diff --git a/src/share/vm/prims/jvmtiEnv.cpp b/src/share/vm/prims/jvmtiEnv.cpp
index 9cafbd1..e24f8c9 100644
--- a/src/share/vm/prims/jvmtiEnv.cpp
+++ b/src/share/vm/prims/jvmtiEnv.cpp
@@ -298,10 +298,12 @@
 //TODO: add locking
   if (AllowEnhancedClassRedefinition) {
     VM_EnhancedRedefineClasses op(class_count, class_definitions, jvmti_class_load_kind_redefine);
+    MutexLocker sd_mutex(RedefineClasses_lock);
     VMThread::execute(&op);
     return (op.check_error());
   }
   VM_RedefineClasses op(class_count, class_definitions, jvmti_class_load_kind_redefine);
+  MutexLocker sd_mutex(RedefineClasses_lock);
   VMThread::execute(&op);
   return (op.check_error());
 } /* end RedefineClasses */
diff --git a/src/share/vm/runtime/mutexLocker.cpp b/src/share/vm/runtime/mutexLocker.cpp
index f358c75..02377a4 100644
--- a/src/share/vm/runtime/mutexLocker.cpp
+++ b/src/share/vm/runtime/mutexLocker.cpp
@@ -38,6 +38,7 @@
 // Consider using GCC's __read_mostly.
 
 Mutex*   Patching_lock                = NULL;
+Mutex*   RedefineClasses_lock         = NULL;
 Monitor* SystemDictionary_lock        = NULL;
 Mutex*   PackageTable_lock            = NULL;
 Mutex*   CompiledIC_lock              = NULL;
@@ -279,6 +280,7 @@
   def(ProfileVM_lock               , Monitor, special,   false); // used for profiling of the VMThread
   def(CompileThread_lock           , Monitor, nonleaf+5,   false );
   def(PeriodicTask_lock            , Monitor, nonleaf+5,   true);
+  def(RedefineClasses_lock         , Mutex  , nonleaf+7,   false ); // for ensuring that class redefinition is not done in parallel
 
 #ifdef INCLUDE_TRACE
   def(JfrMsg_lock                  , Monitor, leaf,        true);
diff --git a/src/share/vm/runtime/mutexLocker.hpp b/src/share/vm/runtime/mutexLocker.hpp
index be86bac..a77f546 100644
--- a/src/share/vm/runtime/mutexLocker.hpp
+++ b/src/share/vm/runtime/mutexLocker.hpp
@@ -46,6 +46,7 @@
 // Mutexes used in the VM.
 
 extern Mutex*   Patching_lock;                   // a lock used to guard code patching of compiled code
+extern Mutex*   RedefineClasses_lock;            // a lock on class redefinition
 extern Monitor* SystemDictionary_lock;           // a lock on the system dictonary
 extern Mutex*   PackageTable_lock;               // a lock on the class loader package table
 extern Mutex*   CompiledIC_lock;                 // a lock used to guard compiled IC patching and access
diff --git a/src/share/vm/runtime/thread.cpp b/src/share/vm/runtime/thread.cpp
index 0dc86d9..9f4c2e9 100644
--- a/src/share/vm/runtime/thread.cpp
+++ b/src/share/vm/runtime/thread.cpp
@@ -910,6 +910,15 @@
   return false;
 }
 
+bool Thread::owns_locks_but_redefine_classes_lock() const {
+  for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
+    if (cur != RedefineClasses_lock && cur->rank() != Mutex::redefine_classes) {
+      return true;
+    }
+  }
+  return false;
+}
+
 
 #endif
 
diff --git a/src/share/vm/runtime/thread.hpp b/src/share/vm/runtime/thread.hpp
index 1117c87..77b716c 100644
--- a/src/share/vm/runtime/thread.hpp
+++ b/src/share/vm/runtime/thread.hpp
@@ -211,11 +211,14 @@
   void enter_signal_handler() { _num_nested_signal++; }
   void leave_signal_handler() { _num_nested_signal--; }
   bool is_inside_signal_handler() const { return _num_nested_signal > 0; }
+  Mutex* redefine_classes_mutex() { return _redefine_classes_mutex; }
 
  private:
   // Debug tracing
   static void trace(const char* msg, const Thread* const thread) PRODUCT_RETURN;
 
+  Mutex* _redefine_classes_mutex;
+
   // Active_handles points to a block of handles
   JNIHandleBlock* _active_handles;
 
@@ -585,6 +588,7 @@
   void print_owned_locks() const                 { print_owned_locks_on(tty);    }
   Monitor* owned_locks() const                   { return _owned_locks;          }
   bool owns_locks() const                        { return owned_locks() != NULL; }
+  bool owns_locks_but_redefine_classes_lock() const;
   bool owns_locks_but_compiled_lock() const;
 
   // Deadlock detection