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[142.162.112.119]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-894d375ce71sm21598586d6.45.2026.01.28.10.06.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Jan 2026 10:06:30 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1vl9vx-00000009aHB-3e3a; Wed, 28 Jan 2026 14:06:29 -0400 Date: Wed, 28 Jan 2026 14:06:29 -0400 From: Jason Gunthorpe To: "D. Wythe" Cc: Leon Romanovsky , Uladzislau Rezki , "David S. Miller" , Andrew Morton , Dust Li , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Sidraya Jayagond , Wenjia Zhang , Mahanta Jambigi , Simon Horman , Tony Lu , Wen Gu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org, netdev@vger.kernel.org, oliver.yang@linux.alibaba.com Subject: Re: [PATCH net-next 2/3] mm: vmalloc: export find_vm_area() Message-ID: <20260128180629.GT1641016@ziepe.ca> References: <20260123082349.42663-1-alibuda@linux.alibaba.com> <20260123082349.42663-3-alibuda@linux.alibaba.com> <20260124093505.GA98529@j66a10360.sqa.eu95> <20260124145754.GA57116@j66a10360.sqa.eu95> <20260127133417.GU13967@unreal> <20260128034558.GA126415@j66a10360.sqa.eu95> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260128034558.GA126415@j66a10360.sqa.eu95> X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 14794140007 X-Stat-Signature: bb6dcakdamrypmzofqn3iqsqgnnckj38 X-HE-Tag: 1769623591-5708 X-HE-Meta: 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 nYrJUOlD fiBk3xikwIcChROJPWU/CPKoOQi6MNAU075ZgjqMXuwkwEGTrYXvVKxbuekz2mHZSc/RVvsifdfuMJKvg+ztsVxmZ6Sch4E2MyrmueiWTA0OYNEyIli6RbbwQBnv3Usfpb7fb3WNhFJ5sP497cT8OiKSDV8Gkshi5UxzY6mQZcLagCi7EkcId8G2paff1orZ0ZVQAcacoHSRCnC7HFLYxnkAKdm2pAUbGFyGqpRhheUv0L3bhRfHj2VEgdPEJsly9gMpr1ZoZ2OgapDSjE5AHs97K1H6VbGcqU7r7zm1dU3mpLwiP1XAT7dXyGw5Czn4ehfoVIcz6pZ57vqY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jan 28, 2026 at 11:45:58AM +0800, D. Wythe wrote: > By leveraging vmalloc_huge() and the proposed helper to increase the > page_size in ib_map_mr_sg(), each MTTE covers a much larger contiguous > physical block. This doesn't seem right, if your goal is to take a vmalloc() pointer and convert it to a MR via a scatterlist and ib_map_mr_sg() then you should be asking for a helper to convert a kernel pointer into a scatterlist. Even if you do this in a naive way and call the sg_alloc_append_table_from_pages() function it will automatically join physically contiguous ranges together for you. >From there you can check the resulting scatterlist and compute the page_size to pass to ib_map_mr_sg(). No need to ask the MM for anything other than the list of physicals to build the scatterlist with. Still, I wouldn't mind seeing a helper to convert a kernel pointer into a scatterlist because I have see that opencoded in a few places, and maybe there are ways to optimize that using more information from the MM - but it should be APIs used only by this helper not exposed to drivers. Jason