Re: [PATCH RFC 0/3] pagemap: make useable for non-privilege users

[Mark Williamson <mwilliamson@undo-software.com>]

Hi Konstantin,

I modified our code to check for the map-exclusive flag where it used
to compare pageframe numbers.  First tests look pretty promising, so
this patch looks like a viable approach for us.

Is there anything further we can do to help?

Thanks,
Mark

On Tue, May 12, 2015 at 12:13 PM, Mark Williamson
<mwilliamson@undo-software.com> wrote:
> Hi Konstantin,
>
> Thanks very much for continuing to look at this!  It's very much
> appreciated.  I've been investigating from our end but got caught up
> in some gnarly details of our pagemap-consuming code.
>
> I like the approach and it seems like the information you're exposing
> will be useful for our application.  I'll test the patch and see if it
> works for us as-is.
>
> Will follow up with any comments on the individual patches.
>
> Thanks,
> Mark
>
> On Tue, May 12, 2015 at 10:43 AM, Konstantin Khlebnikov
> <khlebnikov@yandex-team.ru> wrote:
>> This patchset tries to make pagemap useable again in the safe way.
>> First patch adds bit 'map-exlusive' which is set if page is mapped only here.
>> Second patch restores access for non-privileged users but hides pfn if task
>> has no capability CAP_SYS_ADMIN. Third 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).
>>
>> ---
>>
>> Konstantin Khlebnikov (3):
>>       pagemap: add mmap-exclusive bit for marking pages mapped only here
>>       pagemap: hide physical addresses from non-privileged users
>>       pagemap: switch to the new format and do some cleanup
>>
>>
>>  Documentation/vm/pagemap.txt |    3 -
>>  fs/proc/task_mmu.c           |  178 +++++++++++++++++-------------------------
>>  tools/vm/page-types.c        |   35 ++++----
>>  3 files changed, 91 insertions(+), 125 deletions(-)

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