netdev - Re: [PATCH v3 net-next 01/12] mptcp: Fix up subflow's memcg when CONFIG_SOCK_CGROUP

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ukfrq6ybrbb2yds5duyj2ms6i7xgssjsywzgknxctfgkpzupor@tjxbuiil5ptt>
Date: Thu, 14 Aug 2025 14:30:05 +0200
From: Michal Koutný <mkoutny@...e.com>
To: Kuniyuki Iwashima <kuniyu@...gle.com>
Cc: "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
	Neal Cardwell <ncardwell@...gle.com>, Paolo Abeni <pabeni@...hat.com>, 
	Willem de Bruijn <willemb@...gle.com>, Matthieu Baerts <matttbe@...nel.org>, 
	Mat Martineau <martineau@...nel.org>, Johannes Weiner <hannes@...xchg.org>, 
	Michal Hocko <mhocko@...nel.org>, Roman Gushchin <roman.gushchin@...ux.dev>, 
	Shakeel Butt <shakeel.butt@...ux.dev>, Andrew Morton <akpm@...ux-foundation.org>, 
	Tejun Heo <tj@...nel.org>, Simon Horman <horms@...nel.org>, 
	Geliang Tang <geliang@...nel.org>, Muchun Song <muchun.song@...ux.dev>, 
	Mina Almasry <almasrymina@...gle.com>, Kuniyuki Iwashima <kuni1840@...il.com>, netdev@...r.kernel.org, 
	mptcp@...ts.linux.dev, cgroups@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v3 net-next 01/12] mptcp: Fix up subflow's memcg when
 CONFIG_SOCK_CGROUP_DATA=n.

Hello.

On Tue, Aug 12, 2025 at 05:58:19PM +0000, Kuniyuki Iwashima <kuniyu@...gle.com> wrote:
> When sk_alloc() allocates a socket, mem_cgroup_sk_alloc() sets
> sk->sk_memcg based on the current task.
> 
> MPTCP subflow socket creation is triggered from userspace or
> an in-kernel worker.

I somewhat remembered
d752a4986532c ("net: memcg: late association of sock to memcg")

but IIUC this MPTCP codepath, the socket would never be visible to
userspace nor manipulated from a proper process context, so there is no
option to defer the association in similar fashion, correct?

Then, I wonder whether this isn't a scenario for
	o = set_active_memcg(sk->sk_memcg);
	newsk =  sk_alloc();
	...
	set_active_memcg(o);

i.e. utilize the existing remote charging infra instead of introducing
specific mem_cgroup_sk_inherit() helper.

Regards,
Michal

Download attachment "signature.asc" of type "application/pgp-signature" (229 bytes)