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([2a01:4b00:bd21:4f00:7cc6:d3ca:494:116c]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4836131d52bsm36821225e9.28.2026.02.12.02.52.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 12 Feb 2026 02:52:28 -0800 (PST) Message-ID: <809cd04b-007b-46c6-9418-161e757e0e80@gmail.com> Date: Thu, 12 Feb 2026 10:52:29 +0000 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 03/11] io_uring/kbuf: add support for kernel-managed buffer rings To: Christoph Hellwig , Joanne Koong Cc: axboe@kernel.dk, io-uring@vger.kernel.org, csander@purestorage.com, krisman@suse.de, bernd@bsbernd.com, linux-fsdevel@vger.kernel.org References: <20260210002852.1394504-1-joannelkoong@gmail.com> <20260210002852.1394504-4-joannelkoong@gmail.com> <89c75fc1-2def-4681-a790-78b12b45478a@gmail.com> <1c657f67-0862-4e13-9c71-7217aeecef61@gmail.com> Content-Language: en-US From: Pavel Begunkov In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2/12/26 10:07, Christoph Hellwig wrote: > On Wed, Feb 11, 2026 at 02:06:18PM -0800, Joanne Koong wrote: >>> I don't think I follow. I'm saying that it might be interesting >>> to separate rings from how and with what they're populated on the >>> kernel API level, but the fuse kernel module can do the population >> >> Oh okay, from your first message I (and I think christoph too) thought >> what you were saying is that the user should be responsible for >> allocating the buffers with complete ownership over them, and then >> just pass those allocated to the kernel to use. But what you're saying >> is that just use a different way for getting the kernel to allocate >> the buffers (eg through the IORING_REGISTER_MEM_REGION interface). Am >> I reading this correctly? > > I'm arguing exactly against this. For my use case I need a setup > where the kernel controls the allocation fully and guarantees user > processes can only read the memory but never write to it. I'd love > to be able to piggy back than onto your work. IORING_REGISTER_MEM_REGION supports both types of allocations. It can have a new registration flag for read-only, and then you either make the bounce avoidance optional or reject binding fuse to unsupported setups during init. Any arguments against that? I need to go over Joanne's reply, but I don't see any contradiction in principal with your use case. -- Pavel Begunkov