Ensure zero's are written to backing store of at least one page size and sync it so that we can be 100% sure that mmap'ing the page into memory is backed with data so we don't get BUS errors on some platforms such as armhf Raspi2.
Ensure zero's are written to backing store of at least one page size and sync it so that we can be 100% sure that mmap'ing the page into memory is backed with data so we don't get BUS errors on some platforms such as armhf Raspi2.