Index: head/tests/sys/kern/Makefile
===================================================================
--- head/tests/sys/kern/Makefile
+++ head/tests/sys/kern/Makefile
@@ -2,6 +2,7 @@
 
 TESTSDIR=	${TESTSBASE}/sys/kern
 
+ATF_TESTS_C+=	kern_copyin
 ATF_TESTS_C+=	kern_descrip_test
 ATF_TESTS_C+=	ptrace_test
 ATF_TESTS_C+=	unix_seqpacket_test
Index: head/tests/sys/kern/kern_copyin.c
===================================================================
--- head/tests/sys/kern/kern_copyin.c
+++ head/tests/sys/kern/kern_copyin.c
@@ -0,0 +1,86 @@
+/*-
+ * Copyright (c) 2015 The FreeBSD Foundation
+ * All rights reserved.
+ *
+ * This software was developed by Konstantin Belousov <kib@FreeBSD.org>
+ * under sponsorship from the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <atf-c.h>
+#include <vm/vm.h>
+#include <vm/pmap.h>
+#include <machine/vmparam.h>
+
+static int scratch_file;
+
+static int
+copyin_checker(uintptr_t uaddr, size_t len)
+{
+	ssize_t ret;
+
+	ret = write(scratch_file, (const void *)uaddr, len);
+	return (ret == -1 ? errno : 0);
+}
+
+#define	FMAX	ULONG_MAX
+
+ATF_TC_WITHOUT_HEAD(kern_copyin);
+ATF_TC_BODY(kern_copyin, tc)
+{
+	char template[] = "copyin.XXXXXX";
+
+	scratch_file = mkstemp(template);
+	ATF_REQUIRE(scratch_file != -1);
+	unlink(template);
+
+	ATF_CHECK(copyin_checker(0, 0) == 0);
+	ATF_CHECK(copyin_checker(VM_MAXUSER_ADDRESS - 10, 9) == 0);
+	ATF_CHECK(copyin_checker(VM_MAXUSER_ADDRESS - 10, 10) == 0);
+	ATF_CHECK(copyin_checker(VM_MAXUSER_ADDRESS - 10, 11) == EFAULT);
+	ATF_CHECK(copyin_checker(VM_MAXUSER_ADDRESS - 1, 1) == 0);
+	ATF_CHECK(copyin_checker(VM_MAXUSER_ADDRESS, 0) == 0);
+	ATF_CHECK(copyin_checker(VM_MAXUSER_ADDRESS, 1) == EFAULT);
+	ATF_CHECK(copyin_checker(VM_MAXUSER_ADDRESS, 2) == EFAULT);
+	ATF_CHECK(copyin_checker(VM_MAXUSER_ADDRESS + 1, 0) == 0);
+	ATF_CHECK(copyin_checker(VM_MAXUSER_ADDRESS + 1, 2) == EFAULT);
+	ATF_CHECK(copyin_checker(FMAX - 10, 9) == EFAULT);
+	ATF_CHECK(copyin_checker(FMAX - 10, 10) == EFAULT);
+	ATF_CHECK(copyin_checker(FMAX - 10, 11) == EFAULT);
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+
+	ATF_TP_ADD_TC(tp, kern_copyin);
+	return (atf_no_error());
+}