diff --git a/kernel/fork.c b/kernel/fork.c
index 135b7a49ad59..c814e590cf76 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1367,9 +1367,6 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
 	sig->oom_score_adj = current->signal->oom_score_adj;
 	sig->oom_score_adj_min = current->signal->oom_score_adj_min;
 
-	sig->has_child_subreaper = current->signal->has_child_subreaper ||
-				   current->signal->is_child_subreaper;
-
 	mutex_init(&sig->cred_guard_mutex);
 
 	return 0;
@@ -1800,6 +1797,13 @@ static __latent_entropy struct task_struct *copy_process(
 
 			p->signal->leader_pid = pid;
 			p->signal->tty = tty_kref_get(current->signal->tty);
+			/*
+			 * Inherit has_child_subreaper flag under the same
+			 * tasklist_lock with adding child to the process tree
+			 * for propagate_has_child_subreaper optimization.
+			 */
+			p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
+							 p->real_parent->signal->is_child_subreaper;
 			list_add_tail(&p->sibling, &p->real_parent->children);
 			list_add_tail_rcu(&p->tasks, &init_task.tasks);
 			attach_pid(p, PIDTYPE_PGID);
diff --git a/kernel/sys.c b/kernel/sys.c
index 842914ef7de4..0e4d566a6f16 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2063,6 +2063,24 @@ static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
 }
 #endif
 
+static int propagate_has_child_subreaper(struct task_struct *p, void *data)
+{
+	/*
+	 * If task has has_child_subreaper - all its decendants
+	 * already have these flag too and new decendants will
+	 * inherit it on fork, skip them.
+	 *
+	 * If we've found child_reaper - skip descendants in
+	 * it's subtree as they will never get out pidns.
+	 */
+	if (p->signal->has_child_subreaper ||
+	    is_child_reaper(task_pid(p)))
+		return 0;
+
+	p->signal->has_child_subreaper = 1;
+	return 1;
+}
+
 SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 		unsigned long, arg4, unsigned long, arg5)
 {
@@ -2214,6 +2232,10 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 		break;
 	case PR_SET_CHILD_SUBREAPER:
 		me->signal->is_child_subreaper = !!arg2;
+		if (!arg2)
+			break;
+
+		walk_process_tree(me, propagate_has_child_subreaper, NULL);
 		break;
 	case PR_GET_CHILD_SUBREAPER:
 		error = put_user(me->signal->is_child_subreaper,