On 2018/11/21 11:49, Jens Axboe wrote:
> On 11/20/18 7:45 PM, Damien Le Moal wrote:
>> On 2018/11/21 11:11, Jens Axboe wrote:
>>> On 11/20/18 4:58 PM, Damien Le Moal wrote:
>>>> On 2018/11/21 2:31, Jens Axboe wrote:
>>>>> I think the below should fix it, we haven't necessarily setup an
>>>>> ioc if we're just doing as passthrough request.
>>>>>
>>>>>
>>>>> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
>>>>> index 13b8dc332541..f096d8989773 100644
>>>>> --- a/block/blk-mq-sched.c
>>>>> +++ b/block/blk-mq-sched.c
>>>>> @@ -34,9 +34,16 @@ EXPORT_SYMBOL_GPL(blk_mq_sched_free_hctx_data);
>>>>> void blk_mq_sched_assign_ioc(struct request *rq)
>>>>> {
>>>>> struct request_queue *q = rq->q;
>>>>> - struct io_context *ioc = current->io_context;
>>>>> + struct io_context *ioc;
>>>>> struct io_cq *icq;
>>>>>
>>>>> + /*
>>>>> + * May not have an IO context if it's a passthrough request
>>>>> + */
>>>>> + ioc = current->io_context;
>>>>> + if (!ioc)
>>>>> + return;
>>>>> +
>>>>> spin_lock_irq(&q->queue_lock);
>>>>> icq = ioc_lookup_icq(ioc, q);
>>>>> spin_unlock_irq(&q->queue_lock);
>>>>
>>>> This seems reasonable to me, but I wonder why this problem was not triggering
>>>> before. The previous code getting the ioc with the rq_ioc(bio) call was
>>>> essentially the same and there was no "if (!ioc) return;" in
>>>> blk_mq_sched_assign_ioc() before the patch.
>>>> Any idea why this is popping up now ?
>>>>
>>>> Ming,
>>>>
>>>> Is this a new test your are running ? If this same problem triggers on stable
>>>> kernels, Jens patch needs to go to stable too.
>>>
>>> No, it's definitely introduced in your patches:
>>>
>>> - if (e->type->icq_cache && rq_ioc(bio))
>>> - blk_mq_sched_assign_ioc(rq, bio);
>>> + if (e->type->icq_cache)
>>> + blk_mq_sched_assign_ioc(rq);
>>>
>>> Please run blktests on a series. Always. There's no excuse not to.
>>
>> By the way, should I send an updated patch 2 to include your fix ?
>> Or will you add an incremental fix ?
>
> I had to add the incremental fix, I already merged your patches
> earlier. It's all pushed out now.
Thank you.
--
Damien Le Moal
Western Digital Research
