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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?OrKOQ9xqwHYRl8y+ERZWvnb2OZTgOJSSZv2hHCuPs3NFEtpP6+c+9kLdKjfr?= =?us-ascii?Q?hxyjuvhTuDf9+9+tu1KfL5KLaPf35mZpjiheZVmpeXxeZ+hxspjyxQVPROjk?= =?us-ascii?Q?UnHxdpo0nEYDyfXMpLXC+Q6ck9QCQUHdCH+jDo2dA4S6L7RJild8cVcCRXNA?= =?us-ascii?Q?rEnANSLqzrtY1AnfB6NPYF9ITovL0wLDp2SI8DEq3EEDh5BsVJur7gajBSv9?= =?us-ascii?Q?uMfbPNMYhXheMgE1GdEYtROUpyY2mYiLIhqe5X1t/0ss6t5QyiGwgHCsGyOT?= =?us-ascii?Q?zsEWEACxb+l6boh2n0JfCjvE9XOHVUqDzpqaeDdRXxHIIC2UyBqqIX0Aq1uq?= =?us-ascii?Q?PAQ175SYYRMB3Uplc9UwWZZL+OVwPylPlQunlutq5/dP65cVOjNFlKfukm7w?= =?us-ascii?Q?vTfqvUSYXGrw1E3mzYA/u9a5E9eZdOgrPykGAPD39zE95aSDgHn9F0SHMn96?= =?us-ascii?Q?jo36YwFUYeTBYnEuvqUvuB0fA74mrnZ3vFjaENK2OP1frYVbB+x5sWk4cPMT?= =?us-ascii?Q?R1ziM15uBKqJuaymjOa2477JX1HL4p+m2s9+ucxA2Udu3shoH35pYkvXzz1q?= =?us-ascii?Q?gEtI+SplvBKzTcmNb9upZlQD1/Lv8sF2rUxUgjdDByHPSYo6L5A0VaSIwMdF?= =?us-ascii?Q?T1r4h6P9iPNeRt/y9/nVsUk2XZutHY9fKDMuWzxRlKftOkU3G1Mr67jWnuEB?= =?us-ascii?Q?uhcknudnPV9ripyOxkMBYnVD87c6A1WivU+kGMiVozuvXZg3StVxUznWRVYc?= =?us-ascii?Q?Ujq1StdNuXO3FCtf2yyZaV8ZKMMdtUm+H9lGsmGqJZYnrM3UqtbesljXyUQF?= =?us-ascii?Q?xI/jJh3sMfMRGyDcyTnBgPgPs3o8e0CX4D0DApI6AfQ8XBnlowPwb33WLbC3?= =?us-ascii?Q?MBr9x+0Dj0k3wc/7kgsDPGk/awIv86tPz28EK58zKUiNbkjPnzjBs6ERZJsp?= =?us-ascii?Q?7GbFAklbfB83NpJOQXqEOV8GRf4/VIjEuHHQRUw8WljPFKfA/814rxgHnC6A?= =?us-ascii?Q?KAil9n1i8GvA1eaWIjsMIzqWfF5jWNHK+UaBci+z2YeNwJt0FQ4yLoiycdYu?= =?us-ascii?Q?ndjTfyOJ8+uZzPI9Bs4kD4KSCUDkMTTdePfrTAEl4SARFo9TnsIVutJXlMSI?= =?us-ascii?Q?xB2fIhpu8DqQx87+mTKjsERcsWJwaNcLrDgQDMFQGO17ufpQA29JxomsamOC?= =?us-ascii?Q?c7HmmY+sIErddKSw9MgMR2Bpw8hYnSGk6vThYr+WMi5W37eYO39KSvJygCBu?= =?us-ascii?Q?Ytjrfxm3O28ThAl/BBT6SHTkZtTM2A43U+vOU0RWGnPSTSv+D0Y/QyDY0/Cl?= =?us-ascii?Q?NGUUadhw+UJ23g4NqLC6fwUPLZ2sENB+PsaK5csZ3b1B2OLLcZ38is8e4qvk?= =?us-ascii?Q?5MyvwkOsaZNmOmEQ8ep8FOeh1eXRFZhdQGYek4GGSULkncY0UJ8IUk2VPIY5?= =?us-ascii?Q?D+k3Znq3ONga9u3+ZJg5T7lDDiVJ09FhZx5AhnFigJ3duPGEkjTAsBEh/ZLJ?= =?us-ascii?Q?kxecIrD/9qUpiMJw2WmGnL3twYpobLGelV8WFJd30m+mFhKKQEitp1ZEXqL8?= =?us-ascii?Q?OSWlYz4IzWHvgNVtIB0=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: e7cecf60-989f-4b68-4e58-08ddd4239da4 X-MS-Exchange-CrossTenant-AuthSource: CH3PR12MB8659.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Aug 2025 13:25:59.1711 (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: +VkDW3YIV9jLIJPx4p8WSFgUaX2ErtsLSdS6iFB2K0pqSpnyCP/263MNomS7Hh/m X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN0PR12MB5835 On Tue, Aug 05, 2025 at 04:00:53PM +0300, Linus Torvalds wrote: > On Tue, 5 Aug 2025 at 10:47, David Hildenbrand wrote: > > > > The concern is rather false positives, meaning, you want consecutive > > PFNs (just like within a folio), but -- because the stars aligned -- > > you get consecutive "struct page" that do not translate to consecutive PFNs. > > So I don't think that can happen with a valid 'struct page', because > if the 'struct page's are in different sections, they will have been > allocated separately too. This is certainly true for the CONFIG_SPARSEMEM_VMEMMAP case, but in the other cases I thought we end up with normal allocations for struct page? This is what David was talking about. So then we are afraid of this: a = kvmalloc_array(nelms_a); b = kvmalloc_array(nelms_b); assert(a + nelms_a != b) I thought this was possible with our allocator, especially vmemmap? David, there is another alternative to prevent this, simple though a bit wasteful, just allocate a bit bigger to ensure the allocation doesn't end on an exact PAGE_SIZE boundary? Jason