command ouput for debugging lxc snapshot hangs

pct enter 142

ps ax 
 PID TTY      STAT   TIME COMMAND
    1 ?        Ss     0:00 init [2]  
  831 ?        Ss     0:00 /sbin/rpcbind -w
  951 ?        Ssl    0:00 /usr/sbin/rsyslogd
 1025 ?        Ss     0:00 /usr/sbin/atd
 1071 ?        Ss     0:00 /usr/sbin/cron
 1086 ?        Ss     0:00 /usr/bin/dbus-daemon --system
 1121 ?        Ss     0:00 /usr/sbin/sshd
 1123 ?        Ss     0:00 nginx: master process /usr/sbin/nginx
 1125 ?        S      0:00 nginx: worker process
 1128 ?        S      0:00 nginx: worker process
 1129 ?        S      0:00 nginx: worker process
 1130 ?        S      0:00 nginx: worker process
 1167 ?        S      0:00 avahi-daemon: running [ct142.local]
 1170 ?        S      0:00 avahi-daemon: chroot helper
 1254 ?        Ss     0:00 /usr/lib/postfix/master
 1258 ?        S      0:00 pickup -l -t unix -u -c
 1259 ?        S      0:00 qmgr -l -t unix -u
 1280 tty1     Ss+    0:00 /sbin/getty --noclear 38400 tty1
 1281 tty2     Ss+    0:00 /sbin/getty --noclear 38400 tty2
 1287 pts/1    S      0:00 /bin/bash
 1288 pts/1    R+     0:00 ps ax

#on the host, iotop run 5s then interrupter with Ctrl-C
root@pve4:~# iotop --batch --only --quiet -qq
 2397 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.01 % [kmmpd-loop0]
 2086 be/4 root        0.00 B/s    7.87 K/s  0.00 %  0.00 % pmxcfs [cfs_loop]
  192 be/3 root        0.00 B/s   15.71 K/s  0.00 %  0.04 % [jbd2/dm-0-8]
    6 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.01 % [kworker/u4:0]
 2086 be/4 root        0.00 B/s    7.85 K/s  0.00 %  0.00 % pmxcfs [cfs_loop]
 2086 be/4 root        0.00 B/s    7.85 K/s  0.00 %  0.00 % pmxcfs [cfs_loop]
    6 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.01 % [kworker/u4:0]
 2086 be/4 root        0.00 B/s   23.57 K/s  0.00 %  0.00 % pmxcfs [cfs_loop]
 2139 be/4 root        0.00 B/s    7.86 K/s  0.00 %  0.00 % pve-firewall
    6 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.01 % [kworker/u4:0]
 2397 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [kmmpd-loop0]
  192 be/3 root        0.00 B/s    0.00 B/s  0.00 %  0.05 % [jbd2/dm-0-8]
 2086 be/4 root        0.00 B/s    7.86 K/s  0.00 %  0.00 % pmxcfs [cfs_loop]
    6 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.01 % [kworker/u4:0]
 2086 be/4 root        0.00 B/s   11.78 K/s  0.00 %  0.00 % pmxcfs [cfs_loop]

zgrep 'blocked for more' /var/log/*
/var/log/kern.log.2.gz:Jan 14 17:16:35 pve4 kernel: [27240.467212] INFO: task polkitd:2004 blocked for more than 120 seconds.
/var/log/kern.log.2.gz:Jan 14 17:18:35 pve4 kernel: [27360.470563] INFO: task polkitd:2004 blocked for more than 120 seconds.
/var/log/syslog.6.gz:Jan 14 17:16:35 pve4 kernel: [27240.467212] INFO: task polkitd:2004 blocked for more than 120 seconds.
/var/log/syslog.6.gz:Jan 14 17:18:35 pve4 kernel: [27360.470563] INFO: task polkitd:2004 blocked for more than 120 seconds.

cat /sys/fs/cgroup/freezer/lxc/142/tasks 
2439
3288
3411
3414
3415
3416
3491
3537
3552
3587
3589
3591
3594
3595
3596
3633
3636
3720
3724
3725
3746
3747

cat /sys/fs/cgroup/freezer/lxc/142/cgroup.procs 
2439
3288
3411
3491
3537
3552
3587
3589
3591
3594
3595
3596
3633
3636
3720
3724
3725
3746
3747