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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,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 D13A7C10F03 for ; Fri, 22 Mar 2019 12:47:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9FF312070D for ; Fri, 22 Mar 2019 12:47:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553258841; bh=0fI+ZXnX7s2QP62W3hcyl+l7OMo8QRcIQj7SwJzuci4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=P9mXpG5M8r5OlTcITm2KLHn3M9SK1knm4ATwZi5HIec7yqynn1znKLlZqjKVmozCc vAeBQ3BKFRyCfyPCsWrHgKb4L/3fjTBgSi9XKjg25nhLgxcVg4JmldjwUy0ZPEvdiF Ny5bu39EaCv6kBhWWzhgg3O+kHeHGqdb9ECOuI4k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732963AbfCVL6e (ORCPT ); Fri, 22 Mar 2019 07:58:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:35218 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387838AbfCVL6a (ORCPT ); Fri, 22 Mar 2019 07:58:30 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 031B820850; Fri, 22 Mar 2019 11:58:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553255909; bh=0fI+ZXnX7s2QP62W3hcyl+l7OMo8QRcIQj7SwJzuci4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EluuUmnbJFUiH3rHuw2uMdRLXdUmHdbd6pQ5iFv//6ROhSYKAMZfe6rVnm515HgsC A8ZBROx3ymAIWZ+Tq8qrmsAEHxDQvF5+y0o8H8+c/Hf91rXtSqdsGchz6rPxqB3raS xiuTYuaS3fmmgV+bloeUlGpxIX+4Qo3LQkGGrL1Y= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jens Axboe , Jianchao Wang , Sasha Levin Subject: [PATCH 4.19 051/280] blk-mq: insert rq with DONTPREP to hctx dispatch list when requeue Date: Fri, 22 Mar 2019 12:13:24 +0100 Message-Id: <20190322111309.169307172@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190322111306.356185024@linuxfoundation.org> References: <20190322111306.356185024@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit aef1897cd36dcf5e296f1d2bae7e0d268561b685 ] When requeue, if RQF_DONTPREP, rq has contained some driver specific data, so insert it to hctx dispatch list to avoid any merge. Take scsi as example, here is the trace event log (no io scheduler, because RQF_STARTED would prevent merging), kworker/0:1H-339 [000] ...1 2037.209289: block_rq_insert: 8,0 R 4096 () 32768 + 8 [kworker/0:1H] scsi_inert_test-1987 [000] .... 2037.220465: block_bio_queue: 8,0 R 32776 + 8 [scsi_inert_test] scsi_inert_test-1987 [000] ...2 2037.220466: block_bio_backmerge: 8,0 R 32776 + 8 [scsi_inert_test] kworker/0:1H-339 [000] .... 2047.220913: block_rq_issue: 8,0 R 8192 () 32768 + 16 [kworker/0:1H] scsi_inert_test-1996 [000] ..s1 2047.221007: block_rq_complete: 8,0 R () 32768 + 8 [0] scsi_inert_test-1996 [000] .Ns1 2047.221045: block_rq_requeue: 8,0 R () 32776 + 8 [0] kworker/0:1H-339 [000] ...1 2047.221054: block_rq_insert: 8,0 R 4096 () 32776 + 8 [kworker/0:1H] kworker/0:1H-339 [000] ...1 2047.221056: block_rq_issue: 8,0 R 4096 () 32776 + 8 [kworker/0:1H] scsi_inert_test-1986 [000] ..s1 2047.221119: block_rq_complete: 8,0 R () 32776 + 8 [0] (32768 + 8) was requeued by scsi_queue_insert and had RQF_DONTPREP. Then it was merged with (32776 + 8) and issued. Due to RQF_DONTPREP, the sdb only contained the part of (32768 + 8), then only that part was completed. The lucky thing was that scsi_io_completion detected it and requeued the remaining part. So we didn't get corrupted data. However, the requeue of (32776 + 8) is not expected. Suggested-by: Jens Axboe Signed-off-by: Jianchao Wang Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-mq.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 23a53b67cf0d..7d53f2314d7c 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -701,12 +701,20 @@ static void blk_mq_requeue_work(struct work_struct *work) spin_unlock_irq(&q->requeue_lock); list_for_each_entry_safe(rq, next, &rq_list, queuelist) { - if (!(rq->rq_flags & RQF_SOFTBARRIER)) + if (!(rq->rq_flags & (RQF_SOFTBARRIER | RQF_DONTPREP))) continue; rq->rq_flags &= ~RQF_SOFTBARRIER; list_del_init(&rq->queuelist); - blk_mq_sched_insert_request(rq, true, false, false); + /* + * If RQF_DONTPREP, rq has contained some driver specific + * data, so insert it to hctx dispatch list to avoid any + * merge. + */ + if (rq->rq_flags & RQF_DONTPREP) + blk_mq_request_bypass_insert(rq, false); + else + blk_mq_sched_insert_request(rq, true, false, false); } while (!list_empty(&rq_list)) { -- 2.19.1