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Date: Thu, 27 Nov 2025 14:39:55 +0100
From: Greg KH <gregkh@linuxfoundation.org>
To: Zheng Qixing <zhengqixing@huaweicloud.com>
Cc: cve@kernel.org, linux-cve-announce@vger.kernel.org,
	linux-kernel@vger.kernel.org, yukuai@fnnas.com, ming.lei@redhat.com,
	Nilay Shroff <nilay@linux.ibm.com>,
	"zhangyi (F)" <yi.zhang@huawei.com>,
	yangerkun <yangerkun@huawei.com>, Hou Tao <houtao1@huawei.com>
Subject: Re: CVE-2025-40146: blk-mq: fix potential deadlock while nr_requests
 grown
Message-ID: <2025112730-semicolon-verse-164a@gregkh>
References: <2025111256-CVE-2025-40146-b919@gregkh>
 <15fb6eed-e107-4ef7-a569-3328a02e2c39@huaweicloud.com>
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In-Reply-To: <15fb6eed-e107-4ef7-a569-3328a02e2c39@huaweicloud.com>

On Thu, Nov 27, 2025 at 09:22:42PM +0800, Zheng Qixing wrote:
> Hi,
> 
> Commit b86433721f46 ("blk-mq: fix potential deadlock while nr_requests
> grown")  aims to avoid a deadlock issue when the queue is frozen and memory
> reclaim is triggered.
> 
> However, the sysfs nr_requests update path is already under a
> memalloc_noio_save() region while the queue is frozen (via
> blk_mq_freeze_queue()).

Did the lockdep splat in
https://lore.kernel.org/all/0659ea8d-a463-47c8-9180-43c719e106eb@linux.ibm.com/
not describe the issue here that the commit is attempting to solve?

thanks,

greg k-h