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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?g59bSy/WWF+UDDwf0MyuK4SO3Udnc+QIicvBNFw8olRQquo3LZ785Jx/Qxa+?= =?us-ascii?Q?LXP+1IV/fMO+s1fyyQPJkAMdOdsYBQXjGoMJuzLKQ0zciR+tuFkmsLxsS/o0?= =?us-ascii?Q?DCUohLZ9h6LS59f0SmhwW4azXek3yKv0Zy2lwlpO5djlT4THd2y+jKLmE1HM?= =?us-ascii?Q?qQBnyoo/6eRtxCgI6R1pVEy/UjNWjuo481if00GUIf21fJgn5xbyWDs+DkVN?= =?us-ascii?Q?VoeUwv2SrKJerohWuuyJjE4z+Puboyf0mpvgeRFiITkv8ognQLfNz4sv0QRP?= =?us-ascii?Q?kQrZrpEZ5owzMkupDf2XZAEsfwCXgHrgrYHiilygKsHm3p25xkekoCKbXXRo?= =?us-ascii?Q?hHVpstnW9tNyjldi1STAC9hh2xPmxiNcaUXIP82KSllQ7VS/IteKz20gbYRq?= =?us-ascii?Q?5W8HDYp0OotTy8H5RBzPPCHp5YUIixjqxQRY4oftkf7aHZQneyEvoLKPTERt?= =?us-ascii?Q?tlreOqcYIVeod0/ptcNyMuqF+m0zQiGYYzs2mIjqZJiCFd+w6teGqtet9X08?= =?us-ascii?Q?qIr/MPb5gk7D/iftoWMld5eMuG/Tymw9DetXudwmrTywM3mExcfp0yaJwfRD?= =?us-ascii?Q?P4Q2HL01Wo9CRr8lnbO8qj9eBPETEJjhMYv1mE/FAnlrKr/B65WogpZM1uKP?= =?us-ascii?Q?dcmYteRyyPnWLm1Csxu3wKwa/bW/qIIHwtuqt6veuxs6ml/8PoEwkChIaGIo?= =?us-ascii?Q?eTDEfSPSyEG4HURayNlYzFgVmxTVb4asBa4Rbr3k8yYlKGOALTTaxM1kHSxe?= =?us-ascii?Q?IvHYd7Mb23opjP6zftJIqqQTXHzlGlrdHCiTHS3V2jqyfOOoOpA/KGw9Tig7?= =?us-ascii?Q?LlYs8/f84K5CEAL+IjB8NVVFH4yTJNW/FtB7SZaUwpiYXHvVBfzzK29XEOr5?= =?us-ascii?Q?zpXiWXSWnnNqnN2myCcSKnl14gwtZbgnBCq2azs+xgw0YHbs4gRxY56DsroP?= =?us-ascii?Q?Az1CoAbHBAL4sFqTPNfkL1U4YPpAkxIRnbOF7hzUPivNEQ4rduUNL1KXdZyX?= =?us-ascii?Q?pfTc0BM2mtZJWpid0miQAmIcr1iDk2lDqZ3r1XxDZu0dcu6jeRp+5SO5KvHt?= =?us-ascii?Q?j1Ib40zraO2AB1g0lYZiOv2qcbT+fS212/E50wAbMcV0v+Syh2XtoYHMiurj?= =?us-ascii?Q?dFLlP9HG9ZJCP/5eNT+t5rIm9Vspi4BD+Yn6dAOyJnmwibd8orwdjNKII+Ub?= =?us-ascii?Q?N6JIFwfxymF5qKwJFjBSRk4C5X+TuL/LPUe/+yiFIMCpC8VUUIjPGka3mALv?= =?us-ascii?Q?DibpgLfMRN4D/aARtsUFQjbebhxtxVGAoxb9KV/UdPBgRoaxT3e5i7HvhB/J?= =?us-ascii?Q?rWKb7/dWg1S20/YWnVlnv1ImclDVWmwewabADH7DVy5vnNqm3By+btgzxzEA?= =?us-ascii?Q?6wWmXWwva5yBK/o0hDknvGkilIZYOoCkA1RjdlXLbEU8poj4p8vB32mQvY2w?= =?us-ascii?Q?lvfJUh5E5dvvjtVVtkeXXT4hP4nBc85gusoR2Zmag6Klp/fthL/pXiev/YOZ?= =?us-ascii?Q?3PEbGfBrje0llIuqAJ8ErhfnHZRyuZrAft+SCiTqHE++DRxwRXPUYBVphW86?= =?us-ascii?Q?kAAZw6c3Z8D0qDEabJ3OYyPvqPXwVzgce5fVsrJr/ozlrwBEP2qdBw+MR7pw?= =?us-ascii?Q?6GjnTUKO4aJeV2oTYRMlmth+NbxwCmk3i9NjkyxxhcOr?= X-MS-Exchange-CrossTenant-Network-Message-Id: 20447994-c9d1-45f4-58cc-08dccbee8b71 X-MS-Exchange-CrossTenant-AuthSource: DM4PR11MB6020.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Sep 2024 08:00:58.3301 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 16zQMS/mnPtvPrM46s/V5hirWrzeJc+o+eglKiOY6MPCc67B/9pQuTBUo4LIGQLzwLmgMFtuuvKmYl1LNE/nkg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY8PR11MB7195 X-OriginatorOrg: intel.com Hi Christoph, On 2024-09-03 at 09:35:21 +0200, Christoph Hellwig wrote: > On Sat, Aug 31, 2024 at 07:01:19PM +0800, Chen Yu wrote: > > When the CMA allocation succeeds but isn't addressable, its > > buffer has already been released and the page is set to NULL. > > So later when the normal page allocation succeeds but isn't > > addressable, __free_pages() should be used to free that normal > > page rather than freeing continuous page(CMA). > > So the patch is obviously correct and probably useful, but I don't think > the existing code is buggy. > > dma_free_contiguous calls into cma_release, which uses cma_pages_valid to > check if the page belongs to the CMA pool and retuns early if not, > letting dma_free_contiguous fall back to __free_pages eventually. > > What am I missing here? > Thanks for taking a look. Your are right, the pfn will be checked in cma_pages_valid() to see it is within the CMA range, if not, it prints some messages and return false, finally falls into __free_pages(). From the functional point of view, there is no bug. From the efficiency point of view(extra checks/printed message), and from the code readability to avoid confusing, maybe we can refine it? thanks, Chenyu