Merge patch series "Improve pid_nr_ns()"

In various places pid_nr_ns() can be called with a NULL pointer.
Fix those up and improve pid_nr_ns() callers.

Link: https://lore.kernel.org/20250802022123.3536934-1-gxxa03070307@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: brauner

fs/proc/array.c

@@ -157,13 +157,11 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
 	unsigned int max_fds = 0;
 
 	rcu_read_lock();
-	ppid = pid_alive(p) ?
-		task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
-
 	tracer = ptrace_parent(p);
 	if (tracer)
 		tpid = task_pid_nr_ns(tracer, ns);
 
+	ppid = task_ppid_nr_ns(p, ns);
 	tgid = task_tgid_nr_ns(p, ns);
 	ngid = task_numa_group_id(p);
 	cred = get_task_cred(p);

kernel/pid.c

@@ -491,7 +491,7 @@ pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
 	struct upid *upid;
 	pid_t nr = 0;
 
-	if (pid && ns->level <= pid->level) {
+	if (pid && ns && ns->level <= pid->level) {
 		upid = &pid->numbers[ns->level];
 		if (upid->ns == ns)
 			nr = upid->nr;
@@ -514,7 +514,8 @@ pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
 	rcu_read_lock();
 	if (!ns)
 		ns = task_active_pid_ns(current);
-	nr = pid_nr_ns(rcu_dereference(*task_pid_ptr(task, type)), ns);
+	if (ns)
+		nr = pid_nr_ns(rcu_dereference(*task_pid_ptr(task, type)), ns);
 	rcu_read_unlock();
 
 	return nr;

kernel/tsacct.c

@@ -57,12 +57,11 @@ void bacct_add_tsk(struct user_namespace *user_ns,
 	stats->ac_sched	 = tsk->policy;
 	stats->ac_pid	 = task_pid_nr_ns(tsk, pid_ns);
 	stats->ac_tgid   = task_tgid_nr_ns(tsk, pid_ns);
+	stats->ac_ppid	 = task_ppid_nr_ns(tsk, pid_ns);
 	rcu_read_lock();
 	tcred = __task_cred(tsk);
 	stats->ac_uid	 = from_kuid_munged(user_ns, tcred->uid);
 	stats->ac_gid	 = from_kgid_munged(user_ns, tcred->gid);
-	stats->ac_ppid	 = pid_alive(tsk) ?
-		task_tgid_nr_ns(rcu_dereference(tsk->real_parent), pid_ns) : 0;
 	rcu_read_unlock();
 
 	task_cputime(tsk, &utime, &stime);