--- old/src/hotspot/share/gc/g1/g1ConcurrentMark.cpp	2018-04-26 11:17:55.264837768 +0200
+++ new/src/hotspot/share/gc/g1/g1ConcurrentMark.cpp	2018-04-26 11:17:54.646819532 +0200
@@ -1706,6 +1706,44 @@
   }
 }
 
+class G1PrecleanYieldClosure : public YieldClosure {
+  G1ConcurrentMark* _cm;
+
+public:
+  G1PrecleanYieldClosure(G1ConcurrentMark* cm) : _cm(cm) { }
+
+  virtual bool should_return() {
+    return _cm->has_aborted();
+  }
+
+  virtual bool should_return_fine_grain() {
+    _cm->do_yield_check();
+    return _cm->has_aborted();
+  }
+};
+
+void G1ConcurrentMark::preclean() {
+  assert(G1UseReferencePrecleaning, "Precleaning must be enabled.");
+
+  SuspendibleThreadSetJoiner joiner;
+
+  G1CMKeepAliveAndDrainClosure keep_alive(this, task(0), true /* is_serial */);
+  G1CMDrainMarkingStackClosure drain_mark_stack(this, task(0), true /* is_serial */);
+
+  set_concurrency_and_phase(1, true);
+
+  G1PrecleanYieldClosure yield_cl(this);
+
+  ReferenceProcessor* rp = _g1h->ref_processor_cm();
+  // Precleaning is single threaded. Temporarily disable MT discovery.
+  ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(rp, false);
+  rp->preclean_discovered_references(rp->is_alive_non_header(),
+                                     &keep_alive,
+                                     &drain_mark_stack,
+                                     &yield_cl,
+                                     _gc_timer_cm);
+}
+
 // When sampling object counts, we already swapped the mark bitmaps, so we need to use
 // the prev bitmap determining liveness.
 class G1ObjectCountIsAliveClosure: public BoolObjectClosure {