+#ifdef CONFIG_WANT_PAGE_DEBUG_FLAGS
+ unsigned long debug_flags; /* Use atomic bitops on this */
+#endif
+
+#ifdef CONFIG_KMEMCHECK
+ /*
+ * kmemcheck wants to track the status of each byte in a page; this
+ * is a pointer to such a status block. NULL if not tracked.
+ */
+ void *shadow;
+#endif
+};
+
+/*
+ * A region containing a mapping of a non-memory backed file under NOMMU
+ * conditions. These are held in a global tree and are pinned by the VMAs that
+ * map parts of them.
+ */
+struct vm_region {
+ struct rb_node vm_rb; /* link in global region tree */
+ unsigned long vm_flags; /* VMA vm_flags */
+ unsigned long vm_start; /* start address of region */
+ unsigned long vm_end; /* region initialised to here */
+ unsigned long vm_top; /* region allocated to here */
+ unsigned long vm_pgoff; /* the offset in vm_file corresponding to vm_start */
+ struct file *vm_file; /* the backing file or NULL */
+
+ atomic_t vm_usage; /* region usage count */