diff -ru /usr/src/sys.old/kern/kern_malloc.c /usr/src/sys/kern/kern_malloc.c
--- /usr/src/sys.old/kern/kern_malloc.c	Wed Apr 18 18:27:46 2001
+++ /usr/src/sys/kern/kern_malloc.c	Wed Apr 18 18:54:39 2001
@@ -475,8 +475,8 @@
 	if ((vm_kmem_size / 2) > (cnt.v_page_count * PAGE_SIZE))
 		vm_kmem_size = 2 * cnt.v_page_count * PAGE_SIZE;
 
-	npg = (nmbufs * MSIZE + nmbclusters * MCLBYTES + vm_kmem_size)
-		/ PAGE_SIZE;
+	npg = (nmbufs * MSIZE + nmbclusters * MCLBYTES + nmbcnt *
+	    sizeof(union mext_refcnt) + vm_kmem_size) / PAGE_SIZE;
 
 	kmemusage = (struct kmemusage *) kmem_alloc(kernel_map,
 		(vm_size_t)(npg * sizeof(struct kmemusage)));
diff -ru /usr/src/sys.old/kern/uipc_mbuf.c /usr/src/sys/kern/uipc_mbuf.c
--- /usr/src/sys.old/kern/uipc_mbuf.c	Wed Apr 18 18:27:48 2001
+++ /usr/src/sys/kern/uipc_mbuf.c	Wed Apr 18 18:54:47 2001
@@ -121,14 +121,15 @@
 static void
 mbinit(void *dummy)
 {
-	vm_offset_t maxaddr, mb_map_size;
+	vm_offset_t maxaddr;
+	vm_size_t mb_map_size;
 
 	/*
 	 * Setup the mb_map, allocate requested VM space.
 	 */
-	mb_map_size = nmbufs * MSIZE + nmbclusters * MCLBYTES + nmbcnt
-	    * sizeof(union mext_refcnt);
-	mb_map_size = roundup2(mb_map_size, PAGE_SIZE);
+	mb_map_size = (vm_size_t)(nmbufs * MSIZE + nmbclusters * MCLBYTES +
+	    nmbcnt * sizeof(union mext_refcnt));
+	mb_map_size = rounddown(mb_map_size, PAGE_SIZE);
 	mb_map = kmem_suballoc(kmem_map, (vm_offset_t *)&mbutl, &maxaddr,
 	    mb_map_size);
 	/* XXX XXX XXX: mb_map->system_map = 1; */
diff -ru /usr/src/sys.old/sys/mbuf.h /usr/src/sys/sys/mbuf.h
--- /usr/src/sys.old/sys/mbuf.h	Wed Apr 18 18:28:28 2001
+++ /usr/src/sys/sys/mbuf.h	Wed Apr 18 18:34:11 2001
@@ -666,6 +666,7 @@
 extern	struct mcntfree_lst	mcntfree;
 extern	struct mbffree_lst	mmbfree;
 extern	int		 nmbclusters;
+extern	int		 nmbcnt;
 extern	int		 nmbufs;
 extern	int		 nsfbufs;