Index: sys/amd64/amd64/pmap.c
===================================================================
--- sys/amd64/amd64/pmap.c
+++ sys/amd64/amd64/pmap.c
@@ -10788,9 +10788,11 @@
 	    sva >= VM_MAXUSER_ADDRESS)
 		return (true);
 	MPASS(eva <= VM_MAXUSER_ADDRESS);
-	for (va = sva, prev_ppr = NULL; va < eva;) {
+	for (va = sva; va < eva; prev_ppr = ppr) {
 		ppr = rangeset_lookup(&pmap->pm_pkru, va);
-		if ((ppr == NULL) ^ (prev_ppr == NULL))
+		if (va == sva)
+			prev_ppr = ppr;
+		else if ((ppr == NULL) ^ (prev_ppr == NULL))
 			return (false);
 		if (ppr == NULL) {
 			va += PAGE_SIZE;
Index: tests/sys/vm/Makefile
===================================================================
--- tests/sys/vm/Makefile
+++ tests/sys/vm/Makefile
@@ -6,6 +6,7 @@
 
 ATF_TESTS_C+=	mlock_test \
 		mmap_test \
-		page_fault_signal
+		page_fault_signal \
+		pkru_test
 
 .include <bsd.test.mk>
Index: tests/sys/vm/pkru_test.c
===================================================================
--- /dev/null
+++ tests/sys/vm/pkru_test.c
@@ -0,0 +1,140 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2020 Eric van Gyzen
+ *
+ * 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/param.h>
+#include <sys/mman.h>
+
+#include <machine/sysarch.h>
+
+#include <atf-c.h>
+#include <errno.h>
+#include <stdio.h>
+
+#define MEM_SIZE (2*1024*1024)
+
+static char *
+pkru_super_setup(void)
+{
+	char *mem;
+
+	if (x86_pkru_set_perm(1, 1, 0)) {
+		if (errno == EOPNOTSUPP) {
+			atf_tc_skip("requires PKRU support");
+		}
+		ATF_REQUIRE_MSG(false, "x86_pkru_set_perm: %s",
+		    strerror(errno));
+	}
+
+	mem = mmap(NULL, MEM_SIZE, PROT_READ | PROT_WRITE,
+	    MAP_PRIVATE | MAP_ANON | MAP_ALIGNED(21), -1, 0);
+	ATF_REQUIRE_MSG(mem != MAP_FAILED, "mmap: %s", strerror(errno));
+
+	return (mem);
+}
+
+static void
+pkru_super_test(char *mem, bool super_expected)
+{
+	char incore[MEM_SIZE / PAGE_SIZE];
+	int sum;
+
+	sum = 0;
+	for (int i = 0; i < MEM_SIZE; i += PAGE_SIZE) {
+		sum += mem[i];
+	}
+	// Prevent dead-store warnings or excessive optimization.
+	printf("sum %d\n", sum);
+
+	ATF_REQUIRE_EQ_MSG(mincore(mem, MEM_SIZE, incore), 0,
+	    "%s", strerror(errno));
+	ATF_CHECK_EQ(incore[0] & MINCORE_SUPER,
+	     super_expected ? MINCORE_SUPER : 0);
+	ATF_REQUIRE_EQ_MSG(munmap(mem, MEM_SIZE), 0, "%s", strerror(errno));
+}
+
+#if 0
+ATF_TC_WITHOUT_HEAD(pkru_super_default);
+ATF_TC_BODY(pkru_super_default, tc)
+{
+	char *mem;
+
+	mem = pkru_super_setup();
+	// Keep the default PKRU protections.
+	pkru_super_test(mem, true);
+}
+#endif
+
+ATF_TC_WITHOUT_HEAD(pkru_super_first_page);
+ATF_TC_BODY(pkru_super_first_page, tc)
+{
+	char *mem;
+
+	mem = pkru_super_setup();
+	ATF_REQUIRE_EQ_MSG(0,
+	    x86_pkru_protect_range(mem, PAGE_SIZE, 1, 0),
+	    "x86_pkru_protect_range: %s", strerror(errno));
+	pkru_super_test(mem, false);
+}
+
+ATF_TC_WITHOUT_HEAD(pkru_super_second_page);
+ATF_TC_BODY(pkru_super_second_page, tc)
+{
+	char *mem;
+
+	mem = pkru_super_setup();
+	ATF_REQUIRE_EQ_MSG(0,
+	    x86_pkru_protect_range(mem + PAGE_SIZE, PAGE_SIZE, 1, 0),
+	    "x86_pkru_protect_range: %s", strerror(errno));
+	pkru_super_test(mem, false);
+}
+
+#if 0
+ATF_TC_WITHOUT_HEAD(pkru_super_whole_range);
+ATF_TC_BODY(pkru_super_whole_range, tc)
+{
+	char *mem;
+
+	mem = pkru_super_setup();
+	ATF_REQUIRE_EQ_MSG(0,
+	    x86_pkru_protect_range(mem, MEM_SIZE, 1, 0),
+	    "x86_pkru_protect_range: %s", strerror(errno));
+	pkru_super_test(mem, true);
+}
+#endif
+
+ATF_TP_ADD_TCS(tp)
+{
+	// This test does not pass yet.  MINCORE_SUPER is not set,
+	// though it should be.
+	// ATF_TP_ADD_TC(tp, pkru_super_default);
+	ATF_TP_ADD_TC(tp, pkru_super_first_page);
+	ATF_TP_ADD_TC(tp, pkru_super_second_page);
+	// Ditto pkru_super_default.
+	// ATF_TP_ADD_TC(tp, pkru_super_whole_range);
+
+	return (atf_no_error());
+}