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[2003:cb:c713:a600:7ca0:23b3:d48a:97c7]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-36b367d9576sm4396129f8f.31.2024.07.26.01.04.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 26 Jul 2024 01:04:47 -0700 (PDT) Message-ID: <17256b99-ab26-4f7b-9100-2fc42b233af2@redhat.com> Date: Fri, 26 Jul 2024 10:04:46 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 2/2] mm/hugetlb: fix hugetlb vs. core-mm PT locking To: Baolin Wang , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Andrew Morton , Muchun Song , Peter Xu , Oscar Salvador , stable@vger.kernel.org References: <20240725183955.2268884-1-david@redhat.com> <20240725183955.2268884-3-david@redhat.com> <0067dfe6-b9a6-4e98-9eef-7219299bfe58@linux.alibaba.com> <707d8937-d4c8-43b3-bc19-70f0038522a9@linux.alibaba.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: <707d8937-d4c8-43b3-bc19-70f0038522a9@linux.alibaba.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: CAADE1A0026 X-Stat-Signature: pre68y65jzio8gx65phakrbckrjh63fw X-Rspam-User: X-HE-Tag: 1721981091-305822 X-HE-Meta: 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 V4CfDvs7 uIBCQ0XOz+Na+XwqVS/A540f67GuV1mbE9GbS37JBvC4dPukq+j8YMtYA4y5D/OF136rWejjZMI8L+434MQEM6N//f5v9CPDMN3S09JxF2iz5ZDpHTKTjNV6mKDCEjT/+tDCO73xLvMcWSZ0qC6qZMJxDreeyW+QAQY/FLER5yfvy1E8j2BN/0dkrwrIgFElvdbvi2M+gLJtWBaRoT7M8JniXT+tbA6Rhm1Ee3vb/aF5mAtKM0DWx58nffcfRdMxrjAfWe9MuxDup4xwIlYbYCWss4lmknmp/r/+3VMYc7IstpJyqpCwBiS17yK30knEIPgvxl8yFEM7soip0Q6L8d6PSwsYmmIdWSydJ 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: >> >>> +     * >>> +     * If that does not hold for an architecture, then that architecture >>> +     * must disable split PT locks such that all *_lockptr() functions >>> +     * will give us the same result: the per-MM PT lock. >>> +     */ >>> +    if (huge_page_size(h) < PMD_SIZE) >>> +        return pte_lockptr(mm, pte); >>> +    else if (huge_page_size(h) < PUD_SIZE) >>>           return pmd_lockptr(mm, (pmd_t *) pte); >> >> IIUC, as I said above, this change doesn't fix the inconsistent lock for >> cont-PMD size hugetlb for GUP, and it will also break the lock rule for >> unmapping/migrating a cont-PMD size hugetlb (use mm->page_table_lock >> before for cont-PMD size hugetlb before). > > After more thinking, I realized I confused the PMD table with the PMD > entry. Therefore, using the PMD table's lock is safe for cont-PMD size > hugetlb. This change looks good to me. Sorry for noise. > Thanks for the review, highly appreciated! -- Cheers, David / dhildenb