From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2B82ECAAD3 for ; Thu, 15 Sep 2022 12:47:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230026AbiIOMrz (ORCPT ); Thu, 15 Sep 2022 08:47:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48084 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229761AbiIOMrw (ORCPT ); Thu, 15 Sep 2022 08:47:52 -0400 Received: from mail-pg1-x52b.google.com (mail-pg1-x52b.google.com [IPv6:2607:f8b0:4864:20::52b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D288581688 for ; Thu, 15 Sep 2022 05:47:51 -0700 (PDT) Received: by mail-pg1-x52b.google.com with SMTP id q9so8107896pgq.8 for ; Thu, 15 Sep 2022 05:47:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date; bh=URE3/J3RANnPHCClBrc/4NGVv2emAKT3zL/Qo/JABk0=; b=dj3VKLtvBttzG9eaXf9+khQo4R3mg2ja3pCX+3deq9Gr60Dl+EVRvhmqyubCdACo9z HbKkJhYbMNup1JgJEb7HOYe3Gdj2MPRAvFe13mlqp/pFH5+FXEoIPZJtygZDH5O/AUF9 VfJZVQeNqd25j2G9BDMoLT60HWTx01k+xa82uzijIBoqOh4N3JdORZ/rsO+RS3L54v3S Zzb979uyoFptJc9sIwqUy/wb+LVtAep49ncJ4R3MXTZ8XqZX2QPyUITTt09OvWkE+y+l eGaG2DkD69vl17ry7jXmQfQsTN9SWPGOgVDcfDLG71EkRPbNYGMv7yWrenv27U5nTNFS RwfQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date; bh=URE3/J3RANnPHCClBrc/4NGVv2emAKT3zL/Qo/JABk0=; b=CD6slV0nztXnGGuQyE3w6ulZ85/K2MM9WxT032768Z40dFAqvgw1Y/8F8P+GhokADc x6AXtE3kVJSD8q9A7C+r0LuoJqfogiRqzjCk0C7lqSOJ5RafuWo5cm3vE93OCFqkZOyM Ewv8YvFrC+7CbT0JN21VDXqq3wxdTpEUqFEwgfHKlO7AS3Ruwp172EfjBxXRXiUAFBM9 Rt5TXI1ESqeRYkHbSRjotZ/9W0Kq70WThD8wHh3FiqKvEMTSoxYbZw+j3mv2Oysqk1En a5Qbz3IQ1DYMkA73pBEYjfuUyQX76hYRbLseI8qNXZzzPQ9jBkibUgvg7N1i8CncSacV PlFw== X-Gm-Message-State: ACrzQf0WQrSZO3m6U4vpjLEZ30iEp6fZW93v22RSRqYg3AheGd/lJ+pM f7q7YS00K++FLCoj9l8G6ESNrJ5CSBqb83BX X-Google-Smtp-Source: AMsMyM5lrmcGia5DM+NRJg5O8euN8FrBOaYjnQFifyC7n+j+MNEB7quBU7e8F3XUizsNpijMiWRzmQ== X-Received: by 2002:a63:7704:0:b0:439:ae51:3bc1 with SMTP id s4-20020a637704000000b00439ae513bc1mr544134pgc.558.1663246071216; Thu, 15 Sep 2022 05:47:51 -0700 (PDT) Received: from hyeyoo ([114.29.91.56]) by smtp.gmail.com with ESMTPSA id x12-20020a17090a46cc00b001fd9c63e56bsm1550567pjg.32.2022.09.15.05.47.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Sep 2022 05:47:49 -0700 (PDT) Date: Thu, 15 Sep 2022 21:47:44 +0900 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Maurizio Lombardi Cc: vbabka@suse.cz, linux-mm@kvack.org, rientjes@google.com, penberg@kernel.org, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, bigeasy@linutronix.de Subject: Re: [PATCH V2] mm: slub: fix flush_cpu_slab()/__free_slab() invocations in task context. Message-ID: References: <20220912161140.34281-1-mlombard@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220912161140.34281-1-mlombard@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 12, 2022 at 06:11:40PM +0200, Maurizio Lombardi wrote: > Commit 5a836bf6b09f ("mm: slub: move flush_cpu_slab() invocations > __free_slab() invocations out of IRQ context") moved all flush_cpu_slab() > invocations to the global workqueue to avoid a problem related > with deactivate_slab()/__free_slab() being called from an IRQ context > on PREEMPT_RT kernels. > > When the flush_all_cpu_locked() function is called from a task context > it may happen that a workqueue with WQ_MEM_RECLAIM bit set ends up > flushing the global workqueue, this will cause a dependency issue. > > workqueue: WQ_MEM_RECLAIM nvme-delete-wq:nvme_delete_ctrl_work [nvme_core] > is flushing !WQ_MEM_RECLAIM events:flush_cpu_slab > WARNING: CPU: 37 PID: 410 at kernel/workqueue.c:2637 > check_flush_dependency+0x10a/0x120 > Workqueue: nvme-delete-wq nvme_delete_ctrl_work [nvme_core] > RIP: 0010:check_flush_dependency+0x10a/0x120[ 453.262125] Call Trace: > __flush_work.isra.0+0xbf/0x220 > ? __queue_work+0x1dc/0x420 > flush_all_cpus_locked+0xfb/0x120 > __kmem_cache_shutdown+0x2b/0x320 > kmem_cache_destroy+0x49/0x100 > bioset_exit+0x143/0x190 > blk_release_queue+0xb9/0x100 > kobject_cleanup+0x37/0x130 > nvme_fc_ctrl_free+0xc6/0x150 [nvme_fc] > nvme_free_ctrl+0x1ac/0x2b0 [nvme_core] > > Fix this bug by creating a workqueue for the flush operation with > the WQ_MEM_RECLAIM bit set. > > v2: Create a workqueue with WQ_MEM_RECLAIM > instead of trying to revert the changes. > > Signed-off-by: Maurizio Lombardi > --- > mm/slub.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 862dbd9af4f5..cdb8011884d0 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -310,6 +310,11 @@ static inline void stat(const struct kmem_cache *s, enum stat_item si) > */ > static nodemask_t slab_nodes; > > +/* > + * Workqueue used for flush_cpu_slab(). > + */ > +static struct workqueue_struct *flushwq; > + > /******************************************************************** > * Core slab cache functions > *******************************************************************/ > @@ -2730,7 +2735,7 @@ static void flush_all_cpus_locked(struct kmem_cache *s) > INIT_WORK(&sfw->work, flush_cpu_slab); > sfw->skip = false; > sfw->s = s; > - schedule_work_on(cpu, &sfw->work); > + queue_work_on(cpu, flushwq, &sfw->work); > } > > for_each_online_cpu(cpu) { > @@ -4858,6 +4863,8 @@ void __init kmem_cache_init(void) > > void __init kmem_cache_init_late(void) > { > + flushwq = create_workqueue("slub_flushwq"); > + BUG_ON(!flushwq); > } > > struct kmem_cache * > -- > 2.31.1 > No objection about this patch, but it seems create_workqueue is deprecated? -- Thanks, Hyeonggon