https://github.com/openjdk/jdk/blob/f71f9dc93a6963ce36953e0ad770edd761afd0b4/src/hotspot/share/gc/parallel/parallelScavengeHeap.cpp#L87

When JDK-8202286 (Allocation of old generation of Java heap on alternate memory devices) is enabled, we call ReservedSpace::first_part with (split == true). 

ReservedSpace::first_part() calls os::split_reserved_memory, which, on Windows, would release the space and try to reserve it again as two spaces. However, due to change in overall system memory pressure, the reservation attempts may fail.

https://github.com/openjdk/jdk/blob/1332ba3c3c168d9fa368338e451c8c20a4c47ccc/src/hotspot/share/memory/virtualspace.cpp#L258

ReservedSpace ReservedSpace::first_part(size_t partition_size, size_t alignment, bool split) {
  assert(partition_size <= size(), "partition failed");
  if (split && partition_size > 0 && partition_size < size()) {
    os::split_reserved_memory(base(), size(), partition_size);
  }
  ReservedSpace result(base(), partition_size, alignment, special(),
                       executable());
  return result;
}

https://github.com/openjdk/jdk/blob/1332ba3c3c168d9fa368338e451c8c20a4c47ccc/src/hotspot/os/windows/os_windows.cpp#L3120

void os::split_reserved_memory(char *base, size_t size, size_t split) {
   ...
  release_memory(base, size);
  attempt_reserve_memory_at(base, split);
  attempt_reserve_memory_at(split_address, size - split);