diff --git a/sys/kern/subr_smp.c b/sys/kern/subr_smp.c
--- a/sys/kern/subr_smp.c
+++ b/sys/kern/subr_smp.c
@@ -630,7 +630,7 @@
 	smp_rendezvous_cpus(all_cpus, setup_func, action_func, teardown_func, arg);
 }
 
-static struct cpu_group group[MAXCPU * MAX_CACHE_LEVELS + 1];
+static struct cpu_group *group;
 
 static void
 smp_topo_fill(struct cpu_group *cg)
@@ -647,7 +647,14 @@
 smp_topo(void)
 {
 	char cpusetbuf[CPUSETBUFSIZ], cpusetbuf2[CPUSETBUFSIZ];
-	struct cpu_group *top;
+	static struct cpu_group *top = NULL;
+
+	/*
+	 * The first caller of smp_topo() is guaranteed to occur
+	 * during the kernel boot while we are still single-threaded.
+	 */
+	if (top != NULL)
+		return (top);
 
 	/*
 	 * Check for a fake topology request for debugging purposes.
@@ -710,12 +717,22 @@
 	return (top);
 }
 
+static void
+smp_topo_alloc_group(void)
+{
+	if (group != NULL)
+		return;
+	group = mallocarray((mp_maxid + 1) * MAX_CACHE_LEVELS + 1,
+	    sizeof(*group), M_DEVBUF, M_WAITOK | M_ZERO);
+}
+
 struct cpu_group *
 smp_topo_alloc(u_int count)
 {
 	static u_int index;
 	u_int curr;
 
+	smp_topo_alloc_group();
 	curr = index;
 	index += count;
 	return (&group[curr]);
@@ -726,6 +743,7 @@
 {
 	struct cpu_group *top;
 
+	smp_topo_alloc_group();
 	top = &group[0];
 	top->cg_parent = NULL;
 	top->cg_child = NULL;
@@ -779,6 +797,7 @@
 	int cpu;
 	int i;
 
+	smp_topo_alloc_group();
 	cpu = 0;
 	top = &group[0];
 	packages = mp_ncpus / count;
@@ -800,6 +819,7 @@
 	int i;
 	int j;
 
+	smp_topo_alloc_group();
 	cpu = 0;
 	top = &group[0];
 	l2g = &group[1];
@@ -975,7 +995,8 @@
 
 	error = 0;
 	if ((prio & PDROP) == 0) {
-		gen = malloc(sizeof(u_int) * MAXCPU, M_TEMP, M_WAITOK);
+		gen = mallocarray(sizeof(u_int), mp_maxid + 1, M_TEMP,
+		    M_WAITOK);
 		for (cpu = 0; cpu <= mp_maxid; cpu++) {
 			if (!CPU_ISSET(cpu, &map) || CPU_ABSENT(cpu))
 				continue;