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Date:   Tue, 14 Jun 2022 00:12:03 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Ming Lei <ming.lei@redhat.com>
Cc:     Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        Yi Zhang <yi.zhang@redhat.com>
Subject: Re: [PATCH] block: fix rq_qos leak for bio based queue
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On Tue, Jun 14, 2022 at 02:44:26PM +0800, Ming Lei wrote:
> Commit 5ca7546fe317 ("block: move rq_qos_exit() into disk_release()")
> moves rq_qos_exit() to disk_release(), but only done for blk-mq queue.
> 
> However, now rq qos can be created via blkcg_init_queue() for bio based
> queue, so we need to call rq_qos_exit() for bio queue too.
> 
> In theory, so far, rq_qos is only implemented for request based queue,
> and we should only add it for blk-mq queue. However, if using blk-mq
> during allocating queue may not be known, fix the rq qos leak issue by
> always releasing rq qos for both two kinds of queues.

This is also fixed by "block: disable the elevator int del_gendisk"
which was just resent yesterday, and fundamentally gets the lifetimes
right rather than doctoring around even more.