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[95.203.6.24]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-30a819f5e4asm5422341fa.63.2025.02.26.06.31.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Feb 2025 06:31:04 -0800 (PST) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Wed, 26 Feb 2025 15:31:01 +0100 To: Vlastimil Babka Cc: Uladzislau Rezki , Keith Busch , "Paul E. McKenney" , Joel Fernandes , Josh Triplett , Boqun Feng , Christoph Lameter , David Rientjes , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Julia Lawall , Jakub Kicinski , "Jason A. Donenfeld" , Andrew Morton , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, Alexander Potapenko , Marco Elver , Dmitry Vyukov , kasan-dev@googlegroups.com, Jann Horn , Mateusz Guzik , linux-nvme@lists.infradead.org, leitao@debian.org Subject: Re: [PATCH v2 6/7] mm, slab: call kvfree_rcu_barrier() from kmem_cache_destroy() Message-ID: References: <20240807-b4-slab-kfree_rcu-destroy-v2-6-ea79102f428c@suse.cz> <2811463a-751f-4443-9125-02628dc315d9@suse.cz> <8d7aabb2-2836-4c09-9fc7-8bde271e7f23@suse.cz> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8d7aabb2-2836-4c09-9fc7-8bde271e7f23@suse.cz> On Wed, Feb 26, 2025 at 11:59:53AM +0100, Vlastimil Babka wrote: > On 2/25/25 7:21 PM, Uladzislau Rezki wrote: > >> > > WQ_MEM_RECLAIM-patch fixes this for me: > > Sounds good, can you send a formal patch then? > Do you mean both? Test case and fix? I can :) > Some nits below: > > > > > diff --git a/mm/slab_common.c b/mm/slab_common.c > > index 4030907b6b7d..1b5ed5512782 100644 > > --- a/mm/slab_common.c > > +++ b/mm/slab_common.c > > @@ -1304,6 +1304,8 @@ module_param(rcu_min_cached_objs, int, 0444); > > static int rcu_delay_page_cache_fill_msec = 5000; > > module_param(rcu_delay_page_cache_fill_msec, int, 0444); > > > > +static struct workqueue_struct *rcu_reclaim_wq; > > + > > /* Maximum number of jiffies to wait before draining a batch. */ > > #define KFREE_DRAIN_JIFFIES (5 * HZ) > > #define KFREE_N_BATCHES 2 > > @@ -1632,10 +1634,10 @@ __schedule_delayed_monitor_work(struct kfree_rcu_cpu *krcp) > > if (delayed_work_pending(&krcp->monitor_work)) { > > delay_left = krcp->monitor_work.timer.expires - jiffies; > > if (delay < delay_left) > > - mod_delayed_work(system_unbound_wq, &krcp->monitor_work, delay); > > + mod_delayed_work(rcu_reclaim_wq, &krcp->monitor_work, delay); > > return; > > } > > - queue_delayed_work(system_unbound_wq, &krcp->monitor_work, delay); > > + queue_delayed_work(rcu_reclaim_wq, &krcp->monitor_work, delay); > > } > > > > static void > > @@ -1733,7 +1735,7 @@ kvfree_rcu_queue_batch(struct kfree_rcu_cpu *krcp) > > // "free channels", the batch can handle. Break > > // the loop since it is done with this CPU thus > > // queuing an RCU work is _always_ success here. > > - queued = queue_rcu_work(system_unbound_wq, &krwp->rcu_work); > > + queued = queue_rcu_work(rcu_reclaim_wq, &krwp->rcu_work); > > WARN_ON_ONCE(!queued); > > break; > > } > > @@ -1883,7 +1885,7 @@ run_page_cache_worker(struct kfree_rcu_cpu *krcp) > > if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING && > > !atomic_xchg(&krcp->work_in_progress, 1)) { > > if (atomic_read(&krcp->backoff_page_cache_fill)) { > > - queue_delayed_work(system_unbound_wq, > > + queue_delayed_work(rcu_reclaim_wq, > > &krcp->page_cache_work, > > msecs_to_jiffies(rcu_delay_page_cache_fill_msec)); > > } else { > > @@ -2120,6 +2122,10 @@ void __init kvfree_rcu_init(void) > > int i, j; > > struct shrinker *kfree_rcu_shrinker; > > > > + rcu_reclaim_wq = alloc_workqueue("rcu_reclaim", > > Should we name it "kvfree_rcu_reclaim"? rcu_reclaim sounds too generic > as if it's part of rcu itself? > > > + WQ_UNBOUND | WQ_MEM_RECLAIM, 0); > > Do we want WQ_SYSFS? Or maybe only when someone asks, with a use case? > If someone asks, IMO. -- Uladzislau Rezki