linux-kernel - Re: CVE-2025-40146: blk-mq: fix potential deadlock while nr

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Message-ID: <2025112730-semicolon-verse-164a@gregkh>
Date: Thu, 27 Nov 2025 14:39:55 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Zheng Qixing <zhengqixing@...weicloud.com>
Cc: cve@...nel.org, linux-cve-announce@...r.kernel.org,
	linux-kernel@...r.kernel.org, yukuai@...as.com, ming.lei@...hat.com,
	Nilay Shroff <nilay@...ux.ibm.com>,
	"zhangyi (F)" <yi.zhang@...wei.com>,
	yangerkun <yangerkun@...wei.com>, Hou Tao <houtao1@...wei.com>
Subject: Re: CVE-2025-40146: blk-mq: fix potential deadlock while nr_requests
 grown

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