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AJvYcCVAkPlaGCn1rkcGPN3W9CkeJbhOsuavGsM16EhZMcKVVahRQbd9x8/YpIUqunRiFdE7SQYsAfNeNA==@kvack.org X-Gm-Message-State: AOJu0YwgjhMAMe6DGWDcxRXNVIV8GzO15I1y/HwitW3+u+4zvb0c9gW4 iiN0+Rj0aueFbBXeDVsGpoVFtmzNxUBA/Y0KUxn8FRtA3unsRbB2ocPNWsX4LFqNvVEPIkoMsGi qvPVNnsWEPmpwN2LWUvi1ramiJl15pUSk1sDt X-Gm-Gg: ASbGnct9AMnBVipXBOSEPTf9ib6IareCLq/n6A9nFHERRvqKvd6VbEqHIKl++68boWQ NhSA914qhxwt22HP8CkX89uOez67X3xi1Wpso1UBj8zv7GdaGG0ALY/DX9W5z1Q== X-Google-Smtp-Source: AGHT+IFg434w4z8s8tFqBhE5av51BwZ42Q5HKcJ0oYopIV4HP+3g/md6jNDkoJ8cd/1hXD6iFlXDlWN68Eo2+u/s9YQ= X-Received: by 2002:a05:6000:1866:b0:385:e5d8:3ef1 with SMTP id ffacd0b85a97d-385fd4374d8mr9050329f8f.44.1733395215402; Thu, 05 Dec 2024 02:40:15 -0800 (PST) MIME-Version: 1.0 References: <20241129-vma-v10-0-4dfff05ba927@google.com> <20241129-vma-v10-2-4dfff05ba927@google.com> In-Reply-To: <20241129-vma-v10-2-4dfff05ba927@google.com> From: Alice Ryhl Date: Thu, 5 Dec 2024 11:40:03 +0100 Message-ID: Subject: Re: [PATCH v10 2/8] mm: rust: add vm_area_struct methods that require read access To: Miguel Ojeda , Matthew Wilcox , Lorenzo Stoakes , Vlastimil Babka , John Hubbard , "Liam R. Howlett" , Andrew Morton , Greg Kroah-Hartman , Arnd Bergmann , Christian Brauner , Jann Horn , Suren Baghdasaryan Cc: Alex Gaynor , Boqun Feng , Gary Guo , =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Trevor Gross , linux-kernel@vger.kernel.org, linux-mm@kvack.org, rust-for-linux@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 4B57240011 X-Stat-Signature: 63f1mf9mg7qd7htmftu9si93afirm18y X-Rspam-User: X-HE-Tag: 1733395205-1164 X-HE-Meta: U2FsdGVkX18qs81OTUB+pZskA0ADfvEVUE43uGIbWBko74T1rGieTuGT/spCrdbBp2eKImR/JjWRoYRNiiIyLhDFGJOXdRf6LxuLb2Ky9CUUoAPYku65vWx4qEp2LWVCgky7cP3ry/d4M+OKg1OU6zxXuLmYn7a3O8mk4wDjKkKYvgmBqi8TogJPyVGHhPSVROEWYbALLO/gfpEMFe0YCey04FGmxmps2e2Jzm58cDZoINnk8VBIeudbaNvEuDPbcrPiaGdskkwxhHM45Di71aXN5VbHiVlL/dtDq+V/irD/AfKLnFtA9CD5j9a2mvGz8UKk0+XaT3yhe+2P8Q7rieXY7bkzUbE0gURVWWOUTfLFPSrqjROVHnBvxzrBAkeLghKD4yKmlTNcUs+6tFxgW4Byg0GylAHWRecLQp7THhUL3DkoarDmsdXsZd/FZnUaoK/MsvMRhZohvIM+Udr08uGSPv5/U/h4kDSxaWVAQybrFQAGq7pSvmUTJmvv0MUeLFUGa/sYFeBMKb2sCtkGP1jolUde5Qzo0P5uCQRQxZv5PXHsSq7AAqGvfIdb4AZnIMC8cMxQW2DEn7g4R8HH0e2q7SVNczkP9RvRRgFc9tyN4uJjZD3rms6S7638NwGgCJAPCJCNDVayRFVNNMpLayuf64w+VRcTq1dveqP+GGnUGcVMbT2lQYQuQeSMCzxYHMNaVovTak8E5oMnEQYdnNYBeeS1PhXVZDgSvAd/3hFiZxy0IcqlvBsqQuvsmqkOD+nVvk6uZZbWCSwQ3+TB2xelOskCVhxGhTFgX2NBuTAHe8p1a//ifwllJvItbqjYu65rAR4jHUlBt6E8qkgH0p2w5j7XNlafOzt5eD+hMMKGQK0G6ptRNIdnkzBX51nkHapRsaLBkbAZW81fJIkGy6kSqTiQZ6vBmvKNL+hkrx5TisVm5Ajvsbg/TZS7HnUhki7oCGdOvVWP+h8N2th xf3DIEY4 yTEQjCmUtqXzvob7N8bjJ7+YNZ0v3OGiunibMwypLynZcocDhPD1yCj1Uu8agSv/R5Hz+9yPosARopi6WE6/1rXINmE8MQ4xDX4l2/yrh9MQ1YozsnjavnwUeqhAGAvTae8ENqARjl48tiZ7Re2kbVn3LvvugoNiG60YAR/34wKqbDjAQ9yFaMEvFJ5GjZEhHhzonJmiVuJCHUA7OWSnnFbINUmPGUmtb2czTy8uK8tQVTruy1RTo5mWWXLlRBfYsCEx/lbIMWR4B1rnWMfaJhOJ820Z24kUMpDFhHPm0+nEjYXGkcPDzzMyWpVvqpvcmXwm9mlS7iQCYm5UM4Re8NLFEzDoRcjC3BbM5umSFKVuDPCM= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, 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 Fri, Nov 29, 2024 at 5:32=E2=80=AFPM Alice Ryhl w= rote: > > This adds a type called VmAreaRef which is used when referencing a vma > that you have read access to. Here, read access means that you hold > either the mmap read lock or the vma read lock (or stronger). > > Additionally, a vma_lookup method is added to the mmap read guard, which > enables you to obtain a &VmAreaRef in safe Rust code. > > This patch only provides a way to lock the mmap read lock, but a > follow-up patch also provides a way to just lock the vma read lock. > > Acked-by: Lorenzo Stoakes (for mm bits) > Reviewed-by: Jann Horn > Signed-off-by: Alice Ryhl It looks like binder needs a way to check whether a given vma is associated with a given mm. I guess we can do that by adding a method to VmAreaRef that returns a &MmWithUser. This indicates that vma->vm_mm references an mm with non-zero mm_users whenever it's legal to have a reference to the vma. Alice