diff --git a/include/linux/sched.h b/include/linux/sched.h
index 848d1f20086e..9e5a88afe6be 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2059,6 +2059,7 @@ extern int kill_pgrp(struct pid *pid, int sig, int priv);
 extern int kill_pid(struct pid *pid, int sig, int priv);
 extern int kill_proc_info(int, struct siginfo *, pid_t);
 extern int do_notify_parent(struct task_struct *, int);
+extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
 extern void force_sig(int, struct task_struct *);
 extern void force_sig_specific(int, struct task_struct *);
 extern int send_sig(int, struct task_struct *, int);
diff --git a/kernel/exit.c b/kernel/exit.c
index 60d6fdcc9265..782b2e1f7ca2 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1575,6 +1575,11 @@ static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
 	return 0;
 }
 
+void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
+{
+	wake_up_interruptible_sync(&parent->signal->wait_chldexit);
+}
+
 static long do_wait(struct wait_opts *wo)
 {
 	DECLARE_WAITQUEUE(wait, current);
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 307c285af59e..23bd09cd042e 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -266,9 +266,10 @@ static int ignoring_children(struct sighand_struct *sigh)
  * or self-reaping.  Do notification now if it would have happened earlier.
  * If it should reap itself, return true.
  *
- * If it's our own child, there is no notification to do.
- * But if our normal children self-reap, then this child
- * was prevented by ptrace and we must reap it now.
+ * If it's our own child, there is no notification to do. But if our normal
+ * children self-reap, then this child was prevented by ptrace and we must
+ * reap it now, in that case we must also wake up sub-threads sleeping in
+ * do_wait().
  */
 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
 {
@@ -278,8 +279,10 @@ static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
 		if (!task_detached(p) && thread_group_empty(p)) {
 			if (!same_thread_group(p->real_parent, tracer))
 				do_notify_parent(p, p->exit_signal);
-			else if (ignoring_children(tracer->sighand))
+			else if (ignoring_children(tracer->sighand)) {
+				__wake_up_parent(p, tracer);
 				p->exit_signal = -1;
+			}
 		}
 		if (task_detached(p)) {
 			/* Mark it as in the process of being reaped. */
diff --git a/kernel/signal.c b/kernel/signal.c
index 64c5deeaca5d..534ea81cde47 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1382,15 +1382,6 @@ ret:
 	return ret;
 }
 
-/*
- * Wake up any threads in the parent blocked in wait* syscalls.
- */
-static inline void __wake_up_parent(struct task_struct *p,
-				    struct task_struct *parent)
-{
-	wake_up_interruptible_sync(&parent->signal->wait_chldexit);
-}
-
 /*
  * Let a parent know about the death of a child.
  * For a stopped/continued status change, use do_notify_parent_cldstop instead.