Re: Memory providers multiplexing (Was: [PATCH net-next v4 4/5] page_pool: remove PP_FLAG_PAGE_FRAG flag)

[David Ahern]

On 7/3/23 11:13 AM, Eric Dumazet wrote:
> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
> index a2dbeb264f260e5b8923ece9aac99fe19ddfeb62..aa4133d1b1e0676e408499ea4534b51262394432
> 100644
> --- a/net/packet/af_packet.c
> +++ b/net/packet/af_packet.c
> @@ -2152,7 +2152,7 @@ static int packet_rcv(struct sk_buff *skb,
> struct net_device *dev,
>                 }
>         }
> 
> -       snaplen = skb->len;
> +       snaplen = skb->devmem ? skb_headlen(skb) : skb->len;
> 

Ok, so you expect a flag on the skb noting the use of 'untouchable'
memory. That aligns with my expectations based on POCs.

Based on the above: 1) skb->head is expected to be host memory, and 2)
the flag is a global for all frags, so no mix and match.