Re: [PATCH v3 1/3] cgroup/cpuset: Reject updates that empty the top sched domain

[Guopeng Zhang <guopeng.zhang@linux.dev>]

在 2026/11/10 20:13, Ridong Chen 写道:
> 
> 
> On 11/10/2026 1:03 PM, Guopeng Zhang wrote:
>> From: Guopeng Zhang <zhangguopeng@kylinos.cn>
>>
>> Boot-isolated CPUs remain in top_cpuset.effective_cpus, but are excluded
>> from its scheduling domain by generate_sched_domains(). Checking only
>> effective_cpus when distributing CPUs to partitions can therefore allow
>> all boot domain housekeeping CPUs to be taken from the top cpuset.
>>
>> The resulting empty domain triggers a warning in build_sched_domains()
>> and can cause an out-of-bounds CPU access in build_perf_domains(). Both
>> root and isolated partitions can trigger this, whether local or remote.
>> For example, on a 32-CPU system booted with isolcpus=domain,10-31:
>>
>>    echo 0-9 > A/cpuset.cpus
>>    echo root > A/cpuset.cpus.partition
>>    Oops: general protection fault
>>    RIP: 0010:build_perf_domains+...
>>
>> Require local and remote partition creation and CPU mask updates to
>> leave an active boot domain housekeeping CPU in the top cpuset,
>> accounting for CPUs returned by the same update.
>>
>> Add test cases to test_cpuset_prs.sh to verify that every partition
>> update leaves an active boot domain housekeeping CPU in the top cpuset.
>>
>> Fixes: 9b496a8bbed9 ("cgroup/cpuset: Prevent leakage of isolated CPUs into sched domains")
>> Co-developed-by: Ridong Chen <ridong.chen@linux.dev>
>> Signed-off-by: Ridong Chen <ridong.chen@linux.dev>
> 
> It would be better with: Ridong Chen <chenridong@xiaomi.com>
> 
Yeah, I'll update it.

Thanks，
Guopeng