Re: [PATCH v3 net-next 12/12] net-memcg: Decouple controlled memcg from global protocol memory accounting.

On Tue, Aug 12, 2025 at 05:58:30PM +0000, Kuniyuki Iwashima wrote:

If all workloads were guaranteed to be controlled under memcg, the issue
could be worked around by setting tcp_mem[0~2] to UINT_MAX.

In reality, this assumption does not always hold, and processes that
belong to the root cgroup or opt out of memcg can consume memory up to
the global limit, becoming a noisy neighbour.

As per the last thread, this is not a supported usecase. Opting out of
memcg coverage for individual cgroups is a self-inflicted problem and
misconfiguration. There is *no* memory isolation *at all* on such
containers. Maybe their socket buffers is the only thing that happens
to matter to *you*, but this is in no way a generic, universal,
upstreamable solution. Knob or auto-detection is not the issue.

Nacked-by: Johannes Weiner [off-list ref]