[PATCH] mempolicy optimisation

Some optimizations in mempolicy.c (like to avoid rebalancing the tree while
destroying it and by breaking loops early and not checking for invariant
conditions in the replace operation).
Signed-off-by: Andrea Arcangeli <andrea@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

mm/mempolicy.c

@@ -1028,12 +1028,10 @@ static int shared_policy_replace(struct shared_policy *sp, unsigned long start,
 						return -ENOMEM;
 					goto restart;
 				}
-				n->end = end;
+				n->end = start;
 				sp_insert(sp, new2);
-				new2 = NULL;
-			}
-			/* Old crossing beginning, but not end (easy) */
-			if (n->start < start && n->end > start)
+				break;
+			} else
 				n->end = start;
 		}
 		if (!next)
@@ -1086,11 +1084,11 @@ void mpol_free_shared_policy(struct shared_policy *p)
 	while (next) {
 		n = rb_entry(next, struct sp_node, nd);
 		next = rb_next(&n->nd);
-		rb_erase(&n->nd, &p->root);
 		mpol_free(n->policy);
 		kmem_cache_free(sn_cache, n);
 	}
 	spin_unlock(&p->lock);
+	p->root = RB_ROOT;
 }
 
 /* assumes fs == KERNEL_DS */