On Fri, Apr 9, 2021 at 12:30 AM Mel Gorman <mgor...@techsingularity.net> wrote: > > Under what circumstances do you expect sk_memalloc_socks() to be false > and skb_pfmemalloc() to be true that would cause a problem?
For example, if at the time the skb is allocated, "sk_memalloc_socks()" was true, then the skb might be allocated as a pfmemalloc skb. However, if after this skb is allocated and before this skb reaches "__netif_receive_skb", "sk_memalloc_socks()" has changed from "true" to "false", then "__netif_receive_skb" will see "sk_memalloc_socks()" being false and "skb_pfmemalloc(skb)" being true. This is a problem because this would cause a pfmemalloc skb to be delivered to "taps" and protocols that don't support pfmemalloc skbs.
