Description of problem:

The reason is deadlock. In the createUser of anaconda, fork a child process. When the child process calls libuser.admin(), the deadlock causes the thread to block.

# pstack processid
#0  pthread_rwlock_wrlock () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_rwlock_wrlock.S:85
#1  0x00007f39e4ced975 in set_binding_values (...) at bindtextdom.c:117
#2  __bindtextdomain (...) at bindtextdom.c:348
#3  0x00007f39cdfe1a5e in lu_start (...) at lib/user.c:110
#4  0x00007f39ce1f378c in libuser_admin_new (...) at python/admin.c:1593
#9  PyEval_EvalFrameEx (f=f@entry=Frame 0x564c3c4e40e0, for file /usr/lib64/python2.7/site-packages/pyanaconda/users.py, line 554, in createUser 

Because _nl_state_lock is locked.
(gdb) p _nl_state_lock
$1 = {__data = {__lock = 0, __nr_readers = 1, __readers_wakeup = 0, __writer_wakeup = 0, __nr_readers_queued = 0, __nr_writers_queued = 1, __writer = 0, __shared = 0, __pad1 = 0...

That's because anaconda is multi-threaded. In a sub-thread, fork the child process. Since _nl_state_lock is a global variable lock, it may cause the child process to deadlock.

we should not use fork in /pyanaconda/users.py, which will cause a deadlock.
The later version of anaconda has got rid of libuser. if i want to continue using libuser, how to fix this problem.

Version-Release number of selected component (if applicable):
anaconda-21.48.22.134

How reproducible:
Occasionally

Steps to Reproduce:
1.
2.
3.

Actual results:


Expected results:


Additional info:
users.py code is below:
    def _prepareChroot(self, root):
        # Unfortunately libuser doesn't have an API to operate on a
        # chroot, so we hack it here by forking a child and calling
        # chroot() in that child's context.

        childpid = os.fork()
        if not childpid:
            if not root in ["","/"]:
                os.chroot(root)
                os.chdir("/")
                # This is ok because it's after a fork
                del(os.environ["LIBUSER_CONF"]) # pylint: disable=environment-modify

            self.admin = libuser.admin()

        return childpid