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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?utvGPNA7di8GbOl7SrchNiFfdLt6Ynw3IzAoXUVZuXwlCGZNH6zUiNeUb9gt?= =?us-ascii?Q?friza3GJT8UU7GXljbwDEb0hInbVnuCf79dnmXWRVwRTOZVHeWqBJHdbN+Fn?= =?us-ascii?Q?wEdoyA3Wd15/Bb3wZYNrJrLpoI4faT/gOoEKhL19yvLP/qJcpMU9UAtCidxe?= =?us-ascii?Q?N0eix55yL0RiGmlsTRVzLo2ZGyeYMdzMM0il3hpahueO6TrEd1gvOdhjM/l1?= =?us-ascii?Q?JdmaGqdHsUYHJ12mHWn1ZeKNW9b9aDH99K+3DnRoiFf43SBE8bVbvD2f4PXt?= =?us-ascii?Q?2DkJlD+A/+b10ERFLTTBow2yIhJhDAYK0pM4x5DcshoiAf29HrRAMG//ayWQ?= =?us-ascii?Q?P0AJr47hCMFVwpiSZKDh5NIdWczsfG85t3Kj2PM0RhD9Vz3ck7XO9gs+9k/q?= =?us-ascii?Q?7GdsYJT+zFfhZ8VZTIRzEYeNmVdQnXoX2896Sgt5mX8iU1uSFGATOI1SoxaN?= =?us-ascii?Q?r6/ibDgF/3dS5QyHVtKVKhxKOOg2Gqr0PzZmWAgeqW6ZVfkgamRVx8zrIA2E?= =?us-ascii?Q?DoDS3jhJunkQF8EDmpgiE+PNAOBW4QdwSWlrOyC/xZ7JCauP0eD5Qw6stBxz?= =?us-ascii?Q?z55xnvZ468viFzzHeh17B5jOO6ssA2U8NEhanZuASEsi8QVIYA43eENStC5Y?= =?us-ascii?Q?fNIt+F9AVT49CMjS+iu1I6Wi69o23lCccwTiXOn/aorm2KiD7VZ7bqvIUYhR?= =?us-ascii?Q?t/GlEGpc2Z/qLQkjyx1fmUTQHDELK6dtsbQTH6F+M5sVQSKaQ1laUxM11/gw?= =?us-ascii?Q?pPqic/8RizTyt+19pOEUrp9XV6uVxQrqi6T1ZGSqIS84zHXYMN70pJycP+zd?= =?us-ascii?Q?WGOneZVwmaJOq5Ify8qu2IhfdS2sMuRFx6gkrZc5HNhAtGsIKNt/019MbOAW?= =?us-ascii?Q?44Vq9kwXpwHMEO9MSRAaWHKvHPmKRqE7sMWoUK4hsjlT+DQSrEbhPUt5oVQX?= =?us-ascii?Q?038JThdbopljz1JeBdkO1/Xi3CqqWb97Pjub/gZE5f5K35Cr7U31qRNecxr0?= =?us-ascii?Q?YwFaIYu/JVJFJ4DiUWhzyWSdlf+b24gqqZ+brqDCujo/ZYcxOUl9m3yjiw6u?= =?us-ascii?Q?uuQMtapdInRFHNtd5G+cQkWX9qCsSjvPPs0v/8+Int9GZOXRNqVrjhVT0rJy?= =?us-ascii?Q?7sh8n/fjdN843uA6VQAxKs1INwiZ6SgAAUCk/6s1kLr74jJaW+7d0Wk/GBYZ?= =?us-ascii?Q?fm15zxvEyXui9GYaTQCP0oFIhqSF0hnB5jF+eHrakY0dtALsrNgFd/OWzY55?= =?us-ascii?Q?6qC/CZZELbgh1v8UN987SgRsfE64gjoA3dRLYkxhAsnkbeUKL0HeYpkFOeaV?= =?us-ascii?Q?jxtCgYcitqyYVi2D6LkJ1by7nYuHKvbV555CYvGFZIz77oS3NnnkZNIjxRPu?= =?us-ascii?Q?q4kwaQPQljqw4+I7LW0dIW6A4v6AzVNKD9Zl1vw3KmPxBOEuyzIMfHW6VP0L?= =?us-ascii?Q?/kAQl/0AiMfo6OCmVduz9wn77NQIrlzYXw8heYxacfVNAfnWal7FQJupWnyj?= =?us-ascii?Q?9WXBO2efL7tNKcY+Ww8fC0vhxFJhjaYz1IihUDdNpVflj4JHLq8ylZV+jsU6?= =?us-ascii?Q?41yMayM7mI+EkGtGmTCaUz/po6pJDevR4In1IJabkJBoS6Q8zSjoS8TUQ0Iu?= =?us-ascii?Q?slFNEfOOBR1ofGivYObb9vTXzI7qfsYoCJnBgPn4nmFS8AIqSIjt1zkWTh25?= =?us-ascii?Q?h+rYaaR6bImdaZ230CjAVh8CAC6AXNd5+Sr2WIU4iCV8c57UWNv/NXGfX5gz?= =?us-ascii?Q?Z1E391zONg=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: aca26890-ba46-43b1-7a1e-08de6429eab6 X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB9473.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Feb 2026 20:13:52.8597 (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: OP58+6kMMHwRWiwiCmuYG85ydKgdcf41arZ5PAKgOPlPtiz0lqq05wZ06qTAxxWc X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB7780 On 4 Feb 2026, at 14:55, David Hildenbrand (arm) wrote: > On 2/4/26 20:48, Zi Yan wrote: >> On 4 Feb 2026, at 14:18, David Hildenbrand (arm) wrote: >> >>> On 2/4/26 18:41, Zi Yan wrote: >>>> >>>> >>>> More details: >>>> later at sg_vma_fault(), the driver just handles a page fault by sup= plying >>>> a subpage from a pre-allocated compound page[3]. We then get a large= folio >>>> without !CONFIG_TRANSPARENT_HUGEPAGE. >>> >>> We can identify such non-folio (but compound) things by looking at PG= _large_rmappable IIRC. >> >> What do you mean? Changing memory failure code to only handle large_rm= appable? >> large_rmappable is a folio flag, memory failure code should see such > > Did you mean "should not" ? :) Yes. > >> non-folio but compound things to begin with, IMHO. > > I would say that we could right now reject in memory failure code any c= ompound pages that do not have PG_large_rmappable set. > > I have the faint recollection that we don't set PG_large_rmappable on h= ugetlb folios yet, so they have to identified as well. Right. My patchset[1] is trying to add it, since hugetlb is used as a fol= io in most places and large_rmappable is a folio flag. [1] https://lore.kernel.org/all/20260130034818.472804-1-ziy@nvidia.com/ >> >> I think we need to be able to tell between raw page (compound or not),= >> mappable page (compound or not, especially for those used with vm_inse= rt_*), >> and folio. > > We can't identify (small) folios just yet. We'd need another page flag = for that (just like PG_large_rmappable), and we all know how that ends ;)= Yes, I am thinking about removing mapcount in struct page to achieve that= =2E And only pages used for vm_insert_*() and folios need mapcount. Code uses vm_insert_*() on pages would probably have a struct mappable_page with mapcount. > > With Willy's work we'll be able to identify folios reliably. > > How to deal with that vm_insert_* crap, especially for non-folio pages,= is also future work based on that. I think it might the other way around. memdesc does not have mapcount, if we do not have a separate struct for these mappable pages now, what do we use at memdesc time? folio? Best Regards, Yan, Zi