On Tue, 10 Apr 2018, Vlastimil Babka wrote: > cache_reap() is initially scheduled in start_cpu_timer() via > schedule_delayed_work_on(). But then the next iterations are scheduled via > schedule_delayed_work(), thus using WORK_CPU_UNBOUND.
That is a bug.. cache_reap must run on the same cpu since it deals with the per cpu queues of the current cpu. Scheduled_delayed_work() used to guarantee running on teh same cpu. > This patch makes sure schedule_delayed_work_on() is used with the proper cpu > when scheduling the next iteration. The cpu is stored with delayed_work on a > new slab_reap_work_struct super-structure. The current cpu is readily available via smp_processor_id(). Why a super structure? > @@ -4074,7 +4086,8 @@ static void cache_reap(struct work_struct *w) > next_reap_node(); > out: > /* Set up the next iteration */ > - schedule_delayed_work(work, round_jiffies_relative(REAPTIMEOUT_AC)); > + schedule_delayed_work_on(reap_work->cpu, work, > + round_jiffies_relative(REAPTIMEOUT_AC)); schedule_delayed_work_on(smp_processor_id(), work, round_jiffies_relative(REAPTIMEOUT_AC)); instead all of the other changes?
