From 31383c6865a578834dd953d9dbc88e6b19fe3997 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Wed, 29 Nov 2017 16:10:28 -0800 Subject: mm, hugetlbfs: introduce ->split() to vm_operations_struct Patch series "device-dax: fix unaligned munmap handling" When device-dax is operating in huge-page mode we want it to behave like hugetlbfs and fail attempts to split vmas into unaligned ranges. It would be messy to teach the munmap path about device-dax alignment constraints in the same (hstate) way that hugetlbfs communicates this constraint. Instead, these patches introduce a new ->split() vm operation. This patch (of 2): The device-dax interface has similar constraints as hugetlbfs in that it requires the munmap path to unmap in huge page aligned units. Rather than add more custom vma handling code in __split_vma() introduce a new vm operation to perform this vma specific check. Link: http://lkml.kernel.org/r/151130418135.4029.6783191281930729710.stgit@dwillia2-desk3.amr.corp.intel.com Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap") Signed-off-by: Dan Williams Cc: Jeff Moyer Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mmap.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'mm/mmap.c') diff --git a/mm/mmap.c b/mm/mmap.c index 924839fac0e6..a4d546821214 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2555,9 +2555,11 @@ int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma, struct vm_area_struct *new; int err; - if (is_vm_hugetlb_page(vma) && (addr & - ~(huge_page_mask(hstate_vma(vma))))) - return -EINVAL; + if (vma->vm_ops && vma->vm_ops->split) { + err = vma->vm_ops->split(vma, addr); + if (err) + return err; + } new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); if (!new) -- cgit v1.2.1