Re: [PATCH 4/8] mm/slab: introduce kfree_rcu_nolock()

["Alexei Starovoitov" <alexei.starovoitov@gmail.com>]

On Thu Apr 16, 2026 at 2:10 AM PDT, Harry Yoo (Oracle) wrote:
>  struct kfree_rcu_cpu {
> +	// Objects queued on a lockless linked list, used to free objects
> +	// in unknown contexts when trylock fails.
> +	struct llist_head defer_head;
> +
> +	struct irq_work defer_free;
> +	struct irq_work sched_delayed_monitor;
> +	struct irq_work run_page_cache_worker;
> +
>  	// Objects queued on a linked list
>  	struct rcu_ptr *head;
>  	unsigned long head_gp_snap;
> @@ -1333,12 +1341,99 @@ struct kfree_rcu_cpu {
>  	struct llist_head bkvcache;
>  	int nr_bkv_objs;
>  };
> +
> +static void defer_kfree_rcu_irq_work_fn(struct irq_work *work);
> +static void sched_delayed_monitor_irq_work_fn(struct irq_work *work);
> +static void run_page_cache_worker_irq_work_fn(struct irq_work *work);
> +
> +static DEFINE_PER_CPU(struct kfree_rcu_cpu, krc) = {
> +	.lock = __RAW_SPIN_LOCK_UNLOCKED(krc.lock),
> +	.defer_head = LLIST_HEAD_INIT(defer_head),
> +	.defer_free = IRQ_WORK_INIT(defer_kfree_rcu_irq_work_fn),
> +	.sched_delayed_monitor =
> +		IRQ_WORK_INIT_LAZY(sched_delayed_monitor_irq_work_fn),
> +	.run_page_cache_worker =
> +		IRQ_WORK_INIT_LAZY(run_page_cache_worker_irq_work_fn),
> +};

I think kfree_rcu_cpu doesn't need to be per-cpu.
It can be global llist with single irq_work for them all.
Not sure about sched_delayed_monitor/run_page_cache_worker.
Do they have to be per-cpu ? Can all 3 share single irq_work?