From nobody Fri Dec 19 20:35:44 2025 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 9FD8EC32771 for ; Mon, 26 Sep 2022 11:17:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237709AbiIZLRr (ORCPT ); Mon, 26 Sep 2022 07:17:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55026 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233413AbiIZLQg (ORCPT ); Mon, 26 Sep 2022 07:16:36 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DDCBE63F35; Mon, 26 Sep 2022 03:37:37 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 85B2860C8E; Mon, 26 Sep 2022 10:37:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 77AB9C433D6; Mon, 26 Sep 2022 10:37:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1664188655; bh=BZfPRIWoeGzi/oHpfpQnFPSeDCql6EZMgdNhQrWC0hU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WFTy57uL/Dmfjq2EkGDZVSKUy/Qatwz4KgfmiKNN/uG+DZqqrpM4It3Cd6ip7ZZCJ aOQg0l/92Wi6kJCYLKXADEwmyM6f1U5pBUc2b/nhgKPbpExf7d1ULs4YgaJzz0VaJa GCY/EtnhzrX7vvcu+Ur7pstgluLCEUpMS+NWEn5M= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Maurizio Lombardi , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Vlastimil Babka Subject: [PATCH 5.15 051/148] mm: slub: fix flush_cpu_slab()/__free_slab() invocations in task context. Date: Mon, 26 Sep 2022 12:11:25 +0200 Message-Id: <20220926100757.943420252@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220926100756.074519146@linuxfoundation.org> References: <20220926100756.074519146@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Maurizio Lombardi commit e45cc288724f0cfd497bb5920bcfa60caa335729 upstream. 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. Fixes: 5a836bf6b09f ("mm: slub: move flush_cpu_slab() invocations __free_sl= ab() invocations out of IRQ context") Cc: Signed-off-by: Maurizio Lombardi Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Signed-off-by: Vlastimil Babka Signed-off-by: Greg Kroah-Hartman --- mm/slub.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/mm/slub.c +++ b/mm/slub.c @@ -308,6 +308,11 @@ static inline void stat(const struct kme */ static nodemask_t slab_nodes; =20 +/* + * Workqueue used for flush_cpu_slab(). + */ +static struct workqueue_struct *flushwq; + /******************************************************************** * Core slab cache functions *******************************************************************/ @@ -2688,7 +2693,7 @@ static void flush_all_cpus_locked(struct INIT_WORK(&sfw->work, flush_cpu_slab); sfw->skip =3D false; sfw->s =3D s; - schedule_work_on(cpu, &sfw->work); + queue_work_on(cpu, flushwq, &sfw->work); } =20 for_each_online_cpu(cpu) { @@ -4850,6 +4855,8 @@ void __init kmem_cache_init(void) =20 void __init kmem_cache_init_late(void) { + flushwq =3D alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM, 0); + WARN_ON(!flushwq); } =20 struct kmem_cache *