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Message-ID: <8c7b011e-1379-c151-a187-94d8e0697fd9@oracle.com>
Date: Thu, 24 May 2018 09:50:35 +0800
From: "jianchao.wang" <jianchao.w.wang@...cle.com>
To: qla2xxx-upstream@...gic.com, himanshu.madhani@...ium.com,
jthumshirn@...e.de
Cc: linux-scsi@...r.kernel.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"jejb@...ux.vnet.ibm.com" <jejb@...ux.vnet.ibm.com>,
"Martin K. Petersen" <martin.petersen@...cle.com>,
Junxiao Bi <junxiao.bi@...cle.com>
Subject: Re: BUG: scsi/qla2xxx: BUG_ON(blk_queued_rq(req) is triggered in
blk_finish_request
Would anyone please take a look at this ?
Thanks in advance
Jianchao
On 05/23/2018 11:55 AM, jianchao.wang wrote:
>
>
> Hi all
>
> Our customer met a panic triggered by BUG_ON in blk_finish_request.
>>>From the dmesg log, the BUG_ON was triggered after command abort occurred many times.
> There is a race condition in the following scenario.
>
> cpu A cpu B
> kworker interrupt
>
> scmd_eh_abort_handler()
> -> scsi_try_to_abort_cmd()
> -> qla2xxx_eh_abort()
> -> qla2x00_eh_wait_on_command() qla2x00_status_entry()
> -> qla2x00_sp_compl()
> -> qla2x00_sp_free_dma()
> -> scsi_queue_insert()
> -> __scsi_queue_insert()
> -> blk_requeue_request()
> -> blk_clear_rq_complete()
> -> scsi_done
> -> blk_complete_request
> -> blk_mark_rq_complete
> -> elv_requeue_request() -> __blk_complete_request()
> -> __elv_add_request()
> // req will be queued here
> BLK_SOFTIRQ
> scsi_softirq_done()
> -> scsi_finish_command()
> -> scsi_io_completion()
> -> scsi_end_request()
> -> blk_finish_request() // BUG_ON(blk_queued_rq(req)) !!!
>
> The issue will not be triggered most of time, because the request is marked as complete by timeout path.
> So the scsi_done from qla2x00_sp_compl does nothing.
> But as the scenario above, if the complete state has been cleaned by blk_requeue_request, we will get
> the request both requeued and completed, and then BUG_ON(blk_queued_rq(req)) in blk_finish_request comes up.
>
> Is there any solution for this in qla2xxx driver side ?
>
> Thanks
> Jianchao
>
>
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