Re: [PATCH v7 12/15] sh: Drop cache flush of the zero page at boot

Geert Uytterhoeven <[email protected]> Mon, 1 Jun 2026 10:11:45 +0200
Newsgroups org.kernel.vger.linux-sh,org.infradead.lists.linux-arm-kernel,org.kernel.vger.linux-hardening,org.kernel.vger.linux-kernel,org.kvack.linux-mm,org.ozlabs.lists.linuxppc-dev
Message-ID <CAMuHMdXp0qp38vHJTDFMrY-AUDXPSJtc5Dds_qu58FSeS_242w@mail.gmail.com>
On Fri, 29 May 2026 at 17:02, Ard Biesheuvel <[email protected]> wrote:
> From: Ard Biesheuvel <[email protected]>
>
> SuperH performs cache maintenance on the zero page during boot,
> presumably because before commit
>
>   6215d9f4470f ("arch, mm: consolidate empty_zero_page")
>
> the zero page did double duty as a boot params region, and was cleared
> separately, as it was not part of BSS. The memset() in question was
> dropped by that commit, but the __flush_wback_region() call remained.
>
> As empty_zero_page[] has been moved to BSS, it can be treated as any
> other BSS memory, and so the cache flush can be dropped.
>
> Cc: Yoshinori Sato <[email protected]>
> Cc: Rich Felker <[email protected]>
> Cc: John Paul Adrian Glaubitz <[email protected]>
> Cc: Mike Rapoport <[email protected]>
> Cc: Geert Uytterhoeven <[email protected]>
> Signed-off-by: Ard Biesheuvel <[email protected]>

Reviewed-by: Geert Uytterhoeven <[email protected]>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds