By the way, there is a note in the "Change History" section of the msync() documentation at http://pubs.opengroup.org/onlinepubs/9699919799/

    The second [EINVAL] error condition is made mandatory.

The second EINVAL error condition they mention is:

    [EINVAL] The value of addr is not a multiple of the page size as returned by sysconf().

So unless I'm missing something obvious, the "the msync() function may fail if" part may now be outdated?

Also, I noticed that we don't have tests for mm.flush(offset) and mm.flush(offset, size) cases. It would be nice to add some tests even if we decide to not merge the documentation PR.