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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?MRERbjznk3/7mUSQtOGaAqiRXOQWLx8G6GsCBTku/N5MIMWTyet1c1kiU81A?= =?us-ascii?Q?hpOEG/vNVswIKkXGZXTdUloYadrYLZy1UuNAGhr3ncVVBvm5F96GsDnFais0?= =?us-ascii?Q?mRyvrSU/O2dJvrbnQ/G4bQhJ2rHheY60dvroSRtxUpVFtt0U4GHwrreXpfdF?= =?us-ascii?Q?EqhrhKhFSJmmtyrFW5V7Jh89p1QghZzzA+eeLgYJq5MtKNu8dD283gP63KfE?= =?us-ascii?Q?KNzik9PJtibSnR9audM2QXtm7RcfO2kEDAdE1g9bZFq+MwYhokrKwGhQLtDY?= =?us-ascii?Q?oEIPrEd/CfoFarLz2lgLq3Z3K/qY+us0Dc+yCYVvdE8ZFrOfIwqDtc4rsyIE?= =?us-ascii?Q?IQcMf8Li6kTcCblqJBS73xcJnxTgFhy9Uo9unWT03yqlAED8GgMfOwI6j/zx?= =?us-ascii?Q?DAxbDant10EC9zcQ2YWwEkgIQRl/zIh7vIkU9oUSkipI7lrXHreEkKqVqVv6?= =?us-ascii?Q?qX2VidLaoPmfpMzv+QqkYc5LE/Vq8tPbPpFqDKh55fSBeIFz/h55HMhcm04h?= =?us-ascii?Q?tMdLtGezwQI1wrn2OW1psJWOdmSOP83EhWMqWVQR16JM6eX6eCMNcbVnYW8E?= =?us-ascii?Q?dIRw4Y80e9JGYw9J8mn0xEGjxAeS+pOZiMbbjVO66uw663Z4vQqjgPv0GU8A?= =?us-ascii?Q?OT3mjO23Ik5hTe5Rg/fNA+Z2efZIU26RSBm1yvZ2AgPDU5Ia2+70+vuJSjqO?= =?us-ascii?Q?6Bf43JJ7FE1sfEhO9Aiy9rDWCGXEvyXpGCdBLmVbYl+lAvmvXozEAryHiIbU?= =?us-ascii?Q?rw5ikTHV/JEs1KJCIA4OwuZvp7lUht7gFKEZ8R7OMGpNevKI/l9h+K0p6y23?= =?us-ascii?Q?LelEAovaZmJLfTTzQe48u1pCDtGgUv6FJtAG2CFJh27g71sdLFBQb4yGqSgy?= =?us-ascii?Q?+b0LXnwuDp6yntD1kVXWnoQDI7MjJsAV6dZ6lEs27AETjpZA5bkjLpqkrrgE?= =?us-ascii?Q?0ApN4L7GsKIdVosrQg/otORqdnX7FkYn1qrFHg5+K8yE+4QvnkS0Iie9CeO7?= =?us-ascii?Q?+tZm6qVdsj35pfo0aPssX2xYPjeSS8RaykTVagPO5znMjAw2GDx1KUtZX9kj?= =?us-ascii?Q?7B0A4Mz1if0RWuMORGhQHWL+p5UIsC/28VqqLCPL03do26/gj20TAj1Jrp3b?= =?us-ascii?Q?eyWyLxH9UDO32Cy5pkefIXy+AEUj0LyZ9sgJoJcwXlQjHv9U3CJjkJ1VC8E0?= =?us-ascii?Q?ZTuxLiaDEBQrTW54fVxSg/i5XUcEchFfqBVEcgnP+/DYkC5wt8079XhMO3cN?= =?us-ascii?Q?B1qw56o8dYD9c7Y4Ri/vaGZvdY+mkUTcZBdsVYjlUjKioip68hSG3747AK3b?= =?us-ascii?Q?EgkvfI4azTpmVEOZLQeuwIwA8ivwET7laU9VvURHpn4BS5sImyMI1IzkEnd2?= =?us-ascii?Q?WaBAJp8gP1Wo9w7JZLshdwp4EHhoZp5vZ1i14FbAecEb/FhEHYn5rtwFS9Gk?= =?us-ascii?Q?0FJdNaNPLocC3VDqhbyMap+GjgfXYR/3TxqI58Q9qVx8NvGFnw1oaOlXleZG?= =?us-ascii?Q?T/qsgFaxaq5NHLFwhiwWkU80jG6Nwk4pohPW6j1/ocvyTPKjBBb0c7bF6Yde?= =?us-ascii?Q?JmbPeCp3U+50bWaDZDGvRvdiJciTszWqorMPddQROCjgsE6B1aoxACXZSWAS?= =?us-ascii?Q?I69y3v63hDaSfkAHg1nwzucRMDCjbQF2IZm9TVxLhxQgzlSPs7nsZMUT98ze?= =?us-ascii?Q?DUpoPLdFr4j2PlVPHETuEEmSIkl8wfY41xthF8qQxhIIIeVFhgCaQCqORW0v?= =?us-ascii?Q?Xd5rupf3wQ=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 9d038a72-9903-484a-0133-08de8a7fff67 X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB9473.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Mar 2026 15:05:48.5126 (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: uRCf/livCuFanaYXKRuYeGXd3qX6v9mFZb1nUbD23cIwSDg/918eSDYZkamg9VUE X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB8901 On 25 Mar 2026, at 11:04, David Hildenbrand (Arm) wrote: > On 3/25/26 16:00, Zi Yan wrote: >> On 25 Mar 2026, at 10:53, David Hildenbrand (Arm) wrote: >> >>> On 3/25/26 15:21, Zi Yan wrote: >>>> >>>> >>>> Hi David, >>> >>> Hi, >>> >>>> >>>> In terms of folio_change_private(), I did not think it is related to >>>> folio_{attach,detach}_private(), since the latter change folio refcount during >>>> the operation. If folio_change_private() is related to attach/detach, >>>> I imagine it would check folio refcount before touches ->private. But >>>> that is my interpretation. >>> >>> I mean, given that >>> >>> a) It's located in pagemap.h in between folio_attach_private() and >>> folio_detach_private() >>> >>> b) It clearly states that "The page must previously have had data >>> attached and the data must be detached before the folio will be freed." >>> >>> This is the wrong API to use? >>> >>> Sure, it sets folio->private but in different context. >>> >>> I can spot one user in mm/hugetlb.c, that likely also should not be >>> using this API, because there likely was no previous attach/detach. >>> >>>> >>>> BTW, do you know why we have set_page_private() but no folio_set_private()? >>>> I would suggest folio_set_private() if it exists. >>> >>> folio_set_private() sets ... PG_private. :) >>> >>> folio_test_private() checks PG_private and folio_get_private() returns >>> page->private. >>> >>> A cursed interface. >> >> Oh man. folio_get_private() should be renamed to folio_get_private_data(), >> so that we can have folio_set_private_data(). > > Likely we should strive towards only using folio->private (and the API) > really for fs-private data (i.e., the pagemap.h interface), and add > proper custom members for all other use cases. > > For page->private it's a different discussion (requires more work I > guess, because there are many more use cases. > Makes sense to me. Best Regards, Yan, Zi