--- old/src/hotspot/share/gc/g1/g1CollectedHeap.cpp	2018-11-20 15:09:31.576860296 -0800
+++ new/src/hotspot/share/gc/g1/g1CollectedHeap.cpp	2018-11-20 15:09:31.128860314 -0800
@@ -1573,7 +1573,7 @@
     //    And ReservedSpace calls it 'special'. If we failed to set 'special',
     //    we reserved memory without large page.
     if (os::can_commit_large_page_memory() || rs.special()) {
-      page_size = os::large_page_size();
+      page_size = rs.alignment();
     }
   }
 
@@ -1586,10 +1586,11 @@
   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 = actual_reserved_page_size(rs);
   G1RegionToSpaceMapper* result  =
     G1RegionToSpaceMapper::create_mapper(rs,
                                          size,
-                                         rs.alignment(),
+                                         page_size,
                                          HeapRegion::GrainBytes,
                                          translation_factor,
                                          mtGC);
@@ -1597,7 +1598,7 @@
   os::trace_page_sizes_for_requested_size(description,
                                           size,
                                           preferred_page_size,
-                                          rs.alignment(),
+                                          page_size,
                                           rs.base(),
                                           rs.size());