+#ifdef CONFIG_UNEVICTABLE_LRU
+#define AS_UNEVICTABLE (__GFP_BITS_SHIFT + 2) /* e.g., ramdisk, SHM_LOCK */
+
+static inline void mapping_set_unevictable(struct address_space *mapping)
+{
+ set_bit(AS_UNEVICTABLE, &mapping->flags);
+}
+
+static inline void mapping_clear_unevictable(struct address_space *mapping)
+{
+ clear_bit(AS_UNEVICTABLE, &mapping->flags);
+}
+
+static inline int mapping_unevictable(struct address_space *mapping)
+{
+ if (likely(mapping))
+ return test_bit(AS_UNEVICTABLE, &mapping->flags);
+ return !!mapping;
+}
+#else
+static inline void mapping_set_unevictable(struct address_space *mapping) { }
+static inline void mapping_clear_unevictable(struct address_space *mapping) { }
+static inline int mapping_unevictable(struct address_space *mapping)
+{
+ return 0;
+}
+#endif
+