From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3EF693AA1BF; Thu, 5 Feb 2026 12:03:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770293027; cv=none; b=ZhwmwdYUL9qW2vWv401f9PfodCNlL0yUSh3vAe2mGKAnMK6UCcjzZ3Sj7lqGJwoXQuy1fcEuQKPbJSHXPZEzyjpVYgsjQ2/37wfw03flLfzNkW6B4TfNxpMG97xwmYLnEep9cdlbUFoz/z3YYeU2A3FW3JYIRWomVakm7NibOUc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770293027; c=relaxed/simple; bh=zfq4qj3iLBvccfTblZ0Z7fVCeUnHgrtGgZzNA+DYoQM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TXPyCdW5ZvGx4sXWjiAOhv2dDaP8rD+AtckM/zlrSmvczLAk56kEJ1lZcfYIdhLGalMlkNfOrVwsbuHyaH0VCXuOSV5rD4CZ6AKD7r2SEwQQujvI8ivc4lCXwM9w0WudAdfyHDquUpbuoSzWMdDrUm/5tJVa9F2z+l9yit91Xek= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=iB8TpwPL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="iB8TpwPL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 56E33C4CEF7; Thu, 5 Feb 2026 12:03:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770293026; bh=zfq4qj3iLBvccfTblZ0Z7fVCeUnHgrtGgZzNA+DYoQM=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=iB8TpwPLF4c34Fd7ZWYKxYeEbiCxrIVVcxOPLVTsfHfQlx9RqDu3pkZ+svMudOkJl JIqjXaGWmlIgLmVjhUr5CqiT7Q/IYIoeTzvwWMXSBAcFWdnucJo0PizFhrvpMkckMj V43itHLCt7VRR2G/zLMOxyeZFlRS1cRuEvxe8R7U2hLXZx6UxRR9UyTt2R90gwO9u0 hN5L2f3nQDQn+Bo8fr1gEmqRPx0DxdGx4GG1Bhlbk4wvF/RHqN1iYnxy1jLJZUtnkw dJ/VM2dGHy8E+dRe46y7O9OE/E7ABjsMQ9UAnjt4bdDzz98ddGyr/UOA9g4jImZT86 sh6RW+WFrHaiA== Message-ID: <507d24e0-4563-4b33-864c-cd1a499fe517@kernel.org> Date: Thu, 5 Feb 2026 13:03:35 +0100 Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/5] mm: export zap_page_range_single and list_lru_add/del To: Lorenzo Stoakes Cc: Alice Ryhl , Greg Kroah-Hartman , Carlos Llamas , Alexander Viro , Christian Brauner , Jan Kara , Paul Moore , James Morris , "Serge E. Hallyn" , Andrew Morton , Dave Chinner , Qi Zheng , Roman Gushchin , Muchun Song , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Miguel Ojeda , Boqun Feng , Gary Guo , =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Trevor Gross , Danilo Krummrich , kernel-team@android.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-mm@kvack.org, rust-for-linux@vger.kernel.org, Christoph Hellwig References: <20260205-binder-tristate-v1-0-dfc947c35d35@google.com> <20260205-binder-tristate-v1-3-dfc947c35d35@google.com> <02801464-f4cb-4e38-8269-f8b9cf0a5965@lucifer.local> <21d90844-1cb1-46ab-a2bb-62f2478b7dfb@kernel.org> From: "David Hildenbrand (arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2/5/26 12:57, Lorenzo Stoakes wrote: > +cc Christoph for his input on exports here. > > On Thu, Feb 05, 2026 at 12:43:03PM +0100, David Hildenbrand (arm) wrote: >> On 2/5/26 12:29, Lorenzo Stoakes wrote: >>> >>> Same point as before about exporting symbols, but given the _obj variants are >>> exported already this one is more valid. >>> >>> >>> Sorry but I don't want this exported at all. >>> >>> This is an internal implementation detail which allows fine-grained control of >>> behaviour via struct zap_details (which binder doesn't use, of course :) >> >> I don't expect anybody to set zap_details, but yeah, it could be abused. >> It could be abused right now from anywhere else in the kernel >> where we don't build as a module :) >> >> Apparently we export a similar function in rust where we just removed the last parameter. > > What?? > > Alice - can you confirm rust isn't exporting stuff that isn't explicitly marked > EXPORT_SYMBOL*() for use by other rust modules? > > It's important we keep this in sync, otherwise rust is overriding kernel policy. > >> >> I think zap_page_range_single() is only called with non-NULL from mm/memory.c. >> >> So the following makes likely sense even outside of the context of this series: >> > > Yeah this looks good so feel free to add a R-b from me tag when you send it > BUT... > > I'm still _very_ uncomfortable with exporting this just for binder which seems > to be doing effectively mm tasks itself in a way that makes me think it needs a > rework to not be doing that and to update core mm to add functionality if it's > needed. > > In any case, if we _do_ export this I think I'm going to insist on this being > EXPORT_SYMBOL_FOR_MODULES() _only_ for the binder in-tree module. Works for me. Staring at it again, I think I landed in cleanup land. zap_vma_ptes() is exported and does the same thing as zap_page_range_single(), just with some additional safety checks. Fun. Let me cleanup. Good finger exercise after one month of almost-not coding :) -- Cheers, David