--- old/src/hotspot/share/services/management.cpp	2018-08-07 15:31:27.184934757 +0200
+++ new/src/hotspot/share/services/management.cpp	2018-08-07 15:31:26.801922753 +0200
@@ -713,50 +713,53 @@
 JVM_ENTRY(jobject, jmm_GetMemoryUsage(JNIEnv* env, jboolean heap))
   ResourceMark rm(THREAD);
 
-  // Calculate the memory usage
-  size_t total_init = 0;
-  size_t total_used = 0;
-  size_t total_committed = 0;
-  size_t total_max = 0;
-  bool   has_undefined_init_size = false;
-  bool   has_undefined_max_size = false;
-
-  for (int i = 0; i < MemoryService::num_memory_pools(); i++) {
-    MemoryPool* pool = MemoryService::get_memory_pool(i);
-    if ((heap && pool->is_heap()) || (!heap && pool->is_non_heap())) {
-      MemoryUsage u = pool->get_memory_usage();
-      total_used += u.used();
-      total_committed += u.committed();
+  MemoryUsage usage;
 
-      if (u.init_size() == (size_t)-1) {
-        has_undefined_init_size = true;
-      }
-      if (!has_undefined_init_size) {
-        total_init += u.init_size();
+  if (heap) {
+    usage = Universe::heap()->memory_usage();
+  } else {
+    // Calculate the memory usage by summing up the pools.
+    size_t total_init = 0;
+    size_t total_used = 0;
+    size_t total_committed = 0;
+    size_t total_max = 0;
+    bool   has_undefined_init_size = false;
+    bool   has_undefined_max_size = false;
+
+    for (int i = 0; i < MemoryService::num_memory_pools(); i++) {
+      MemoryPool* pool = MemoryService::get_memory_pool(i);
+      if (pool->is_non_heap()) {
+        MemoryUsage u = pool->get_memory_usage();
+        total_used += u.used();
+        total_committed += u.committed();
+
+        if (u.init_size() == MemoryUsage::undefined_size()) {
+          has_undefined_init_size = true;
+        }
+        if (!has_undefined_init_size) {
+          total_init += u.init_size();
+        }
+
+        if (u.max_size() == MemoryUsage::undefined_size()) {
+          has_undefined_max_size = true;
+        }
+        if (!has_undefined_max_size) {
+          total_max += u.max_size();
+        }
       }
+    }
 
-      if (u.max_size() == (size_t)-1) {
-        has_undefined_max_size = true;
-      }
-      if (!has_undefined_max_size) {
-        total_max += u.max_size();
-      }
+    // if any one of the memory pool has undefined init_size or max_size,
+    // set it to MemoryUsage::undefined_size()
+    if (has_undefined_init_size) {
+      total_init = MemoryUsage::undefined_size();
+    }
+    if (has_undefined_max_size) {
+      total_max = MemoryUsage::undefined_size();
     }
-  }
 
-  // if any one of the memory pool has undefined init_size or max_size,
-  // set it to -1
-  if (has_undefined_init_size) {
-    total_init = (size_t)-1;
+    usage = MemoryUsage(total_init, total_used, total_committed, total_max);
   }
-  if (has_undefined_max_size) {
-    total_max = (size_t)-1;
-  }
-
-  MemoryUsage usage((heap ? InitialHeapSize : total_init),
-                    total_used,
-                    total_committed,
-                    (heap ? Universe::heap()->max_capacity() : total_max));
 
   Handle obj = MemoryService::create_MemoryUsage_obj(usage, CHECK_NULL);
   return JNIHandles::make_local(env, obj());