Index: sys/vm/vm_map.c
===================================================================
--- sys/vm/vm_map.c
+++ sys/vm/vm_map.c
@@ -796,13 +796,14 @@
 {
 
 	map->header.next = map->header.prev = &map->header;
+	map->header.left = map->header.right = NULL;
 	map->needs_wakeup = FALSE;
 	map->system_map = 0;
 	map->pmap = pmap;
 	map->min_offset = min;
 	map->max_offset = max;
 	map->flags = 0;
-	map->root = NULL;
+	map->root = &map->header;
 	map->timestamp = 0;
 	map->busy = 0;
 }
@@ -900,10 +901,6 @@
 	vm_map_entry_t ltree, rtree;
 	vm_map_entry_t y;
 
-	/* Special case of empty tree. */
-	if (root == NULL)
-		return (root);
-
 	/*
 	 * Pass One: Splay down the tree until we find addr or a NULL
 	 * pointer where addr would go.  llist and rlist are the two
@@ -914,31 +911,11 @@
 	 */
 	llist = NULL;
 	rlist = NULL;
-	for (;;) {
+	do {
 		/* root is never NULL in here. */
-		if (addr < root->start) {
-			y = root->left;
-			if (y == NULL)
-				break;
-			if (addr < y->start && y->left != NULL) {
-				/* Rotate right and put y on rlist. */
-				root->left = y->right;
-				y->right = root;
-				vm_map_entry_set_max_free(root);
-				root = y->left;
-				y->left = rlist;
-				rlist = y;
-			} else {
-				/* Put root on rlist. */
-				root->left = rlist;
-				rlist = root;
-				root = y;
-			}
-		} else if (addr >= root->end) {
+		if (addr >= root->end) {
 			y = root->right;
-			if (y == NULL)
-				break;
-			if (addr >= y->end && y->right != NULL) {
+			if (y != NULL && addr >= y->end) {
 				/* Rotate left and put y on llist. */
 				root->right = y->left;
 				y->left = root;
@@ -952,8 +929,46 @@
 				llist = root;
 				root = y;
 			}
+		} else if (addr < root->start) {
+			y = root->left;
+			if (y != NULL && addr < y->start) {
+				/* Rotate right and put y on rlist. */
+				root->left = y->right;
+				y->right = root;
+				vm_map_entry_set_max_free(root);
+				root = y->left;
+				y->left = rlist;
+				rlist = y;
+			} else {
+				/* Put root on rlist. */
+				root->left = rlist;
+				rlist = root;
+				root = y;
+			}
 		} else
 			break;
+	} while (root != NULL);
+
+	if (root == NULL) {
+		/*
+		 * With no matching node found, recover the greatest
+		 * node in the left subtree and make it the root.
+		 * There is such a node, since map->header is in the
+		 * tree and left of all addresses.
+		 */
+		if (llist != NULL) {
+			root = llist;
+			llist = root->right;
+			root->right = NULL;
+		} else {
+			/* addr must lie below the range defined by
+			 * map->header, so recover the map->header
+			 * from the right tree instead.
+			 */
+			root = rlist;
+			rlist = root->left;
+			root->left = NULL;
+		}
 	}
 
 	/*
@@ -1016,18 +1031,13 @@
 	entry->next->prev = entry;
 	after_where->next = entry;
 
-	if (after_where != &map->header) {
-		if (after_where != map->root)
-			vm_map_entry_splay(after_where->start, map->root);
-		entry->right = after_where->right;
-		entry->left = after_where;
-		after_where->right = NULL;
-		after_where->adj_free = entry->start - after_where->end;
-		vm_map_entry_set_max_free(after_where);
-	} else {
-		entry->right = map->root;
-		entry->left = NULL;
-	}
+	if (after_where != map->root)
+		vm_map_entry_splay(after_where->start, map->root);
+	entry->right = after_where->right;
+	entry->left = after_where;
+	after_where->right = NULL;
+	after_where->adj_free = entry->start - after_where->end;
+	vm_map_entry_set_max_free(after_where);
 	entry->adj_free = entry->next->start - entry->end;
 	vm_map_entry_set_max_free(entry);
 	map->root = entry;
@@ -1042,14 +1052,10 @@
 	VM_MAP_ASSERT_LOCKED(map);
 	if (entry != map->root)
 		vm_map_entry_splay(entry->start, map->root);
-	if (entry->left == NULL)
-		root = entry->right;
-	else {
-		root = vm_map_entry_splay(entry->start, entry->left);
-		root->right = entry->right;
-		root->adj_free = entry->next->start - root->end;
-		vm_map_entry_set_max_free(root);
-	}
+	root = vm_map_entry_splay(entry->start, entry->left);
+	root->right = entry->right;
+	root->adj_free = entry->next->start - root->end;
+	vm_map_entry_set_max_free(root);
 	map->root = root;
 
 	prev = entry->prev;
@@ -1111,13 +1117,11 @@
 	 * "address" is the map's header.
 	 */
 	cur = map->root;
-	if (cur == NULL)
-		*entry = &map->header;
-	else if (address >= cur->start && cur->end > address) {
+	if (address >= cur->start && cur->end > address) {
 		*entry = cur;
 		return (TRUE);
-	} else if ((locked = vm_map_locked(map)) ||
-	    sx_try_upgrade(&map->lock)) {
+	}
+	if ((locked = vm_map_locked(map)) || sx_try_upgrade(&map->lock)) {
 		/*
 		 * Splay requires a write lock on the map.  However, it only
 		 * restructures the binary search tree; it does not otherwise
@@ -1128,40 +1132,25 @@
 		if (!locked)
 			sx_downgrade(&map->lock);
 
-		/*
-		 * If "address" is contained within a map entry, the new root
-		 * is that map entry.  Otherwise, the new root is a map entry
-		 * immediately before or after "address".
-		 */
-		if (address >= cur->start) {
-			*entry = cur;
-			if (cur->end > address)
-				return (TRUE);
-		} else
-			*entry = cur->prev;
+		*entry = cur;
+		if (cur->end > address)
+			return (TRUE);
 	} else
 		/*
 		 * Since the map is only locked for read access, perform a
 		 * standard binary search tree lookup for "address".
 		 */
-		for (;;) {
-			if (address < cur->start) {
-				if (cur->left == NULL) {
-					*entry = cur->prev;
-					break;
-				}
+		do {
+			if (cur->end <= address) {
+				*entry = cur;
+				cur = cur->right;
+			} else if (address < cur->start) {
 				cur = cur->left;
-			} else if (cur->end > address) {
+			} else {
 				*entry = cur;
 				return (TRUE);
-			} else {
-				if (cur->right == NULL) {
-					*entry = cur;
-					break;
-				}
-				cur = cur->right;
 			}
-		}
+		} while (cur != NULL);
 	return (FALSE);
 }
 
@@ -1410,20 +1399,11 @@
 	}
 
 	/*
-	 * After splay, if start comes before root node, then there
-	 * must be a gap from start to the root.
-	 */
-	map->root = vm_map_entry_splay(start, map->root);
-	if (start + length <= map->root->start) {
-		*addr = start;
-		return (0);
-	}
-
-	/*
 	 * Root is the last node that might begin its gap before
 	 * start, and this is the last comparison where address
 	 * wrap might be a problem.
 	 */
+	map->root = vm_map_entry_splay(start, map->root);
 	st = (start > map->root->end) ? start : map->root->end;
 	if (length <= map->root->end + map->root->adj_free - st) {
 		*addr = st;