On 05/17, Aleksa Sarai wrote:

On 2019-05-16, Oleg Nesterov [off-list ref] wrote:

quoted

On 05/16, Christian Brauner wrote:

quoted

With the introduction of pidfds through CLONE_PIDFD it is possible to
created pidfds at process creation time.

Now I am wondering why do we need CLONE_PIDFD, you can just do

	pid = fork();
	pidfd_open(pid);

While the race window would be exceptionally short, there is the
possibility that the child will die

Yes,

and their pid will be recycled
before you do pidfd_open().

No.

Unless the caller's sub-thread does wait() before pidfd_open(), of course.
Or unless you do signal(SIGCHILD, SIG_IGN).

Oleg.