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[107.191.0.158]) by smtp.gmail.com with ESMTPSA id g23-v6sm649248iob.88.2018.08.02.10.08.23 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 02 Aug 2018 10:08:24 -0700 (PDT) Subject: Re: [PATCH] blk-mq: fix blk_mq_tagset_busy_iter To: Ming Lei , James Bottomley Cc: linux-block@vger.kernel.org, Josef Bacik , Christoph Hellwig , Guenter Roeck , Mark Brown , Matt Hart , Johannes Thumshirn , John Garry , Hannes Reinecke , "Martin K. Petersen" , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org References: <20180802164329.11900-1-ming.lei@redhat.com> <1533228846.3915.17.camel@HansenPartnership.com> <20180802170601.GC8928@ming.t460p> From: Jens Axboe Message-ID: Date: Thu, 2 Aug 2018 11:08:22 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <20180802170601.GC8928@ming.t460p> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/2/18 11:06 AM, Ming Lei wrote: > On Thu, Aug 02, 2018 at 09:54:06AM -0700, James Bottomley wrote: >> On Fri, 2018-08-03 at 00:43 +0800, Ming Lei wrote: >>> Commit d250bf4e776ff09d5("blk-mq: only iterate over inflight requests >>> in blk_mq_tagset_busy_iter") uses 'blk_mq_rq_state(rq) == >>> MQ_RQ_IN_FLIGHT' >>> to replace 'blk_mq_request_started(req)', this way is wrong, and >>> causes >>> lots of test system hang during booting. >>> >>> Fix the issue by using blk_mq_request_started(req) inside >>> bt_tags_iter(). >>> >>> Fixes: d250bf4e776ff09d5 ("blk-mq: only iterate over inflight >>> requests in blk_mq_tagset_busy_iter") >>> Cc: Josef Bacik >>> Cc: Christoph Hellwig >>> Cc: Guenter Roeck >>> Cc: Mark Brown >>> Cc: Matt Hart >>> Cc: Johannes Thumshirn >>> Cc: John Garry >>> Cc: Hannes Reinecke , >>> Cc: "Martin K. Petersen" , >>> Cc: James Bottomley >>> Cc: linux-scsi@vger.kernel.org >>> Cc: linux-kernel@vger.kernel.org >>> Signed-off-by: Ming Lei >>> --- >>>  block/blk-mq-tag.c | 2 +- >>>  1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c >>> index 09b2ee6694fb..3de0836163c2 100644 >>> --- a/block/blk-mq-tag.c >>> +++ b/block/blk-mq-tag.c >>> @@ -271,7 +271,7 @@ static bool bt_tags_iter(struct sbitmap *bitmap, >>> unsigned int bitnr, void *data) >>>    * test and set the bit before assining ->rqs[]. >>>    */ >>>   rq = tags->rqs[bitnr]; >>> - if (rq && blk_mq_rq_state(rq) == MQ_RQ_IN_FLIGHT) >>> + if (rq && blk_mq_request_started(rq)) >> >> So now we have dueling versions of this patch: >> >> https://marc.info/?l=linux-scsi&m=153322802207688 >> >> Can we at least make sure we've root caused the problem and confirmed >> we've got it fixed before we start the formal patch process? When we > > EH uses scsi_host_busy to check if the error handler needs to be waken > up. And blk_mq_tagset_busy_iter() is used for implementing scsi_host_busy(), > so causes EH not waken up, then this timed-out request can't be handled. > >> do start the formal patch process, please give appropriate credit to >> the reporter(s) since this has been a royal pain for them to help us >> track down. > > Sure. > > Jens, could you add reported-by if you are fine with this version? Or please > just let me know if new version is needed, then I can add it. I'll add that, would also love a tested-by from the reporter. The patch looks good to me, however. -- Jens Axboe