Re: [PATCH net] skbuff: back tiny skbs with kmalloc() in __netdev_alloc_skb() too

[Eric Dumazet]

On Fri, Jan 15, 2021 at 12:55 AM Alexander Lobakin <alobakin@xxxxx> wrote:
>
> Commit 3226b158e67c ("net: avoid 32 x truesize under-estimation for
> tiny skbs") ensured that skbs with data size lower than 1025 bytes
> will be kmalloc'ed to avoid excessive page cache fragmentation and
> memory consumption.
> However, the same issue can still be achieved manually via
> __netdev_alloc_skb(), where the check for size hasn't been changed.
> Mirror the condition from __napi_alloc_skb() to prevent from that.
>
> Fixes: 3226b158e67c ("net: avoid 32 x truesize under-estimation for tiny skbs")

No, this tag is wrong, if you fix a bug, bug is much older than linux-5.11

My fix was about GRO head and virtio_net heads, both using pre-sized
small buffers.

You want to fix something else, and this is fine, because some drivers
are unfortunately
doing copy break ( at the cost of additional copy, even for packets
that might be consumed right away)