+
+ /*
+ * If the page isn't exclusively mapped into this vma,
+ * we must use the _oldest_ possible anon_vma for the
+ * page mapping!
+ *
+ * So take the last AVC chain entry in the vma, which is
+ * the deepest ancestor, and use the anon_vma from that.
+ */
+ if (!exclusive) {
+ struct anon_vma_chain *avc;
+ avc = list_entry(vma->anon_vma_chain.prev, struct anon_vma_chain, same_vma);
+ anon_vma = avc->anon_vma;
+ }
+