cgroup_kn_unlock(9)

💅 cgroup_kn_unlock(9) — a Kernel API Manual moment

okay bestie, welcome to the Kernel API Manual page for cgroup_kn_unlock — yes this is the real deal, it's a section 9 kernel thing, and it's lowkey one of the shortest pages you'll ever read, so hydrate and let's go 🫶

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✨ NAME ✨

cgroup_kn_unlock — the unlocking helper for cgroup kernfs methods. that's it, that's the whole job description 💅

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🎀 SYNOPSIS 🎀

void cgroup_kn_unlock (struct kernfs_node *kn );

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🦋 ARGUMENTS 🦋

• kn — the kernfs_node being serviced. like, the node in question, the main character of this function call 👑

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🌸 DESCRIPTION 🌸

so this helper does the exact opposite of cgroup_kn_lock_live — it undoes what that one did. the way to use it is: if your locking succeeded, call this before the method finishes. that's the whole vibe check ✨

⚠️ real talk, and this part matters: once this function returns, the cgroup you got back from cgroup_kn_lock_live may become inaccessible at any time. any time. no warning, no text, just gone 😭 so if you plan on continuing to touch that cgroup afterward, you gotta pin it before you invoke this function. pin first, unlock after. that's the order. periodt 💅

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💜 SEE ALSO 💜

the kernel file lives at ./kernel/cgroup/cgroup.c and here's the full friend group, all in (9)-land, all accounted for, no cap:

• cgroup_ssid_enabled(9), cgroup_on_dfl(9), cgroup_e_css_by_mask(9), cgroup_e_css(9), cgroup_get_e_css(9), __cgroup_task_count(9), cgroup_task_count(9), for_each_css(9), do_each_subsys_mask(9), css_set_populated(9)
• css_update_populated(9), css_set_update_populated(9), css_set_move_task(9), compare_css_sets(9), find_existing_css_set(9), allocate_cgrp_cset_links(9), link_css_set(9), find_css_set(9), cgroup_file_mode(9), cgroup_calc_subtree_ss_mask(9)
• cgroup_kn_lock_live(9), css_clear_dir(9), css_populate_dir(9), cgroup_attach_lock(9), cgroup_attach_unlock(9), cgroup_migrate_add_task(9), cgroup_taskset_first(9), cgroup_taskset_next(9), cgroup_migrate_execute(9), cgroup_migrate_vet_dst(9)
• cgroup_migrate_finish(9), cgroup_migrate_add_src(9), cgroup_migrate_prepare_dst(9), cgroup_migrate(9), cgroup_attach_task(9), cgroup_update_dfl_csses(9), cgroup_lock_and_drain_offline(9), cgroup_save_control(9), cgroup_propagate_control(9), cgroup_restore_control(9)
• cgroup_apply_control_enable(9), cgroup_apply_control_disable(9), cgroup_apply_control(9), cgroup_finalize_control(9), cgroup_enable_threaded(9), cgroup_tryget_css(9), cgroup_addrm_files(9), cgroup_rm_cftypes(9), cgroup_add_cftypes(9), cgroup_add_dfl_cftypes(9)
• cgroup_add_legacy_cftypes(9), cgroup_file_notify(9), cgroup_file_show(9), css_next_child(9), css_next_descendant_pre(9), css_rightmost_descendant(9), css_next_descendant_post(9), css_has_online_children(9), css_task_iter_advance_css_set(9), css_task_iter_start(9)
• css_task_iter_next(9), css_task_iter_end(9), css_create(9), kill_css_sync(9), kill_css_finish(9), cgroup_destroy_locked(9), cgroup_init_early(9), cgroup_init(9), cgroup_fork(9), cgroup_v1v2_get_from_file(9)
• cgroup_get_from_file(9), cgroup_css_set_fork(9), cgroup_css_set_put_fork(9), cgroup_can_fork(9), cgroup_cancel_fork(9), cgroup_post_fork(9), cgroup_task_exit(9), css_tryget_online_from_dir(9), css_from_id(9), cgroup_get_from_path(9)
• cgroup_v1v2_get_from_fd(9), cgroup_get_from_fd(9), cgroup_parse_float(9)

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🌈 sign-off 🌈

and that's the page!! this little guy comes from the source tree at ./kernel/cgroup, dated October 2026, and it's filed under cgroup_kn_unlock(9) in the Kernel API Manual 💖 go forth, pin your cgroups, unlock responsibly, iykyk 🧚‍♀️✨