Re: [PATCH v20 2/5] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs

On Wed, 21 Jun 2023 at 09:24, Muhammad Usama Anjum usama.anjum@collabora.com wrote: [...]

+static int pagemap_scan_test_walk(unsigned long start, unsigned long end,

•                             struct mm_walk *walk)
  

+{

•   struct pagemap_scan_private *p = walk->private;
  

•   struct vm_area_struct *vma = walk->vma;
  

•   if ((p->flags & PM_SCAN_REQUIRE_UFFD) && (!userfaultfd_wp_async(vma) ||
  

•       !userfaultfd_wp_use_markers(vma)))
  

•           return -EPERM;
  

•   if (vma->vm_flags & VM_PFNMAP)
  

•           return 1;
  

•   return 0;
  

+}

This could actually short-circuit all vma flags (e.g. IS_FILE): if (required_mask & IS_FILE && vma is not file-backed) return 0;

Best Regards Michał Mirosław