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Date: Mon, 24 Feb 2025 07:54:59 -0700
From: Keith Busch <kbusch@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Xinyu Zhang <xizhang@purestorage.com>, linux-nvme@lists.infradead.org,
	linux-kernel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
	Sagi Grimberg <sagi@grimberg.me>,
	Caleb Sander Mateos <csander@purestorage.com>
Subject: Re: [PATCH] nvme: map uring_cmd data even if address is 0
Message-ID: <Z7yIQzPhgD1Elx-H@kbusch-mbp>
References: <20250220235101.119852-1-xizhang@purestorage.com>
 <20250224143350.GB1406@lst.de>
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In-Reply-To: <20250224143350.GB1406@lst.de>

On Mon, Feb 24, 2025 at 03:33:51PM +0100, Christoph Hellwig wrote:
> On Thu, Feb 20, 2025 at 04:51:01PM -0700, Xinyu Zhang wrote:
> > When using kernel registered bvec fixed buffers, the "address" is
> > actually the offset into the bvec rather than userspace address.
> > Therefore it can be 0.
> 
> How is that actually going to work?  Who is interpreting that address?

io_import_fixed() treats the address as an offset into its bio_vec.