linux-kernel - Re: [PATCH RFC 4/7] riscv/vdso: don't clear PG

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Message-ID: <mhng-3e6b4869-d5d7-42f4-a9d8-789a6772f52a@palmer-si-x1c4>
Date:   Fri, 07 Dec 2018 10:45:13 -0800 (PST)
From:   Palmer Dabbelt <palmer@...ive.com>
To:     david@...hat.com
CC:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-m68k@...ts.linux-m68k.org, linuxppc-dev@...ts.ozlabs.org,
        linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
        linux-mediatek@...ts.infradead.org, david@...hat.com,
        aou@...s.berkeley.edu, tklauser@...tanz.ch,
        akpm@...ux-foundation.org, mhocko@...nel.org, willy@...radead.org
Subject:     Re: [PATCH RFC 4/7] riscv/vdso: don't clear PG_reserved

On Wed, 05 Dec 2018 04:28:48 PST (-0800), david@...hat.com wrote:
> The VDSO is part of the kernel image and therefore the struct pages are
> marked as reserved during boot.
>
> As we install a special mapping, the actual struct pages will never be
> exposed to MM via the page tables. We can therefore leave the pages
> marked as reserved.
>
> Cc: Palmer Dabbelt <palmer@...ive.com>
> Cc: Albert Ou <aou@...s.berkeley.edu>
> Cc: Tobias Klauser <tklauser@...tanz.ch>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Michal Hocko <mhocko@...nel.org>
> Cc: Matthew Wilcox <willy@...radead.org>
> Signed-off-by: David Hildenbrand <david@...hat.com>
> ---
>  arch/riscv/kernel/vdso.c | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
> index 582cb153eb24..0cd044122234 100644
> --- a/arch/riscv/kernel/vdso.c
> +++ b/arch/riscv/kernel/vdso.c
> @@ -54,7 +54,6 @@ static int __init vdso_init(void)
>  		struct page *pg;
>
>  		pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
> -		ClearPageReserved(pg);
>  		vdso_pagelist[i] = pg;
>  	}
>  	vdso_pagelist[i] = virt_to_page(vdso_data);

I'm going to assume this will go in through another tree along with the rest of 
the set assuming everyone else is happy with it.

Acked-by: Palmer Dabbelt <palmer@...ive.com>

Thanks!