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From: Keith Busch <kbusch@kernel.org>
To: Yu Zhang <yuz08559@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	Chaitanya Kulkarni <kch@nvidia.com>,
	Maurizio Lombardi <mlombard@arkamax.eu>,
	linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH v2] nvmet: take subsys->lock while force-reconnecting in nvmet_subsys_attr_qid_max_store()
Date: Wed, 21 Oct 2026 14:59:46 -0600	[thread overview]
Message-ID: <atknwrTGQ6GqNksl@kbusch-mbp> (raw)
In-Reply-To: <20261020025047.88297-1-yuz08559@gmail.com>

On Tue, Oct 20, 2026 at 12:50:47PM +1000, Yu Zhang wrote:
> nvmet_subsys_attr_qid_max_store() sets subsys->max_qid and then walks
> subsys->ctrls to force every controller to reconnect, but it holds only
> nvmet_config_sem (for write).  subsys->ctrls is protected by subsys->lock:
> nvmet_alloc_ctrl() adds an entry under subsys->lock, and nvmet_ctrl_free()
> removes it under subsys->lock with list_del() + kfree() (not kfree_rcu).
> The free path takes no nvmet_config_sem, so the two locks are independent.
> 
> A controller teardown (host disconnect, keep-alive timeout or fatal error
> -> nvmet_sq_destroy() -> nvmet_ctrl_put() -> nvmet_ctrl_free()) can
> therefore list_del() an entry while qid_max_store() is iterating the list,
> corrupting the walk.

Thanks, applied to nvme-7.4.

      parent reply	other threads:[~2026-10-21 20:59 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-14  5:47 [PATCH] " Yu Zhang
2026-10-14  6:23 ` Maurizio Lombardi
2026-10-20  2:50 ` [PATCH v2] " Yu Zhang
2026-10-21 14:02   ` Maurizio Lombardi
2026-10-21 20:59   ` Keith Busch [this message]

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