RE:(2) [bug report] WARNING: CPU: 1 PID: 1386 at block/blk-mq-sched.c:432 blk_mq_sched_insert_request+0x54/0x178

[Daejun Park <daejun7.park@samsung.com>]

Hi Jens,

>>> Can either one of you try with this patch? Won't fix anything, but it'll
>>> hopefully shine a bit of light on the issue.
>>>
>> Hi Jens
>> 
>> Here is the full log:
> 
>Thanks! I think I see what it could be - can you try this one as well,
>would like to confirm that the condition I think is triggering is what
>is triggering.
> 
>diff --git a/block/blk-mq.c b/block/blk-mq.c
>index 07eb1412760b..81dede885231 100644
>--- a/block/blk-mq.c
>+++ b/block/blk-mq.c
>@@ -2515,6 +2515,8 @@ void blk_mq_submit_bio(struct bio *bio)
>         if (plug && plug->cached_rq) {
>                 rq = rq_list_pop(&plug->cached_rq);
>                 INIT_LIST_HEAD(&rq->queuelist);
>+                WARN_ON_ONCE(q->elevator && !(rq->rq_flags & RQF_ELV));
>+                WARN_ON_ONCE(!q->elevator && (rq->rq_flags & RQF_ELV));
>         } else {
>                 struct blk_mq_alloc_data data = {
>                         .q                = q,
>@@ -2535,6 +2537,8 @@ void blk_mq_submit_bio(struct bio *bio)
>                                 bio_wouldblock_error(bio);
>                         goto queue_exit;
>                 }
>+                WARN_ON_ONCE(q->elevator && !(rq->rq_flags & RQF_ELV));
>+                WARN_ON_ONCE(!q->elevator && (rq->rq_flags & RQF_ELV));
>         }
> 
>         trace_block_getrq(bio);
> 
>-- 
>Jens Axboe

The first reported warning was started from calling scsi_execute(), so how
about add the checking code in __scsi_execute()?

Thanks,
Daejun