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On 10/12/2025 1:42 AM, Chen, Yu C wrote: > On 10/11/2025 2:43 PM, Adam Li wrote: >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> index bc0b7ce8a65d..d5ec15050ebc 100644 >> --- a/kernel/sched/fair.c >> +++ b/kernel/sched/fair.c >> @@ -10671,7 +10671,7 @@ static inline void update_sg_wakeup_stats(struct sched_domain *sd, >>       if (sd->flags & SD_ASYM_CPUCAPACITY) >>           sgs->group_misfit_task_load = 1; >>   -    for_each_cpu(i, sched_group_span(group)) { >> +    for_each_cpu_and(i, sched_group_span(group), p->cpus_ptr) { > > Looks good to me. One minor question, would pre-calculating the mask be better? I do agree pre-calculating the cpumask can save cpu cycles, without doing mask AND at each loop. > Copied from select_idle_cpu(): > > cpus = this_cpu_cpumask_var_ptr(select_rq_mask); > cpumask_and(cpus, sched_group_span(sd), p->cpus_ptr); > for_each_cpu(i, cpus) { > But I am not sure if it is safe to use the percpu 'select_rq_mask' in update_sg_wakeup_stats(). Or we have to allocate a 'struct cpumask'. I tested bellow patch. It can work and fix the bug. If it is safe to use 'select_rq_mask' , I can submit V2 patch. --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10664,6 +10664,7 @@ static inline void update_sg_wakeup_stats(struct sched_domain *sd, struct task_struct *p) { int i, nr_running; + struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask); memset(sgs, 0, sizeof(*sgs)); @@ -10671,7 +10672,8 @@ static inline void update_sg_wakeup_stats(struct sched_domain *sd, if (sd->flags & SD_ASYM_CPUCAPACITY) sgs->group_misfit_task_load = 1; - for_each_cpu(i, sched_group_span(group)) { + cpumask_and(cpus, sched_group_span(group), p->cpus_ptr); + for_each_cpu(i, cpus) { struct rq *rq = cpu_rq(i); unsigned int local; Thanks, -adam