--- a/hotspot/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Fri Jan 21 11:30:22 2011 -0500
+++ b/hotspot/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Tue Jan 25 17:58:19 2011 -0500
@@ -1500,21 +1500,19 @@
   size_t _max_live_bytes;
   size_t _regions_claimed;
   size_t _freed_bytes;
-  FreeRegionList _local_cleanup_list;
-  HumongousRegionSet _humongous_proxy_set;
+  FreeRegionList* _local_cleanup_list;
+  HumongousRegionSet* _humongous_proxy_set;
+  HRRSCleanupTask* _hrrs_cleanup_task;
   double _claimed_region_time;
   double _max_region_time;
 
 public:
   G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1,
-                             int worker_num);
+                             int worker_num,
+                             FreeRegionList* local_cleanup_list,
+                             HumongousRegionSet* humongous_proxy_set,
+                             HRRSCleanupTask* hrrs_cleanup_task);
   size_t freed_bytes() { return _freed_bytes; }
-  FreeRegionList* local_cleanup_list() {
-    return &_local_cleanup_list;
-  }
-  HumongousRegionSet* humongous_proxy_set() {
-    return &_humongous_proxy_set;
-  }
 
   bool doHeapRegion(HeapRegion *r);
 
@@ -1541,7 +1539,12 @@
 
   void work(int i) {
     double start = os::elapsedTime();
-    G1NoteEndOfConcMarkClosure g1_note_end(_g1h, i);
+    FreeRegionList local_cleanup_list("Local Cleanup List");
+    HumongousRegionSet humongous_proxy_set("Local Cleanup Humongous Proxy Set");
+    HRRSCleanupTask hrrs_cleanup_task;
+    G1NoteEndOfConcMarkClosure g1_note_end(_g1h, i, &local_cleanup_list,
+                                           &humongous_proxy_set,
+                                           &hrrs_cleanup_task);
     if (G1CollectedHeap::use_parallel_gc_threads()) {
       _g1h->heap_region_par_iterate_chunked(&g1_note_end, i,
                                             HeapRegion::NoteEndClaimValue);
@@ -1553,15 +1556,17 @@
     // Now update the lists
     _g1h->update_sets_after_freeing_regions(g1_note_end.freed_bytes(),
                                             NULL /* free_list */,
-                                            g1_note_end.humongous_proxy_set(),
+                                            &humongous_proxy_set,
                                             true /* par */);
     {
       MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
       _max_live_bytes += g1_note_end.max_live_bytes();
       _freed_bytes += g1_note_end.freed_bytes();
 
-      _cleanup_list->add_as_tail(g1_note_end.local_cleanup_list());
-      assert(g1_note_end.local_cleanup_list()->is_empty(), "post-condition");
+      _cleanup_list->add_as_tail(&local_cleanup_list);
+      assert(local_cleanup_list.is_empty(), "post-condition");
+
+      HeapRegionRemSet::finish_cleanup_task(&hrrs_cleanup_task);
     }
     double end = os::elapsedTime();
     if (G1PrintParCleanupStats) {
@@ -1602,13 +1607,17 @@
 
 G1NoteEndOfConcMarkClosure::
 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1,
-                           int worker_num)
+                           int worker_num,
+                           FreeRegionList* local_cleanup_list,
+                           HumongousRegionSet* humongous_proxy_set,
+                           HRRSCleanupTask* hrrs_cleanup_task)
   : _g1(g1), _worker_num(worker_num),
     _max_live_bytes(0), _regions_claimed(0),
     _freed_bytes(0),
     _claimed_region_time(0.0), _max_region_time(0.0),
-    _local_cleanup_list("Local Cleanup List"),
-    _humongous_proxy_set("Local Cleanup Humongous Proxy Set") { }
+    _local_cleanup_list(local_cleanup_list),
+    _humongous_proxy_set(humongous_proxy_set),
+    _hrrs_cleanup_task(hrrs_cleanup_task) { }
 
 bool G1NoteEndOfConcMarkClosure::doHeapRegion(HeapRegion *hr) {
   // We use a claim value of zero here because all regions
@@ -1619,11 +1628,12 @@
     _regions_claimed++;
     hr->note_end_of_marking();
     _max_live_bytes += hr->max_live_bytes();
-    _g1->free_region_if_totally_empty(hr,
-                                      &_freed_bytes,
-                                      &_local_cleanup_list,
-                                      &_humongous_proxy_set,
-                                      true /* par */);
+    _g1->free_region_if_empty(hr,
+                              &_freed_bytes,
+                              _local_cleanup_list,
+                              _humongous_proxy_set,
+                              _hrrs_cleanup_task,
+                              true /* par */);
     double region_time = (os::elapsedTime() - start);
     _claimed_region_time += region_time;
     if (region_time > _max_region_time) _max_region_time = region_time;
@@ -1659,6 +1669,8 @@
 
   double start = os::elapsedTime();
 
+  HeapRegionRemSet::reset_for_cleanup_tasks();
+
   // Do counting once more with the world stopped for good measure.
   G1ParFinalCountTask g1_par_count_task(g1h, nextMarkBitMap(),
                                         &_region_bm, &_card_bm);

--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Fri Jan 21 11:30:22 2011 -0500
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Tue Jan 25 17:58:19 2011 -0500
@@ -4925,10 +4925,11 @@
   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 }
 
-void G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr,
+void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
                                      size_t* pre_used,
                                      FreeRegionList* free_list,
                                      HumongousRegionSet* humongous_proxy_set,
+                                     HRRSCleanupTask* hrrs_cleanup_task,
                                      bool par) {
   if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
     if (hr->isHumongous()) {
@@ -4937,6 +4938,8 @@
     } else {
       free_region(hr, pre_used, free_list, par);
     }
+  } else {
+    hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
   }
 }
 

--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp	Fri Jan 21 11:30:22 2011 -0500
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp	Tue Jan 25 17:58:19 2011 -0500
@@ -40,6 +40,7 @@
 
 class HeapRegion;
 class HeapRegionSeq;
+class HRRSCleanupTask;
 class PermanentGenerationSpec;
 class GenerationSpec;
 class OopsInHeapRegionClosure;
@@ -1099,11 +1100,12 @@
   // all dead. It calls either free_region() or
   // free_humongous_region() depending on the type of the region that
   // is passed to it.
-  void free_region_if_totally_empty(HeapRegion* hr,
-                                    size_t* pre_used,
-                                    FreeRegionList* free_list,
-                                    HumongousRegionSet* humongous_proxy_set,
-                                    bool par);
+  void free_region_if_empty(HeapRegion* hr,
+                            size_t* pre_used,
+                            FreeRegionList* free_list,
+                            HumongousRegionSet* humongous_proxy_set,
+                            HRRSCleanupTask* hrrs_cleanup_task,
+                            bool par);
 
   // It appends the free list to the master free list and updates the
   // master humongous list according to the contents of the proxy

--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegionRemSet.cpp	Fri Jan 21 11:30:22 2011 -0500
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegionRemSet.cpp	Tue Jan 25 17:58:19 2011 -0500
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -463,7 +463,6 @@
   }
 
   static void par_contract_all();
-
 };
 
 void PosParPRT::par_contract_all() {
@@ -1070,6 +1069,11 @@
 
 }
 
+void
+OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
+  _sparse_table.do_cleanup_work(hrrs_cleanup_task);
+}
+
 // Determines how many threads can add records to an rset in parallel.
 // This can be done by either mutator threads together with the
 // concurrent refinement threads or GC threads.
@@ -1384,6 +1388,19 @@
   }
 }
 
+void HeapRegionRemSet::reset_for_cleanup_tasks() {
+  SparsePRT::reset_for_cleanup_tasks();
+}
+
+void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
+  _other_regions.do_cleanup_work(hrrs_cleanup_task);
+}
+
+void
+HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
+  SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
+}
+
 #ifndef PRODUCT
 void HeapRegionRemSet::test() {
   os::sleep(Thread::current(), (jlong)5000, false);

--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp	Fri Jan 21 11:30:22 2011 -0500
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp	Tue Jan 25 17:58:19 2011 -0500
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -38,6 +38,10 @@
 class PosParPRT;
 class SparsePRT;
 
+// Essentially a wrapper around SparsePRTCleanupTask. See
+// sparsePRT.hpp for more details.
+class HRRSCleanupTask : public SparsePRTCleanupTask {
+};
 
 // The "_coarse_map" is a bitmap with one bit for each region, where set
 // bits indicate that the corresponding region may contain some pointer
@@ -156,6 +160,8 @@
   // "from_hr" is being cleared; remove any entries from it.
   void clear_incoming_entry(HeapRegion* from_hr);
 
+  void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task);
+
   // Declare the heap size (in # of regions) to the OtherRegionsTable.
   // (Uses it to initialize from_card_cache).
   static void init_from_card_cache(size_t max_regions);
@@ -165,10 +171,8 @@
   static void shrink_from_card_cache(size_t new_n_regs);
 
   static void print_from_card_cache();
-
 };
 
-
 class HeapRegionRemSet : public CHeapObj {
   friend class VMStructs;
   friend class HeapRegionRemSetIterator;
@@ -342,11 +346,16 @@
   static void print_recorded();
   static void record_event(Event evnt);
 
+  // These are wrappers for the similarly-named methods on
+  // SparsePRT. Look at sparsePRT.hpp for more details.
+  static void reset_for_cleanup_tasks();
+  void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task);
+  static void finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task);
+
   // Run unit tests.
 #ifndef PRODUCT
   static void test();
 #endif
-
 };
 
 class HeapRegionRemSetIterator : public CHeapObj {

--- a/hotspot/src/share/vm/gc_implementation/g1/sparsePRT.cpp	Fri Jan 21 11:30:22 2011 -0500
+++ b/hotspot/src/share/vm/gc_implementation/g1/sparsePRT.cpp	Tue Jan 25 17:58:19 2011 -0500
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -415,6 +415,38 @@
   return NULL;
 }
 
+void SparsePRT::reset_for_cleanup_tasks() {
+  _head_expanded_list = NULL;
+}
+
+void SparsePRT::do_cleanup_work(SparsePRTCleanupTask* sprt_cleanup_task) {
+  if (should_be_on_expanded_list()) {
+    sprt_cleanup_task->add(this);
+  }
+}
+
+void SparsePRT::finish_cleanup_task(SparsePRTCleanupTask* sprt_cleanup_task) {
+  assert(ParGCRareEvent_lock->owned_by_self(), "pre-condition");
+  SparsePRT* head = sprt_cleanup_task->head();
+  SparsePRT* tail = sprt_cleanup_task->tail();
+  if (head != NULL) {
+    assert(tail != NULL, "if head is not NULL, so should tail");
+
+    tail->set_next_expanded(_head_expanded_list);
+    _head_expanded_list = head;
+  } else {
+    assert(tail == NULL, "if head is NULL, so should tail");
+  }
+}
+
+bool SparsePRT::should_be_on_expanded_list() {
+  if (_expanded) {
+    assert(_cur != _next, "if _expanded is true, cur should be != _next");
+  } else {
+    assert(_cur == _next, "if _expanded is false, cur should be == _next");
+  }
+  return expanded();
+}
 
 void SparsePRT::cleanup_all() {
   // First clean up all expanded tables so they agree on next and cur.
@@ -484,6 +516,7 @@
     _cur->clear();
   }
   _next = _cur;
+  _expanded = false;
 }
 
 void SparsePRT::cleanup() {
@@ -518,3 +551,15 @@
   }
   add_to_expanded_list(this);
 }
+
+void SparsePRTCleanupTask::add(SparsePRT* sprt) {
+  assert(sprt->should_be_on_expanded_list(), "pre-condition");
+
+  sprt->set_next_expanded(NULL);
+  if (_tail != NULL) {
+    _tail->set_next_expanded(sprt);
+  } else {
+    _head = sprt;
+  }
+  _tail = sprt;
+}

--- a/hotspot/src/share/vm/gc_implementation/g1/sparsePRT.hpp	Fri Jan 21 11:30:22 2011 -0500
+++ b/hotspot/src/share/vm/gc_implementation/g1/sparsePRT.hpp	Tue Jan 25 17:58:19 2011 -0500
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -212,8 +212,11 @@
 // mutex.
 
 class SparsePRTIter;
+class SparsePRTCleanupTask;
 
 class SparsePRT VALUE_OBJ_CLASS_SPEC {
+  friend class SparsePRTCleanupTask;
+
   //  Iterations are done on the _cur hash table, since they only need to
   //  see entries visible at the start of a collection pause.
   //  All other operations are done using the _next hash table.
@@ -238,6 +241,8 @@
   SparsePRT* next_expanded() { return _next_expanded; }
   void set_next_expanded(SparsePRT* nxt) { _next_expanded = nxt; }
 
+  bool should_be_on_expanded_list();
+
   static SparsePRT* _head_expanded_list;
 
 public:
@@ -284,12 +289,36 @@
   static void add_to_expanded_list(SparsePRT* sprt);
   static SparsePRT* get_from_expanded_list();
 
+  // The purpose of these three methods is to help the GC workers
+  // during the cleanup pause to recreate the expanded list, purging
+  // any tables from it that belong to regions that are freed during
+  // cleanup (if we don't purge those tables, there is a race that
+  // causes various crashes; see CR 7014261).
+  //
+  // We chose to recreate the expanded list, instead of purging
+  // entries from it by iterating over it, to avoid this serial phase
+  // at the end of the cleanup pause.
+  //
+  // The three methods below work as follows:
+  // * reset_for_cleanup_tasks() : Nulls the expanded list head at the
+  //   start of the cleanup pause.
+  // * do_cleanup_work() : Called by the cleanup workers for every
+  //   region that is not free / is being freed by the cleanup
+  //   pause. It creates a list of expanded tables whose head / tail
+  //   are on the thread-local SparsePRTCleanupTask object.
+  // * finish_cleanup_task() : Called by the cleanup workers after
+  //   they complete their cleanup task. It adds the local list into
+  //   the global expanded list. It assumes that the
+  //   ParGCRareEvent_lock is being held to ensure MT-safety.
+  static void reset_for_cleanup_tasks();
+  void do_cleanup_work(SparsePRTCleanupTask* sprt_cleanup_task);
+  static void finish_cleanup_task(SparsePRTCleanupTask* sprt_cleanup_task);
+
   bool contains_card(RegionIdx_t region_id, CardIdx_t card_index) const {
     return _next->contains_card(region_id, card_index);
   }
 };
 
-
 class SparsePRTIter: public RSHashTableIter {
 public:
   void init(const SparsePRT* sprt) {
@@ -300,4 +329,22 @@
   }
 };
 
+// This allows each worker during a cleanup pause to create a
+// thread-local list of sparse tables that have been expanded and need
+// to be processed at the beginning of the next GC pause. This lists
+// are concatenated into the single expanded list at the end of the
+// cleanup pause.
+class SparsePRTCleanupTask VALUE_OBJ_CLASS_SPEC {
+private:
+  SparsePRT* _head;
+  SparsePRT* _tail;
+
+public:
+  SparsePRTCleanupTask() : _head(NULL), _tail(NULL) { }
+
+  void add(SparsePRT* sprt);
+  SparsePRT* head() { return _head; }
+  SparsePRT* tail() { return _tail; }
+};
+
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_SPARSEPRT_HPP