[PATCH v2 1/2] mm, hugetlbfs: introduce ->pagesize() to vm_operations_struct

From: Dan Williams <dan.j.williams(a)intel.com&gt; 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. Cc: Benjamin Herrenschmidt <benh(a)kernel.crashing.org&gt; Cc: Paul Mackerras <paulus(a)samba.org&gt; Cc: Michael Ellerman <mpe(a)ellerman.id.au&gt; Reported-by: Jane Chu <jane.chu(a)oracle.com&gt; Signed-off-by: Dan Williams <dan.j.williams(a)intel.com&gt; Signed-off-by: Dave Jiang <dave.jiang(a)intel.com&gt; --- arch/powerpc/mm/hugetlbpage.c | 5 +---- include/linux/mm.h | 1 + mm/hugetlb.c | 23 ++++++++++++----------- 3 files changed, 14 insertions(+), 15 deletions(-) diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c index a9b9083c5e49..c6a2e577e842 100644 --- a/arch/powerpc/mm/hugetlbpage.c +++ b/arch/powerpc/mm/hugetlbpage.c @@ -568,10 +568,7 @@ unsigned long vma_mmu_pagesize(struct vm_area_struct *vma) if (!radix_enabled()) return 1UL << mmu_psize_to_shift(psize); #endif - if (!is_vm_hugetlb_page(vma)) - return PAGE_SIZE; - - return huge_page_size(hstate_vma(vma)); + return vma_kernel_pagesize(vma); } static inline bool is_power_of_4(unsigned long x) diff --git a/include/linux/mm.h b/include/linux/mm.h index ea818ff739cd..37b9aef91ec7 100644 --- 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); /* notification that a previously read-only page is about to become * writable, if an error is returned it will cause a SIGBUS */ diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 9a334f5fb730..8fa069b5cb4d 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -637,14 +637,9 @@ EXPORT_SYMBOL_GPL(linear_hugepage_index); */ unsigned long vma_kernel_pagesize(struct vm_area_struct *vma) { - struct hstate *hstate; - - if (!is_vm_hugetlb_page(vma)) - return PAGE_SIZE; - - hstate = hstate_vma(vma); - - return 1UL << huge_page_shift(hstate); + if (vma->vm_ops && vma->vm_ops->pagesize) + return vma->vm_ops->pagesize(vma); + return PAGE_SIZE; } EXPORT_SYMBOL_GPL(vma_kernel_pagesize); @@ -654,12 +649,10 @@ EXPORT_SYMBOL_GPL(vma_kernel_pagesize); * architectures where it differs, an architecture-specific version of this * function is required. */ -#ifndef vma_mmu_pagesize -unsigned long vma_mmu_pagesize(struct vm_area_struct *vma) +__weak unsigned long vma_mmu_pagesize(struct vm_area_struct *vma) { return vma_kernel_pagesize(vma); } -#endif /* * Flags for MAP_PRIVATE reservations. These are stored in the bottom @@ -3132,6 +3125,13 @@ static int hugetlb_vm_op_split(struct vm_area_struct *vma, unsigned long addr) return 0; } +static unsigned long hugetlb_vm_op_pagesize(struct vm_area_struct *vma) +{ + struct hstate *hstate = hstate_vma(vma); + + return 1UL << huge_page_shift(hstate); +} + /* * We cannot handle pagefaults against hugetlb pages at all. They cause * handle_mm_fault() to try to instantiate regular-sized pages in the @@ -3149,6 +3149,7 @@ const struct vm_operations_struct hugetlb_vm_ops = { .open = hugetlb_vm_op_open, .close = hugetlb_vm_op_close, .split = hugetlb_vm_op_split, + .pagesize = hugetlb_vm_op_pagesize, }; static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,