From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 D307B261399 for ; Wed, 25 Jun 2025 16:47:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750870070; cv=none; b=eg4RlBqrOoRksqXq4RyyqSZuUQQ1h8M99kiiz24ivoOg6QlPEyA/gy4krkDvuxBZWP+Vuh6qWMqhLHqLlPOGdBcqBdoomArTH9mAd3DIVttJk8noUE3+8abKhO5bqVLvfLCEO/ZtdoWTkuKcPJJxl3qYZXQcF0F6y2/X6uAq63M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750870070; c=relaxed/simple; bh=ZIcwd55I+y4/P3j3gLsFy59kLpT72V5RSK8H+BKGMpc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=kvTTqMJ8l8pM2z8tzXCmLi/JE1ikvwA1YNI7PZkMlo2BoCd8pSkqq1Km1YHFJKGXtVXj2hhuV0ZP2m8M14DTrMo368ZUpDfg52hQ9Px/+YAaObDT0J5x+JKnyA2XqVWjZKUjF8/+H1OEgj6VSTayM8nr8DQQOqdGWrtSJW+qCWU= 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=hJyxPrLj; arc=none smtp.client-ip=170.10.133.124 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="hJyxPrLj" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1750870067; 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=9M1vHfXIFS9l+R39Mf9youJQuWwRJBkeTDzWO25k2Ts=; b=hJyxPrLj/i8+FzXB4cFp1OGXESZHLUkEj7anSWhnSN0L7IaNH4rqY/SfwnC7gNLl9c2sqf tRchCNX9CrTiVFNYdFUhTUpZsAQMs99a1P5YIGmvKVt5IJbhqzGMqt7HEf4SquCG3pzW48 JlLeNA+s/hQSTc+Ruw8l2sEmrIidA10= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-494-bEQgapodPSqnMQ8ZxcJDlw-1; Wed, 25 Jun 2025 12:47:45 -0400 X-MC-Unique: bEQgapodPSqnMQ8ZxcJDlw-1 X-Mimecast-MFC-AGG-ID: bEQgapodPSqnMQ8ZxcJDlw_1750870064 Received: by mail-wr1-f69.google.com with SMTP id ffacd0b85a97d-3a4eb6fcd88so12636f8f.1 for ; Wed, 25 Jun 2025 09:47:45 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1750870064; x=1751474864; 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=9M1vHfXIFS9l+R39Mf9youJQuWwRJBkeTDzWO25k2Ts=; b=CWUqQVv/gKKJ+67wJWXuTNK/zIzgnpoyDhgpX0yOD7tn1uSjb9pToHdeMHDyLLQ79a Rc+ddckxJ1Vla3MoOk1Yyt6tGMPF9zXJn9OIk0l//tiqLopC6bLIOhZtHYhjAXUgVQzG Phl/jDHar92jYCQqW31bQsnrszffzQePtZ2qiGxVEvtumKEHf18NAfxqaluxNZVnOYGa W+6hH+26SF1604czl60SOUmW51HmakJPPPla9pZIrnPhatwZyySO5EmRC8Ec80c0jMTN 4Y5rjG1yddkNhpaRBy4IzNJLJmGe69+O3inxOJoQw6wz8qHidU/cmrMBGp4qFMpYTM3g y+JA== X-Forwarded-Encrypted: i=1; AJvYcCXDQvVytBdd+g/tBYszFxOaGw7Z37T7YDyRHOcn6s9El6FcJWZkN8ijFRDOIPvFqTpZkrmMSejeiE69hsQ=@vger.kernel.org X-Gm-Message-State: AOJu0Yygwwes3uSZNLvlFJ2WIesD9eARNE6MgXZMdtcBHp0vCPk0VSL1 IsHOZYt7VyZ+ea4pmxOFUV/O+e7Udv+5ufwJlLqisvLrnH14b5sJGmgZ/j2s3HauQlPjecOF/9R u8dyZDXWrnKZxtNQnY8N1JU79fJuLzBMG630mcdix94QgY7/f6tq3eOBb3EDu1Oy8dQ== X-Gm-Gg: ASbGnctzGn9/wIHdMYowRGgdOMhNvB0b0tm7P/A7QAYIA9q6KK48e5ajavN+FP6AC6l X1t74af3Blt6IgKtM8KVrL6Jaxo44MAxLtsdeUBX4vURLzkE57W/0n18mduAQBIb3cB2T4G5i/3 DbOSSLnXzy/OmxcN+wg8KeR3VJX498lcG0GfjIay0vBHh5V8DuCuiYtznx5Yc57hr+DIyqhgLXW ZCWiHQw7/Bkv5KadtDbliOFHQ5C1DQPBcvp5VRGXAXmOB/hJXziVfyIhyCHWf8uwDV+lpoqDNut Tg8bNr1DaVqVFWFOhbUSnb9wYFhFWnmsBNdf3vl7bnE7IOpG1yZvu+lK3SDNgRg0tBzfX8DJLFr VCnfbNUqokUNcwbTrhqJhq425b/EVPVoyCD5uNubn7Bix X-Received: by 2002:a05:6000:1888:b0:3a4:f038:af74 with SMTP id ffacd0b85a97d-3a6ed65b664mr3237862f8f.51.1750870064314; Wed, 25 Jun 2025 09:47:44 -0700 (PDT) X-Google-Smtp-Source: AGHT+IF9YekvGRPkYe/kZTrXaL/81esEkFz4ElnXXiExctA2VcZJSnui1u8qYRsgiNhzuyyjmJbBvg== X-Received: by 2002:a05:6000:1888:b0:3a4:f038:af74 with SMTP id ffacd0b85a97d-3a6ed65b664mr3237838f8f.51.1750870063878; Wed, 25 Jun 2025 09:47:43 -0700 (PDT) Received: from ?IPV6:2003:d8:2f12:1b00:5d6b:db26:e2b7:12? (p200300d82f121b005d6bdb26e2b70012.dip0.t-ipconnect.de. [2003:d8:2f12:1b00:5d6b:db26:e2b7:12]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a6e80f2b8fsm5089801f8f.59.2025.06.25.09.47.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 25 Jun 2025 09:47:43 -0700 (PDT) Message-ID: Date: Wed, 25 Jun 2025 18:47:42 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 1/1] mm/debug_vm_pgtable: Use a swp_entry_t input value for swap tests To: Gerald Schaefer , Anshuman Khandual Cc: Andrew Morton , Matthew Wilcox , LKML , linux-mm , linux-s390@vger.kernel.org References: <20250623184321.927418-1-gerald.schaefer@linux.ibm.com> <20250623184321.927418-2-gerald.schaefer@linux.ibm.com> <9fb04185-5b71-46c0-b62c-0e0e6ee59e6e@arm.com> <20250625182846.5bce1aaf@thinkpad-T15> 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: <20250625182846.5bce1aaf@thinkpad-T15> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit > [...] >>> @@ -1166,6 +1173,7 @@ static void __init init_fixed_pfns(struct pgtable_debug_args *args) >>> >>> static int __init init_args(struct pgtable_debug_args *args) >>> { >>> + unsigned long max_swap_offset; >>> struct page *page = NULL; >>> int ret = 0; >>> >>> @@ -1248,6 +1256,11 @@ static int __init init_args(struct pgtable_debug_args *args) >>> >>> init_fixed_pfns(args); >>> >>> + /* See generic_max_swapfile_size(): probe the maximum offset */ >>> + max_swap_offset = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0, ~0UL)))); >> Why not directly use generic_max_swapfile_size() which is doing exact same thing. >> >> unsigned long generic_max_swapfile_size(void) >> { >> return swp_offset(pte_to_swp_entry( >> swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1; >> } > > Good question. I just moved this code here from pte_swap_exclusive_tests(), > see above, and did not think about that. Now I also wonder why > generic_max_swapfile_size() wasn't used before. > > But it is not exactly the same thing, there is an extra "+ 1" there. > Maybe that is the reason, but I don't really understand the details / > difference, and therefore would not want to change it. > > David, do you remember why you didn't use generic_max_swapfile_size() > in your pte_swap_exclusive_tests()? Excellent question. If only I would remember :) generic_max_swapfile_size() resides in mm/swapfile.c, which is only around with CONFIG_SWAP. It makes sense to have that function only if there are ... actual swapfiles. These checks here are independent of CONFIG_SWAP (at least in theory -- for migration entries etc we don't need CONFIG_SWAP), and we simply want to construct a swap PTE with all possible bits set. -- Cheers, David / dhildenb