linux-kernel - Re: [PATCH v4] tun: avoid high-order page allocation for packet header

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Message-ID: <64d4ee63a11e9_8e54c294a9@willemb.c.googlers.com.notmuch>
Date:   Thu, 10 Aug 2023 10:04:19 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Tahsin Erdogan <trdgn@...zon.com>,
        Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        Jason Wang <jasowang@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Herbert Xu <herbert@...dor.apana.org.au>
Cc:     Tahsin Erdogan <trdgn@...zon.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] tun: avoid high-order page allocation for packet
 header

Tahsin Erdogan wrote:
> 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 change
> makes write()/writev() and sendmsg() paths more consistent.
> 
> Signed-off-by: Tahsin Erdogan <trdgn@...zon.com>

Reviewed-by: Willem de Bruijn <willemb@...gle.com>