Merge tag 'for-linus-20190730' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

Pull pidfd fixes from Christian Brauner:
 "This makes setting the exit_state in exit_notify() consistent after
  fixing the pidfd polling race pre-rc1. Related to the race fix, this
  adds a WARN_ON() to do_notify_pidfd() to catch any future exit_state
  races.

  Last, this removes an obsolete comment from the pidfd tests"

* tag 'for-linus-20190730' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  exit: make setting exit_state consistent
  pidfd: Add warning if exit_state is 0 during notification
  pidfd: remove obsolete comments from test

kernel/exit.c

@@ -734,9 +734,10 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
 		autoreap = true;
 	}
 
-	tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
-	if (tsk->exit_state == EXIT_DEAD)
+	if (autoreap) {
+		tsk->exit_state = EXIT_DEAD;
 		list_add(&tsk->ptrace_entry, &dead);
+	}
 
 	/* mt-exec, de_thread() is waiting for group leader */
 	if (unlikely(tsk->signal->notify_count < 0))

kernel/signal.c

@@ -1885,6 +1885,7 @@ static void do_notify_pidfd(struct task_struct *task)
 {
 	struct pid *pid;
 
+	WARN_ON(task->exit_state == 0);
 	pid = task_pid(task);
 	wake_up_all(&pid->wait_pidfd);
 }

tools/testing/selftests/pidfd/pidfd_test.c

@@ -339,13 +339,9 @@ static int test_pidfd_send_signal_syscall_support(void)
 
 	ret = sys_pidfd_send_signal(pidfd, 0, NULL, 0);
 	if (ret < 0) {
-		/*
-		 * pidfd_send_signal() will currently return ENOSYS when
-		 * CONFIG_PROC_FS is not set.
-		 */
 		if (errno == ENOSYS)
 			ksft_exit_skip(
-				"%s test: pidfd_send_signal() syscall not supported (Ensure that CONFIG_PROC_FS=y is set)\n",
+				"%s test: pidfd_send_signal() syscall not supported\n",
 				test_name);
 
 		ksft_exit_fail_msg("%s test: Failed to send signal\n",