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To: Kuniyuki Iwashima Cc: "David S. Miller" , Jakub Kicinski , Neal Cardwell , Paolo Abeni , Willem de Bruijn , Matthieu Baerts , Mat Martineau , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Andrew Morton , Simon Horman , Geliang Tang , Muchun Song , Kuniyuki Iwashima , netdev@vger.kernel.org, mptcp@lists.linux.dev, cgroups@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, Jul 21, 2025 at 1:36=E2=80=AFPM Kuniyuki Iwashima wrote: > > memcg->socket_isolated can change at any time, so we must > snapshot the value for each socket to ensure consistency. > > Given sk->sk_memcg can be accessed in the fast path, it would > be preferable to place the flag field in the same cache line > as sk->sk_memcg. > > However, struct sock does not have such a 1-byte hole. > > Let's store the flag in the lowest bit of sk->sk_memcg and > add a helper to check the bit. > > Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet