src/hotspot/cpu/s390/sharedRuntime_s390.cpp

*** 2153,2174 ****
    {
      Label no_block, sync;
  
      save_native_result(masm, ret_type, workspace_slot_offset); // Make Z_R2 available as work reg.
  
-     if (os::is_MP()) {
        if (UseMembar) {
          // Force this write out before the read below.
          __ z_fence();
        } else {
          // Write serialization page so VM thread can do a pseudo remote membar.
          // We use the current thread pointer to calculate a thread specific
          // offset to write to within the page. This minimizes bus traffic
          // due to cache line collision.
          __ serialize_memory(Z_thread, Z_R1, Z_R2);
        }
!     }
      __ safepoint_poll(sync, Z_R1);
  
      __ load_and_test_int(Z_R0, Address(Z_thread, JavaThread::suspend_flags_offset()));
      __ z_bre(no_block);
  
--- 2153,2173 ----
    {
      Label no_block, sync;
  
      save_native_result(masm, ret_type, workspace_slot_offset); // Make Z_R2 available as work reg.
  
      if (UseMembar) {
        // Force this write out before the read below.
        __ z_fence();
      } else {
        // Write serialization page so VM thread can do a pseudo remote membar.
        // We use the current thread pointer to calculate a thread specific
        // offset to write to within the page. This minimizes bus traffic
        // due to cache line collision.
        __ serialize_memory(Z_thread, Z_R1, Z_R2);
      }
! 
      __ safepoint_poll(sync, Z_R1);
  
      __ load_and_test_int(Z_R0, Address(Z_thread, JavaThread::suspend_flags_offset()));
      __ z_bre(no_block);