From patchwork Tue Dec 14 13:31:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: QiuLaibin X-Patchwork-Id: 12676001 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 A1ED0C433F5 for ; Tue, 14 Dec 2021 13:15:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234304AbhLNNPu (ORCPT ); Tue, 14 Dec 2021 08:15:50 -0500 Received: from szxga02-in.huawei.com ([45.249.212.188]:28316 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234288AbhLNNPu (ORCPT ); Tue, 14 Dec 2021 08:15:50 -0500 Received: from dggpemm500024.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4JCzQB0p1QzbjN4; Tue, 14 Dec 2021 21:15:30 +0800 (CST) Received: from dggpemm500004.china.huawei.com (7.185.36.219) by dggpemm500024.china.huawei.com (7.185.36.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Tue, 14 Dec 2021 21:15:47 +0800 Received: from huawei.com (10.175.124.27) by dggpemm500004.china.huawei.com (7.185.36.219) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Tue, 14 Dec 2021 21:15:47 +0800 From: Laibin Qiu To: , , CC: , , Subject: [PATCH v3 -next] block/wbt: fix negative inflight counter when remove scsi device Date: Tue, 14 Dec 2021 21:31:03 +0800 Message-ID: <20211214133103.551813-1-qiulaibin@huawei.com> X-Mailer: git-send-email 2.22.0 MIME-Version: 1.0 X-Originating-IP: [10.175.124.27] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm500004.china.huawei.com (7.185.36.219) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Now that we disable wbt by set WBT_STATE_OFF_DEFAULT in wbt_disable_default() when switch elevator to bfq. And when we remove scsi device, wbt will be enabled by wbt_enable_default. If it become false positive between wbt_wait() and wbt_track() when submit write request. The following is the scenario that triggered the problem. T1 T2 T3 elevator_switch_mq bfq_init_queue wbt_disable_default <= Set rwb->enable_state (OFF) Submit_bio blk_mq_make_request rq_qos_throttle <= rwb->enable_state (OFF) scsi_remove_device sd_remove del_gendisk blk_unregister_queue elv_unregister_queue wbt_enable_default <= Set rwb->enable_state (ON) q_qos_track <= rwb->enable_state (ON) ^^^^^^ this request will mark WBT_TRACKED without inflight add and will lead to drop rqw->inflight to -1 in wbt_done() which will trigger IO hung. Fix this by move wbt_enable_default() from elv_unregister to bfq_exit_queue(). Only re-enable wbt when bfq exit. Fixes: 76a8040817b4b ("blk-wbt: make sure throttle is enabled properly") Signed-off-by: Laibin Qiu Reviewed-by: Christoph Hellwig Reviewed-by: Ming Lei --- block/bfq-iosched.c | 4 ++++ block/elevator.c | 2 -- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 0c612a911696..8b7524450835 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -6996,6 +6996,7 @@ static void bfq_exit_queue(struct elevator_queue *e) { struct bfq_data *bfqd = e->elevator_data; struct bfq_queue *bfqq, *n; + struct request_queue *q = bfqd->queue; hrtimer_cancel(&bfqd->idle_slice_timer); @@ -7019,6 +7020,9 @@ static void bfq_exit_queue(struct elevator_queue *e) #endif kfree(bfqd); + + /* Re-enable throttling in case elevator disabled it */ + wbt_enable_default(q); } static void bfq_init_root_group(struct bfq_group *root_group, diff --git a/block/elevator.c b/block/elevator.c index ec98aed39c4f..482df2a350fc 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -525,8 +525,6 @@ void elv_unregister_queue(struct request_queue *q) kobject_del(&e->kobj); e->registered = 0; - /* Re-enable throttling in case elevator disabled it */ - wbt_enable_default(q); } }