--- a/src/share/vm/gc_implementation/g1/vm_operations_g1.cpp	Fri Oct 21 12:42:42 2011 -0400
+++ b/src/share/vm/gc_implementation/g1/vm_operations_g1.cpp	Thu Oct 20 12:06:20 2011 -0700
@@ -23,6 +23,7 @@
  */
 
 #include "precompiled.hpp"
+#include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
 #include "gc_implementation/g1/vm_operations_g1.hpp"
@@ -165,6 +166,20 @@
   }
 }
 
+void VM_CGC_Operation::acquire_pending_list_lock() {
+  // The caller may block while communicating
+  // with the SLT thread in order to acquire/release the PLL.
+  ConcurrentMarkThread::slt()->
+    manipulatePLL(SurrogateLockerThread::acquirePLL);
+}
+
+void VM_CGC_Operation::release_and_notify_pending_list_lock() {
+  // The caller may block while communicating
+  // with the SLT thread in order to acquire/release the PLL.
+  ConcurrentMarkThread::slt()->
+    manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);
+}
+
 void VM_CGC_Operation::doit() {
   gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
   TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
@@ -180,12 +195,19 @@
 }
 
 bool VM_CGC_Operation::doit_prologue() {
+  // Note the relative order of the locks must match that in
+  // VM_GC_Operation::doit_prologue() or deadlocks can occur
+  acquire_pending_list_lock();
+
   Heap_lock->lock();
   SharedHeap::heap()->_thread_holds_heap_lock_for_gc = true;
   return true;
 }
 
 void VM_CGC_Operation::doit_epilogue() {
+  // Note the relative order of the unlocks must match that in
+  // VM_GC_Operation::doit_epilogue()
   SharedHeap::heap()->_thread_holds_heap_lock_for_gc = false;
   Heap_lock->unlock();
+  release_and_notify_pending_list_lock();
 }