linux-kernel - Re: [PATCH 01/30] x86, mm: do not set _PAGE_USER for init

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Message-ID: <CA+55aFwuFT48RS=Bn9qvgjr+2r+jNroQHw1F+G_GxtU12nJmaw@mail.gmail.com>
Date:   Wed, 8 Nov 2017 11:52:12 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Dave Hansen <dave.hansen@...ux.intel.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        moritz.lipp@...k.tugraz.at,
        Daniel Gruss <daniel.gruss@...k.tugraz.at>,
        michael.schwarz@...k.tugraz.at, richard.fellner@...dent.tugraz.at,
        Andrew Lutomirski <luto@...nel.org>,
        Kees Cook <keescook@...gle.com>,
        Hugh Dickins <hughd@...gle.com>,
        "the arch/x86 maintainers" <x86@...nel.org>
Subject: Re: [PATCH 01/30] x86, mm: do not set _PAGE_USER for init_mm page tables

On Wed, Nov 8, 2017 at 11:46 AM, Dave Hansen
<dave.hansen@...ux.intel.com> wrote:
>
> +
>  static inline void pmd_populate_kernel(struct mm_struct *mm,
>                                        pmd_t *pmd, pte_t *pte)
>  {
> +       pteval_t pgtable_flags = mm_pgtable_flags(mm);

Why is "pmd_populate_kernel()" using mm_pgtable_flags(mm)?

It should just use _KERNPG_TABLE unconditionally, shouldn't it?
Nothing to do with init_mm, it's populating a _kernel_ page table
regardless, no?

            Linus