On Fri, Oct 26, 2012 at 11:46 AM, Rik van Riel <riel@xxxxxxxxxx> wrote:
>
> The function ptep_set_access_flags is only ever used to upgrade
> access permissions to a page.
NOTE: It's *not* "access permissions". It's "access flags".
Big difference. This is not about permissions at all.
The access flags are the Accessed and Dirty bits. And the dirty bit is
never *cleared* by this function, it's only ever potentially set.
That, together with the fact that the accessed flag is "best effort"
rather than exact, is what makes this function so special to begin
with.
Linus
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