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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 C705EC432BE for ; Wed, 1 Sep 2021 12:32:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A904F61027 for ; Wed, 1 Sep 2021 12:32:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244895AbhIAMdj (ORCPT ); Wed, 1 Sep 2021 08:33:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:33934 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245002AbhIAMcJ (ORCPT ); Wed, 1 Sep 2021 08:32:09 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D69DE61027; Wed, 1 Sep 2021 12:31:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1630499472; bh=SijOpYyQqdDkOkhH1GYx8Q4As3/+YQr7M6n8X6rjOwg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L0x+E0jpb3ESISoHu0hH+rouDuA4yHyQoVO6L+r4FlB8L80XsvyRjnHLslWTx8gl2 1EyW6jR/ntUApO0Vt+nTRtIi6iINZqUvhPS6nbss0Qn6EqWuFCS/rLZnp8KkmoL+q0 u9zKIfKiwQndLzStlduDzwNkbSxVY56xXpqjd23s= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Bart Van Assche , Li Jinlin , Qiu Laibin , "Martin K. Petersen" Subject: [PATCH 5.4 13/48] scsi: core: Fix hang of freezing queue between blocking and running device Date: Wed, 1 Sep 2021 14:28:03 +0200 Message-Id: <20210901122253.840151831@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210901122253.388326997@linuxfoundation.org> References: <20210901122253.388326997@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Li Jinlin commit 02c6dcd543f8f051973ee18bfbc4dc3bd595c558 upstream. We found a hang, the steps to reproduce are as follows: 1. blocking device via scsi_device_set_state() 2. dd if=/dev/sda of=/mnt/t.log bs=1M count=10 3. echo none > /sys/block/sda/queue/scheduler 4. echo "running" >/sys/block/sda/device/state Step 3 and 4 should complete after step 4, but they hang. CPU#0 CPU#1 CPU#2 --------------- ---------------- ---------------- Step 1: blocking device Step 2: dd xxxx ^^^^^^ get request q_usage_counter++ Step 3: switching scheculer elv_iosched_store elevator_switch blk_mq_freeze_queue blk_freeze_queue > blk_freeze_queue_start ^^^^^^ mq_freeze_depth++ > blk_mq_run_hw_queues ^^^^^^ can't run queue when dev blocked > blk_mq_freeze_queue_wait ^^^^^^ Hang here!!! wait q_usage_counter==0 Step 4: running device store_state_field scsi_rescan_device scsi_attach_vpd scsi_vpd_inquiry __scsi_execute blk_get_request blk_mq_alloc_request blk_queue_enter ^^^^^^ Hang here!!! wait mq_freeze_depth==0 blk_mq_run_hw_queues ^^^^^^ dispatch IO, q_usage_counter will reduce to zero blk_mq_unfreeze_queue ^^^^^ mq_freeze_depth-- To fix this, we need to run queue before rescanning device when the device state changes to SDEV_RUNNING. Link: https://lore.kernel.org/r/20210824025921.3277629-1-lijinlin3@huawei.com Fixes: f0f82e2476f6 ("scsi: core: Fix capacity set to zero after offlinining device") Reviewed-by: Bart Van Assche Signed-off-by: Li Jinlin Signed-off-by: Qiu Laibin Signed-off-by: Martin K. Petersen Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/scsi_sysfs.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -788,12 +788,15 @@ store_state_field(struct device *dev, st ret = scsi_device_set_state(sdev, state); /* * If the device state changes to SDEV_RUNNING, we need to - * rescan the device to revalidate it, and run the queue to - * avoid I/O hang. + * run the queue to avoid I/O hang, and rescan the device + * to revalidate it. Running the queue first is necessary + * because another thread may be waiting inside + * blk_mq_freeze_queue_wait() and because that call may be + * waiting for pending I/O to finish. */ if (ret == 0 && state == SDEV_RUNNING) { - scsi_rescan_device(dev); blk_mq_run_hw_queues(sdev->request_queue, true); + scsi_rescan_device(dev); } mutex_unlock(&sdev->state_mutex);