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([2620:10d:c092:600::1:541b]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2d0a9f93703sm3064405ad.7.2026.08.04.01.39.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 04 Aug 2026 01:39:51 -0700 (PDT) Message-ID: <214cf82d-742a-4753-bc86-c249366b54ed@gmail.com> Date: Tue, 4 Aug 2026 09:39:31 +0100 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 02/16] iov_iter: add iterator type for dmabuf maps To: Anuj gupta Cc: Jens Axboe , Keith Busch , Christoph Hellwig , Sagi Grimberg , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, Alexander Viro , Christian Brauner , Andrew Morton , Sumit Semwal , =?UTF-8?Q?Christian_K=C3=B6nig?= , Nitesh Shetty , Kanchan Joshi , Anuj Gupta , Tushar Gohad , William Power , Phil Cayton , Jason Gunthorpe , Damien Le Moal , Alasdair Kergon , Mike Snitzer , Mikulas Patocka , Benjamin Marzinski , Vishal Verma , David Sterba , Ilya Dryomov , dm-devel@lists.linux.dev, nvdimm@lists.linux.dev, linux-btrfs@vger.kernel.org, ceph-devel@vger.kernel.org References: Content-Language: en-US From: Pavel Begunkov In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 8/3/26 14:20, Anuj gupta wrote: > On Sat, Aug 1, 2026 at 9:19 PM Pavel Begunkov wrote: >> @@ -841,7 +857,7 @@ static unsigned long iov_iter_alignment_bvec(const struct iov_iter *i) >> >> unsigned long iov_iter_alignment(const struct iov_iter *i) >> { >> - if (likely(iter_is_ubuf(i))) { >> + if (likely(iter_is_ubuf(i)) || iov_iter_is_dmabuf_map(i)) { >> size_t size = i->count; >> if (size) >> return ((unsigned long)i->ubuf + i->iov_offset) | size; > > dmabuf_map shares the same union slot as ubuf, so this reads the map > pointer as a user address. gap_alignment() below already returns 0 > correctly for dmabuf - this should too. Checked the rest of this patch > (advance/revert/restore) - none of them dereference the union pointer > for dmabuf, so it's isolated to this one spot. Doesn't affect the > current series, nothing reaches this with a dmabuf iter yet. Ah yes, that's nonsense, it should've checked iov_offset instead. Thanks -- Pavel Begunkov