Re: [PATCH v2 1/3] selftests/cgroup: Drop invalid boot isolation comparison

[Waiman Long <longman@redhat.com>]

On 8/23/26 10:01 PM, Guopeng Zhang wrote:
> From: Guopeng Zhang <zhangguopeng@kylinos.cn>
>
> check_isolcpus() clears ISOLCPUS before rebuilding it from sched domain
> data. Comparing that empty value with
> /sys/devices/system/cpu/isolated makes the test fail whenever
> isolcpus=domain is present.
>
> That sysfs file is generated from HK_TYPE_DOMAIN_BOOT and does not change
> when cpuset updates HK_TYPE_DOMAIN. Re-reading it cannot validate dynamic
> housekeeping updates. The cpuset.cpus.isolated and sched domain checks
> already cover the two dynamic interfaces, so remove the invalid comparison.
>
> This can be reproduced on a kernel booted with isolcpus=domain,15:
>
>      # tools/testing/selftests/cgroup/test_cpuset_prs.sh
>
> The test fails its first state-matrix isolation check before the change and
> continues past that check afterward.
>
> Fixes: 6df415aa46ec ("cgroup/cpuset: Defer housekeeping_update() calls from CPU hotplug to workqueue")
> Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
> ---
>   tools/testing/selftests/cgroup/test_cpuset_prs.sh | 6 ------
>   1 file changed, 6 deletions(-)
>
> diff --git a/tools/testing/selftests/cgroup/test_cpuset_prs.sh b/tools/testing/selftests/cgroup/test_cpuset_prs.sh
> index da8f7b920178..fdb3185570d4 100755
> --- a/tools/testing/selftests/cgroup/test_cpuset_prs.sh
> +++ b/tools/testing/selftests/cgroup/test_cpuset_prs.sh
> @@ -797,7 +797,6 @@ check_isolcpus()
>   	EXPECTED_ISOLCPUS=$1
>   	ISCPUS=${CGROUP2}/cpuset.cpus.isolated
>   	ISOLCPUS=$(cat $ISCPUS)
> -	HKICPUS=$(cat /sys/devices/system/cpu/isolated)
>   	LASTISOLCPU=
>   	SCHED_DOMAINS=/sys/kernel/debug/sched/domains
>   	if [[ $EXPECTED_ISOLCPUS = . ]]
> @@ -835,11 +834,6 @@ check_isolcpus()
>   	ISOLCPUS=
>   	EXPECTED_ISOLCPUS=$EXPECTED_SDOMAIN
>   
> -	#
> -	# The inverse of HK_TYPE_DOMAIN cpumask in $HKICPUS should match $ISOLCPUS
> -	#
> -	[[ "$ISOLCPUS" != "$HKICPUS" ]] && return 1
> -
>   	#
>   	# Use the sched domain in debugfs to check isolated CPUs, if available
>   	#

The /sys/devices/system/cpu/isolated had recently be changed to report 
the boot time isolcpus=domain value. So the check is no longer valid and 
should be removed. Of course the position of the check is also 
problematic. So it should be removed.

Reviewed-by: Waiman Long <longman@redhat.com>