linux-kernel - Re: dma_zalloc_coherent broken with 57bf5a8963f80fb3828c46c3e3a5b2dd790e09a7

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Message-ID: <CAMuHMdX_aTqi=8FmBR07K6-C=ycCrPQ+dT=ujXzNTcekdXB5ag@mail.gmail.com>
Date:   Tue, 27 Mar 2018 10:21:24 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Sebastian Ott <sebott@...ux.vnet.ibm.com>
Cc:     Christoph Hellwig <hch@....de>,
        Jesper Nilsson <jesper.nilsson@...s.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: dma_zalloc_coherent broken with 57bf5a8963f80fb3828c46c3e3a5b2dd790e09a7

Hi Sebastian,

On Tue, Mar 27, 2018 at 10:12 AM, Sebastian Ott
<sebott@...ux.vnet.ibm.com> wrote:
> commit 57bf5a8963f80fb3828c46c3e3a5b2dd790e09a7 broke usage of dma
> allocations specifying __GFP_ZERO by silently removing that flag.

How did it break? The flag is now always added.

> Why should "the memory returned [] always be zeroed."?

To avoid leaking information.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

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