*/
atomic_t refcount;
+ /*
+ * Count of child anon_vmas and VMAs which points to this anon_vma.
+ *
+ * This counter is used for making decision about reusing anon_vma
+ * instead of forking new one. See comments in function anon_vma_clone.
+ */
+ unsigned degree;
+
+ struct anon_vma *parent; /* Parent of this anon_vma */
+
/*
* NOTE: the LSB of the rb_root.rb_node is set by
* mm_take_all_locks() _after_ taking the above lock. So the