Index: head/sys/amd64/amd64/pmap.c
===================================================================
--- head/sys/amd64/amd64/pmap.c
+++ head/sys/amd64/amd64/pmap.c
@@ -8810,8 +8810,11 @@
 
 	oldpmap = PCPU_GET(curpmap);
 	pmap = vmspace_pmap(td->td_proc->p_vmspace);
-	if (oldpmap == pmap)
+	if (oldpmap == pmap) {
+		if (cpu_vendor_id != CPU_VENDOR_INTEL)
+			mfence();
 		return;
+	}
 	cpuid = PCPU_GET(cpuid);
 #ifdef SMP
 	CPU_SET_ATOMIC(cpuid, &pmap->pm_active);