cgroup/cpuset: Do housekeeping check when isolated child with root parent may get more xcpus

It is reported by sashiko and Guopeng that when an isolated child with
root parent gets more isolated CPUs from the expansion of the parent's
effective_xcpus, it is possible that all the active housekeeping CPUs
may be gone. So a prstate_housekeeping_conflict() should be performed
when that happens. Add the check to make sure that we can't exhaust
all the active housekeeping CPUs.

Test cases are added to the NOHZ_FULL_TEST_MATRIX of test_cpuset_prs.sh
to test that.

Reported-by: Guopeng Zhang <guopeng.zhang@linux.dev>
Link: https://lore.kernel.org/lkml/ed6fecb4-38e9-4a73-8c1a-7bdd80175a69@linux.dev
Fixes: e2ffe502ba45 ("cgroup/cpuset: Add cpuset.cpus.exclusive for v2")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Tested-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>

0 files changed, 0 insertions, 0 deletions