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Date: Thu, 24 Jul 2025 18:49:02 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Kuniyuki Iwashima <kuniyu@google.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>, Eric Dumazet
 <edumazet@google.com>, Michal =?UTF-8?B?S291dG7DvQ==?= <mkoutny@suse.com>,
 Tejun Heo <tj@kernel.org>, "David S. Miller" <davem@davemloft.net>, Neal
 Cardwell <ncardwell@google.com>, Paolo Abeni <pabeni@redhat.com>, Willem de
 Bruijn <willemb@google.com>, Matthieu Baerts <matttbe@kernel.org>, Mat
 Martineau <martineau@kernel.org>, Johannes Weiner <hannes@cmpxchg.org>,
 Michal Hocko <mhocko@kernel.org>, Roman Gushchin
 <roman.gushchin@linux.dev>, Andrew Morton <akpm@linux-foundation.org>,
 Simon Horman <horms@kernel.org>, Geliang Tang <geliang@kernel.org>, Muchun
 Song <muchun.song@linux.dev>, Kuniyuki Iwashima <kuni1840@gmail.com>,
 netdev@vger.kernel.org, mptcp@lists.linux.dev, cgroups@vger.kernel.org,
 linux-mm@kvack.org
Subject: Re: [PATCH v1 net-next 13/13] net-memcg: Allow decoupling memcg
 from global protocol memory accounting.
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On Wed, 23 Jul 2025 11:06:14 -0700 Kuniyuki Iwashima wrote:
> > 3. Will there ever be a reasonable use-case where there is non-isolated
> >    sub-tree under an isolated ancestor?  
> 
> I think no, but again, we need to think about the scenario above,
> otherwise, your ideal semantics is just broken.
> 
> Also, "no reasonable scenario" does not always mean "we must
> prevent the scenario".
> 
> If there's nothing harmful, we can just let it be, especially if such
> restriction gives nothing andrather hurts performance with no
> good reason.

Stating the obvious perhaps but it's probably too late in the release
cycle to get enough agreement here to merge the series. So I'll mark
it as Deferred.

While I'm typing, TBH I'm not sure I'm following the arguments about
making the property hierarchical. Since the memory limit gets inherited
I don't understand why the property of being isolated would not.
Either I don't understand the memcg enough, or I don't understand your
intended semantics. Anyway..