libc segfault in OpenLDAP on guest after upgrade to Proxmox 8

[eit-jc]

After upgrading to Proxmox 8, running 6.2.16-12-pve, a guest running slapd (OpenLdap) experiences segfaults of this service

Message below is after upgrading to the guest to Debian Bookworm (Linux jupiter 6.1.0-12-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.52-1 (2023-09-07) x86_64 GNU/Linux)

2023-09-15T11:50:53.780941+01:00 jupiter kernel: [  950.129323] slapd[1036]: segfault at 1 ip 00007fb398dc60d4 sp 00007fb325be96a0 error 6 in libc.so.6[7fb398d06000+155000] likely on CPU 1 (core 1, socket 0)

The segfault has been seen on 2 hosts in a three host cluster, both running Opteron 6380 CPUs. Guest is configured with 1 socket, 2 cores, CPU set to 'host'.

 

[BobhWasatch]

That is an old CPU and there have been reports in this forum of issues with certain instructions emitted by newer compilers not being supported on it. See for example this thread: https://forum.proxmox.com/threads/p...rking-on-amd-opteron-2427.129613/#post-568822

That thread links to a Debian bug report on the issue.

ETA: You might try a non-host setting for the CPU type of this VM.

 

[eit-jc]

Thank you @BobhWasatch actually coincidentally I did see that there was a pending amd-microcode update on the hosts which might help (Debian have split the non-free repo in two and I hadn't added non-free-firmware). Will keep an eye and feed back if it fixes the problem.

 

[eit-jc]

@BobhWasatch early days but we've not seen the segfault since updating the microcode.

Short summary in case anyone comes across this thread:

- Debian bookworm repositories split out the non-free-firmware from the generic non-free section, requiring a modification to the /etc/apt/sources.list over and above simply changing the distribution version from bullseye to bookworm
- Without adding non-free-firmware, a pending amd microcode (and probably intel microcode is the same) was not installed during the upgrade from Proxmox 7 to 8
- The fix is to add non-free-firmware to the end of the sources.list entry (entries?) and run an apt update/upgrade