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.
--
Jens Axboe
