Re: [PATCH/for-next v3 3/3] cgroup/cpuset: Call housekeeping_update() without holding cpus_read_lock

[Waiman Long <llong@redhat.com>]

On 2/3/26 9:51 PM, Chen Ridong wrote:
>
> On 2026/2/3 4:11, Waiman Long wrote:
>> --- a/kernel/time/timer_migration.c
>> +++ b/kernel/time/timer_migration.c
>> @@ -1559,8 +1559,6 @@ int tmigr_isolated_exclude_cpumask(struct cpumask *exclude_cpumask)
>>   	cpumask_var_t cpumask __free(free_cpumask_var) = CPUMASK_VAR_NULL;
>>   	int cpu;
>>   
>> -	lockdep_assert_cpus_held();
>> -
>>   	if (!works)
>>   		return -ENOMEM;
>>   	if (!alloc_cpumask_var(&cpumask, GFP_KERNEL))
>> @@ -1570,6 +1568,7 @@ int tmigr_isolated_exclude_cpumask(struct cpumask *exclude_cpumask)
>>   	 * First set previously isolated CPUs as available (unisolate).
>>   	 * This cpumask contains only CPUs that switched to available now.
>>   	 */
>> +	guard(cpus_read_lock)();
>>   	cpumask_andnot(cpumask, cpu_online_mask, exclude_cpumask);
>>   	cpumask_andnot(cpumask, cpumask, tmigr_available_cpumask);
>>   
> It may lead to lockdep issue.
>
> tmigr_init_isolation
> 	guard(cpus_read_lock)()
> 	tmigr_isolated_exclude_cpumask(cpumask)
> 		guard(cpus_read_lock)()
>
Good catch. I haven't set up "isolcpus" in my test environment. That is 
why this lockdep splat didn't get triggered. I will fix that in the next 
version.

Cheers,
Longman