task_under_cgroup_hierarchy(9)

okay bestie, welcome to the task_under_cgroup_hierarchy(9) page from the Kernel API Manual ✨ it’s literally the cgroup-ancestry membership check and it’s giving kernel-internals realness 💅

💖 NAME 💖

• task_under_cgroup_hierarchy — test task's membership of cgroup ancestry. periodt. 🫶

✨ SYNOPSIS ✨

okay so the signature is exactly this, no edits, no cap:

bool task_under_cgroup_hierarchy (struct task_struct *task , struct
       cgroup *ancestor );

🎀 ARGUMENTS 🎀

• task — the task to be tested, bestie 🧚
• ancestor — possible ancestor of task's cgroup 👑

🌸 DESCRIPTION 🌸

So here’s the tea: this function tests whether task's default cgroup hierarchy is a descendant of ancestor. It follows all the same rules as cgroup_is_descendant, and it only applies to the default hierarchy. No cap, that’s the whole vibe. 💖

🦋 SEE ALSO 🦋

Kernel file: ./include/linux/cgroup.h 📁

• cgroup_subsys_enabled(9)
• cgroup_subsys_on_dfl(9)
• css_for_each_child(9)
• css_for_each_descendant_pre(9)
• css_for_each_descendant_post(9)
• cgroup_taskset_for_each(9)
• cgroup_taskset_for_each_leader(9)
• cgroup_css(9)
• css_is_dying(9)
• task_css_set_check(9)
• task_css_check(9)
• task_css_set(9)
• task_css(9)
• task_get_css(9)
• task_css_is_root(9)
• cgroup_is_descendant(9)
• cgroup_ancestor(9)
• cgroup_common_ancestor(9)

xoxo from ./include/linux, October 2026 — task_under_cgroup_hierarchy(9) out 💅🎀