--- old/src/hotspot/cpu/arm/macroAssembler_arm.cpp	2018-09-26 10:00:31.166722981 -0400
+++ new/src/hotspot/cpu/arm/macroAssembler_arm.cpp	2018-09-26 10:00:29.610632420 -0400
@@ -1657,8 +1657,6 @@
 // Serializes memory.
 // tmp register is not used on AArch64, this parameter is provided solely for better compatibility with 32-bit ARM
 void MacroAssembler::membar(Membar_mask_bits order_constraint, Register tmp) {
-  if (!os::is_MP()) return;
-
   // TODO-AARCH64 investigate dsb vs dmb effects
   if (order_constraint == StoreStore) {
     dmb(DMB_st);
@@ -1679,7 +1677,6 @@
                             Register tmp,
                             bool preserve_flags,
                             Register load_tgt) {
-  if (!os::is_MP()) return;
 
   if (order_constraint == StoreStore) {
     dmb(DMB_st, tmp);