Description of problem:
systemd crashed on ppc64 system. I was running realmd join/leave many times but after a while it stared to fail and it was not possible to start the daemon. I couldn't reproduce again but it might be still worth to report (core file and val/log/messages attached)

Version-Release number of selected component (if applicable):
systemd-206-6.el7.ppc64

How reproducible:
it happened once

Steps to Reproduce:
1. realm join/leave many times

Actual results:
# gdb /usr/lib/systemd/systemd core.4083 
GNU gdb (GDB) Red Hat Enterprise Linux (7.6.1-40.el7)
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "ppc64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /usr/lib/systemd/systemd...Reading symbols from /usr/lib/debug/usr/lib/systemd/systemd.debug...done.
done.
[New LWP 4083]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
Core was generated by `/usr/lib/systemd/systemd --switched-root --system --deserialize 22 '.
Program terminated with signal 11, Segmentation fault.
#0  0x00001fffffc77364 in raise (sig=<optimized out>) at ../nptl/sysdeps/unix/sysv/linux/pt-raise.c:37
37	  return INLINE_SYSCALL (tgkill, 3, pid, THREAD_GETMEM (THREAD_SELF, tid),
Missing separate debuginfos, use: debuginfo-install libattr-2.4.46-10.el7.ppc64 pcre-8.32-7.el7.ppc64 zlib-1.2.7-10.el7.ppc64
(gdb) bt
#0  0x00001fffffc77364 in raise (sig=<optimized out>) at ../nptl/sysdeps/unix/sysv/linux/pt-raise.c:37
#1  0x000000003cf64770 in crash (sig=<optimized out>) at src/core/main.c:144
#2  <signal handler called>
#3  0x000000003cfc7eec in isempty (p=0x201730000000020 <Address 0x201730000000020 out of bounds>) at src/shared/util.h:106
#4  join_path (controller=0x3d0144c8 "systemd", path=0x201730000000020 <Address 0x201730000000020 out of bounds>, suffix=0x3d03eb10 "cgroup.procs", fs=0x3fffe2c559d8)
    at src/shared/cgroup-util.c:454
#5  0x000000003cfc8b10 in cg_enumerate_processes (controller=controller@entry=0x3d00a168 "name=systemd", path=path@entry=0x201730000000020 <Address 0x201730000000020 out of bounds>, 
    _f=_f@entry=0x3fffe2c55a68) at src/shared/cgroup-util.c:50
#6  0x000000003cfc8f80 in cg_is_empty (controller=controller@entry=0x3d00a168 "name=systemd", path=path@entry=0x201730000000020 <Address 0x201730000000020 out of bounds>, 
    ignore_self=ignore_self@entry=true) at src/shared/cgroup-util.c:827
#7  0x000000003cfc91e0 in cg_is_empty_recursive (controller=0x3d00a168 "name=systemd", path=0x201730000000020 <Address 0x201730000000020 out of bounds>, ignore_self=<optimized out>)
    at src/shared/cgroup-util.c:868
#8  0x000000003cfb5b90 in manager_notify_cgroup_empty (m=<optimized out>, cgroup=<optimized out>) at src/core/cgroup.c:741
#9  0x000000003cfa235c in private_bus_message_filter (connection=0x5bcccd70, message=0x5bd6dab0, data=0x5b96c790) at src/core/dbus.c:491
#10 0x00001fffffd30c68 in dbus_connection_dispatch (connection=<optimized out>) at dbus-connection.c:4631
#11 0x000000003cfa31b0 in bus_dispatch (m=0x5b96c790) at src/core/dbus.c:525
#12 0x000000003cf6be7c in manager_loop (m=0x5b96c790) at src/core/manager.c:1816
#13 0x000000003cf6161c in main (argc=<optimized out>, argv=0x3fffe2c56c78) at src/core/main.c:1705