From patchwork Mon Feb 21 08:49:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 544883 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 08BE7C433F5 for ; Mon, 21 Feb 2022 09:14:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347940AbiBUJPM (ORCPT ); Mon, 21 Feb 2022 04:15:12 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:33914 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349197AbiBUJMJ (ORCPT ); Mon, 21 Feb 2022 04:12:09 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A8BC2AC74; Mon, 21 Feb 2022 01:05:01 -0800 (PST) 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 1441D6114D; Mon, 21 Feb 2022 09:05:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E9A19C36AE2; Mon, 21 Feb 2022 09:04:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1645434300; bh=0E/SeavlfFJPRCXvDa8gF2rgjtqzO+JBB0+eJp6JAvk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wrRmVFNiK9Toxn690rJmbyF+RXIcktvWGr1XzvzHuRpm4DUFENjeB7oPVuzGzkS91 YZQ+wqETELvQrw4eCNXxPxcsLMKJohluGrjSV2wZIcBMEeB2YIXJkOaj67vUQf2Kej S2HjAEpavUWumpi97Y9V+DFV3j4bNQmiGsgLqK20= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ming Lei , Christoph Hellwig , Laibin Qiu , Jens Axboe Subject: [PATCH 5.10 081/121] block/wbt: fix negative inflight counter when remove scsi device Date: Mon, 21 Feb 2022 09:49:33 +0100 Message-Id: <20220221084923.945989057@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220221084921.147454846@linuxfoundation.org> References: <20220221084921.147454846@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Laibin Qiu commit e92bc4cd34de2ce454bdea8cd198b8067ee4e123 upstream. 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") Remove oneline stale comment, and kill one oneshot local variable. Signed-off-by: Ming Lei Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/linux-block/20211214133103.551813-1-qiulaibin@huawei.com/ Signed-off-by: Laibin Qiu Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- block/bfq-iosched.c | 2 ++ block/elevator.c | 2 -- 2 files changed, 2 insertions(+), 2 deletions(-) --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -6404,6 +6404,8 @@ static void bfq_exit_queue(struct elevat spin_unlock_irq(&bfqd->lock); #endif + wbt_enable_default(bfqd->queue); + kfree(bfqd); } --- a/block/elevator.c +++ b/block/elevator.c @@ -518,8 +518,6 @@ void elv_unregister_queue(struct request kobject_del(&e->kobj); e->registered = 0; - /* Re-enable throttling in case elevator disabled it */ - wbt_enable_default(q); } }