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 X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 90C1EC2BA19 for ; Sat, 18 Apr 2020 03:10:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 671F5221F7 for ; Sat, 18 Apr 2020 03:10:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Mc4IEvzn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725988AbgDRDJ7 (ORCPT ); Fri, 17 Apr 2020 23:09:59 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:25074 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725867AbgDRDJ7 (ORCPT ); Fri, 17 Apr 2020 23:09:59 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1587179398; 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: in-reply-to:in-reply-to:references:references; bh=D3pJdpF3f7njMwi/a6CIeNn/MdKnC9+1DPhYUosgdn4=; b=Mc4IEvznweVp5+KUjjTYc7Un/gXxtYAu2LLi7klFbHb2TZTzuBhH8J/ij1EfgUdObXhPh1 eCwEoTiLN6krGUbBwfFiDSgxYfniOQaRmolDnu81GYEZUpvdud6PKjZHJ64HEcxRk2whmR 5XmPX2I+eYmHHK8Wgeh/tAcccYo33HE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-191-kKcCWOb1NXGD6CKMaYegTw-1; Fri, 17 Apr 2020 23:09:52 -0400 X-MC-Unique: kKcCWOb1NXGD6CKMaYegTw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BE2B513F8; Sat, 18 Apr 2020 03:09:50 +0000 (UTC) Received: from localhost (ovpn-8-23.pek2.redhat.com [10.72.8.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id 59E65196AE; Sat, 18 Apr 2020 03:09:46 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, Ming Lei , John Garry , Bart Van Assche , Hannes Reinecke , Christoph Hellwig , Thomas Gleixner Subject: [PATCH V7 3/9] blk-mq: prepare for draining IO when hctx's all CPUs are offline Date: Sat, 18 Apr 2020 11:09:19 +0800 Message-Id: <20200418030925.31996-4-ming.lei@redhat.com> In-Reply-To: <20200418030925.31996-1-ming.lei@redhat.com> References: <20200418030925.31996-1-ming.lei@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Content-Transfer-Encoding: quoted-printable Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Most of blk-mq drivers depend on managed IRQ's auto-affinity to setup up queue mapping. Thomas mentioned the following point[1]: " That was the constraint of managed interrupts from the very beginning: The driver/subsystem has to quiesce the interrupt line and the associat= ed queue _before_ it gets shutdown in CPU unplug and not fiddle with it until it's restarted by the core when the CPU is plugged in again. " However, current blk-mq implementation doesn't quiesce hw queue before the last CPU in the hctx is shutdown. Even worse, CPUHP_BLK_MQ_DEAD is one cpuhp state handled after the CPU is down, so there isn't any chance to quiesce hctx for blk-mq wrt. CPU hotplug. Add new cpuhp state of CPUHP_AP_BLK_MQ_ONLINE for blk-mq to stop queues and wait for completion of in-flight requests. We will stop hw queue and wait for completion of in-flight requests when one hctx is becoming dead in the following patch. This way may cause dead-lock for some stacking blk-mq drivers, such as dm-rq and loop. Add blk-mq flag of BLK_MQ_F_NO_MANAGED_IRQ and mark it for dm-rq and loop, so we needn't to wait for completion of in-flight requests from dm-rq & loop, then the potential dead-lock can be avoided. [1] https://lore.kernel.org/linux-block/alpine.DEB.2.21.1904051331270.180= 2@nanos.tec.linutronix.de/ Cc: John Garry Cc: Bart Van Assche Cc: Hannes Reinecke Cc: Christoph Hellwig Cc: Thomas Gleixner Signed-off-by: Ming Lei --- block/blk-mq-debugfs.c | 1 + block/blk-mq.c | 19 +++++++++++++++++++ drivers/block/loop.c | 2 +- drivers/md/dm-rq.c | 2 +- include/linux/blk-mq.h | 3 +++ include/linux/cpuhotplug.h | 1 + 6 files changed, 26 insertions(+), 2 deletions(-) diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c index b3f2ba483992..8e745826eb86 100644 --- a/block/blk-mq-debugfs.c +++ b/block/blk-mq-debugfs.c @@ -239,6 +239,7 @@ static const char *const hctx_flag_name[] =3D { HCTX_FLAG_NAME(TAG_SHARED), HCTX_FLAG_NAME(BLOCKING), HCTX_FLAG_NAME(NO_SCHED), + HCTX_FLAG_NAME(NO_MANAGED_IRQ), }; #undef HCTX_FLAG_NAME =20 diff --git a/block/blk-mq.c b/block/blk-mq.c index 29ffa40db793..a28daefd7dd6 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2259,6 +2259,16 @@ int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, s= truct blk_mq_tags *tags, return -ENOMEM; } =20 +static int blk_mq_hctx_notify_online(unsigned int cpu, struct hlist_node= *node) +{ + return 0; +} + +static int blk_mq_hctx_notify_offline(unsigned int cpu, struct hlist_nod= e *node) +{ + return 0; +} + /* * 'cpu' is going away. splice any existing rq_list entries from this * software queue to the hw queue dispatch list, and ensure that it @@ -2295,6 +2305,9 @@ static int blk_mq_hctx_notify_dead(unsigned int cpu= , struct hlist_node *node) =20 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx) { + if (!(hctx->flags & BLK_MQ_F_NO_MANAGED_IRQ)) + cpuhp_state_remove_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE, + &hctx->cpuhp_online); cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead); } @@ -2354,6 +2367,9 @@ static int blk_mq_init_hctx(struct request_queue *q= , { hctx->queue_num =3D hctx_idx; =20 + if (!(hctx->flags & BLK_MQ_F_NO_MANAGED_IRQ)) + cpuhp_state_add_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE, + &hctx->cpuhp_online); cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead); =20 hctx->tags =3D set->tags[hctx_idx]; @@ -3608,6 +3624,9 @@ static int __init blk_mq_init(void) { cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL, blk_mq_hctx_notify_dead); + cpuhp_setup_state_multi(CPUHP_AP_BLK_MQ_ONLINE, "block/mq:online", + blk_mq_hctx_notify_online, + blk_mq_hctx_notify_offline); return 0; } subsys_initcall(blk_mq_init); diff --git a/drivers/block/loop.c b/drivers/block/loop.c index da693e6a834e..784f2e038b55 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -2037,7 +2037,7 @@ static int loop_add(struct loop_device **l, int i) lo->tag_set.queue_depth =3D 128; lo->tag_set.numa_node =3D NUMA_NO_NODE; lo->tag_set.cmd_size =3D sizeof(struct loop_cmd); - lo->tag_set.flags =3D BLK_MQ_F_SHOULD_MERGE; + lo->tag_set.flags =3D BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_NO_MANAGED_IRQ; lo->tag_set.driver_data =3D lo; =20 err =3D blk_mq_alloc_tag_set(&lo->tag_set); diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c index 3f8577e2c13b..5f1ff70ac029 100644 --- a/drivers/md/dm-rq.c +++ b/drivers/md/dm-rq.c @@ -547,7 +547,7 @@ int dm_mq_init_request_queue(struct mapped_device *md= , struct dm_table *t) md->tag_set->ops =3D &dm_mq_ops; md->tag_set->queue_depth =3D dm_get_blk_mq_queue_depth(); md->tag_set->numa_node =3D md->numa_node_id; - md->tag_set->flags =3D BLK_MQ_F_SHOULD_MERGE; + md->tag_set->flags =3D BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_NO_MANAGED_IRQ; md->tag_set->nr_hw_queues =3D dm_get_blk_mq_nr_hw_queues(); md->tag_set->driver_data =3D md; =20 diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index f389d7c724bd..786614753d73 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -140,6 +140,8 @@ struct blk_mq_hw_ctx { */ atomic_t nr_active; =20 + /** @cpuhp_online: List to store request if CPU is going to die */ + struct hlist_node cpuhp_online; /** @cpuhp_dead: List to store request if some CPU die. */ struct hlist_node cpuhp_dead; /** @kobj: Kernel object for sysfs. */ @@ -391,6 +393,7 @@ struct blk_mq_ops { enum { BLK_MQ_F_SHOULD_MERGE =3D 1 << 0, BLK_MQ_F_TAG_SHARED =3D 1 << 1, + BLK_MQ_F_NO_MANAGED_IRQ =3D 1 << 2, BLK_MQ_F_BLOCKING =3D 1 << 5, BLK_MQ_F_NO_SCHED =3D 1 << 6, BLK_MQ_F_ALLOC_POLICY_START_BIT =3D 8, diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index 77d70b633531..24b3a77810b6 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -152,6 +152,7 @@ enum cpuhp_state { CPUHP_AP_SMPBOOT_THREADS, CPUHP_AP_X86_VDSO_VMA_ONLINE, CPUHP_AP_IRQ_AFFINITY_ONLINE, + CPUHP_AP_BLK_MQ_ONLINE, CPUHP_AP_ARM_MVEBU_SYNC_CLOCKS, CPUHP_AP_X86_INTEL_EPB_ONLINE, CPUHP_AP_PERF_ONLINE, --=20 2.25.2