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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Mike Rapoport , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/4] mm/compaction: stop recording free page order in page->private Date: Mon, 29 Jun 2026 11:03:38 -0400 X-Mailer: MailMate (2.0r6290) Message-ID: <4CD1FE9D-3860-4A55-ABCE-13C97DB205BC@nvidia.com> In-Reply-To: <220774cb-ba5b-4a12-a649-955c83bfc704@kernel.org> References: <20260628-keep-subpage-private-zero-at-free-v1-0-f4ce3930d10f@nvidia.com> <20260628-keep-subpage-private-zero-at-free-v1-1-f4ce3930d10f@nvidia.com> <220774cb-ba5b-4a12-a649-955c83bfc704@kernel.org> Content-Type: text/plain X-ClientProxiedBy: BL1PR13CA0208.namprd13.prod.outlook.com (2603:10b6:208:2be::33) To IA0PR12MB8374.namprd12.prod.outlook.com (2603:10b6:208:40e::7) 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: IA0PR12MB8374:EE_|DS0PR12MB999103:EE_ X-MS-Office365-Filtering-Correlation-Id: 73201922-ad59-436b-4f00-08ded5ef9a7a X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|7416014|376014|366016|1800799024|22082099003|18002099003|56012099006|6133799003|11063799006|4143699003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?z4T8r32oL7Y0n5kve72EaGLjiF6iZfnnbLxyMKCJeKg1qT8nqdAg2LtO94Ju?= =?us-ascii?Q?AP1Z9bLzMuEr89n+Vfx3scoRx3hbRYJE8sgEE6l2ewAM3eVDVbcP1k6Mqa9o?= =?us-ascii?Q?0DBMdMqdXWZxAbny7sKu2ciJZ7lgEGu8U4KKr3MtfqDYCT8NpE0Jhx6tT8qQ?= =?us-ascii?Q?bD6KPTe4RSL8sXZFl5aV/V0FAIiMNj3PGixkQV2vqXmw6xPy3qEhx4uk9GR8?= =?us-ascii?Q?oYg3hZhhwwJaErU4Nw7N6caeDp6mnc6UmxaGLEnmQz0ldxzlRlEXLdi60YMx?= =?us-ascii?Q?kegHwA9muOaXkB3AjZRiO+SCBclPsCUPmLgTC+b/llLYymfI2d9OYUv9Q+P0?= =?us-ascii?Q?djSrkgeD/t2z7eXFPs1RuU4s3uDd0QLmwWAldDU9TByYBFF5TvdMyhcjmdu7?= =?us-ascii?Q?7P91GFkQyHeNePcKc99EjSfIMC/WPDvFSGcw9zMoQPHI0LZpeTP7cuqrQdPm?= =?us-ascii?Q?UpHFfySw8J0VDjdBARQjRmH2kuR5rk9dm5/GJTbko0Ssa4iMfUQWbsPQhhyl?= =?us-ascii?Q?AeJ2B+ywnTPedpf59BhuZFhGWaavdbhpfWcpw4E1p0MIpy4bI7qhgLcEUQL/?= =?us-ascii?Q?9eTIv7gYlcs9DZ7U/CDThrXRjB5SqvvVJ0+qSMi8d7x0NJ3HYzlvwaB/afZ9?= =?us-ascii?Q?wAoNdfPtpO3GzqORbQN8wiTRTLFi8wY6n/q/68LK8Ai8rpGmjBSTa1hI6YHa?= =?us-ascii?Q?c4BEXJ15TkhTdu1H5HyqTetYohcYNt/uwePySHv5pftFSHchtwDZ6hM2svB+?= =?us-ascii?Q?im1UkJtQsv2YFXls9ipJXWj71nPpd7CUnXj1hsbUAWjMFxJMwo7eTobC3vl6?= =?us-ascii?Q?sPYsoWgHcXCoXy2NLMAl95dOv+wY2V3Ty9agAvrPrf4vXS6ro1Y/lLDnF/fK?= =?us-ascii?Q?dZl9en0l+NvZ+DvXs3awWkwlNSTee6mKuILIbT05S9CWdRDua1jf3GRO8g7w?= =?us-ascii?Q?OD8ljnMg9wQU6GL0rPQpK8XGNO7cohPpg2NO6BE66vhXDVsyDtYphhONK8vS?= =?us-ascii?Q?gEs22oiH5gIUVNMNtK3jrGs54KjYM16rwFIe1ILvRvt966RDuvzJDfssJNeC?= =?us-ascii?Q?B69Cs/OdR1py/yU3pLlzDyByH/6YnwoJoHsE78oI43zIsGZDu6rBpsa/lIez?= =?us-ascii?Q?q0vIE5yQdeILsWgeAyt6vpkVX1jWQPQQxqxuCFSq8sGnRzEdkiu6LRs0u7aX?= =?us-ascii?Q?DqPdTt5vkVoqh/eKIq1LBIfX+Lvh+Oa9LDdqlkAltZNh02/GquI3CsmPARK8?= =?us-ascii?Q?TwUmLTujFt9XTxeuZr0FEnPm15dI0Pv+DPoE+gDXEme+FkRoX4dGIH5nEQUK?= =?us-ascii?Q?9gHrKfmTHrwsdUAf+bu5tN3RdoWvnFDUUnvy9XRfzZjcJifwuvf7GEwHFdFS?= =?us-ascii?Q?kIeNDTKEAzrLM/Pw4eo0NTLRh6Nqkcq8XE/PPDv6H4C9vZMcozwSKe0xzVg9?= =?us-ascii?Q?IyQfCxzQuHTpXObI4qfi/3UZsq7jUM8O4d1bJX73VYB2ci8dK1hl1JJxpdmh?= =?us-ascii?Q?q1kKg9TX6M18H3znKidKrJ4LgqH3apvgMUlKRrQ0emP70D6ETbGy6BKGasNN?= =?us-ascii?Q?/AzR2XHa+4+HMbfvBo+/o4w2UY/NFHAjLMBChZ+CHDBudSr/GHP/sws7mGI1?= =?us-ascii?Q?C5m63TpBjV6mpqej8i7OB2NjwyuNz/Tv1BoRCmmV7FmrYouMlefUcKNCArhL?= =?us-ascii?Q?qHxW+tn3OMwNLvLhLdTHk4K7Yi85x9YuE23uEz66BUFPHJ7q?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 73201922-ad59-436b-4f00-08ded5ef9a7a X-MS-Exchange-CrossTenant-AuthSource: IA0PR12MB8374.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Jun 2026 15:03:40.0079 (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: xSLWax/TGUJVVhhK5GjofCYdAsEazr9RONh0hOeoGazy2yB6yHG5M1HAeb6L07FE X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB999103 On 29 Jun 2026, at 10:28, Vlastimil Babka (SUSE) wrote: > On 6/29/26 04:56, Zi Yan wrote: >> Commit 733aea0b3a7bb ("mm/compaction: add support for >0 order folio >> memory compaction.") stores isolated free pages in an array indexed by free >> page orders, it is no longer needed to store the order in each page's >> ->private field. And there is no code using the stored order. Stop doing >> that. > > Ah, great observation. Cool. > >> It also prepares for an upcoming change that ensures subpage->private is >> zero at page free time and the removal of set_page_private(0) from >> prep_compound_tail(). In alloc_contig_frozen_range_noprof(), >> isolate_freepages_range() is used to grab free pages from buddy allocator >> and it leaves the aforementioned page->private set until >> either split_free_frozen_pages() or prep_new_page() is called. >> That >> triggers the upcoming subpage->private nonzero check along once >> set_page_private(0) is removed from prep_compound_tail(), which is called >> via prep_new_page(). > > I'm not sure it needs to be said here (or in such detail?) Will move it to the cover letter. > >> Signed-off-by: Zi Yan > > Reviewed-by: Vlastimil Babka (SUSE) Thanks. Best Regards, Yan, Zi