Re: [PATCH v4 2/4] pidfd: add CLONE_PIDFD_AUTOKILL

[Oleg Nesterov <oleg@redhat.com>]

On 02/23, Oleg Nesterov wrote:
>
> On 02/23, Christian Brauner wrote:
> >
> > @@ -2259,13 +2268,20 @@ __latent_entropy struct task_struct *copy_process(
> >  	 * if the fd table isn't shared).
> >  	 */
> >  	if (clone_flags & CLONE_PIDFD) {
> > -		int flags = (clone_flags & CLONE_THREAD) ? PIDFD_THREAD : 0;
> > +		unsigned flags = PIDFD_STALE;
> > +
> > +		if (clone_flags & CLONE_THREAD)
> > +			flags |= PIDFD_THREAD;
> > +		if (clone_flags & CLONE_PIDFD_AUTOKILL) {
> > +			task_set_no_new_privs(p);
> > +			flags |= PIDFD_AUTOKILL;
> > +		}
> >
> >  		/*
> >  		 * Note that no task has been attached to @pid yet indicate
> >  		 * that via CLONE_PIDFD.
> >  		 */
> > -		retval = pidfd_prepare(pid, flags | PIDFD_STALE, &pidfile);
> > +		retval = pidfd_prepare(pid, flags, &pidfile);
>
> Confused... I think you also need to change pidfs_alloc_file() to restore
> O_TRUNC after do_dentry_open() clears this flag? Just like it curently does
>
> 	pidfd_file->f_flags |= (flags & PIDFD_THREAD);

Aah! please ignore me. Somehow I missed exactly this change in your patch.

Sorry for noise!

Oleg.