diff --git a/test/zdtm/static/session04.c b/test/zdtm/static/session04.c
index 007ebe403..155480ff3 100644
--- a/test/zdtm/static/session04.c
+++ b/test/zdtm/static/session04.c
@@ -2,11 +2,16 @@
 #include <sched.h>
 #include <unistd.h>
 #include <stdlib.h>
+#include <fcntl.h>
+#include <limits.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/wait.h>
 #include <sys/prctl.h>
 #include <sys/user.h>
+#include <sys/mount.h>
+#include <sys/types.h>
+#include <sys/stat.h>
 
 #include "zdtmtst.h"
 
@@ -22,7 +27,7 @@ struct process
 };
 
 struct process *processes;
-int nr_processes = 20;
+int nr_processes = 21;
 int current = 0;
 
 static void cleanup()
@@ -40,6 +45,7 @@ enum commands
 	TEST_SETSID,
 	TEST_DIE,
 	TEST_GETSID,
+	TEST_SETNS,
 };
 
 struct command
@@ -94,6 +100,79 @@ static int make_child(int id, int flags)
 	return cid;
 }
 
+static int open_proc(void)
+{
+	int fd;
+	char proc_mountpoint[] = "session04_proc.XXXXXX";
+
+	if (mkdtemp(proc_mountpoint) == NULL) {
+		pr_perror("mkdtemp failed %s", proc_mountpoint);
+		return -1;
+	}
+
+	if (mount("proc", proc_mountpoint, "proc", MS_MGC_VAL | MS_NOSUID | MS_NOEXEC | MS_NODEV, NULL)) {
+		pr_perror("mount proc failed");
+		rmdir(proc_mountpoint);
+		return -1;
+	}
+
+	fd = open(proc_mountpoint, O_RDONLY | O_DIRECTORY, 0);
+	if (fd < 0)
+		pr_perror("can't open proc");
+
+	if (umount2(proc_mountpoint, MNT_DETACH)) {
+		pr_perror("can't umount proc");
+		goto err_close;
+	}
+
+	if (rmdir(proc_mountpoint)) {
+		pr_perror("can't remove tmp dir");
+		goto err_close;
+	}
+
+	return fd;
+err_close:
+	if (fd >= 0)
+		close(fd);
+	return -1;
+}
+
+static int open_pidns(int pid)
+{
+	int proc, fd;
+	char pidns_path[PATH_MAX];
+
+	proc = open_proc();
+	if (proc < 0) {
+		pr_err("open proc");
+		return -1;
+	}
+
+	sprintf(pidns_path, "%d/ns/pid", pid);
+	fd = openat(proc, pidns_path, O_RDONLY);
+	if (fd == -1)
+		pr_err("open pidns fd");
+
+	close(proc);
+	return fd;
+}
+
+static int setns_pid(int pid, int nstype)
+{
+	int pidns, ret;
+
+	pidns = open_pidns(pid);
+	if (pidns < 0)
+		return -1;
+
+	ret = setns(pidns, nstype);
+	if (ret == -1)
+		pr_perror("setns");
+
+	close(pidns);
+	return ret;
+}
+
 static void handle_command()
 {
 	int sk = processes[current].sks[0], ret, status = 0;
@@ -150,6 +229,12 @@ static void handle_command()
 		if(status == -1)
 			pr_perror("getsid");
 		break;
+	case TEST_SETNS:
+		test_msg("%3d: setns(%d, %d) = %d\n", current,
+				cmd.arg1, cmd.arg2, processes[cmd.arg1].pid);
+		setns_pid(processes[cmd.arg1].pid, cmd.arg2);
+
+		break;
 	case TEST_DIE:
 		test_msg("%3d: die()\n", current);
 		processes[current].dead = 1;
@@ -264,6 +349,39 @@ int main(int argc, char ** argv)
 	send_command(7, TEST_DIE,	0, 0);
 	send_command(6, TEST_WAIT,	7, 0);
 
+	/*
+	 * Branch of (11,10) - [(12,12)->(13,10)] reparents to init (1,1),
+	 * have session leader but it is not reachable, and branch of
+	 * (16,15) - [(17,15)] reparents to init of second pidns (14,14),
+	 * so have session leader in other pidns.
+	 */
+	send_command(1, TEST_FORK,	10, 0);
+	send_command(10, TEST_SETSID,	0, 0);
+	send_command(10, TEST_FORK,	11, 0);
+	send_command(11, TEST_FORK,	12, 0);
+	send_command(12, TEST_FORK,	13, 0);
+	send_command(12, TEST_SETSID,	0, 0);
+	send_command(12, TEST_FORK,	14, CLONE_NEWPID);
+	send_command(1, TEST_FORK,	15, 0);
+	send_command(15, TEST_SETSID,	0, 0);
+	send_command(15, TEST_SETNS,	14, CLONE_NEWPID);
+	send_command(15, TEST_FORK,	16, 0);
+	send_command(16, TEST_FORK,	17, 0);
+	send_command(11, TEST_DIE,	0, 0);
+	send_command(10, TEST_WAIT,	11, 0);
+	send_command(16, TEST_DIE,	0, 0);
+	send_command(15, TEST_WAIT,	16, 0);
+
+	/*
+	 * Add session 15's adopted representative to third pidns
+	 */
+	send_command(1, TEST_FORK,	18, CLONE_NEWPID);
+	send_command(15, TEST_SETNS,	18, CLONE_NEWPID);
+	send_command(15, TEST_FORK,	19, 0);
+	send_command(19, TEST_FORK,	20, 0);
+	send_command(19, TEST_DIE,	0, 0);
+	send_command(15, TEST_WAIT,	19, 0);
+
 	for (i = 0; i < nr_processes; i++) {
 		if (processes[i].dead)
 			continue;