On Tue, Jan 08, 2019 at 11:54:15AM -0600, Serge E. Hallyn wrote: > On Tue, Jan 08, 2019 at 10:53:06AM -0700, Tycho Andersen wrote: > > On Wed, Jan 02, 2019 at 05:16:54PM +0100, Christian Brauner wrote: > > > + /* > > > + * Stop the child so we can inspect whether we have > > > + * recycled pid PID_RECYCLE. > > > + */ > > > + close(pipe_fds[0]); > > > + ret = kill(recycled_pid, SIGSTOP); > > > + close(pipe_fds[1]); > > > + if (ret) { > > > + (void)wait_for_pid(recycled_pid); > > > + _exit(PIDFD_ERROR); > > > + } > > > > Sorry for being late to the party, but I wonder if this whole thing > > couldn't be simplified with /proc/sys/kenrel/ns_last_pid? > > no, bc it's not namespaced :) Huh? It looks like it is... static int pid_ns_ctl_handler(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { struct pid_namespace *pid_ns = task_active_pid_ns(current); struct ctl_table tmp = *table; int ret, next; if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN)) return -EPERM; ... Tycho