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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 97A62C433F5 for ; Thu, 17 Feb 2022 07:45:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=GT4aVrhYrEdmEgtfruWtIslwHD4HVx1rdWxtZIW44yw=; b=yMrsZ/114wR2kCiDjbFeOvBROt cb3kbJVRz1kdv3SqWDHDC0TqbtuIm1i8qiPmOxL/QF/pvtXgrmthhM0QErrfVIJtRoBaAh7AmKJfz SyXuArrvSD7xYLQG2Ns/Om+tnbLqp4oeuk4wtDSHS3O2UakmeUjpg80sAtQ8grfTag9ibrFLoblZR ijK4qI89BA05Y2/RZRGV96iT+kYp8GIzEQfqnsJHkHI7ocFzfitTrbl3Jw6LlrO5uKJFLjcQsN+ZY 8BYSU3Hm+J1sZITENtnAzeFtTlnIgloI6Zj36am2bnnAt6I5Dv0JBg9YEhCdzxbEWFaUB2juwyPx6 Q1QeguBQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nKbTV-009FyJ-0d; Thu, 17 Feb 2022 07:45:13 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nKbTQ-009FxC-HG for linux-nvme@lists.infradead.org; Thu, 17 Feb 2022 07:45:11 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id BF89F68B05; Thu, 17 Feb 2022 08:45:03 +0100 (CET) Date: Thu, 17 Feb 2022 08:45:02 +0100 From: Christoph Hellwig To: Jens Axboe Cc: Christoph Hellwig , Ming Lei , "Martin K . Petersen" , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, Laibin Qiu , Ming Lei Subject: Re: [PATCH V2 04/13] block/wbt: fix negative inflight counter when remove scsi device Message-ID: <20220217074502.GA1333@lst.de> References: <20220122111054.1126146-1-ming.lei@redhat.com> <20220122111054.1126146-5-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220122111054.1126146-5-ming.lei@redhat.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220216_234508_746701_681E96FC X-CRM114-Status: GOOD ( 24.07 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org Jens, can you pick this up for the block-5.17 tree? On Sat, Jan 22, 2022 at 07:10:45PM +0800, Ming Lei wrote: > From: Laibin Qiu > > 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 > --- > block/bfq-iosched.c | 2 ++ > block/elevator.c | 2 -- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c > index 0c612a911696..36a66e97e3c2 100644 > --- a/block/bfq-iosched.c > +++ b/block/bfq-iosched.c > @@ -7018,6 +7018,8 @@ static void bfq_exit_queue(struct elevator_queue *e) > spin_unlock_irq(&bfqd->lock); > #endif > > + wbt_enable_default(bfqd->queue); > + > kfree(bfqd); > } > > 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); > } > } > > -- > 2.31.1 ---end quoted text---