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

[Michał Mirosław]

On Wed, 21 Jun 2023 at 16:16, Muhammad Usama Anjum
<usama.anjum@xxxxxxxxxxxxx> wrote:
> On 6/21/23 6:42 PM, Michał Mirosław wrote:
> > On Wed, 21 Jun 2023 at 09:24, Muhammad Usama Anjum
> > <usama.anjum@xxxxxxxxxxxxx> 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;
> Sorry, unable to understand you. Should we do something here?

It seems I had an earlier version of the patch in my mind, where
PAGE_IS_FILE was based on vma type. Sorry for the noise.

Best Regards
Michał Mirosław

>
> >
> > Best Regards
> > Michał Mirosław
>
> --
> BR,
> Muhammad Usama Anjum