From patchwork Mon Dec 13 04:09:07 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: QiuLaibin X-Patchwork-Id: 12673043 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 98AA0C433F5 for ; Mon, 13 Dec 2021 03:53:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231529AbhLMDxx (ORCPT ); Sun, 12 Dec 2021 22:53:53 -0500 Received: from szxga01-in.huawei.com ([45.249.212.187]:32913 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229724AbhLMDxx (ORCPT ); Sun, 12 Dec 2021 22:53:53 -0500 Received: from dggpemm500022.china.huawei.com (unknown [172.30.72.54]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4JC70H4gDbzgY7T; Mon, 13 Dec 2021 11:53:35 +0800 (CST) Received: from dggpemm500004.china.huawei.com (7.185.36.219) by dggpemm500022.china.huawei.com (7.185.36.162) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Mon, 13 Dec 2021 11:53:51 +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; Mon, 13 Dec 2021 11:53:51 +0800 From: Laibin Qiu To: CC: , , Subject: [PATCH -next] block/wbt: fix negative inflight counter when remove scsi device Date: Mon, 13 Dec 2021 12:09:07 +0800 Message-ID: <20211213040907.2669480-1-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 judge whether QUEUE_FLAG_REGISTERED is marked to distinguish scsi remove scene. Fixes: 76a8040817b4b ("blk-wbt: make sure throttle is enabled properly") Signed-off-by: Laibin Qiu --- block/blk-wbt.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/block/blk-wbt.c b/block/blk-wbt.c index 3ed71b8da887..537f77bb1365 100644 --- a/block/blk-wbt.c +++ b/block/blk-wbt.c @@ -637,6 +637,10 @@ void wbt_enable_default(struct request_queue *q) { struct rq_qos *rqos = wbt_rq_qos(q); + /* Queue not registered? Maybe shutting down... */ + if (!blk_queue_registered(q)) + return; + /* Throttling already enabled? */ if (rqos) { if (RQWB(rqos)->enable_state == WBT_STATE_OFF_DEFAULT) @@ -644,10 +648,6 @@ void wbt_enable_default(struct request_queue *q) return; } - /* Queue not registered? Maybe shutting down... */ - if (!blk_queue_registered(q)) - return; - if (queue_is_mq(q) && IS_ENABLED(CONFIG_BLK_WBT_MQ)) wbt_init(q); }