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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2548FECAAD3 for ; Mon, 19 Sep 2022 16:39:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0D7276B0071; Mon, 19 Sep 2022 12:39:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 05F3180007; Mon, 19 Sep 2022 12:39:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E1CB0940007; Mon, 19 Sep 2022 12:39:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id CFA766B0071 for ; Mon, 19 Sep 2022 12:39:40 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id ABC0781C98 for ; Mon, 19 Sep 2022 16:39:40 +0000 (UTC) X-FDA: 79929396120.08.CF7C2E9 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf13.hostedemail.com (Postfix) with ESMTP id 56EE52002C for ; Mon, 19 Sep 2022 16:39:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1663605579; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=s3aQ3mNOXvUI82qCNmM4rRvK0fQP5iRzzY1v7eC67g8=; b=M+nkpOYwfe2NyZ795ihyUvF9EU/frmsgKV9iNXPg9zmPfbR6FMkRaIHsb8ElB0jletEWc+ /lXXIS/2VAGmsb1q3btz9/DYaXWId5mZ+xIrE7AlvDcimbhW9zv2JhjjdZ24shEH5Vn+Hx EL55kyRFybRab8An+JR/kDNm9ZuYZ6Y= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-59-thqDVXE3MCu2hUdXlspK_w-1; Mon, 19 Sep 2022 12:39:32 -0400 X-MC-Unique: thqDVXE3MCu2hUdXlspK_w-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 3C9E685A59D; Mon, 19 Sep 2022 16:39:32 +0000 (UTC) Received: from raketa.redhat.com (unknown [10.40.193.252]) by smtp.corp.redhat.com (Postfix) with ESMTP id AF71E492CA2; Mon, 19 Sep 2022 16:39:30 +0000 (UTC) From: Maurizio Lombardi To: vbabka@suse.cz Cc: 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: [PATCH V3] mm: slub: fix flush_cpu_slab()/__free_slab() invocations in task context. Date: Mon, 19 Sep 2022 18:39:29 +0200 Message-Id: <20220919163929.351068-1-mlombard@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1663605580; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:references:dkim-signature; bh=s3aQ3mNOXvUI82qCNmM4rRvK0fQP5iRzzY1v7eC67g8=; b=VZGdxMr7/mxW5gsbs7UmvadpUlLkJ6ek1UGPrUCz2K98mNyuGP4CJj/z/AfdKaQ3dhNuAo CPQ3f2s2yJXUX9NbmBND2hXOwTebRxbR4Oqx6CLpU0Jzziobzi+FALfBL/9M7WNCcTPNEe F2NUmm5ixtEh8fVrSnJvUri+hnLUhGI= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=M+nkpOYw; spf=pass (imf13.hostedemail.com: domain of mlombard@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=mlombard@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1663605580; a=rsa-sha256; cv=none; b=KTdrnkXB3DLV+Us0J8fj4pGotkihaeW2PW81X+d01m9NiXCrb3J2XROS+b8ra6nHyKWhAh d4Rt0rUH8iteMxPn95qUwA8+O9klOx7KJynANhbjeVMU2xvbq72/GjBFjJ37t6RY6dqB97 HVl3JpN3q7esG5k0VQJDVBOP9+05Iuk= X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 56EE52002C X-Rspam-User: Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=M+nkpOYw; spf=pass (imf13.hostedemail.com: domain of mlombard@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=mlombard@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Stat-Signature: zfuh9ckpr5pi67k47eneojboqb5mtu1r X-HE-Tag: 1663605580-862727 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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. v3: replace create_workqueue() with alloc_workqueue() and BUG_ON() with WARN_ON() 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..016da09608fb 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 = alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM, 0); + WARN_ON(!flushwq); } struct kmem_cache * -- 2.31.1