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

[Muhammad Usama Anjum <usama.anjum@collabora.com>]

On 6/21/23 6:42 PM, Michał Mirosław wrote:
> 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;
Sorry, unable to understand you. Should we do something here?

> 
> Best Regards
> Michał Mirosław

-- 
BR,
Muhammad Usama Anjum