On Tue, Feb 12, 2019 at 10:56:25AM +0800, Peter Xu wrote: > We've have multiple (and more coming) places that would like to find a > userfault enabled VMA from a mm struct that covers a specific memory > range. This patch introduce the helper for it, meanwhile apply it to > the code. > > Suggested-by: Mike Rapoport <[email protected]> > Signed-off-by: Peter Xu <[email protected]>
Reviewed-by: Jérôme Glisse <[email protected]> > --- > mm/userfaultfd.c | 54 +++++++++++++++++++++++++++--------------------- > 1 file changed, 30 insertions(+), 24 deletions(-) > > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c > index 80bcd642911d..fefa81c301b7 100644 > --- a/mm/userfaultfd.c > +++ b/mm/userfaultfd.c > @@ -20,6 +20,34 @@ > #include <asm/tlbflush.h> > #include "internal.h" > > +/* > + * Find a valid userfault enabled VMA region that covers the whole > + * address range, or NULL on failure. Must be called with mmap_sem > + * held. > + */ > +static struct vm_area_struct *vma_find_uffd(struct mm_struct *mm, > + unsigned long start, > + unsigned long len) > +{ > + struct vm_area_struct *vma = find_vma(mm, start); > + > + if (!vma) > + return NULL; > + > + /* > + * Check the vma is registered in uffd, this is required to > + * enforce the VM_MAYWRITE check done at uffd registration > + * time. > + */ > + if (!vma->vm_userfaultfd_ctx.ctx) > + return NULL; > + > + if (start < vma->vm_start || start + len > vma->vm_end) > + return NULL; > + > + return vma; > +} > + > static int mcopy_atomic_pte(struct mm_struct *dst_mm, > pmd_t *dst_pmd, > struct vm_area_struct *dst_vma, > @@ -228,20 +256,9 @@ static __always_inline ssize_t > __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, > */ > if (!dst_vma) { > err = -ENOENT; > - dst_vma = find_vma(dst_mm, dst_start); > + dst_vma = vma_find_uffd(dst_mm, dst_start, len); > if (!dst_vma || !is_vm_hugetlb_page(dst_vma)) > goto out_unlock; > - /* > - * Check the vma is registered in uffd, this is > - * required to enforce the VM_MAYWRITE check done at > - * uffd registration time. > - */ > - if (!dst_vma->vm_userfaultfd_ctx.ctx) > - goto out_unlock; > - > - if (dst_start < dst_vma->vm_start || > - dst_start + len > dst_vma->vm_end) > - goto out_unlock; > > err = -EINVAL; > if (vma_hpagesize != vma_kernel_pagesize(dst_vma)) > @@ -488,20 +505,9 @@ static __always_inline ssize_t __mcopy_atomic(struct > mm_struct *dst_mm, > * both valid and fully within a single existing vma. > */ > err = -ENOENT; > - dst_vma = find_vma(dst_mm, dst_start); > + dst_vma = vma_find_uffd(dst_mm, dst_start, len); > if (!dst_vma) > goto out_unlock; > - /* > - * Check the vma is registered in uffd, this is required to > - * enforce the VM_MAYWRITE check done at uffd registration > - * time. > - */ > - if (!dst_vma->vm_userfaultfd_ctx.ctx) > - goto out_unlock; > - > - if (dst_start < dst_vma->vm_start || > - dst_start + len > dst_vma->vm_end) > - goto out_unlock; > > err = -EINVAL; > /* > -- > 2.17.1 >
