1 files changed, 38 insertions, 19 deletions

diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index db95d8eb761..a65ba137fd1 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -105,9 +105,10 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
 	if (ns->pid_cachep == NULL)
 		goto out_free_map;
 
-	err = proc_alloc_inum(&ns->proc_inum);
+	err = ns_alloc_inum(&ns->ns);
 	if (err)
 		goto out_free_map;
+	ns->ns.ops = &pidns_operations;
 
 	kref_init(&ns->kref);
 	ns->level = level;
@@ -142,7 +143,7 @@ static void destroy_pid_namespace(struct pid_namespace *ns)
 {
 	int i;
 
-	proc_free_inum(ns->proc_inum);
+	ns_free_inum(&ns->ns);
 	for (i = 0; i < PIDMAP_ENTRIES; i++)
 		kfree(ns->pidmap[i].page);
 	put_user_ns(ns->user_ns);
@@ -190,7 +191,11 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
 	/* Don't allow any more processes into the pid namespace */
 	disable_pid_allocation(pid_ns);
 
-	/* Ignore SIGCHLD causing any terminated children to autoreap */
+	/*
+	 * Ignore SIGCHLD causing any terminated children to autoreap.
+	 * This speeds up the namespace shutdown, plus see the comment
+	 * below.
+	 */
 	spin_lock_irq(&me->sighand->siglock);
 	me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
 	spin_unlock_irq(&me->sighand->siglock);
@@ -223,15 +228,31 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
 	}
 	read_unlock(&tasklist_lock);
 
-	/* Firstly reap the EXIT_ZOMBIE children we may have. */
+	/*
+	 * Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD.
+	 * sys_wait4() will also block until our children traced from the
+	 * parent namespace are detached and become EXIT_DEAD.
+	 */
 	do {
 		clear_thread_flag(TIF_SIGPENDING);
 		rc = sys_wait4(-1, NULL, __WALL, NULL);
 	} while (rc != -ECHILD);
 
 	/*
-	 * sys_wait4() above can't reap the TASK_DEAD children.
-	 * Make sure they all go away, see free_pid().
+	 * sys_wait4() above can't reap the EXIT_DEAD children but we do not
+	 * really care, we could reparent them to the global init. We could
+	 * exit and reap ->child_reaper even if it is not the last thread in
+	 * this pid_ns, free_pid(nr_hashed == 0) calls proc_cleanup_work(),
+	 * pid_ns can not go away until proc_kill_sb() drops the reference.
+	 *
+	 * But this ns can also have other tasks injected by setns()+fork().
+	 * Again, ignoring the user visible semantics we do not really need
+	 * to wait until they are all reaped, but they can be reparented to
+	 * us and thus we need to ensure that pid->child_reaper stays valid
+	 * until they all go away. See free_pid()->wake_up_process().
+	 *
+	 * We rely on ignored SIGCHLD, an injected zombie must be autoreaped
+	 * if reparented.
 	 */
 	for (;;) {
 		set_current_state(TASK_UNINTERRUPTIBLE);
@@ -313,7 +334,12 @@ int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
 	return 0;
 }
 
-static void *pidns_get(struct task_struct *task)
+static inline struct pid_namespace *to_pid_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct pid_namespace, ns);
+}
+
+static struct ns_common *pidns_get(struct task_struct *task)
 {
 	struct pid_namespace *ns;
 
@@ -323,18 +349,18 @@ static void *pidns_get(struct task_struct *task)
 		get_pid_ns(ns);
 	rcu_read_unlock();
 
-	return ns;
+	return ns ? &ns->ns : NULL;
 }
 
-static void pidns_put(void *ns)
+static void pidns_put(struct ns_common *ns)
 {
-	put_pid_ns(ns);
+	put_pid_ns(to_pid_ns(ns));
 }
 
-static int pidns_install(struct nsproxy *nsproxy, void *ns)
+static int pidns_install(struct nsproxy *nsproxy, struct ns_common *ns)
 {
 	struct pid_namespace *active = task_active_pid_ns(current);
-	struct pid_namespace *ancestor, *new = ns;
+	struct pid_namespace *ancestor, *new = to_pid_ns(ns);
 
 	if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
 	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
@@ -362,19 +388,12 @@ static int pidns_install(struct nsproxy *nsproxy, void *ns)
 	return 0;
 }
 
-static unsigned int pidns_inum(void *ns)
-{
-	struct pid_namespace *pid_ns = ns;
-	return pid_ns->proc_inum;
-}
-
 const struct proc_ns_operations pidns_operations = {
 	.name		= "pid",
 	.type		= CLONE_NEWPID,
 	.get		= pidns_get,
 	.put		= pidns_put,
 	.install	= pidns_install,
-	.inum		= pidns_inum,
 };
 
 static __init int pid_namespaces_init(void)