src/share/vm/gc_implementation/g1/concurrentMark.cpp

rev 7327 : 8075215: SATB buffer processing found reclaimed humongous object
Summary: Don't assume SATB buffer entries are valid objects
Reviewed-by: brutisso, ecaspole

*** 2638,2673 ****
    CMBitMapRO* temp = _prevMarkBitMap;
    _prevMarkBitMap  = (CMBitMapRO*)_nextMarkBitMap;
    _nextMarkBitMap  = (CMBitMap*)  temp;
  }
  
! class CMObjectClosure;
! 
! // Closure for iterating over objects, currently only used for
! // processing SATB buffers.
! class CMObjectClosure : public ObjectClosure {
  private:
    CMTask* _task;
  
! public:
!   void do_object(oop obj) {
!     _task->deal_with_reference(obj);
    }
  
!   CMObjectClosure(CMTask* task) : _task(task) { }
  };
  
  class G1RemarkThreadsClosure : public ThreadClosure {
!   CMObjectClosure _cm_obj;
    G1CMOopClosure _cm_cl;
    MarkingCodeBlobClosure _code_cl;
    int _thread_parity;
    bool _is_par;
  
   public:
    G1RemarkThreadsClosure(G1CollectedHeap* g1h, CMTask* task, bool is_par) :
!     _cm_obj(task), _cm_cl(g1h, g1h->concurrent_mark(), task), _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
      _thread_parity(SharedHeap::heap()->strong_roots_parity()), _is_par(is_par) {}
  
    void do_thread(Thread* thread) {
      if (thread->is_Java_thread()) {
        if (thread->claim_oops_do(_is_par, _thread_parity)) {
--- 2638,2692 ----
    CMBitMapRO* temp = _prevMarkBitMap;
    _prevMarkBitMap  = (CMBitMapRO*)_nextMarkBitMap;
    _nextMarkBitMap  = (CMBitMap*)  temp;
  }
  
! // Closure for marking entries in SATB buffers.
! class CMSATBBufferClosure : public SATBBufferClosure {
  private:
    CMTask* _task;
+   G1CollectedHeap* _g1h;
  
!   // This is very similar to CMTask::deal_with_reference, but with
!   // more relaxed requirements for the argument, so this must be more
!   // circumspect about treating the argument as an object.
!   void do_entry(void* entry) const {
!     _task->increment_refs_reached();
!     HeapRegion* hr = _g1h->heap_region_containing_raw(entry);
!     if (entry < hr->next_top_at_mark_start()) {
!       // Until we get here, we don't know whether entry refers to a valid
!       // object; it could instead have been a stale reference.
!       oop obj = static_cast<oop>(entry);
!       assert(obj->is_oop(true /* ignore mark word */),
!              err_msg("Invalid oop in SATB buffer: " PTR_FORMAT, p2i(obj)));
!       _task->make_reference_grey(obj, hr);
!     }
    }
  
! public:
!   CMSATBBufferClosure(CMTask* task, G1CollectedHeap* g1h)
!     : _task(task), _g1h(g1h) { }
! 
!   virtual void do_buffer(void** buffer, size_t size) {
!     for (size_t i = 0; i < size; ++i) {
!       do_entry(buffer[i]);
!     }
!   }
  };
  
  class G1RemarkThreadsClosure : public ThreadClosure {
!   CMSATBBufferClosure _cm_satb_cl;
    G1CMOopClosure _cm_cl;
    MarkingCodeBlobClosure _code_cl;
    int _thread_parity;
    bool _is_par;
  
   public:
    G1RemarkThreadsClosure(G1CollectedHeap* g1h, CMTask* task, bool is_par) :
!     _cm_satb_cl(task, g1h),
!     _cm_cl(g1h, g1h->concurrent_mark(), task),
!     _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
      _thread_parity(SharedHeap::heap()->strong_roots_parity()), _is_par(is_par) {}
  
    void do_thread(Thread* thread) {
      if (thread->is_Java_thread()) {
        if (thread->claim_oops_do(_is_par, _thread_parity)) {
*** 2679,2693 ****
          // * Weakly reachable otherwise
          // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
          // live by the SATB invariant but other oops recorded in nmethods may behave differently.
          jt->nmethods_do(&_code_cl);
  
!         jt->satb_mark_queue().apply_closure_and_empty(&_cm_obj);
        }
      } else if (thread->is_VM_thread()) {
        if (thread->claim_oops_do(_is_par, _thread_parity)) {
!         JavaThread::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(&_cm_obj);
        }
      }
    }
  };
  
--- 2698,2712 ----
          // * Weakly reachable otherwise
          // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
          // live by the SATB invariant but other oops recorded in nmethods may behave differently.
          jt->nmethods_do(&_code_cl);
  
!         jt->satb_mark_queue().apply_closure_and_empty(&_cm_satb_cl);
        }
      } else if (thread->is_VM_thread()) {
        if (thread->claim_oops_do(_is_par, _thread_parity)) {
!         JavaThread::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(&_cm_satb_cl);
        }
      }
    }
  };
  
*** 3974,3990 ****
    // middle of draining buffers and doesn't set the abort flag when it
    // notices that SATB buffers are available for draining. It'd be
    // very counter productive if it did that. :-)
    _draining_satb_buffers = true;
  
!   CMObjectClosure oc(this);
    SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
  
    // This keeps claiming and applying the closure to completed buffers
    // until we run out of buffers or we need to abort.
    while (!has_aborted() &&
!          satb_mq_set.apply_closure_to_completed_buffer(&oc)) {
      if (_cm->verbose_medium()) {
        gclog_or_tty->print_cr("[%u] processed an SATB buffer", _worker_id);
      }
      statsOnly( ++_satb_buffers_processed );
      regular_clock_call();
--- 3993,4009 ----
    // middle of draining buffers and doesn't set the abort flag when it
    // notices that SATB buffers are available for draining. It'd be
    // very counter productive if it did that. :-)
    _draining_satb_buffers = true;
  
!   CMSATBBufferClosure satb_cl(this, _g1h);
    SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
  
    // This keeps claiming and applying the closure to completed buffers
    // until we run out of buffers or we need to abort.
    while (!has_aborted() &&
!          satb_mq_set.apply_closure_to_completed_buffer(&satb_cl)) {
      if (_cm->verbose_medium()) {
        gclog_or_tty->print_cr("[%u] processed an SATB buffer", _worker_id);
      }
      statsOnly( ++_satb_buffers_processed );
      regular_clock_call();