This patch has been successfully tested. Try to allocate some 2M
hugepages in the host, then boot up a VM with the memory size
unaligned and backed by a file, QEMU prompts the following message:
qemu-system-x86_64: backend 'memory-backend-file' memory size must be
multiple of 2 MiB
Tested-by: Mari
If memory-backend-{file,ram} has a size that's not aligned to
underlying page size it is not only wasteful, but also may lead
to hard to debug behaviour. For instance, in case
memory-backend-file and hugepages, madvise() and mbind() fail.
Rightfully so, page is the smallest unit they can work with.
