Re: [PATCHSET v4 0/5] pagemap: make useable for non-privilege users

Andrew Morton
2015-07-14T18:52:55Z

On Tue, 14 Jul 2015 18:37:34 +0300 Konstantin Khlebnikov <khlebnikov@yandex-team.ru> wrote:

> This patchset makes pagemap useable again in the safe way (after row hammer
> bug it was made CAP_SYS_ADMIN-only). This patchset restores access for
> non-privileged users but hides PFNs from them.

Documentation/vm/pagemap.txt hasn't been updated to describe these
privilege issues?

> Also it adds bit 'map-exlusive' which is set if page is mapped only here:
> it helps in estimation of working set without exposing pfns and allows to
> distinguish CoWed and non-CoWed private anonymous pages.
>
> Second patch removes page-shift bits and completes migration to the new
> pagemap format: flags soft-dirty and mmap-exlusive are available only
> in the new format.

I'm not really seeing a description of the new format in these
changelogs. Precisely what got removed, what got added and which
capabilities change the output in what manner?