On Tue, Nov 5, 2019 at 8:24 AM Andrea Arcangeli <aarcange@xxxxxxxxxx> wrote: > The long term plan is to introduce UFFD_FEATURE_EVENT_FORK2 feature > flag that uses the ioctl to receive the child uffd, it'll consume more > CPU, but it wouldn't require the PTRACE privilege anymore. Why not just have callers retrieve FDs using recvmsg? This way, you retrieve the message packet and the file descriptor at the same time and you don't need any appreciable extra CPU use.