--- a/hotspot/src/share/vm/gc_implementation/g1/vm_operations_g1.cpp	Fri Feb 13 09:48:49 2015 +0100
+++ b/hotspot/src/share/vm/gc_implementation/g1/vm_operations_g1.cpp	Fri Feb 13 10:31:52 2015 +0100
@@ -38,7 +38,7 @@
                                                      size_t word_size)
   : VM_G1OperationWithAllocRequest(gc_count_before, word_size,
                                    GCCause::_allocation_failure) {
-  guarantee(word_size > 0, "an allocation should always be requested");
+  guarantee(word_size != 0, "An allocation should always be requested with this operation.");
 }
 
 void VM_G1CollectForAllocation::doit() {
@@ -73,7 +73,7 @@
 }
 
 bool VM_G1IncCollectionPause::doit_prologue() {
-  bool res = VM_GC_Operation::doit_prologue();
+  bool res = VM_G1OperationWithAllocRequest::doit_prologue();
   if (!res) {
     if (_should_initiate_conc_mark) {
       // The prologue can fail for a couple of reasons. The first is that another GC
@@ -163,7 +163,7 @@
 }
 
 void VM_G1IncCollectionPause::doit_epilogue() {
-  VM_GC_Operation::doit_epilogue();
+  VM_G1OperationWithAllocRequest::doit_epilogue();
 
   // If the pause was initiated by a System.gc() and
   // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle

--- a/hotspot/src/share/vm/gc_implementation/g1/vm_operations_g1.hpp	Fri Feb 13 09:48:49 2015 +0100
+++ b/hotspot/src/share/vm/gc_implementation/g1/vm_operations_g1.hpp	Fri Feb 13 10:31:52 2015 +0100
@@ -36,10 +36,8 @@
 //     - VM_G1CollectForAllocation
 //     - VM_G1IncCollectionPause
 
-class VM_G1OperationWithAllocRequest: public VM_GC_Operation {
+class VM_G1OperationWithAllocRequest : public VM_CollectForAllocation {
 protected:
-  size_t    _word_size;
-  HeapWord* _result;
   bool      _pause_succeeded;
   AllocationContext_t _allocation_context;
 
@@ -47,9 +45,8 @@
   VM_G1OperationWithAllocRequest(uint           gc_count_before,
                                  size_t         word_size,
                                  GCCause::Cause gc_cause)
-    : VM_GC_Operation(gc_count_before, gc_cause),
-      _word_size(word_size), _result(NULL), _pause_succeeded(false) { }
-  HeapWord* result() { return _result; }
+    : VM_CollectForAllocation(word_size, gc_count_before, gc_cause),
+      _pause_succeeded(false) {}
   bool pause_succeeded() { return _pause_succeeded; }
   void set_allocation_context(AllocationContext_t context) { _allocation_context = context; }
   AllocationContext_t  allocation_context() { return _allocation_context; }

--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/vmPSOperations.cpp	Fri Feb 13 09:48:49 2015 +0100
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/vmPSOperations.cpp	Fri Feb 13 10:31:52 2015 +0100
@@ -32,12 +32,10 @@
 #include "utilities/dtrace.hpp"
 
 // The following methods are used by the parallel scavenge collector
-VM_ParallelGCFailedAllocation::VM_ParallelGCFailedAllocation(size_t size,
+VM_ParallelGCFailedAllocation::VM_ParallelGCFailedAllocation(size_t word_size,
                                                              uint gc_count) :
-  VM_GC_Operation(gc_count, GCCause::_allocation_failure),
-  _size(size),
-  _result(NULL)
-{
+    VM_CollectForAllocation(word_size, gc_count, GCCause::_allocation_failure) {
+  assert(word_size != 0, "An allocation should always be requested with this operation.");
 }
 
 void VM_ParallelGCFailedAllocation::doit() {
@@ -47,7 +45,7 @@
   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "must be a ParallelScavengeHeap");
 
   GCCauseSetter gccs(heap, _gc_cause);
-  _result = heap->failed_mem_allocate(_size);
+  _result = heap->failed_mem_allocate(_word_size);
 
   if (_result == NULL && GC_locker::is_active_and_needs_gc()) {
     set_gc_locked();

--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/vmPSOperations.hpp	Fri Feb 13 09:48:49 2015 +0100
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/vmPSOperations.hpp	Fri Feb 13 10:31:52 2015 +0100
@@ -29,20 +29,14 @@
 #include "gc_implementation/shared/vmGCOperations.hpp"
 #include "gc_interface/gcCause.hpp"
 
-class VM_ParallelGCFailedAllocation: public VM_GC_Operation {
- private:
-  size_t    _size;
-  HeapWord* _result;
-
+class VM_ParallelGCFailedAllocation : public VM_CollectForAllocation {
  public:
-  VM_ParallelGCFailedAllocation(size_t size, uint gc_count);
+  VM_ParallelGCFailedAllocation(size_t word_size, uint gc_count);
 
   virtual VMOp_Type type() const {
     return VMOp_ParallelGCFailedAllocation;
   }
   virtual void doit();
-
-  HeapWord* result() const       { return _result; }
 };
 
 class VM_ParallelGCSystemGC: public VM_GC_Operation {

--- a/hotspot/src/share/vm/gc_implementation/shared/vmGCOperations.cpp	Fri Feb 13 09:48:49 2015 +0100
+++ b/hotspot/src/share/vm/gc_implementation/shared/vmGCOperations.cpp	Fri Feb 13 10:31:52 2015 +0100
@@ -179,10 +179,10 @@
 
   GenCollectedHeap* gch = GenCollectedHeap::heap();
   GCCauseSetter gccs(gch, _gc_cause);
-  _res = gch->satisfy_failed_allocation(_size, _tlab);
-  assert(gch->is_in_reserved_or_null(_res), "result not in heap");
+  _result = gch->satisfy_failed_allocation(_word_size, _tlab);
+  assert(gch->is_in_reserved_or_null(_result), "result not in heap");
 
-  if (_res == NULL && GC_locker::is_active_and_needs_gc()) {
+  if (_result == NULL && GC_locker::is_active_and_needs_gc()) {
     set_gc_locked();
   }
 }

--- a/hotspot/src/share/vm/gc_implementation/shared/vmGCOperations.hpp	Fri Feb 13 09:48:49 2015 +0100
+++ b/hotspot/src/share/vm/gc_implementation/shared/vmGCOperations.hpp	Fri Feb 13 10:31:52 2015 +0100
@@ -38,11 +38,12 @@
 //  VM_Operation
 //      VM_GC_Operation
 //          VM_GC_HeapInspection
-//          VM_GenCollectForAllocation
 //          VM_GenCollectFull
 //          VM_GenCollectFullConcurrent
-//          VM_ParallelGCFailedAllocation
 //          VM_ParallelGCSystemGC
+//          VM_CollectForAllocation
+//              VM_GenCollectForAllocation
+//              VM_ParallelGCFailedAllocation
 //  VM_GC_Operation
 //   - implements methods common to all classes in the hierarchy:
 //     prevents multiple gc requests and manages lock on heap;
@@ -51,6 +52,7 @@
 //   - prints class histogram on SIGBREAK if PrintClassHistogram
 //     is specified; and also the attach "inspectheap" operation
 //
+//  VM_CollectForAllocation
 //  VM_GenCollectForAllocation
 //  VM_ParallelGCFailedAllocation
 //   - this operation is invoked when allocation is failed;
@@ -160,25 +162,34 @@
   bool collect();
 };
 
+class VM_CollectForAllocation : public VM_GC_Operation {
+ protected:
+  size_t    _word_size; // Size of object to be allocated (in number of words)
+  HeapWord* _result;    // Allocation result (NULL if allocation failed)
 
-class VM_GenCollectForAllocation: public VM_GC_Operation {
+ public:
+  VM_CollectForAllocation(size_t word_size, uint gc_count_before, GCCause::Cause cause)
+    : VM_GC_Operation(gc_count_before, cause), _result(NULL), _word_size(word_size) {}
+
+  HeapWord* result() const {
+    return _result;
+  }
+};
+
+class VM_GenCollectForAllocation : public VM_CollectForAllocation {
  private:
-  HeapWord*   _res;
-  size_t      _size;                       // size of object to be allocated.
   bool        _tlab;                       // alloc is of a tlab.
  public:
-  VM_GenCollectForAllocation(size_t size,
+  VM_GenCollectForAllocation(size_t word_size,
                              bool tlab,
                              uint gc_count_before)
-    : VM_GC_Operation(gc_count_before, GCCause::_allocation_failure),
-      _size(size),
+    : VM_CollectForAllocation(word_size, gc_count_before, GCCause::_allocation_failure),
       _tlab(tlab) {
-    _res = NULL;
+    assert(word_size != 0, "An allocation should always be requested with this operation.");
   }
   ~VM_GenCollectForAllocation()  {}
   virtual VMOp_Type type() const { return VMOp_GenCollectForAllocation; }
   virtual void doit();
-  HeapWord* result() const       { return _res; }
 };
 
 // VM operation to invoke a collection of the heap as a