On 13 Mar 2025, at 21:18, Herbert Xu wrote: > On Thu, Mar 13, 2025 at 12:25:50PM +0000, Matthew Wilcox wrote: >> >> That isn't true. HugeTLB can construct a folio which crosses a >> contiguity boundary. > > Thanks. So thea means we do need to use nth_page when iterating > through a folio or a scatterlist generated from a folio. When you know the folio is hugetlb with gigantic order. Folios come out of buddy allocator are all within contiguity boundaries. To be precise, the boundary here means a section boundary. In addition, nth_page() is a trivial addition for SPARSEMEM_VMEMMAP or FLATMEM. For SPARSEMEM && !SPARSEMEM_VMEMMAP, it needs to use pfn for the calculation. Best Regards, Yan, Zi
