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 01C23C369B2 for ; Thu, 17 Apr 2025 07:18:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 340CE28012D; Thu, 17 Apr 2025 03:18:47 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2C89E28012C; Thu, 17 Apr 2025 03:18:47 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 11BCE28012D; Thu, 17 Apr 2025 03:18:47 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id E53DB28012C for ; Thu, 17 Apr 2025 03:18:46 -0400 (EDT) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 7D5641CCE42 for ; Thu, 17 Apr 2025 07:18:47 +0000 (UTC) X-FDA: 83342683494.22.2BD11E1 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf12.hostedemail.com (Postfix) with ESMTP id 0A20C40002 for ; Thu, 17 Apr 2025 07:18:44 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=EqkQMGo8; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf12.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=1744874325; a=rsa-sha256; cv=none; b=r8Q9O0QgnDV0zUwChmKCaFf3q/C6IFg/dqhf+SIK6us/XYmqUqHrpKORyX7he4ZIhLTKyi H4zcXv7eAnKw2KCAWEJqNgf8wKufXL4CrIzbt0QKBhxifzjM+makFqKx6EbJOQoH5tnJWy DN8kZbSS90HBjGTgybB74HRW74dPv1g= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=EqkQMGo8; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf12.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=1744874325; 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=bmSUkpgdK8g//zTzlgndh4Cu65jFajKMCK56s9Izn2Q=; b=XCXLjXn8/6wmolWTrXDk61fO+CbmGK462EArzAkkO9s1PcRVHZmidJbo4xcwzkEjlbu6F5 9fRtqp5v6LOCPZPNKErOdKcBXmiVbgmxEJQph/SDEFnOj/bS3xfL9VDzw7Ml2ZbAwuUfL0 mVwTCo1h+fJT4PAPwxuLO1psaboTEog= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1744874324; 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=bmSUkpgdK8g//zTzlgndh4Cu65jFajKMCK56s9Izn2Q=; b=EqkQMGo8q2zSau7VoRk7Nz69f6QG55ZySStFpmClme9xXtraGAUZvjE1zks0zweOUHSjJJ B4pmA3B+qnKPbS08pfQmn3nsPz2GawXt5mN5ot31v6sqZjl9U0DeIgUDz+a33QPU670N1K ZPwqjaEQSnttZF6LhMkcY23+XO57tXc= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-45-2qSroNr-MIOELHFkuR_JdQ-1; Thu, 17 Apr 2025 03:18:42 -0400 X-MC-Unique: 2qSroNr-MIOELHFkuR_JdQ-1 X-Mimecast-MFC-AGG-ID: 2qSroNr-MIOELHFkuR_JdQ_1744874321 Received: by mail-wm1-f72.google.com with SMTP id 5b1f17b1804b1-43947a0919aso3808655e9.0 for ; Thu, 17 Apr 2025 00:18:42 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1744874321; x=1745479121; 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=bmSUkpgdK8g//zTzlgndh4Cu65jFajKMCK56s9Izn2Q=; b=YkVL5XFCdv4jdClBre1yGcvVtK6MUzDNQ8dqFT/gxlF7I59w5jY9o7ggCGyuYbGTML XyjLHncFiFJFjoiuX7QqdljQkFDGolR9f75EOXwLpyFCed9YiKP3ds+SaaJZ1/jHZDZb n0pjuMLB/vW9tqAknrTPrPfp0jSqtjekNlgbiY6QodhWdWfkcT+N7x49kn+Jt9A6zUM7 xzyVEak7w4kYRrcwhLjUEzEIcjdkv3x4OKjPhmMgtL1Hie6bNMwaS9wXzTePrRxhStAz JHaeU3pVb0lx65slaqnZLIS02oMk0dXblS5Pt6mA3EkW7z0QAQ6g8ezQ3hG2W6eHMANf Zaug== X-Forwarded-Encrypted: i=1; AJvYcCU+xHUvrh37wc7c50lLzAq+6GtXLzkBOqcsAKyY09a9TfO2JZJs+yRtzOfbxCFPhv3iyyblQOFp6w==@kvack.org X-Gm-Message-State: AOJu0YxYlcXVXF1kngPFlOHju3NNvaiNGoM8Z+N7itlunX7bwCHPOYAY U/KMyX3ephyYn75m6PPGQoAJG7mNS/FenD/bFIqxXhG/twN5UvUbabNAI4wDzjDJ37Awh8PaFaA HXgkE4AKK1rVnsF6p43GtcYO3v2VGDenvGsvf9b0zz2tu9Y8k X-Gm-Gg: ASbGncvc9VuBiziE4rZwu/Yyv8ccEHHcfCX8gql2FuI9gc2ESZk7Elex2PN6iTjJ0+M dgbIb/7Lv71Kx0VBNoCH07Hh0JOlFAeK8X91hcr9Gk2+wZXldVzsD8VAxlkTnYnQyRB9FfLkxtD oE+ncuk7MIBW9Ag72mPXDUBCdQ4L/dUGpuKG5rF7bQ+V1BktgUEsIZ0pbCtNmY1uRyYWL5F1A9B KARfKZTl+LpbtUr1L1ffErQfwCcCJttxHSNRIl1HRNXpsLIqtbClj980v54+hoOYkpfYSxIpbJS mk7yVO0SAGwbida7waJwqDM7r1N7RpAAABvbHLZLdWDf1tzNrDfIYNlyJoImB11OiEO/fkAqdJ3 PVrxDy2vxuC9vAymhYi7L8KMCqfKn5NIiGfXsBV4= X-Received: by 2002:a05:600c:8707:b0:43d:45a:8fc1 with SMTP id 5b1f17b1804b1-4405d5fccd5mr48887115e9.4.1744874321502; Thu, 17 Apr 2025 00:18:41 -0700 (PDT) X-Google-Smtp-Source: AGHT+IG7O/fIzC1C6NrzDLMPScZGhgDYsOSvouSKqJl40ol57ok8JYa4zHptZ2/POyEImueU5svAzg== X-Received: by 2002:a05:600c:8707:b0:43d:45a:8fc1 with SMTP id 5b1f17b1804b1-4405d5fccd5mr48886915e9.4.1744874321118; Thu, 17 Apr 2025 00:18:41 -0700 (PDT) Received: from ?IPV6:2003:cb:c706:2700:abf9:4eac:588c:adab? (p200300cbc7062700abf94eac588cadab.dip0.t-ipconnect.de. [2003:cb:c706:2700:abf9:4eac:588c:adab]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39ed1652a91sm14191026f8f.75.2025.04.17.00.18.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 17 Apr 2025 00:18:40 -0700 (PDT) Message-ID: <83f17b85-c9fa-43a0-bec1-22c8565b67ad@redhat.com> Date: Thu, 17 Apr 2025 09:18:39 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/huge_memory: fix dereferencing invalid pmd migration entry To: Hugh Dickins Cc: Gavin Guo , linux-mm@kvack.org, akpm@linux-foundation.org, willy@infradead.org, ziy@nvidia.com, linmiaohe@huawei.com, revest@google.com, kernel-dev@igalia.com, linux-kernel@vger.kernel.org References: <20250414072737.1698513-1-gavinguo@igalia.com> <27d13454-280f-4966-b694-d7e58d991547@redhat.com> <6787d0ea-a1b9-08cf-1f48-e361058eec20@google.com> From: David Hildenbrand 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: <6787d0ea-a1b9-08cf-1f48-e361058eec20@google.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: _0pWZUvlWfU-zyEgH1y8vDE12L7tj6qU_WgmdgCyiHM_1744874321 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: 0A20C40002 X-Rspamd-Server: rspam04 X-Stat-Signature: 7noogpkg6k46dpeywp613gput7us1yx5 X-HE-Tag: 1744874324-669278 X-HE-Meta: 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 9vkT9Zlk rUWNcAf1IsZqBjFmqbCOabSR02NPG/GwTXUavxMqL6NJ8EQ0DrxElyU7FSRrdp3+6BpbOrCLH8MKhwWLCL0Bsm3ykuCVieyEpzvTbR2aZqcLZnngh0zHG9m7OBewrBn1ZB/k1S+iv42ovSKSA6lwTgBPt1lMNzg10Ra1eTLH6rQ2cjNAHvLQ9jxoBjel47AGMKPaVZbtO8n9SJot4epxhR5VKX3Sd1OMt7cfyniO2SiJ3U7ZfNBrr1gxTQUMpd1fLlGS9ZQ0jLMPlUwGR+A6ArF0RYUudfTNn0MFw2DQ+2emNdCMJQDE/nqnDT3tB5v2oKbNjjN8o6G2k00WMpd9thLVSboiRyjH0wLeh/7YFIA2QKOuYwVMXzX78ot/D2nTFpN/vOL6QZEsfP8QTnhScvGe6j6ULu8ft9rFfSjt9Di8FbiwDTJZhabBpQG4sDJw/p3niKhE3EF0JWds= 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 17.04.25 07:36, Hugh Dickins wrote: > On Wed, 16 Apr 2025, David Hildenbrand wrote: >> >> Why not something like >> >> struct folio *entry_folio; >> >> if (folio) { >> if (is_pmd_migration_entry(*pmd)) >> entry_folio = pfn_swap_entry_folio(pmd_to_swp_entry(*pmd))); >> else >> entry_folio = pmd_folio(*pmd)); >> >> if (folio != entry_folio) >> return; >> } > > My own preference is to not add unnecessary code: > if folio and pmd_migration entry, we're not interested in entry_folio. > But yes it could be written in lots of other ways. While I don't disagree about "not adding unnecessary code" in general, in this particular case just looking the folio up properly might be the better alternative to reasoning about locking rules with conditional input parameters :) -- Cheers, David / dhildenb