diff --git a/src/hotspot/share/gc/serial/defNewGeneration.hpp b/src/hotspot/share/gc/serial/defNewGeneration.hpp
index a2b17b6a9f5..8203c625183 100644
--- a/src/hotspot/share/gc/serial/defNewGeneration.hpp
+++ b/src/hotspot/share/gc/serial/defNewGeneration.hpp
@@ -254,8 +254,8 @@ class DefNewGeneration: public Generation {
   // completed. Even if this method returns true, a collection
   // may not be guaranteed to succeed, and the system should be
   // able to safely unwind and recover from that failure, albeit
-  // at some additional cost. Override superclass's implementation.
-  virtual bool collection_attempt_is_safe();
+  // at some additional cost.
+  bool collection_attempt_is_safe();
 
   virtual void collect(bool   full,
                        bool   clear_all_soft_refs,
diff --git a/src/hotspot/share/gc/serial/generation.hpp b/src/hotspot/share/gc/serial/generation.hpp
index fa5ef14519c..2242e98efff 100644
--- a/src/hotspot/share/gc/serial/generation.hpp
+++ b/src/hotspot/share/gc/serial/generation.hpp
@@ -188,18 +188,6 @@ class Generation: public CHeapObj<mtGC> {
 
   // Thread-local allocation buffers
   virtual bool supports_tlab_allocation() const { return false; }
-  virtual size_t tlab_capacity() const {
-    guarantee(false, "Generation doesn't support thread local allocation buffers");
-    return 0;
-  }
-  virtual size_t tlab_used() const {
-    guarantee(false, "Generation doesn't support thread local allocation buffers");
-    return 0;
-  }
-  virtual size_t unsafe_max_tlab_alloc() const {
-    guarantee(false, "Generation doesn't support thread local allocation buffers");
-    return 0;
-  }
 
   // "obj" is the address of an object in a younger generation.  Allocate space
   // for "obj" in the current (or some higher) generation, and copy "obj" into
@@ -226,16 +214,6 @@ class Generation: public CHeapObj<mtGC> {
     return (full || should_allocate(word_size, is_tlab));
   }
 
-  // Returns true if the collection is likely to be safely
-  // completed. Even if this method returns true, a collection
-  // may not be guaranteed to succeed, and the system should be
-  // able to safely unwind and recover from that failure, albeit
-  // at some additional cost.
-  virtual bool collection_attempt_is_safe() {
-    guarantee(false, "Are you sure you want to call this method?");
-    return true;
-  }
-
   // Perform a garbage collection.
   // If full is true attempt a full garbage collection of this generation.
   // Otherwise, attempting to (at least) free enough space to support an