linux-kernel - Re: [PATCH v2 07/34] mm: clarify __GFP

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CA+fCnZfQr191GvWf+T2=HB3bLK2-sE4DgHSJcXsahM5BN_nPPg@mail.gmail.com>
Date:   Tue, 7 Dec 2021 18:33:09 +0100
From:   Andrey Konovalov <andreyknvl@...il.com>
To:     Peter Collingbourne <pcc@...gle.com>
Cc:     Marco Elver <elver@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Evgenii Stepanov <eugenis@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        andrey.konovalov@...ux.dev
Subject: Re: [PATCH v2 07/34] mm: clarify __GFP_ZEROTAGS comment

On Mon, Dec 6, 2021 at 10:44 PM <andrey.konovalov@...ux.dev> wrote:
>
> From: Andrey Konovalov <andreyknvl@...gle.com>
>
> __GFP_ZEROTAGS is intended as an optimization: if memory is zeroed during
> allocation, it's possible to set memory tags at the same time with little
> performance impact.
>
> Clarify this intention of __GFP_ZEROTAGS in the comment.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
> ---
>  include/linux/gfp.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index b976c4177299..dddd7597689f 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -232,8 +232,8 @@ struct vm_area_struct;
>   *
>   * %__GFP_ZERO returns a zeroed page on success.
>   *
> - * %__GFP_ZEROTAGS returns a page with zeroed memory tags on success, if
> - * __GFP_ZERO is set.
> + * %__GFP_ZEROTAGS zeroes memory tags at allocation time if the memory itself
> + * is being zeroed (either via __GFP_ZERO or via init_on_alloc).
>   *
>   * %__GFP_SKIP_KASAN_POISON returns a page which does not need to be poisoned
>   * on deallocation. Typically used for userspace pages. Currently only has an
> --
> 2.25.1
>

Hi Peter,

Could you check whether I correctly understood the intention of
__GFP_ZEROTAGS and give your ack on this patch and the next one?

Thanks!