From: Jens Axboe <axboe@kernel.dk>
To: Ming Lei <ming.lei@redhat.com>
Cc: linux-block@vger.kernel.org, linux-scsi@vger.kernel.org,
"Martin K. Petersen" <martin.petersen@oracle.com>,
luojiaxing <luojiaxing@huawei.com>
Subject: Re: [PATCH] blk-mq: avoid to iterate over stale request
Date: Sun, 12 Sep 2021 19:31:51 -0600 [thread overview]
Message-ID: <63550f2f-a6d2-f74f-d637-9b4d1d8a0fc8@kernel.dk> (raw)
In-Reply-To: <YT6o3Lt8II2ZIOlf@T590>
On 9/12/21 7:26 PM, Ming Lei wrote:
> On Mon, Sep 06, 2021 at 02:50:03PM +0800, Ming Lei wrote:
>> blk-mq can't run allocating driver tag and updating ->rqs[tag]
>> atomically, meantime blk-mq doesn't clear ->rqs[tag] after the driver
>> tag is released.
>>
>> So there is chance to iterating over one stale request just after the
>> tag is allocated and before updating ->rqs[tag].
>>
>> scsi_host_busy_iter() calls scsi_host_check_in_flight() to count scsi
>> in-flight requests after scsi host is blocked, so no new scsi command can
>> be marked as SCMD_STATE_INFLIGHT. However, driver tag allocation still can
>> be run by blk-mq core. One request is marked as SCMD_STATE_INFLIGHT,
>> but this request may have been kept in another slot of ->rqs[], meantime
>> the slot can be allocated out but ->rqs[] isn't updated yet. Then this
>> in-flight request is counted twice as SCMD_STATE_INFLIGHT. This way causes
>> trouble in handling scsi error.
>>
>> Fixes the issue by not iterating over stale request.
>>
>> Cc: linux-scsi@vger.kernel.org
>> Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
>> Reported-by: luojiaxing <luojiaxing@huawei.com>
>> Signed-off-by: Ming Lei <ming.lei@redhat.com>
>
> Hello Jens,
>
> luojiaxiang has verified that this patch fixes his issue, any chance to
> merge it?
I'll queue it up for 5.15-rc2, thanks.
--
Jens Axboe
next prev parent reply other threads:[~2021-09-13 1:32 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-06 6:50 [PATCH] blk-mq: avoid to iterate over stale request Ming Lei
2021-09-06 22:44 ` Bart Van Assche
2021-09-07 1:14 ` Ming Lei
2021-09-13 1:26 ` Ming Lei
2021-09-13 1:31 ` Jens Axboe [this message]
2021-12-14 18:41 ` Kashyap Desai
2021-12-15 3:36 ` Ming Lei
2021-12-15 7:30 ` Kashyap Desai
2021-12-15 8:02 ` Ming Lei
2021-12-15 8:45 ` Kashyap Desai
2021-12-15 12:56 ` Ming Lei
2021-12-16 11:55 ` Kashyap Desai
2021-12-16 12:50 ` Ming Lei
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