cgroup_apply_control(9)

📦 version 7.3.1, in nixpkgs unstable

💖 cgroup_apply_control(9) — the Kernel API Manual glow-up ✨

okay so bestie, buckle up, because this one is literally from the Kernel API Manual and it's about pushing your control mask updates down through a whole subtree. no cap, it's a whole vibe. 🦋

🌸 NAME 🌸

cgroup_apply_control — apply control mask updates to the subtree. that's it. that's the whole job. slay. 💅

⭐ SYNOPSIS ⭐

int cgroup_apply_control (struct cgroup *cgrp );

like, one function, one pointer, and a whole lot of subtree drama. main character energy fr fr. 👑

🎀 ARGUMENTS 🎀

  • cgrp — the root of the target subtree. this is where all the propagating starts, so like, choose wisely bestie 🫶

✨ DESCRIPTION ✨

so here's the tea: subsystems can be enabled and disabled in a subtree using the following steps. it's a whole little choreography and you gotta do them in order or it's giving chaos 😭

  1. Call cgroup_save_control to stash the current state. (yes, like saving your game before you do something unhinged. iconic.)
  2. Update ->subtree_control masks in the subtree as desired.
  3. Call cgroup_apply_control to apply the changes. 👈 this is the one, this is our girl
  4. Optionally perform other related operations.
  5. Call cgroup_finalize_control to finish up.

This function implements step 3 and propagates the mask changes throughout cgrp's subtree, updates csses accordingly and perform process migrations. so it's not just a pretty face — it actually does the work, walks the whole subtree, fixes up the csses, and does the process migrations too. ate and left no crumbs 🔥

ngl, the whole point is that you don't skip straight to step 3. the save/finalize bracket is there for a reason, bestie 💀

🌈 SEE ALSO 🌈

Kernel file ./kernel/cgroup/cgroup.c — and then the whole extended friend group, iykyk:

and that's the whole page bestie 💜 coming at you from ./kernel/cgroup, dated October 2026. go forth and propagate those masks responsibly 🧚‍♀️🌸

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