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Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jeff Xu References: From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAmgsLPQFCRvGjuMACgkQTd4Q 9wD/g1o0bxAAqYC7gTyGj5rZwvy1VesF6YoQncH0yI79lvXUYOX+Nngko4v4dTlOQvrd/vhb 02e9FtpA1CxgwdgIPFKIuXvdSyXAp0xXuIuRPQYbgNriQFkaBlHe9mSf8O09J3SCVa/5ezKM OLW/OONSV/Fr2VI1wxAYj3/Rb+U6rpzqIQ3Uh/5Rjmla6pTl7Z9/o1zKlVOX1SxVGSrlXhqt kwdbjdj/csSzoAbUF/duDuhyEl11/xStm/lBMzVuf3ZhV5SSgLAflLBo4l6mR5RolpPv5wad GpYS/hm7HsmEA0PBAPNb5DvZQ7vNaX23FlgylSXyv72UVsObHsu6pT4sfoxvJ5nJxvzGi69U s1uryvlAfS6E+D5ULrV35taTwSpcBAh0/RqRbV0mTc57vvAoXofBDcs3Z30IReFS34QSpjvl Hxbe7itHGuuhEVM1qmq2U72ezOQ7MzADbwCtn+yGeISQqeFn9QMAZVAkXsc9Wp0SW/WQKb76 FkSRalBZcc2vXM0VqhFVzTb6iNqYXqVKyuPKwhBunhTt6XnIfhpRgqveCPNIasSX05VQR6/a OBHZX3seTikp7A1z9iZIsdtJxB88dGkpeMj6qJ5RLzUsPUVPodEcz1B5aTEbYK6428H8MeLq NFPwmknOlDzQNC6RND8Ez7YEhzqvw7263MojcmmPcLelYbfOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCaCwtJQUJG8aPFAAKCRBN3hD3AP+DWlDnD/4k2TW+HyOOOePVm23F5HOhNNd7nNv3 Vq2cLcW1DteHUdxMO0X+zqrKDHI5hgnE/E2QH9jyV8mB8l/ndElobciaJcbl1cM43vVzPIWn 01vW62oxUNtEvzLLxGLPTrnMxWdZgxr7ACCWKUnMGE2E8eca0cT2pnIJoQRz242xqe/nYxBB /BAK+dsxHIfcQzl88G83oaO7vb7s/cWMYRKOg+WIgp0MJ8DO2IU5JmUtyJB+V3YzzM4cMic3 bNn8nHjTWw/9+QQ5vg3TXHZ5XMu9mtfw2La3bHJ6AybL0DvEkdGxk6YHqJVEukciLMWDWqQQ RtbBhqcprgUxipNvdn9KwNpGciM+hNtM9kf9gt0fjv79l/FiSw6KbCPX9b636GzgNy0Ev2UV m00EtcpRXXMlEpbP4V947ufWVK2Mz7RFUfU4+ETDd1scMQDHzrXItryHLZWhopPI4Z+ps0rB CQHfSpl+wG4XbJJu1D8/Ww3FsO42TMFrNr2/cmqwuUZ0a0uxrpkNYrsGjkEu7a+9MheyTzcm vyU2knz5/stkTN2LKz5REqOe24oRnypjpAfaoxRYXs+F8wml519InWlwCra49IUSxD1hXPxO WBe5lqcozu9LpNDH/brVSzHCSb7vjNGvvSVESDuoiHK8gNlf0v+epy5WYd7CGAgODPvDShGN g3eXuA== Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: G0z4P5iVGprf_ZS9f2OulZT0jkFn2fYcZobdfTDnlFU_1752673041 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: qnjusrcsr8huqd5zyeayygdb79qs1hti X-Rspam-User: X-Rspamd-Queue-Id: EE4EBC0009 X-Rspamd-Server: rspam02 X-HE-Tag: 1752673043-604705 X-HE-Meta: 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 79zS81fb dBXoBSiPOu1oSNu6ESO0dy5d0SC7xMCHRaUmQmVe/N+Nmnw7nryQfkxMktquC8otpIj/rB6SL8/XCas+zndAJrzdYDrNbmEWzcilU1EeNvuomPqO6wMy6Uz/cvDcnhVG9Ux5G0nAoqQke2rU3CJXWSMy2Uv2mJhKnli09d7yyv80yBqythK734YkU6aRQcmlXZZqbzDEcGrqYlNsP8lGcBKFIc7CROjJ2afHCtQeFojjR+a3SxVktiwBrUDkJSIZzqLYAC/iN5zCzSZdNdaejszYUqzV/SgmmFiWKcry6ajMrNCI20q5Xxv9PGxptpaRwAsCUYNDoITVP1vRJMKPAHfVdIN2lYRg755dsq54wfo6lGJGmpAW7wG2cK3s7Y1ZphUPE9rlQydH7xWKHAjA+H/pjegRENK8qKWe3qB3oKRBRy0gQUf7mDYVg+PJYc+haUimeq9CRhr1GVfSQ90UVRwcyEUQBa3G7qwSj 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 15.07.25 15:37, Lorenzo Stoakes wrote: > The madvise() logic is inexplicably performed in mm/mseal.c - this ought to > be located in mm/madvise.c. > > Additionally can_modify_vma_madv() is inconsistently named and, in > combination with is_ro_anon(), is very confusing logic. > > Put a static function in mm/madvise.c instead - can_madvise_modify() - that > spells out exactly what's happening. Also explicitly check for an anon VMA. > > Also add commentary to explain what's going on. > > Essentially - we disallow discarding of data in mseal()'d mappings in > instances where the user couldn't otherwise write to that data. > > Shared mappings are always backed, so no discard will actually truly > discard the data. Read-only anonymous and MAP_PRIVATE file-backed mappings > are the ones we are interested in. > > We make a change to the logic here to correct a mistake - we must disallow > discard of read-only MAP_PRIVATE file-backed mappings, which previously we > were not. > > The justification for this change is to account for the case where: > > 1. A MAP_PRIVATE R/W file-backed mapping is established. > 2. The mapping is written to, which backs it with anonymous memory. > 3. The mapping is mprotect()'d read-only. > 4. The mapping is mseal()'d. > > If we were to now allow discard of this data, it would mean mseal() would > not prevent the unrecoverable discarding of data and it was thus violate > the semantics of sealed VMAs. > > Finally, update the mseal tests, which were asserting previously that a > read-only MAP_PRIVATE file-backed mapping could be discarded. > > Signed-off-by: Lorenzo Stoakes > Reviewed-by: Liam R. Howlett > Reviewed-by: Pedro Falcato > --- Acked-by: David Hildenbrand -- Cheers, David / dhildenb