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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3313DECAAA3 for ; Fri, 26 Aug 2022 03:25:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244605AbiHZDZf convert rfc822-to-8bit (ORCPT ); Thu, 25 Aug 2022 23:25:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50008 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244299AbiHZDZ3 (ORCPT ); Thu, 25 Aug 2022 23:25:29 -0400 Received: from out30-43.freemail.mail.aliyun.com (out30-43.freemail.mail.aliyun.com [115.124.30.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 66BB4AA4D1 for ; Thu, 25 Aug 2022 20:25:27 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046051;MF=gumi@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0VNHDRld_1661484323; Received: from LR9115VM81021(mailfrom:gumi@linux.alibaba.com fp:SMTPD_---0VNHDRld_1661484323) by smtp.aliyun-inc.com; Fri, 26 Aug 2022 11:25:24 +0800 From: To: "'Bart Van Assche'" , , Cc: Subject: Re: [PATCH v2] block: I/O error occurs during SATA disk stress test Date: Fri, 26 Aug 2022 11:25:23 +0800 Message-ID: <000a01d8b8fb$7b4a7950$71df6bf0$@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Mailer: Microsoft Outlook 16.0 Content-Language: zh-cn Thread-Index: Adi4+jaKMORL0D1OS/WMZ189NjS34g== Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 8/25/22 00:09, Gu Mi wrote: > The problem occurs in two async processes, One is when a new IO calls > the blk_mq_start_request() interface to start sending,The other is > that the block layer timer process calls the blk_mq_req_expired > interface to check whether there is an IO timeout. > > When an instruction out of sequence occurs between blk_add_timer and > WRITE_ONCE(rq->state,MQ_RQ_IN_FLIGHT) in the interface > blk_mq_start_request,at this time, the block timer is checking the new > IO timeout, Since the req status has been set to MQ_RQ_IN_FLIGHT and > req->deadline is 0 at this time, the new IO will be misjudged as a > timeout. > > Our repair plan is for the deadline to be 0, and we do not think that > a timeout occurs. At the same time, because the jiffies of the 32-bit > system will be reversed shortly after the system is turned on, we will > add 1 jiffies to the deadline at this time. > > Signed-off-by: Gu Mi > --- > v1->v2: > > time_after_eq() can handle the overflow, so remove the change on > 32-bit in blk_add_timer(). > > block/blk-mq.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/block/blk-mq.c b/block/blk-mq.c index 4b90d2d..6defaa1 > 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -1451,6 +1451,8 @@ static bool blk_mq_req_expired(struct request *rq, unsigned long *next) > return false; > > deadline = READ_ONCE(rq->deadline); > + if (unlikely(deadline == 0)) > + return false; > if (time_after_eq(jiffies, deadline)) > return true; > rq->deadline == 0 can be a valid deadline value so the above patch doesn't look right to me. Thanks, Bart. --- in patch 1, I added another modification in blk_add_timer(). As follows, > +#ifndef CONFIG_64BIT > +/* In case INITIAL_JIFFIES wraps on 32-bit */ > + expiry |= 1UL; The purpose of this modification is to ensure that rq->deadline is 0 means that it is initialized to 0 in blk_mq_req_expired(). In this case, make sure rq->deadline is an invalid value in blk_mq_req_expired(). Please review my workaround again. Thanks, Gu Mi.