Hello Tejun According to Documentation/cgroup-v2.txt, a "domain invalid" cgroup can't have member tasks. And indeed this is generally not permitted. However, someone recently showed me a scenario where a "domain invalid" cgroup can have member processes. See the following example: # mkdir -p /sys/fs/cgroup/unified/grp0/grp1 # sleep 1000 & [1] 10549 # echo 10549 > /sys/fs/cgroup/unified/grp0/grp1/cgroup.procs # echo threaded > /sys/fs/cgroup/unified/grp0/cgroup.type # cat /sys/fs/cgroup/unified/grp0/cgroup.type threaded # cat /sys/fs/cgroup/unified/grp0/grp1/cgroup.type domain invalid # cat /sys/fs/cgroup/unified/grp0/grp1/cgroup.threads 10549 >From the above, we see that the cgroup grp0/grp1 is of type "domain invalid" and has a member thread. This seems to be a violation of the documented rules, and is I assume a bug, since in the above scenario, we are denied from adding further tasks to the grp0/grp1 cgroup: # sleep 2000 & [2] 10553 # echo 10553 > /sys/fs/cgroup/unified/grp0/grp1/cgroup.procs sh: echo: write error: Operation not supported Could you comment please? Thanks, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
