Hello Hou,
On Thu, Sep 09, 2021 at 05:00:54PM +0800, Hou Tao wrote:
> According to commit 4412efecf7fd ("Revert "blk-mq: remove code for
> dealing with remapping queue""), for some devices queue hctx may not
> being mapped, and tagset->tags[hctx_idx] will be released and be NULL.
>
> If an IO scheduler is used on these devices, blk_mq_clear_rq_mapping()
> will be called for all hctxs in blk_mq_sched_free_requests() during
> scheduler switch, and these will be oops. So checking the existence of
> tags[hctx_idx] before going on in blk_mq_clear_rq_mapping().
unmapped hctx should be caused by blk_mq_update_nr_hw_queues() only,
but scheduler tags is updated there too, so not sure it is one real
issue, did you observe such kernel panic? any kernel log?
Thanks,
Ming
