Error Dumping trivial systemd service

[adanaila]

I have a relatively trivial systemd service that I am not able to dump, this is on linux kernel 5.15.177 ARM (latest supported branch of 5.15. The service is as follows:

[Unit]
Description=Test Dump service
StartLimitBurst=5
StartLimitIntervalSec=10s

[Service]
ExecStart=/bin/sleep 3600
LimitCORE=infinity
DynamicUser=True

Dump command used:
criu dump -t 56164 -D test_service/ -v3 --external 'mnt[]:s' --enable-external-masters

Error is:
(00.081697) Error (criu/files-reg.c:1790): Can't lookup mount=24 for fd=0 path=/dev/null

criu.log

Any ideas would be greatly appreciated.

[adrianreber]

I guess your systemd service is using some systemd security feature to use a separate mount namespace. Does it work if you remove DynamicUser=True. If you want to use DynamicUser=True you need to specify further options to CRIU about mounts. Just guessing.