Should `memory.kmem.tcp.limit_in_bytes` still be supported?

Mostly a question here, as it's somewhat confusing (also see https://github.com/opencontainers/runtime-spec/pull/1093)

Commit https://github.com/opencontainers/runc/commit/2d38476c96e3407eba876e77b301880c6d7e5ccc (https://github.com/opencontainers/runc/pull/2840) removed support for kernel-memory limits.

The PR referred to https://github.com/torvalds/linux/commit/0158115f702b, which deprecated memory.kmem.limit_in_bytes in kernel 5.4, but the PR also removed support for memory.kmem.tcp.limit_in_bytes.

Looking at the Linux kernel, there's no mention (yet) of this option being deprecated as well (but it could be an oversight); https://github.com/torvalds/linux/blob/fdebeae0d75d03dc54eb68cb09bd6604a590b502/Documentation/admin-guide/cgroup-v1/memory.rst

I'm curious if memory.kmem.tcp.limit_in_bytes should also be considered deprecated in the kernel and, if not, if that option should be re-enabled.

Start with runc commit 2d38476c96e3407eba876e77b301880c6d7e5ccc and PR 2840, then compare their handling with the Linux cgroup-v1 memory documentation and kernel commit 0158115f702b. Determine whether memory.kmem.tcp.limit_in_bytes remains supported; done means a documented decision and, if appropriate, a focused change with tests.