Index: lib/libc/sys/cpuset_getaffinity.2
===================================================================
--- lib/libc/sys/cpuset_getaffinity.2
+++ lib/libc/sys/cpuset_getaffinity.2
@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd May 23, 2017
+.Dd April 20, 2022
 .Dt CPUSET_GETAFFINITY 2
 .Os
 .Sh NAME
@@ -71,11 +71,9 @@
 are composed using the
 .Dv CPU_SET
 macros.
-The kernel tolerates large sets as long as all CPUs specified
-in the set exist.
-Sets smaller than the kernel uses generate an error on calls to
-.Fn cpuset_getaffinity
-even if the result set would fit within the user supplied set.
+Sets smaller than the kernel can use to fit all active CPUs generate an
+error on calls to
+.Fn cpuset_getaffinity .
 Calls to
 .Fn cpuset_setaffinity
 tolerate small sets with no restrictions.
@@ -144,7 +142,7 @@
 .It Bq Er ERANGE
 The
 .Fa cpusetsize
-was either preposterously large or smaller than the kernel set size.
+was smaller than needed to fit all active CPUs.
 .It Bq Er EPERM
 The calling process did not have the credentials required to complete the
 operation.
Index: share/man/man3/pthread_attr_affinity_np.3
===================================================================
--- share/man/man3/pthread_attr_affinity_np.3
+++ share/man/man3/pthread_attr_affinity_np.3
@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd October 12, 2021
+.Dd April 20, 2022
 .Dt PTHREAD_ATTR_AFFINITY_NP 3
 .Os
 .Sh NAME
@@ -51,11 +51,9 @@
 are composed using the
 .Dv CPU_SET
 macros.
-The kernel tolerates large sets as long as all CPUs specified
-in the set exist.
-Sets smaller than the kernel uses generate an error on calls to
-.Fn pthread_attr_getaffinity_np
-even if the result set would fit within the user supplied set.
+Sets smaller than the kernel can use to fit all active CPUs generate an
+error on calls to
+.Fn pthread_attr_getaffinity_np .
 Calls to
 .Fn pthread_attr_setaffinity_np
 tolerate small sets with no restrictions.
Index: sys/kern/kern_cpuset.c
===================================================================
--- sys/kern/kern_cpuset.c
+++ sys/kern/kern_cpuset.c
@@ -1896,13 +1896,13 @@
 	int error;
 	size_t size;
 
-	if (cpusetsize < sizeof(cpuset_t) || cpusetsize > CPU_MAXSIZE / NBBY)
+	if (cpusetsize * NBBY < smp_cpus)
 		return (ERANGE);
 	error = cpuset_check_capabilities(td, level, which, id);
 	if (error != 0)
 		return (error);
-	size = cpusetsize;
-	mask = malloc(size, M_TEMP, M_WAITOK | M_ZERO);
+	size = min(cpusetsize, sizeof(cpuset_t));
+	mask = malloc(sizeof(cpuset_t), M_TEMP, M_WAITOK | M_ZERO);
 	error = cpuset_which(which, id, &p, &ttd, &set);
 	if (error)
 		goto out;
@@ -2006,32 +2006,16 @@
 	struct proc *p;
 	cpuset_t *mask;
 	int error;
+	size_t size;
 
-	if (cpusetsize < sizeof(cpuset_t) || cpusetsize > CPU_MAXSIZE / NBBY)
-		return (ERANGE);
 	error = cpuset_check_capabilities(td, level, which, id);
 	if (error != 0)
 		return (error);
-	mask = malloc(cpusetsize, M_TEMP, M_WAITOK | M_ZERO);
-	error = copyin(maskp, mask, cpusetsize);
+	size = min(cpusetsize, sizeof(cpuset_t));
+	mask = malloc(sizeof(cpuset_t), M_TEMP, M_WAITOK | M_ZERO);
+	error = copyin(maskp, mask, size);
 	if (error)
 		goto out;
-	/*
-	 * Verify that no high bits are set.
-	 */
-	if (cpusetsize > sizeof(cpuset_t)) {
-		char *end;
-		char *cp;
-
-		end = cp = (char *)&mask->__bits;
-		end += cpusetsize;
-		cp += sizeof(cpuset_t);
-		while (cp != end)
-			if (*cp++ != 0) {
-				error = EINVAL;
-				goto out;
-			}
-	}
 	if (CPU_EMPTY(mask)) {
 		error = EDEADLK;
 		goto out;