From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793874794; b=x+kPDPe1MUkNpa+ZyX0U9RDgrlMMGy3UYf/wkRseOrT8NGx4dNcLvUwpsMlJVS/+BQ+x KeWyGpGJN61vdDqD//JYgAU5XR+ViSiroLqgbpXm3Ye/3ai2iTmZoKJ6cPIDPnJzj5qpN Q2i9D/oM/SUmtoYXAc9eXwxzxOoMcMw3/aezlYWveZAJuvAfcnP5p9gCeZqjDXa1TKJP/ oZgfFC2qxwNi5w3oUNFeV2Xiv4pJaf+CWbXngq2+VMzXt3vwGraBLlazrfHQh+jjaTTNA wFZvL6UhK/quNAo3u6asVmaGcOmxhdlqng6XK4OIk8yYOYed764M5BpQoDHpZO05nBA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793874794; h=Received:DKIM-Signature:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:From:Content-Language:Autocrypt:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=rW1nil3E5bYjTHxZT0jjYetDQyPmr3fpWazFoftmXjc=; b=akyronwwwVes2r22gwf0J9VBfRi/fTJEHM5ugQjVc6mma6SYkEHwVVPzOv/2OKAwrv6B B0AdIya0xyZA50EA9CalKxYzYsnhXEQATprP4fHU3IxSpFXAU53ZTdla9HqKvttmD5wAz aHNFmlM3Sl2Rlr7dwEmpWg5n1ZTQUCEbDHn39VzWbykCg7G9meL2v8gBgVXMn6Wv8iVn5 dlRAUJGSFIo6ex+rUXIz0xEPWlNcrSlf7FGcQNLuOeHMo7gmnaMJAmp/jwKkN2fneyhS6 R77Cn5aDCrKfeuCKCRYEr/hQ31RZHUQMQ/MlVuyepOv8Fw66EoemBskpA7oxUGB2cKA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=mOEZw52v; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C1553606A326; Thu, 5 Nov 2026 10:33:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=mOEZw52v Received: by smtp.kernel.org (Postfix) with ESMTPSA id E7B2B1F000C1; Thu, 5 Nov 2026 10:33:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793874793; bh=rW1nil3E5bYjTHxZT0jjYetDQyPmr3fpWazFoftmXjc=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=mOEZw52vLFxK3rc/1pzuqdBC+HQCXx9mY2v9zCS7MB1PkcO28hR8mmYR7mquhduqx nKCn9g7Qvm3pg2oAHDiffpJ2cDU2GqwF4uICQfDiPX4l5/O9J0qmW85ilAgvbRkP0U 1FSFR+Ow6AcRdFnndQOPSSu8RyMQ6V5tSfmrn4gdTkXN58WdIUPJ9XvCdUZ4NB8bgh 6pugwhg/dQzmCTa3DNeZNaV3LEU+nCDMPPQyPQivmSGt6TfuLL0FL0WkFPUM/3vgbU A738imanAEwUusrWHcmT2mo/y2jRAKtqB2LSP30ROQRnYP8nrNE4QqaXB4uR9PXbRN KZJLF4jYWfzXA== Message-ID: <0851db25-fef3-4f96-8d37-81ad5c51d6c8@kernel.org> Date: Thu, 5 Nov 2026 11:33:05 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/4] mm: Enforce read-only shared vmemmap tail mappings To: Muchun Song , Andrew Morton , Oscar Salvador , Madhavan Srinivasan , Jonathan Corbet Cc: Muchun Song , Lance Yang , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Ritesh Harjani , Shrikanth Hegde , Shuah Khan , Randy Dunlap , Qi Zheng , linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org References: <20261019090830.1917657-1-songmuchun@bytedance.com> 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: <20261019090830.1917657-1-songmuchun@bytedance.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/19/26 11:08, Muchun Song wrote: > This series is split out from the earlier, larger series "mm: Generalize > HVO for HugeTLB and device DAX" [1]. While the parent series generalizes > vmemmap optimization across HugeTLB and device DAX, this subset addresses > a single, self-contained step: mapping shared vmemmap tail pages read-only > at population time. > > After the previous HugeTLB and device DAX conversions, both can install > optimized shared-tail mappings during vmemmap population. These mappings > should be read-only because each shared tail vmemmap page backs metadata > for many tail pages. HugeTLB applies this protection in a later, > subsystem-specific pass, but device DAX currently lacks it. > > This series moves the protection into the generic sparse-vmemmap and > powerpc radix population paths. This protects device DAX mappings and > makes the HugeTLB-specific vmemmap_wrprotect_hvo() pass redundant. With > that pass gone, the bootmem-only optimization wrapper has no distinct > work and is removed as well. > > This is intended to be the fifth smaller step toward the broader HVO > generalization. The remaining HVO naming and enablement consolidation is > left for follow-up series. I assume this patch series is no longer applicable after we remove the RO protection for HVO. Or am I missing something? :) -- Cheers, David