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

Browse source

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: c188f33c86 ("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>

...

This commit is contained in:

Guopeng Zhang 2026-08-24 10:01:39 +08:00 • committed by Tejun Heo

parent 2bf404b1bd

commit 6c37d7e074

1 changed files with 29 additions and 10 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

39

kernel/cgroup/cpuset.c

View file