From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 82953C369D3 for ; Wed, 23 Apr 2025 07:25:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E52966B0005; Wed, 23 Apr 2025 03:25:12 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E01AC6B0007; Wed, 23 Apr 2025 03:25:12 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C7AC36B000C; Wed, 23 Apr 2025 03:25:12 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id AB66C6B0005 for ; Wed, 23 Apr 2025 03:25:12 -0400 (EDT) Received: from smtpin27.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 8554BBFEC3 for ; Wed, 23 Apr 2025 07:25:13 +0000 (UTC) X-FDA: 83364472506.27.7D8D3B9 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf13.hostedemail.com (Postfix) with ESMTP id 1A64720002 for ; Wed, 23 Apr 2025 07:25:10 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Tp4cOxgC; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf13.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1745393111; a=rsa-sha256; cv=none; b=LngGK+4dvjoThfRKPG0lDcwKYkyiio8YNXU2h10SBW/E3w4iDltrrzpFegR2rCtpEsHqEr pD/5kzfCVRC3qr2TUzTXuYg3j5cVYmKSn4f/f759Xa94YvRpUILokAK3rYmguBD/7W1N2v BoIS6OWq094biaZnETYq5hfJEGS+F9Y= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Tp4cOxgC; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf13.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1745393111; h=from:from:sender: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:dkim-signature; bh=H9oblxL5TFk3MzBoB5qC6ZXg151NO2zDTMpCh9STN7A=; b=iaU0ELIrmQ13nonsnaEL2ZM3opPwqWpN9V2m5UAcltDILEN/jFCHFF8F3ISanRNHUeSzpi 1aZSA1lIoHfsU2XDNdYLz8H/8VO8fevpyGq8fc9pyallRxgFWQYmBDyVuTasUQNXiGKsAk NYg1hv/Pg4k6B+yBRaKKPu33I4riCC0= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1745393110; 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=H9oblxL5TFk3MzBoB5qC6ZXg151NO2zDTMpCh9STN7A=; b=Tp4cOxgCqctEbX2b7Ugx5MFPcsIWUv2sc0CizlHBHe1Q0Vk/nDwmY2KQU/m+xLE8HbNEhl Fy9YbX3elgRQIc8kUrVthAoRdLmM35kGZs57akzUMGpV+HT1C3tDZ+2vpGliQBVlRYMctm rwQW5hrDOZM91HoQfsa7cPxuxfTFjZU= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-393-cN4UvYWnP3-LjOlvWjlrbQ-1; Wed, 23 Apr 2025 03:25:08 -0400 X-MC-Unique: cN4UvYWnP3-LjOlvWjlrbQ-1 X-Mimecast-MFC-AGG-ID: cN4UvYWnP3-LjOlvWjlrbQ_1745393108 Received: by mail-wr1-f71.google.com with SMTP id ffacd0b85a97d-39c2da64df9so2728240f8f.0 for ; Wed, 23 Apr 2025 00:25:08 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1745393108; x=1745997908; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:references:cc:to:from:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=H9oblxL5TFk3MzBoB5qC6ZXg151NO2zDTMpCh9STN7A=; b=YaKAMRiKSjWhzVFvJY4M7WYRgkQVKbpEZ8GryCy/7Uh4ATvAdC5Gpc0vaSoDALpRbj YTLdncD/LZcLmzl/rvqZi7+7PmczJhWil6y0XalsRfOV/ylefhYU6MP9MarfqSECzXMM z14n9eG8/oUssRdwXz+ndpJpAERISTnd67gj0VsEuYMgIiyTyu2+Jqx/J+kG4Kz5ROSq mQWHsfJZIWnI1aIvVKxPMPAe7tF9flZRWRLanfwjq4O8PYaz5z/uzOptCSM0dNXIpL6L 0XkJEmgD5dBhLVQ3G6TgH6v86JfW3YlxYTQGzDwZ59oaVYMObhKWApMlXU0dATwkpS4g 7f7w== X-Forwarded-Encrypted: i=1; AJvYcCWi6MxJbv7MGIyeWof73DpM2bhjSmzVdeC8zVk7243JS7UEoBHogtJKdZKrSryaitjt3YSi1t2MFg==@kvack.org X-Gm-Message-State: AOJu0YySSkWfJ4sHkDAdJOyw5AkeiFszWMkcKKNvQDYLNRGVo9WF7ZOt ei6BHqmlc5lNJ0p/HUteqRCUZBU51ZnTntIVaY+OdWghM+Gr0hsONQ39+ZMrLq6SLJYjLbQxVRp cpEzPQauNWj6YHuyriYFTXPqqpv8zuoc6RgjhJVQPSU+F5I+X X-Gm-Gg: ASbGncu9kNe/xp3WEnvU5s/Cc5b1SbE8zihauOj37WibX40A7nZVlkFGFn+EfQQiCk6 pI97eLyRP3I6D2L/fsN2nseHBJGa+SRlcnoCESF2m6yRvLo8WlQbxqoQa4laSpHViGDaTKhpwrk 3BJCUW4LKROnbD+I18CSrd7WfrUMZLgIsz9loET3nQNcaXfYpCdpBNjlFTbXwmOa2Loeqeg/bPU KCgE8B5DM1ktK5VUTeXGFoX6LnIAiAU0VMZAKLT63aEJiA1bQxYmgJQjPSQThQW7k+HG9fqkFn/ mXxvwjY3FEVdmTAZkPO0vD0lYogfwd0D+EUFt6Ffp1jV5PCeWqBkUr64znRQbcta8Y37ES7E52h PjvC9C7a5nq3UsdJUKfNF8GhYn3l+1vmowYDh1gA= X-Received: by 2002:a05:6000:4012:b0:399:6dd9:9f40 with SMTP id ffacd0b85a97d-39efba385acmr15017840f8f.9.1745393107704; Wed, 23 Apr 2025 00:25:07 -0700 (PDT) X-Google-Smtp-Source: AGHT+IG74s8pPqbYZHsSrh21SVIY8YNHPjcZYCwN0STxCwH4JIuShxilAUosxVBeO42YGvriqyfMHg== X-Received: by 2002:a05:6000:4012:b0:399:6dd9:9f40 with SMTP id ffacd0b85a97d-39efba385acmr15017821f8f.9.1745393107332; Wed, 23 Apr 2025 00:25:07 -0700 (PDT) Received: from ?IPV6:2003:cb:c740:2c00:d977:12ba:dad2:a87f? (p200300cbc7402c00d97712badad2a87f.dip0.t-ipconnect.de. [2003:cb:c740:2c00:d977:12ba:dad2:a87f]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39efa49313asm17747612f8f.75.2025.04.23.00.25.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 23 Apr 2025 00:25:06 -0700 (PDT) Message-ID: <8f24de4d-5088-498a-968d-9e8bb85201ac@redhat.com> Date: Wed, 23 Apr 2025 09:25:05 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V4 1/2] mm: add folio_migration_expected_refs() as inline function From: David Hildenbrand To: Matthew Wilcox , Andrew Morton Cc: Shivank Garg , shaggy@kernel.org, wangkefeng.wang@huawei.com, jane.chu@oracle.com, ziy@nvidia.com, donettom@linux.ibm.com, apopple@nvidia.com, jfs-discussion@lists.sourceforge.net, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzbot+8bb6fd945af4e0ad9299@syzkaller.appspotmail.com References: <20250422114000.15003-1-shivankg@amd.com> <20250422114000.15003-2-shivankg@amd.com> <20250422164111.f5d3f0756ad94d012180ece5@linux-foundation.org> 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: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: vGdfvsRZhRPfxFe3078L4VjeZlOLpqSDacOpasOzRKI_1745393108 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 1A64720002 X-Rspamd-Server: rspam04 X-Stat-Signature: auagg4atkgy97r3rkw9tfnxmegeja96q X-HE-Tag: 1745393110-726776 X-HE-Meta: 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 oBqj/CIy 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 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 23.04.25 09:22, David Hildenbrand wrote: > On 23.04.25 02:36, Matthew Wilcox wrote: >> On Tue, Apr 22, 2025 at 04:41:11PM -0700, Andrew Morton wrote: >>>> +/** >>>> + * folio_migrate_expected_refs - Count expected references for an unmapped folio. >>> >>> "folio_migration_expected_refs" >> >> Please run make W=1 fs/jfs/ in order to run kernel-doc on this file. >> It'll flag this kind of error. >> >>> It's concerning that one particular filesystem needs this - one >>> suspects that it is doing something wrong, or that the present API >>> offerings were misdesigned. It would be helpful if the changelogs were >>> to explain what is special about JFS. >> >> It doesn't surprise me at all. Almost no filesystem implements its own >> migrate_folio operation. Without going into too much detail, almost >> all filesystems can use filemap_migrate_folio(), buffer_migrate_folio() >> or buffer_migrate_folio_norefs(). So this is not an indication that >> jfs is doing anything wrong (except maybe it's misdesigned in that the >> per-folio metadata caches the address of the folio, but changing that >> seems very much too much work to ask someone to do). >> >> What I do wonder is whether we want to have such a specialised >> function existing. We have can_split_folio() in huge_memory.c >> which is somewhat more comprehensive and doesn't require the folio to be >> unmapped first. > > I was debating with myself whether we should do the usual "refs from > ->private, refs from page table mappings" .. dance, and look up the > mapping from the folio instead of passing it in. > > I concluded that for this (migration) purpose the function is good > enough as it is: if abused in wrong context (e.g., still ->private, > still page table mappings), it would not fake that there are no > unexpected references. Sorry, I forgot that we still care about the reference from ->private here. We expect the folio to be unmapped. -- Cheers, David / dhildenb