linux-kernel - Re: [PATCH v4 5/6] mm: Add a NO_INHERIT flag to the PR_SET

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Date:   Tue, 3 Oct 2023 17:52:38 +0200
From:   Florent Revest <revest@...omium.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        catalin.marinas@....com, anshuman.khandual@....com,
        joey.gouly@....com, mhocko@...e.com, keescook@...omium.org,
        david@...hat.com, peterx@...hat.com, izbyshev@...ras.ru,
        broonie@...nel.org, szabolcs.nagy@....com, kpsingh@...nel.org,
        gthelen@...gle.com, toiwoton@...il.com, ayush.jain3@....com
Subject: Re: [PATCH v4 5/6] mm: Add a NO_INHERIT flag to the PR_SET_MDWE prctl

On Fri, Sep 22, 2023 at 3:33 AM Andrew Morton <akpm@...ux-foundation.org> wrote:
>
> On Mon, 28 Aug 2023 17:08:57 +0200 Florent Revest <revest@...omium.org> wrote:
>
> > This extends the current PR_SET_MDWE prctl arg with a bit to indicate
> > that the process doesn't want MDWE protection to propagate to children.
> >
> > To implement this no-inherit mode, the tag in current->mm->flags must be
> > absent from MMF_INIT_MASK. This means that the encoding for "MDWE but
> > without inherit" is different in the prctl than in the mm flags. This
> > leads to a bit of bit-mangling in the prctl implementation.
>
> Is a manpage update planned?

Ah that's a good point, I didn't think about it, thank you.

> And did we update the manpage for PR_SET_MDWE?

No we didn't but I sent a patch to man-pages here:
https://lore.kernel.org/linux-man/20231003155010.3651349-1-revest@chromium.org/