Re: Problem in pfmemalloc skb handling in net/core/dev.c

[Xie He]

On Fri, Apr 9, 2021 at 12:12 PM Xie He <xie.he.0141@xxxxxxxxx> wrote:
>
> This is exactly what I'm talking about. "skb_pfmemalloc_protocol"
> cannot guarantee pfmemalloc skbs are not delivered to unrelated
> protocols, because "__netif_receive_skb" will sometimes treat
> pfmemalloc skbs as normal skbs.

> I'm not sure if you understand what I'm saying. Please look at the
> code of "__netif_receive_skb" and see what will happen when
> "sk_memalloc_socks()" is false and "skb_pfmemalloc(skb)" is true.

Do you see the problem now? Just think what happens when
"skb_pfmemalloc(skb)" is true and "sk_memalloc_socks()" has just
changed to "false", and whether in this case "skb_pfmemalloc_protocol"
still takes any effect.