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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 7.2 v4 09/12] mm/truncate: use folio_split() in truncate_inode_partial_folio() Date: Fri, 24 Apr 2026 11:07:50 -0400 X-Mailer: MailMate (2.0r6290) Message-ID: In-Reply-To: <896b3956-3cdc-48b5-a0a0-a3ec35aefa07@kernel.org> References: <20260424024915.28758-1-ziy@nvidia.com> <20260424024915.28758-10-ziy@nvidia.com> <896b3956-3cdc-48b5-a0a0-a3ec35aefa07@kernel.org> Content-Type: text/plain X-ClientProxiedBy: BLAPR03CA0173.namprd03.prod.outlook.com (2603:10b6:208:32f::35) To DS7PR12MB9473.namprd12.prod.outlook.com (2603:10b6:8:252::5) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR12MB9473:EE_|SJ2PR12MB9209:EE_ X-MS-Office365-Filtering-Correlation-Id: 56917fd8-b64f-45b5-e791-08dea213443e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|376014|7416014|1800799024|22082099003|56012099003|18002099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?H8VD8+ETLYmekhIRYPNLyPjDKVYEu0RMETAml1k17GzY9eXd8H4MSmiQaWyp?= =?us-ascii?Q?nPQXx+J3OoHMPb5HhnL7Weu/lmz3FHEdDKCSYRGnVpvt5ygjXpwQ7tjHgAdl?= =?us-ascii?Q?focf69Qw+MzBt2jXV9Zut7v4l5dHZdDQbJ2Z6ANjSK6F3AMkG9RdvoWDc8rr?= =?us-ascii?Q?1B0msd9YyBSp8u1u8CZ4KUkhjipkjn8mNGRDGY3PBIlOeE7N/sCTOxbx2cS6?= =?us-ascii?Q?xKq7Pm2WL7mF6Xjj2yH10JQWchrdetk8Xv9mPbwrxzccNAiSffYO6+IBiPUu?= =?us-ascii?Q?XwC9gc7iPKHreXrjwXWBjxwfZDlDw9IPdnzA2+ANb92BH6mQojV9dvf+WjQx?= =?us-ascii?Q?va4QT/rmV5+kY3oDC/kqDztsB7kA08+8SMUwAc6tXAeCLp652PIfyEYfW+WW?= =?us-ascii?Q?HkxlCrnTncVfRGQ+bXrdp77AhH9Hh6u7VNG7pLWh7o2I/EZR3ZilqHRr+WVs?= =?us-ascii?Q?aNly9RqhmU5ZcIU7UZn22YX+Dm7+1hnwzM6iCrIoiYVmclruSVK/9YAQUqRA?= =?us-ascii?Q?Sft3uE45CslbPxCSN60acc8/2W7Ueh784DA4OZHNBK3uDigljnmvFbp5DMPH?= =?us-ascii?Q?vNcpgFWpAnrQrGZhVfTSsIZMIsK+wiNG+Nh4Asv/ucX2dJ1ZSSBpxtasEQdl?= =?us-ascii?Q?G8ppCifh5GAYBtRTgCQY/q7TD4xB/C4koPO0YMvtP8EKf/geoXP4xcd+t2ua?= =?us-ascii?Q?TdbHxtk3/3jfpiesefLRPUgpC9S5zXCy6KXdksEzKXUNRJkWuKt/dF/IKxJX?= =?us-ascii?Q?sT8Avi2YEQIC6Jqq0eN0lmoGTBG3TckInTmCIzID9oH+stXDlOgGg72LNTVP?= =?us-ascii?Q?HxOuND+IxgVCUT4fAf/4JeuFjMdR6r8My9mv0CzzKwhHy1Rz882k/H1AdWqz?= =?us-ascii?Q?KKC+XgubPtjble7mtJQLrhFk0/OMUCVXlwexe7RVOFFfqwpQ7ZmNQuV0NLlV?= =?us-ascii?Q?Ooj6fQhhwMjrA1QEjYygfm4bP6A/hKgiyAYS5OFWBzQ3S1WsKW3CdRNIkpi9?= =?us-ascii?Q?NyfESPKE5LrtP7W1rMnvDUSRVSukMdHyeML1jARFef/vsmdCTuE9gRv5kvA8?= =?us-ascii?Q?/k77ufVWGhy6WF/+AnmXOQgZHaT9lqLHdvdJdqh/BwQ7/8wGxYubS3fWZNAQ?= =?us-ascii?Q?ozt9NyTYB1RFOwbY3pJmrVTERu5sRhFep8U5pLB69waiOsOvsnr3Cueymr/j?= =?us-ascii?Q?qSjs7CskuWTqEMgfurCZ33ZJMxdKXig8nBJlONWKgq21EbAVhcFHPN8Qojgx?= =?us-ascii?Q?CKtSek498Vvt7vdK0ori9mVYAIdaotAldLSZToXNwt2P3Kn2rn/BCapDy1pc?= =?us-ascii?Q?aXyW2v+7GjQXqJoD1QnMJU3zxMukLEzszVtC79wzjjlW6mekdErJ+/wpEUXH?= =?us-ascii?Q?9qsEsrfxxe0lQ0gey0fbXCXRXvMgPFvei/bCaRuBfQ426qzmLjRP2gc0ZzQ/?= =?us-ascii?Q?Gqh9fcleOWpf8NqjmBp2Jcy4mRE2Bfu9UOY+nVjSvLhAD4NBK6mY8lAnjw0c?= =?us-ascii?Q?b3U3DMyh7n9eQ0dBvjDR6xnG8Yqn3CI50oA80st7tOPrUx/Kg1FyomLaVDgE?= =?us-ascii?Q?zO/R/pV7gVY09Imgl4WLxrOWFsVNfDLTSc3m7+VdxszNpv0kGzUKUfgmYhLL?= =?us-ascii?Q?ZoBnfnWb4jBHyzzrTcuXYZf2OHe5Q2CciDrAugkLj+YaK7S5Q8hiFFIhIp+i?= =?us-ascii?Q?6IbVD6AmGPRcgZm0FbqiTONZZy93fU/eFnNqi09Sk0hWsJ1nxFjjahxde6yz?= =?us-ascii?Q?c04ZaaoNPQ=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 56917fd8-b64f-45b5-e791-08dea213443e X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB9473.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Apr 2026 15:07:56.7509 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: gikcUvPpI0WTFQge7FUlddtBb5AsbNWmbSqZl7/Lk2XUV7RxDAzU07v48oKcXzFT X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR12MB9209 On 24 Apr 2026, at 8:54, David Hildenbrand (Arm) wrote: > On 4/24/26 04:49, Zi Yan wrote: >> After READ_ONLY_THP_FOR_FS is removed, FS either supports large folio or >> not. folio_split() can be used on a FS with large folio support without >> worrying about getting a THP on a FS without large folio support. >> >> When READ_ONLY_THP_FOR_FS was present, a PMD large pagecache folio can >> appear in a FS without large folio support after khugepaged or >> madvise(MADV_COLLAPSE) creates it. During truncate_inode_partial_folio(), >> such a PMD large pagecache folio is split and if the FS does not support >> large folio, it needs to be split to order-0 ones and could not be split >> non uniformly to ones with various orders. try_folio_split_to_order() was >> added to handle this situation by checking folio_check_splittable(..., >> SPLIT_TYPE_NON_UNIFORM) to detect if the large folio is created due to >> READ_ONLY_THP_FOR_FS and the FS does not support large folio. Now >> READ_ONLY_THP_FOR_FS is removed, all large pagecache folios are created >> with FSes supporting large folio, this function is no longer needed and all >> large pagecache folios can be split non uniformly. > > In general looks good. Just one question: > > folio_check_splittable() also rejects SPLIT_TYPE_NON_UNIFORM / new_order for > swapcache pages. Since swapcache only supports PMD order or 0 order yet. > > It's confusing, but truncate would never stumble over such folios, correct? Right. Best Regards, Yan, Zi