Re: [PATCH v10 3/6] fs/proc/task_mmu: Implement IOCTL to get and/or the clear info about PTEs

["Michał Mirosław" <emmir@google.com>]

On Thu, 2 Feb 2023 at 12:30, Muhammad Usama Anjum
<usama.anjum@collabora.com> wrote:
[...]
> - The masks are specified in required_mask, anyof_mask, excluded_ mask
>   and return_mask.
[...]

May I suggest a slightly modified interface for the flags?

As I understand, the return_mask is what is applied to page flags to
aggregate the list.
This is a separate thing, and I think it doesn't need changes except
maybe an improvement
in the documentation and visual distinction.

For the page-selection mechanism, currently required_mask and
excluded_mask have conflicting
responsibilities. I suggest to rework that to:
1. negated_flags: page flags which are to be negated before applying
the page selection using following masks;
2. required_flags: flags which all have to be set in the
(negation-applied) page flags;
3. anyof_flags: flags of which at least one has to be set in the
(negation-applied) page flags;

IOW, the resulting algorithm would be:

tested_flags = page_flags ^ negated_flags;
if (~tested_flags & required_flags)
  skip page;
if (!(tested_flags & anyof_flags))
  skip_page;

aggregate_on(page_flags & return_flags);

Best Regards
Michał Mirosław