On Thu, 01 Mar 2018 19:49:07 -0800 Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> When device-dax is operating in huge-page mode we want it to behave like
> hugetlbfs and report the MMU page mapping size that is being enforced by
> the vma. Similar to commit 31383c6865a5 "mm, hugetlbfs: introduce
> ->split() to vm_operations_struct" it would be messy to teach
> vma_mmu_pagesize() about device-dax page mapping sizes in the same
> (hstate) way that hugetlbfs communicates this attribute. Instead, these
> patches introduce a new ->pagesize() vm operation.
>
> ...
>
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -383,6 +383,7 @@ struct vm_operations_struct {
> int (*huge_fault)(struct vm_fault *vmf, enum page_entry_size pe_size);
> void (*map_pages)(struct vm_fault *vmf,
> pgoff_t start_pgoff, pgoff_t end_pgoff);
> + unsigned long (*pagesize)(struct vm_area_struct * area);
fwiw, vm_operations_struct is documented in
Documentation/filesystems/Locking. Some bitrotting has occurred :(
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