--- old/src/hotspot/share/gc/g1/g1CollectedHeap.cpp	2018-11-08 13:48:39.894374977 -0800
+++ new/src/hotspot/share/gc/g1/g1CollectedHeap.cpp	2018-11-08 13:48:39.450374995 -0800
@@ -1570,10 +1570,11 @@
   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
   // Allocate a new reserved space, preferring to use large pages.
   ReservedSpace rs(size, preferred_page_size);
+  size_t page_size = rs.actual_page_size();
   G1RegionToSpaceMapper* result  =
     G1RegionToSpaceMapper::create_mapper(rs,
                                          size,
-                                         rs.alignment(),
+                                         page_size,
                                          HeapRegion::GrainBytes,
                                          translation_factor,
                                          mtGC);
@@ -1581,7 +1582,7 @@
   os::trace_page_sizes_for_requested_size(description,
                                           size,
                                           preferred_page_size,
-                                          rs.alignment(),
+                                          page_size,
                                           rs.base(),
                                           rs.size());
 
@@ -1658,7 +1659,7 @@
 
   // Carve out the G1 part of the heap.
   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
-  size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
+  size_t page_size = heap_rs.actual_page_size();
   G1RegionToSpaceMapper* heap_storage =
     G1RegionToSpaceMapper::create_mapper(g1_rs,
                                          g1_rs.size(),