| Summary: | Some cgroups cleared of processes on daemon-reload. | ||
|---|---|---|---|
| Product: | systemd | Reporter: | xstill |
| Component: | general | Assignee: | systemd-bugs |
| Status: | RESOLVED NOTABUG | QA Contact: | systemd-bugs |
| Severity: | normal | ||
| Priority: | medium | CC: | xstill |
| Version: | unspecified | ||
| Hardware: | All | ||
| OS: | Linux (All) | ||
| Whiteboard: | |||
| i915 platform: | i915 features: | ||
systemd manages the cgroup hierarchy and moves processes around in it, that is expected. The only places where it's OK to manipulate the tree directly is: a) when you run in a service or scope with Delegate=yes b) on controller hierarchies systemd doesn't manager c) when you stick to changing attributes systemd doesn't support natively, but don't touch the hiearchy or process assignemnts. Other than that the cgroup tree is a single-writer hierarchy. if you modify it overriding what systemd does you are on your own |
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Hi, When I create cgroups using filesystem interface and add some processes into them, and later do 'systemctl daemon-reload' and 'systemctl start multi-user.target', in some hierarchies processes are moved from those cgroups, while in other processes stay (no cgroups are deleted though). Here is a way to reproduce this behavior: # systemctl --version systemd 217 +PAM -AUDIT -SELINUX +IMA -APPARMOR +SMACK -SYSVINIT +UTMP -LIBCRYPTSETUP +GCRYPT -GNUTLS +ACL +XZ -LZ4 -SECCOMP +BLKID -ELFUTILS +KMOD -IDN # mkdir /sys/fs/cgroup/{blkio,cpu,cpuset,devices,freezer,memory,net_cls}/group # echo 0-3 > /sys/fs/cgroup/cpuset/group/cpuset.cpus # echo 0 > /sys/fs/cgroup/cpuset/group/cpuset.mems # echo $$ | tee /sys/fs/cgroup/{blkio,cpu,cpuset,devices,freezer,memory,net_cls}/group/tasks 19823 # for t in /sys/fs/cgroup/{blkio,cpu,cpuset,devices,freezer,memory,net_cls}/group/tasks; do echo $t; cat $t; done /sys/fs/cgroup/blkio/group/tasks 19823 20019 /sys/fs/cgroup/cpu/group/tasks 19823 20020 /sys/fs/cgroup/cpuset/group/tasks 19823 20021 /sys/fs/cgroup/devices/group/tasks 19823 20022 /sys/fs/cgroup/freezer/group/tasks 19823 20023 /sys/fs/cgroup/memory/group/tasks 19823 20024 /sys/fs/cgroup/net_cls/group/tasks 19823 20025 # systemctl daemon-reload # systemctl start multi-user.target # for t in /sys/fs/cgroup/{blkio,cpu,cpuset,devices,freezer,memory,net_cls}/group/tasks; do echo $t; cat $t; done /sys/fs/cgroup/blkio/group/tasks /sys/fs/cgroup/cpu/group/tasks /sys/fs/cgroup/cpuset/group/tasks 19823 20041 /sys/fs/cgroup/devices/group/tasks /sys/fs/cgroup/freezer/group/tasks 19823 20043 /sys/fs/cgroup/memory/group/tasks /sys/fs/cgroup/net_cls/group/tasks 19823 20045 I have read some bug reports regarding cg_trim behavior, especially https://bugzilla.redhat.com/show_bug.cgi?id=1139223 which might be related, but the difference is that 1) cgroups are not deleted, processes are just moved away from them 2) in this case cgroups are created manually 3) different hierarchies behave differently This is big problem when using cgroups to limit user resources, not resources of systemd units.