From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 E227E2F0059 for ; Fri, 11 Jul 2025 16:18:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752250732; cv=none; b=rUVLZiiX6ekdAyde+OScbhp6s3LfeEcjTlopCTgeVRXAvg73NPeUCrcszB2B6JdxN6ydr1m3HfIOpFpnDJdj4PJFMlDfuFuFw9Zfeam7q6XMIqjFi0A5c6H2mGiyru5PnsLA1tMx3ikCvAf+c5QNQGizmOQ4Vwm82vBfRE75Hus= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752250732; c=relaxed/simple; bh=RmuyxikP3jhhp0nnQevk5CM+a6W6OZAcoIpkbcZxKzc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=BHPZv30cb/u11Izu8ocQLPx6gQ+guBN0m59AVLRj3d+hhLDbrm7V+Zuhq6AXUdGScS9doK9+VUdF0GT9OyJx0TfH4AjyNP5Yuq+F9+oBMYMEVYNjQzVBjCsLvMTvt+pjoW5VY+5VvGQTdWQPdY1bz6KEvof/KzDtdzCMd7jp/G0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=hJOzn7fF; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hJOzn7fF" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1752250730; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=Nn/tyjLuDZQnek6uqzyr2XAecXIQlMAuAiSgJfPbL7U=; b=hJOzn7fFCTMVb+XLE9nsh9OqivmbyrTCa4fIAcgpdrYb/Tgt8ggYJaI9jzEn+aK1w1w3fl dGBt4jMxho2ks0L9zbBbhmAG4x76SQL8hJq9rKeS0FqB4AemShd2ZHZOGO0oT1WKmyZfek Sa/QbFb4uDu8EOULmt+eJ/iSuFKMLtY= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-399-svrBu6jnMs63c_xyDR_uPA-1; Fri, 11 Jul 2025 12:18:48 -0400 X-MC-Unique: svrBu6jnMs63c_xyDR_uPA-1 X-Mimecast-MFC-AGG-ID: svrBu6jnMs63c_xyDR_uPA_1752250727 Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-3a4f7f1b932so1452363f8f.2 for ; Fri, 11 Jul 2025 09:18:48 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1752250727; x=1752855527; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from:references:cc:to:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=Nn/tyjLuDZQnek6uqzyr2XAecXIQlMAuAiSgJfPbL7U=; b=Gwe5+7fygQjuK3ihuz9YBqNLp/MujNXE+fJItWne3p6SI3rTK830f74nX2j0w9+ZUK zmE2TjxPZDJ9JgRqxz8B3BfLgYkddNZEtROL9QaZq82OAMZUYmiUll5jjjD2IXGAtAed BN/hqvZYrbHhTUlgKTv45vlIMJhdJ1SicElEg5pVQsiI8yYCorPyg/OGqkegVELE0e85 ftT74tBPTjRuld0JG42j9M5ij70ExeVREuKs2X92WIqr53i8+JPUBRna/gRL5qiE1b20 7JxfL+8ZO0RJihOgqXh62jozRgza+6YS49ghufkL5ZerEr84KCjeJNxFFQkZrM8ICdlk AfzQ== X-Forwarded-Encrypted: i=1; AJvYcCX23IO3mO5otEkVQn2reB9d6JyOj+fl07rgow5TlsgxifOYGJWCENswI3EKWDDQJ5WtlRlJz1gLP2vy@vger.kernel.org X-Gm-Message-State: AOJu0Yy0kiZJKC101+wcHI5P0ET1U5VVax0TNU+ESrCuNQO+byWdwywo 3K0GpRm9mY3KAJwUgnqVeqBWYh/pjrp2eN55mQ9lqoCA0Qk3c0FEKQcBAv1Su1uql1d3bCD//z6 pvyU9tLm2sMASlV/wHTubDOCvrxxpOerJoFJAFb+K5dYHywKWw6V94gNhyOObL54= X-Gm-Gg: ASbGnctYOuN9QXzErhl8tnAYEQtR7PLkb8mRDpvtVo868YXeodnJ/KeTsT8buN6GoDn IILwnq4UdRg1QgtUvBXefwony/c8GHs7Okp9gRH+/jadKH2KGvR7fKxrYumO+VjEImigMjEOVS6 mvX5RLCpqYFUElQV1UkmZpSFMwzUCU0drWJvkXOCAHpOPi7An9Ye83+kYwzKnPtIgG8Bp21Ybi2 EAhXzfblRk6+i4ZiTRSoSWPWUuVC7ZRLVjP3ZF2RspcrMIyJWnXaUKoG58WMUtggOVjRAeJLhBh gxObZbXW7xqfyNgfWGxvKj27HuqUDf/Dw3aqlWIo6vYOF+11oWtcWdu/jFHUjoT88eB8DOWYxdu tk6AqRuWGLYnPUZtOkPsUMYddWYwFVn/nMFY1xFNFBoDJ74qjBizmMg9OgN2Fvrsbo5w= X-Received: by 2002:a05:6000:1acb:b0:3a4:ef36:1f4d with SMTP id ffacd0b85a97d-3b5f2dfe068mr3165948f8f.38.1752250727310; Fri, 11 Jul 2025 09:18:47 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFNEjxN0hZ8U7KjaRWXdNv8tLd+TjKw2qwDu6OkeGx6IP2NJytzdTy4QA+AXWSLgx0V7mfpjQ== X-Received: by 2002:a05:6000:1acb:b0:3a4:ef36:1f4d with SMTP id ffacd0b85a97d-3b5f2dfe068mr3165906f8f.38.1752250726806; Fri, 11 Jul 2025 09:18:46 -0700 (PDT) Received: from ?IPV6:2003:d8:2f3c:3a00:5662:26b3:3e5d:438e? (p200300d82f3c3a00566226b33e5d438e.dip0.t-ipconnect.de. [2003:d8:2f3c:3a00:5662:26b3:3e5d:438e]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b5e8e0d732sm4957680f8f.52.2025.07.11.09.18.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 11 Jul 2025 09:18:46 -0700 (PDT) Message-ID: <02146c79-a4de-430f-8357-0608e796fa60@redhat.com> Date: Fri, 11 Jul 2025 18:18:44 +0200 Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC V1 PATCH mm-hotfixes 1/3] mm: introduce and use {pgd,p4d}_populate_kernel() To: Harry Yoo , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Andrey Ryabinin , Arnd Bergmann , Andrew Morton , Dennis Zhou , Tejun Heo , Christoph Lameter Cc: "H . Peter Anvin" , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , Juergen Gross , Kevin Brodsky , Muchun Song , Oscar Salvador , Joao Martins , Lorenzo Stoakes , Jane Chu , Alistair Popple , Mike Rapoport , Gwan-gyeong Mun , "Aneesh Kumar K . V" , x86@kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org References: <20250709131657.5660-1-harry.yoo@oracle.com> <20250709131657.5660-2-harry.yoo@oracle.com> From: David Hildenbrand Content-Language: en-US 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/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz 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+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20250709131657.5660-2-harry.yoo@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 09.07.25 15:16, Harry Yoo wrote: > Intrdocue and use {pgd,p4d}_pouplate_kernel() in core MM code when > populating PGD and P4D entries corresponding to the kernel address > space. The main purpose of these helpers is to ensure synchronization of > the kernel portion of the top-level page tables whenever such an entry > is populated. > > Until now, the kernel has relied on each architecture to handle > synchronization of top-level page tables in an ad-hoc manner. > For example, see commit 9b861528a801 ("x86-64, mem: Update all PGDs for > direct mapping and vmemmap mapping changes"). > > However, this approach has proven fragile, as it's easy to forget to > perform the necessary synchronization when introducing new changes. > > To address this, introduce _kernel() varients of the page table s/varients/variants/ > population helpers that invoke architecture-specific hooks to properly > synchronize the page tables. I was expecting to see the sync be done in common code -- such that it cannot be missed :) But it's really just rerouting to the arch code where the sync can be done, correct? -- Cheers, David / dhildenb