Index: sys/arch/alpha/alpha/pmap.c
===================================================================
RCS file: /cvsroot/src/sys/arch/alpha/alpha/pmap.c,v
retrieving revision 1.259.6.1
diff -u -p -r1.259.6.1 pmap.c
--- sys/arch/alpha/alpha/pmap.c	27 Dec 2015 12:09:27 -0000	1.259.6.1
+++ sys/arch/alpha/alpha/pmap.c	17 Dec 2016 16:18:39 -0000
@@ -2628,6 +2628,11 @@ pmap_emulate_reference(struct lwp *l, va
 		 * We'll unlock below where we're done with the PTE.
 		 */
 	}
+	if (pte == NULL || !pmap_pte_v(pte) {
+		if (didlock)
+			PMAP_UNLOCK(pmap)
+		return 0;
+	}
 	exec = pmap_pte_exec(pte);
 	if (!exec && type == ALPHA_MMCSR_FOE) {
 		if (didlock)