cgroup/cpuset: Preserve boot-isolated CPUs on partition release

isolated_cpus tracks CPUs isolated with isolcpus= as well as CPUs in
isolated cpuset partitions. When an isolated partition is released,
isolated_cpus_update() removes its whole CPU mask. This also clears CPUs
which were already isolated at boot.

This can be reproduced on a cgroup v2 system booted with
isolcpus=domain,15:

    cd /sys/fs/cgroup
    echo +cpuset > cgroup.subtree_control
    mkdir cpuset-repro
    echo 15 > cpuset-repro/cpuset.cpus
    echo isolated > cpuset-repro/cpuset.cpus.partition
    echo member > cpuset-repro/cpuset.cpus.partition
    cat cpuset.cpus.isolated

CPU 15 is absent before the change. It must remain in
cpuset.cpus.isolated after the partition is released.

Update isolated_cpus one CPU at a time and keep CPUs outside the
boot-time domain housekeeping mask isolated.

Fixes: c188f33c864e ("cgroup/cpuset: Account for boot time isolated CPUs")
Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

0 files changed, 0 insertions, 0 deletions