On Tue, Mar 04, 2025 at 06:22:55PM +0100, Oleg Nesterov wrote:
> On 03/04, Christian Brauner wrote:
> >
> > @@ -248,6 +260,37 @@ static long pidfd_info(struct task_struct *task, unsigned int cmd, unsigned long
> > if (copy_from_user(&mask, &uinfo->mask, sizeof(mask)))
> > return -EFAULT;
> >
> > + task = get_pid_task(pid, PIDTYPE_PID);
> > + if (!task) {
> > + if (!(mask & PIDFD_INFO_EXIT))
> > + return -ESRCH;
> > +
> > + if (!current_in_pidns(pid))
> > + return -ESRCH;
> > + }
> > +
> > + if (mask & PIDFD_INFO_EXIT) {
> > + exit_info = READ_ONCE(pidfs_i(inode)->exit_info);
> > + if (exit_info) {
> > +#ifdef CONFIG_CGROUPS
> > + kinfo.cgroupid = exit_info->cgroupid;
> > + kinfo.mask |= PIDFD_INFO_EXIT | PIDFD_INFO_CGROUPID;
> > +#endif
> > + kinfo.exit_code = exit_info->exit_code;
> > + }
>
> Confused... so, without CONFIG_CGROUPS pidfd_info() will never report
> PIDFD_INFO_EXIT in kinfo.mask ?
Fixed.
>
> > --- a/include/uapi/linux/pidfd.h
> > +++ b/include/uapi/linux/pidfd.h
> > @@ -20,6 +20,7 @@
> > #define PIDFD_INFO_PID (1UL << 0) /* Always returned, even if not requested */
> > #define PIDFD_INFO_CREDS (1UL << 1) /* Always returned, even if not requested */
> > #define PIDFD_INFO_CGROUPID (1UL << 2) /* Always returned if available, even if not requested */
> > +#define PIDFD_INFO_EXIT (1UL << 3) /* Always returned if available, even if not requested */
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> The comment doesn't match the "if (mask & PIDFD_INFO_EXIT)" check above...
Also fixed.
