- Simplify pipespace() by eliminating the explicit creation of vm objects.

Instead, let the vm objects be lazily instantiated at fault time.  This
   results in the allocation of fewer vm objects and vm map entries due to
   aggregation in the vm system.

sys/kern/sys_pipe.c

@@ -311,9 +311,8 @@ pipespace(cpipe, size)
 	struct pipe *cpipe;
 	int size;
 {
-	struct vm_object *object;
 	caddr_t buffer;
-	int npages, error;
+	int error;
 	static int curfail = 0;
 	static struct timeval lastfail;
 
@@ -321,26 +320,19 @@ pipespace(cpipe, size)
 	       ("pipespace: pipe mutex locked"));
 
 	size = round_page(size);
-	npages = size / PAGE_SIZE;
 	/*
-	 * Create an object, I don't like the idea of paging to/from
-	 * kernel_object.
 	 * XXX -- minor change needed here for NetBSD/OpenBSD VM systems.
 	 */
-	object = vm_object_allocate(OBJT_DEFAULT, npages);
 	buffer = (caddr_t) vm_map_min(pipe_map);
 
 	/*
-	 * Insert the object into the kernel map, and allocate kva for it.
 	 * The map entry is, by default, pageable.
 	 * XXX -- minor change needed here for NetBSD/OpenBSD VM systems.
 	 */
-	error = vm_map_find(pipe_map, object, 0,
+	error = vm_map_find(pipe_map, NULL, 0,
 		(vm_offset_t *) &buffer, size, 1,
 		VM_PROT_ALL, VM_PROT_ALL, 0);
-
 	if (error != KERN_SUCCESS) {
-		vm_object_deallocate(object);
 		if (ppsratecheck(&lastfail, &curfail, 1))
 			printf("kern.maxpipekva exceeded, please see tuning(7).\n");
 		return (ENOMEM);