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Date: Tue, 13 Oct 2026 09:42:47 -0600
From: Keith Busch <kbusch@kernel.org>
To: Palla Raghunath <raghunathpalla.0209@gmail.com>
Cc: Justin Tee <justin.tee@broadcom.com>,
	Naresh Gottumukkala <nareshgottumukkala83@gmail.com>,
	Paul Ely <paul.ely@broadcom.com>, Christoph Hellwig <hch@lst.de>,
	Sagi Grimberg <sagi@grimberg.me>,
	Chaitanya Kulkarni <kch@nvidia.com>,
	Daniel Wagner <dwagner@suse.de>, Hannes Reinecke <hare@suse.de>,
	linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
	Shuah Khan <shuah@kernel.org>,
	Brigham Campbell <me@brighamcampbell.com>,
	linux-kernel-mentees@lists.linux.dev,
	syzbot+da94a51633758d13bd63@syzkaller.appspotmail.com
Subject: Re: [PATCH] nvmet-fc: don't drop the last assoc reference in
 nvmet_fc_delete_ctrl()
Message-ID: <as5Rd6jGQNtJpW0C@kbusch-mbp>
References: <20261008191848.47066-1-raghunathpalla.0209@gmail.com>
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In-Reply-To: <20261008191848.47066-1-raghunathpalla.0209@gmail.com>

On Thu, Oct 08, 2026 at 08:18:48PM +0100, Palla Raghunath wrote:
> syzbot hit a recursive locking report on subsys->lock when a subsystem
> is unlinked from an FC port.
> 
> nvmet_port_del_ctrls() holds subsys->lock while it calls ->delete_ctrl()
> for each controller. nvmet_fc_delete_ctrl() grabs a reference on the
> association, queues del_work and then drops the reference. If del_work
> gets to run to completion before that put, ours is the last reference.
> Freeing the assoc tears down the queues, the last nvmet_cq_put() drops
> the last ctrl reference, and nvmet_ctrl_free() goes for subsys->lock
> again:

Thanks, applied to nvme-7.4.