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Subject: Re: "blk-mq: fix tag_get wait task can't be awakened" causes hangs
To:     QiuLaibin <qiulaibin@huawei.com>,
        "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        linux-block@vger.kernel.org
Cc:     john.garry@huawei.com, ming.lei@redhat.com,
        martin.petersen@oracle.com, hare@suse.de,
        akpm@linux-foundation.org, bvanassche@acm.org,
        linux-kernel@vger.kernel.org
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From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <723815a5-f716-499a-acce-15028a629f3a@kernel.dk>
Date:   Wed, 26 Jan 2022 06:38:31 -0700
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On 1/24/22 9:08 PM, QiuLaibin wrote:
> Hi Alex
> 
> 1、Please help to import this structure:
> 
> blk_mq_tags <= request_queue->blk_mq_hw_ctx->blk_mq_tags
> 
> If there is no kernel dump, help to see the value of
> 
> cat /sys/block/sda/mq/0/nr_tags
>                 __ <= Change it to the problem device
> 
> And how many block devices in total by lsblk.
> 
> 2、Please describe in detail how to reproduce the issue,
> 
> And what type of USB device?
> 
> 3、Please help to try the attachment patch and see if it can be reproduced.

Any progress on this? I strongly suspect that any QD=1 setup would
trivially show the issue, based on the reports.

-- 
Jens Axboe