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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v1 00/10] Remove READ_ONLY_THP_FOR_FS Kconfig Date: Fri, 27 Mar 2026 10:26:01 -0400 X-Mailer: MailMate (2.0r6290) Message-ID: <6800F1A0-7ABE-4CF6-B9E4-81126D59B43D@nvidia.com> In-Reply-To: <10748785-08a9-41c7-bacd-88f05fdf1a88@kernel.org> References: <20260327014255.2058916-1-ziy@nvidia.com> <10748785-08a9-41c7-bacd-88f05fdf1a88@kernel.org> Content-Type: text/plain X-ClientProxiedBy: IA4P221CA0002.NAMP221.PROD.OUTLOOK.COM (2603:10b6:208:559::8) To DS7PR12MB9473.namprd12.prod.outlook.com (2603:10b6:8:252::5) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR12MB9473:EE_|CY5PR12MB6478:EE_ X-MS-Office365-Filtering-Correlation-Id: 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Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: +MtdRenwI01UMOy81jT7rrXAkQsbnQN88YagZNjSFypp6PQcYCiiDZHEMYbhhR9i X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY5PR12MB6478 X-Rspam-User: X-Rspamd-Queue-Id: E4061C0011 X-Stat-Signature: kp5gfmh75cg9wet3fdwpn4jeh4ut8xhy X-Rspamd-Server: rspam06 X-HE-Tag: 1774621571-837948 X-HE-Meta: U2FsdGVkX189YydAuQm3g8sKx7WgOCem9hHcQ3nCSuPu14rszFa03IWiF/HGACzY6CWtUYo+lHP/HrpPT58V0LGXdkFX0uyUH8nMjF/ZqPfqysMkPLzDlvvlTsbTOzX8ZCHbmhHIvVNA92t3wT/iTbvBbO50IcFvo2qhL1q61jEjZIFCGxdCUL55N4GGB+JNoxPjhzG89MFt8FyRVUZg/VUUUZztfi6zQqPiObNqjvCFjV22NSYuh120rwJXpbv/h0bleWh9gF1+jkVmsKQ72nfxL340JNT1Nqyp2nmakk3+G2ZzddsT9MxQ/TeLI8w6RNh0AhDayyEr4mmvKLCER05q++aOou8eoYUCXgSgWSaNqKVzE2U5yvEO/bF0cF+U6b9krxSQfACgWP4MvAq6MOnP9BEujwr4njYt2q3T9MLrVcZDaxy9xBNi+Zrepu5o7HImvEhHbWhKO6Scy+duBfUv+y52FvT8SewlxiPhDWixMOjOYSDBrXNLDiNSeuGIGfekNTt+PdK8PvNf8CA86vr27H8jmFaBCWCyYvEQbCe0t0pN4Icl3zn1cJ9G+umYQOCEVvj/PBw5TUEoSU5OK2YxaWJ8KBGenMJVFtEPIKPcdQFrxhFBfox0xfrfsjnTEBe7Pfj0fIaQz76wgD8FmZrr+n/Tv4+vj5daZxW88DQg6D9zp16AMDSYaTVKwlgFzsRmy+aYUHBMkmw93+P7BGAA7J5wHBnMesJtcRfx4kSeQKFjjKSRAjn4OsT07b8IdIpeP7lBhA2uAk8B5Q3zq1GZUmbiJTwFmrgggAhCcoehGlLZBw/XmJr9xeN40W4pZGUiIH6eXYhCraQKim6Lgk/6ppg41Yiv50vqs7fCF1RuFC+H5PY1kbm6H0GC+XYLTqR9pst+oIFeRoj8owFNEKdqb6nmnivuyn2LXTlq3BQB1dsgsrBZrzFlpIkIvq4+DDT4t2YCyOLXGF0VNK8 wqVwSa/i KThb9UwQmxY/f1J4CHyPq78w+lRUIycHBeASS2u51wkh651WfzZt9ZkwJECLB/Jb+MMjKEcIANeuJUM/mLZnW1+B1eLHhHZ6ON7Z/0RekKga2bls+aNDEAXYn1BA9AwY8l2gMhQq7P5xZ7wJmPsRgAjox3MzMurNx7ceQaJeMdlWXg1UNri0NS/QAWL/dfzRc+jXO+OJxPyLZOaTlL/6zVmVRcNpWgGShdHFwdM3kJ6aqd/AiRH/tGz1wPP11N2gup0d2C2Z5FLAmgiQcN50jrCY6nzDffk21LxGfRRbNNEM2rKeYHJ3LUkvJUNlJlCmYM6zhW4nEXn+8K1suYYNqyhHddP79LX7cWg/zWdheVzRAsxZOOOXBER/uqA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 27 Mar 2026, at 9:46, David Hildenbrand (Arm) wrote: > On 3/27/26 02:42, Zi Yan wrote: >> Hi all, >> >> This patchset removes READ_ONLY_THP_FOR_FS Kconfig and enables creating >> read-only THPs for FSes with large folio support (the supported orders >> need to include PMD_ORDER) by default. >> >> The changes are: >> 1. collapse_file() from mm/khugepaged.c, instead of checking >> CONFIG_READ_ONLY_THP_FOR_FS, makes sure the mapping_max_folio_order() >> of struct address_space of the file is at least PMD_ORDER. >> 2. file_thp_enabled() also checks mapping_max_folio_order() instead. >> 3. truncate_inode_partial_folio() calls folio_split() directly instead >> of the removed try_folio_split_to_order(), since large folios can >> only show up on a FS with large folio support. >> 4. nr_thps is removed from struct address_space, since it is no longer >> needed to drop all read-only THPs from a FS without large folio >> support when the fd becomes writable. Its related filemap_nr_thps*() >> are removed too. >> 5. folio_check_splittable() no longer checks READ_ONLY_THP_FOR_FS. >> 6. Updated comments in various places. >> >> Changelog >> === >> From RFC[1]: >> 1. instead of removing READ_ONLY_THP_FOR_FS function entirely, turn it >> on by default for all FSes with large folio support and the supported >> orders includes PMD_ORDER. >> >> Suggestions and comments are welcome. > > Hi! :) > > The patch set might be better structured by > > 1) Teaching code paths to not only respect READ_ONLY_THP_FOR_FS but also > filesystems with large folios. At that point, READ_ONLY_THP_FOR_FS would > have no effect. > > 2) Removing READ_ONLY_THP_FOR_FS along with all the old cruft that is no > longer required > > MADV_COLLAPSE will keep working the whole time. OK. I will give this a try. Best Regards, Yan, Zi