Re: [PATCH 6/6] x86: Fix stray A/D bit setting into non-present PTEs

[Eric W. Biederman]

Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> writes:

> On Thu, Jun 30, 2016 at 9:39 PM, Dave Hansen <dave@xxxxxxxx> wrote:
>>
>> I think what you suggest will work if we don't consider A/D in
>> pte_none().  I think there are a bunch of code path where assume that
>> !pte_present() && !pte_none() means swap.
>
> Yeah, we would need to change pte_none() to mask off D/A, but I think
> that might be the only real change needed (other than making sure that
> we don't use the bits in the swap entries, I didn't look at that part
> at all)

It looks like __pte_to_swp_entry also needs to be changed to mask out
those bits when the swap code reads pte entries.  For all of the same
reasons as pte_none.

Eric