Re: [PATCH 3/7] Add a UFFD_SECURE flag to the userfaultfd API.

On Wed, Oct 23, 2019 at 04:01:53PM -0700, Andy Lutomirski wrote:

Delivering events through read() is just fine. The problem is when
delivering an event does more than just returning bytes. As far as
I’ve noticed, uffd’s read() just returns bytes as long as FORK is
disabled.

Yes, fork is the only case where read doesn't return bytes.

Moving only the fd creation to a separate syscall would then avoid
involuntary creation of the fd.