cgroup/cpuset: Fail if isolated and nohz_full don't leave any housekeeping

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Currently the user can set up isolated cpus via cpuset and nohz_full in
such a way that leaves no housekeeping CPU (i.e. no CPU that is neither
domain isolated nor nohz full). This can be a problem for other
subsystems (e.g. the timer wheel imgration).

Prevent this configuration by blocking any assignation that would cause
the union of domain isolated cpus and nohz_full to covers all CPUs.

[longman: Remove isolated_cpus_should_update() and rewrite the checking
 in update_prstate() and update_parent_effective_cpumask()]

Originally-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

...

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Waiman Long 2025-11-04 23:38:45 -05:00 • committed by Tejun Heo

parent 55939cf28a

commit 103b08709e

1 changed files with 73 additions and 1 deletions

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kernel/cgroup/cpuset.c

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