Re: [PATCH] scsi-mq: fix hw queue hang caused by timeout

[Ming Lei]

On Fri, Sep 19, 2014 at 9:07 PM, Ming Lei <ming.lei@xxxxxxxxxxxxx> wrote:
> On Fri, Sep 19, 2014 at 1:03 AM, Jens Axboe <axboe@xxxxxx> wrote:
>> On 2014-09-18 10:35, Christoph Hellwig wrote:
>>>
>>> On Thu, Sep 18, 2014 at 11:59:10PM +0800, Ming Lei wrote:
>>>>
>>>> If there are two requests or more timed out, the dispatch queue
>>>> is put into stopped state and never be recoverd, and there
>>>> is no such problem in non-mq mode.
>>>>
>>>> This patch trys to recover the stopped queue when the queue
>>>> becomes unbusy, then the following retries can move on.
>>>>
>>>> Basically this patch maintains same behavior for this situation
>>>> with non-mq mode.
>>>
>>>
>>> This looks somewhat similar to the issues that Doug reported, and I
>>> remember
>>> when he was last running into boot problems it was timeout related, too.
>>>
>>> As far as the implementation is concerned I think the correct fix is
>>> to clear the BLK_MQ_S_STOPPED queue flags in blk_mq_kick_requeue_list.
>>
>>
>> Since that's the kick part of the requeue, auto-starting the queue for that
>> makes a lot of sense. I say that's the way we go.
>
> Yeah, that looks better.
>
> But it doesn't work after the simple change, and I need to
> investigate further.

It is because of the timer miss, now it starts to work.

Thanks,
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/