Re: unable to attach pid to service delegated directory in unified mode after restart

[Felip Moll <felip@xxxxxxxxxxx>]

On Wed, Mar 16, 2022 at 6:29 PM Felip Moll <felip@xxxxxxxxxxx> wrote:

On Wed, Mar 16, 2022 at 5:53 PM Lennart Poettering <lennart@xxxxxxxxxxxxxx> wrote:

On Mi, 16.03.22 17:30, Felip Moll (felip@xxxxxxxxxxx) wrote:

> AFAIK RemainAfterExit for services actually does cleanup the cgroup tree if
> there are no more processes in it.

It doesn't do that if delegation is on (iirc, if not I'd consider that
a bug). Same logic should apply here.

I will recheck that, but I am quite sure that on some tests I did the cgroup was cleaned up on a delegated service after the main pid terminated.

Is that a bug then?

1. Start a service with Delegate=yes and RemainAfterExit

2. Wait for the main process to start

3. Check that the unit is still active

4. Check that the cgroup is still there <--- It is gone when no pids in it

]# systemd-run -u test -p "Delegate=yes" -p "RemainAfterExit=yes" sleep 60
Running as unit: test.service
]# systemctl status test.service
● test.service - /usr/bin/sleep 60
     Loaded: loaded (/run/systemd/transient/test.service; transient)
  Transient: yes
     Active: active (running) since Fri 2022-03-18 09:47:32 CET; 5s ago
   Main PID: 6083 (sleep)
      Tasks: 1 (limit: 14068)
     Memory: 316.0K
     CGroup: /system.slice/test.service
             └─6083 /usr/bin/sleep 60

de març 18 09:47:32 llagosti systemd[1]: Started /usr/bin/sleep 60.
]# cat /proc/6083/cgroup
12:perf_event:/
11:pids:/system.slice/test.service
10:devices:/system.slice/test.service
9:cpuset:/
8:blkio:/system.slice/test.service
7:net_cls,net_prio:/
6:memory:/system.slice/test.service
5:misc:/
4:cpu,cpuacct:/system.slice/test.service
3:hugetlb:/
2:freezer:/
1:name=systemd:/system.slice/test.service
0::/system.slice/test.service
]# ls /sys/fs/cgroup/memory/system.slice/test.service/
cgroup.clone_children  memory.kmem.failcnt             memory.kme.......

......
[root@llagosti slurm.gitlab.lipixx]# systemctl status test.service
● test.service - /usr/bin/sleep 60
     Loaded: loaded (/run/systemd/transient/test.service; transient)
  Transient: yes
     Active: active (exited) since Fri 2022-03-18 09:47:32 CET; 1min 21s ago
    Process: 6083 ExecStart=/usr/bin/sleep 60 (code=exited, status=0/SUCCESS)
   Main PID: 6083 (code=exited, status=0/SUCCESS)

de març 18 09:47:32 llagosti systemd[1]: Started /usr/bin/sleep 60.
]# ls /sys/fs/cgroup/memory/system.slice/test.service/
ls: cannot access '/sys/fs/cgroup/memory/system.slice/test.service/': No such file or directory
]# systemctl cat test.service
# /run/systemd/transient/test.service
# This is a transient unit file, created programmatically via the systemd API. Do not edit.
[Unit]
Description=/usr/bin/sleep 60

[Service]
Delegate=yes
RemainAfterExit=yes
ExecStart=
ExecStart="/usr/bin/sleep" "60"