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References: <20230809164753.2247594-1-trdgn@amazon.com>
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From:   Eric Dumazet <edumazet@google.com>
Date:   Thu, 10 Aug 2023 08:53:23 +0200
Message-ID: <CANn89iKvh=da2uRkGn5dTX5Yxvz-uZdSJoKf0+pPU16XVDt=fg@mail.gmail.com>
Subject: Re: [PATCH v4] tun: avoid high-order page allocation for packet header
To:     Tahsin Erdogan <trdgn@amazon.com>
Cc:     Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
        Jason Wang <jasowang@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
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On Wed, Aug 9, 2023 at 6:48=E2=80=AFPM Tahsin Erdogan <trdgn@amazon.com> wr=
ote:
>
> When gso.hdr_len is zero and a packet is transmitted via write() or
> writev(), all payload is treated as header which requires a contiguous
> memory allocation. This allocation request is harder to satisfy, and may
> even fail if there is enough fragmentation.
>
> Note that sendmsg() code path limits the linear copy length, so this chan=
ge
> makes write()/writev() and sendmsg() paths more consistent.
>
> Signed-off-by: Tahsin Erdogan <trdgn@amazon.com>

Reviewed-by: Eric Dumazet <edumazet@google.com>

Thanks.