Re: [PATCH] mm/mincore: allow for making sys_mincore() privileged

From: Linus Torvalds
Date: Fri Jan 11 2019 - 02:08:43 EST


On Thu, Jan 10, 2019 at 8:04 PM Dave Chinner <david@xxxxxxxxxxxxx> wrote:
>
> So it will only read the single page we tried to access and won't
> perturb the rest of the message encoded into subsequent pages in
> file.

Dave, you're being intentionally obtuse, aren't you?

It's only that single page that *matters*. That's the page that the
probe reveals the status of - but it's also the page that the probe
then *changes* the status of.

See?

Think of it as "the act of measurement changes that which is
measured". And that makes the measurement pointless.

Linus