _PAGE_BIT_PROTNONE
+#define SWP_TYPE_BITS (_PAGE_BIT_FILE - _PAGE_BIT_PRESENT - 1)
+#define SWP_OFFSET_SHIFT (_PAGE_BIT_PROTNONE + 1)
+#else
+#define SWP_TYPE_BITS (_PAGE_BIT_PROTNONE - _PAGE_BIT_PRESENT - 1)
+#define SWP_OFFSET_SHIFT (_PAGE_BIT_FILE + 1)
+#endif
+
+#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > SWP_TYPE_BITS)
+
+#define __swp_type(x) (((x).val >> (_PAGE_BIT_PRESENT + 1)) \
+ & ((1U << SWP_TYPE_BITS) - 1))
+#define __swp_offset(x) ((x).val >> SWP_OFFSET_SHIFT)
+#define __swp_entry(type, offset) ((swp_entry_t) { \
+ ((type) << (_PAGE_BIT_PRESENT + 1)) \
+ | ((offset) << SWP_OFFSET_SHIFT) })