From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>,
axboe@kernel.dk, shinichiro.kawasaki@wdc.com,
dan.j.williams@intel.com, yukuai3@huawei.com,
linux-block@vger.kernel.org
Subject: Re: [PATCH] block: remove per-disk debugfs files in blk_unregister_queue
Date: Fri, 27 May 2022 09:15:03 +0200 [thread overview]
Message-ID: <20220527071503.GA16342@lst.de> (raw)
In-Reply-To: <YozvXP9/hVhTQt+D@T590>
On Tue, May 24, 2022 at 10:44:44PM +0800, Ming Lei wrote:
> The above line code may cause kernel panic in the following code paths:
>
> 1) blk_mq_debugfs_unregister_hctxs() called from __blk_mq_update_nr_hw_queues()
>
> 2) blk_mq_debugfs_unregister_sched_hctx() called from blk_mq_exit_sched()
Yes. Then again we already have the same sort of race window in reverse
at startup time, where nothing synchronizes between
blk_mq_debugfs_register_hctxs from __blk_mq_update_nr_hw_queues and
add_disk adding debugfs files.
All this probably needs serializing using debugfs_mutex and a check of
QUEUE_FLAG_REGISTERED.
prev parent reply other threads:[~2022-05-27 7:15 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-24 8:33 [PATCH] block: remove per-disk debugfs files in blk_unregister_queue Christoph Hellwig
2022-05-24 9:29 ` Hannes Reinecke
2022-05-24 12:00 ` Christoph Hellwig
2022-05-24 11:47 ` Ming Lei
2022-05-24 12:01 ` Christoph Hellwig
2022-05-24 12:14 ` Ming Lei
2022-05-24 13:06 ` Christoph Hellwig
2022-05-24 14:44 ` Ming Lei
2022-05-27 7:15 ` Christoph Hellwig [this message]
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