bpf_task_under_cgroup(9)

📦 version 7.3.1, in nixpkgs unstable

💅 bpf_task_under_cgroup(9) — kernel API manual, but make it make sense

okay so bestie, this is a page from the Kernel API Manual (that's the manual name, cute) — and it's all about one little kfunc that answers a very specific question for you. Let's go 🎀

✨ NAME ✨

bpf_task_under_cgroup — the kfunc that wraps task_under_cgroup_hierarchy() for you, so you can test whether a task belongs to a cgroup's ancestry 💖

That's the whole job. It's a vibe check for cgroup family trees, no cap.

🌸 SYNOPSIS 🌸

__bpf_kfunc long bpf_task_under_cgroup (struct task_struct *task ,
struct cgroup *ancestor );

look at her. two pointers, one long. she's iconic and she's not doing extra credit 🔥

🦋 ARGUMENTS 🦋

  • task — the task you're testing 👀 like, the one you're asking about
  • ancestor — a possible ancestor of that task's cgroup 🌳 the "is this your grandma" candidate

💀 DESCRIPTION 💀

so here's the tea ☕: it tests whether task's default cgroup hierarchy is a descendant of ancestor.

and before you ask — yes, it follows all the same rules as cgroup_is_descendant, exactly, no remix, no creative liberties. and important: it only applies to the default hierarchy. default only, bestie, don't come at it with anything else 🙈

👑 SEE ALSO 👑

this next part is literally the whole group chat, i'm not kidding. all of these are waiting for you in the kernel file ./kernel/bpf/helpers.c:

like i said. the entire group chat. say hi to all of them for me 🫶

sign-off time 🧚 this page lives in ./kernel/bpf, it's dated October 2026, and yeah — it's bpf_task_under_cgroup(9) all the way down. mwah 💋 periodt. ⭐

📦 where this page comes from