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Date: Tue, 31 Mar 2026 17:22:17 +0200
From: Christoph Hellwig <hch@lst.de>
To: Jackie Liu <liu.yun@linux.dev>
Cc: tj@kernel.org, hch@lst.de, axboe@kernel.dk, cgroups@vger.kernel.org,
	linux-block@vger.kernel.org
Subject: Re: [PATCH] blk-cgroup: fix disk reference leak in
 blkcg_maybe_throttle_current()
Message-ID: <20260331152217.GA8074@lst.de>
References: <20260331085054.46857-1-liu.yun@linux.dev>
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On Tue, Mar 31, 2026 at 04:50:54PM +0800, Jackie Liu wrote:
> From: Jackie Liu <liuyun01@kylinos.cn>
> 
> Add the missing put_disk() on the error path in
> blkcg_maybe_throttle_current(). When blkcg lookup, blkg lookup, or
> blkg_tryget() fails, the function jumps to the out label which only
> calls rcu_read_unlock() but does not release the disk reference acquired
> by blkcg_schedule_throttle() via get_device(). Since current->throttle_disk
> is already set to NULL before the lookup, blkcg_exit() cannot release
> this reference either, causing the disk to never be freed.
> 
> Restore the reference release that was present as blk_put_queue() in the
> original code but was inadvertently dropped during the conversion from
> request_queue to gendisk.

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>