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From: Ming Lei <>
To: Hou Tao <>
Cc: Jens Axboe <>,
Subject: Re: [PATCH] block: check the existence of tags[hctx_idx] in blk_mq_clear_rq_mapping()
Date: Thu, 9 Sep 2021 17:19:47 +0800	[thread overview]
Message-ID: <YTnRsxec3JfPINmu@T590> (raw)
In-Reply-To: <>

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?


  reply	other threads:[~2021-09-09  9:19 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-09  9:00 [PATCH] block: check the existence of tags[hctx_idx] in blk_mq_clear_rq_mapping() Hou Tao
2021-09-09  9:19 ` Ming Lei [this message]
2021-09-09 11:14   ` Hou Tao
2021-09-13  1:43     ` Ming Lei

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