Created attachment 16797 [details]
sample log.smbd when running AD-DC in a LXC container

When running an AD-DC in a LXC container (Proxmox PVE 6.4-13), smbd panics and dumps core every minute or so:

-----------------------------------------------------------
[2021/09/03 19:45:08.216929,  0] ../../lib/util/fault.c:173(smb_panic_log)
  INTERNAL ERROR: sys_setgroups failed in pid 1373 (4.14.7)
[2021/09/03 19:45:08.217030,  0] ../../lib/util/fault.c:177(smb_panic_log)
  If you are running a recent Samba version, and if you think this problem is not yet fixed in the latest versions, please consider reporting this bug, see https://wiki.samba.org/index.php/Bug_Reporting
[2021/09/03 19:45:08.217146,  0] ../../lib/util/fault.c:182(smb_panic_log)
  ===============================================================
[2021/09/03 19:45:08.217250,  0] ../../lib/util/fault.c:183(smb_panic_log)
  PANIC (pid 1373): sys_setgroups failed in 4.14.7
-----------------------------------------------------------

See the attached sample of /var/log/samba/log.smbd for more details.

Additional information:

[root@sdch ~]# uname -a
Linux sdch 5.4.128-1-pve #1 SMP PVE 5.4.128-1 (Wed, 21 Jul 2021 18:32:02 +0200) x86_64 GNU/Linux
[root@sdch ~]# samba -V
Version 4.14.7

The OS is Arch Linux, up-to-date as of September 4, 2021.

This issue is not observed on a member server that is part of the same AD running in a LXC container.

This issue is not observed when an AD-DC runs in a VM on the same Proxmox PVE host.

In other words, the issue appears to be specific only to DCs running in a LXC container.


A somewhat similar issue was described in 2016: https://techblog.devlat.eu/2016/10/05/ubuntu-lxd-samba-and-the-dreaded-sys_setgroups-failed-error/  However, unlike in that report, changing the contents of /etc/subuid and /etc/subgid from "root:100000:65536" to "root:100000:10000000" did not fix the issue.