--- old/src/share/vm/memory/metaspace.cpp	2016-11-22 22:27:46.570318227 +0100
+++ new/src/share/vm/memory/metaspace.cpp	2016-11-22 22:27:46.450314373 +0100
@@ -153,7 +153,7 @@
 
   // Map a size to a list index assuming that there are lists
   // for special, small, medium, and humongous chunks.
-  static ChunkIndex list_index(size_t size);
+  ChunkIndex list_index(size_t size);
 
   // Remove the chunk from its freelist.  It is
   // expected to be on one of the _free_chunks[] lists.
@@ -1783,7 +1783,11 @@
   st->print_cr("Sum free chunk total " SIZE_FORMAT "  count " SIZE_FORMAT,
                 sum_free_chunks(), sum_free_chunks_count());
 }
+
 ChunkList* ChunkManager::free_chunks(ChunkIndex index) {
+  assert(index == SpecializedIndex || index == SmallIndex || index == MediumIndex,
+         "Bad index: %d", (int)index);
+
   return &_free_chunks[index];
 }
 
@@ -1887,7 +1891,7 @@
   }
 
   assert((word_size <= chunk->word_size()) ||
-         list_index(chunk->word_size() == HumongousIndex),
+         (list_index(chunk->word_size()) == HumongousIndex),
          "Non-humongous variable sized chunk");
   Log(gc, metaspace, freelist) log;
   if (log.is_debug()) {
@@ -2338,22 +2342,18 @@
 }
 
 ChunkIndex ChunkManager::list_index(size_t size) {
-  switch (size) {
-    case SpecializedChunk:
-      assert(SpecializedChunk == ClassSpecializedChunk,
-             "Need branch for ClassSpecializedChunk");
-      return SpecializedIndex;
-    case SmallChunk:
-    case ClassSmallChunk:
-      return SmallIndex;
-    case MediumChunk:
-    case ClassMediumChunk:
-      return MediumIndex;
-    default:
-      assert(size > MediumChunk || size > ClassMediumChunk,
-             "Not a humongous chunk");
-      return HumongousIndex;
+  if (free_chunks(SpecializedIndex)->size() == size) {
+    return SpecializedIndex;
   }
+  if (free_chunks(SmallIndex)->size() == size) {
+    return SmallIndex;
+  }
+  if (free_chunks(MediumIndex)->size() == size) {
+    return MediumIndex;
+  }
+
+  assert(size > free_chunks(MediumIndex)->size(), "Not a humongous chunk");
+  return HumongousIndex;
 }
 
 void SpaceManager::deallocate(MetaWord* p, size_t word_size) {
@@ -2377,7 +2377,7 @@
 
   // Find the correct list and and set the current
   // chunk for that list.
-  ChunkIndex index = ChunkManager::list_index(new_chunk->word_size());
+  ChunkIndex index = chunk_manager()->list_index(new_chunk->word_size());
 
   if (index != HumongousIndex) {
     retire_current_chunk();
@@ -4013,4 +4013,41 @@
   TestVirtualSpaceNodeTest::test();
   TestVirtualSpaceNodeTest::test_is_available();
 }
+
+// The following test is placed here instead of a gtest / unittest file
+// because the ChunkManager class is only available in this file.
+void ChunkManager_test_list_index() {
+  ChunkManager manager(ClassSpecializedChunk, ClassSmallChunk, ClassMediumChunk);
+
+  // Test previous bug where a query for a humongous class metachunk,
+  // incorrectly matched the non-class medium metachunk size.
+  {
+    assert(MediumChunk > ClassMediumChunk, "Precondition for test");
+
+    ChunkIndex index = manager.list_index(MediumChunk);
+
+    assert(index == HumongousIndex,
+           "Requested size is larger than ClassMediumChunk,"
+           " so should return HumongousIndex. Got index: %d", (int)index);
+  }
+
+  // Check the specified sizes as well.
+  {
+    ChunkIndex index = manager.list_index(ClassSpecializedChunk);
+    assert(index == SpecializedIndex, "Wrong index returned. Got index: %d", (int)index);
+  }
+  {
+    ChunkIndex index = manager.list_index(ClassSmallChunk);
+    assert(index == SmallIndex, "Wrong index returned. Got index: %d", (int)index);
+  }
+  {
+    ChunkIndex index = manager.list_index(ClassMediumChunk);
+    assert(index == MediumIndex, "Wrong index returned. Got index: %d", (int)index);
+  }
+  {
+    ChunkIndex index = manager.list_index(ClassMediumChunk + 1);
+    assert(index == HumongousIndex, "Wrong index returned. Got index: %d", (int)index);
+  }
+}
+
 #endif