Re: [PATCH] cgroup/cpuset: Add test for partition root invalidation returning wrong CPUs

[Waiman Long <longman@redhat.com>]

On 8/7/26 4:59 AM, Shaojie Sun wrote:
> Add a test case covering the bug fixed by
> commit 345f40166694 ("cgroup/cpuset: Return only actually allocated
> CPUs during partition invalidation"). The test verifies that when a
> sibling partition root changes its cpuset.cpus to overlap with another
> partition root, only actually allocated CPUs (effective_xcpus) are
> returned to the parent, not all CPUs in cpus_allowed.
>
> Signed-off-by: Shaojie Sun <sunshaojie@kylinos.cn>
> ---
>   tools/testing/selftests/cgroup/test_cpuset_prs.sh | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/tools/testing/selftests/cgroup/test_cpuset_prs.sh b/tools/testing/selftests/cgroup/test_cpuset_prs.sh
> index 0d41aa0d343d..a44e92c94081 100755
> --- a/tools/testing/selftests/cgroup/test_cpuset_prs.sh
> +++ b/tools/testing/selftests/cgroup/test_cpuset_prs.sh
> @@ -393,6 +393,12 @@ TEST_MATRIX=(
>   	"  C0-1:P1   .      .  P1:C2-3  C0-2     .      .      .     0 A1:0-1|XA1:0-1|B1:2-3 A1:P1|B1:P1"
>   	"   C0-1     .      .  P1:C2-3  C0-2     .      .      .     0 A1:0-1|B1:2-3 A1:P0|B1:P1"
>   
> +	# However, a partition root changing its own cpuset.cpus to overlap with
> +	# a sibling partition root will invalidate itself. Only actually allocated
> +	# CPUs (effective_xcpus) should be returned to the parent, not all CPUs
> +	# in cpus_allowed. The root cgroup effective CPUs must remain unchanged.
> +	"  C0-1:P1   .      .   C1-2:P1    .      .      .    C0-1    0 A1:0-1 A1:P1|B1:P-1"
> +

The cgroup hierarchy used by TEST_MATRIX may not suitable for doing this 
kind of test as you can't easily check the state of the parent cgroup. I 
would suggest you use the REMOTE_TEST_MATRIX hierarchy with p1, c11, 
c12. After making c12 conflicts with c11, you can check p1 to see if it 
has the right state.

Cheers,
Longman


>   	# cpuset.cpus can overlap with sibling cpuset.cpus.exclusive but not subsumed by it
>   	"   C0-3     .      .    C4-5     X5     .      .      .     0 A1:0-3|B1:4-5"
>