cpuset_cpus_allowed(9)

💖 cpuset_cpus_allowed(9) 💖

okay bestie, welcome to the Kernel API Manual — yes it's a real manual, yes the name is giving "boring", no we are NOT skipping it. this is the page for cpuset_cpus_allowed, and honestly? it's a little icon.

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✨ NAME ✨

cpuset_cpus_allowed — returns the cpus_allowed mask from a task's cpuset. that's it, that's the whole vibe 🎀

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🌸 SYNOPSIS 🌸

void cpuset_cpus_allowed (struct task_struct *tsk , struct cpumask
*pmask );

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🦋 ARGUMENTS 🦋

• tsk — pointer to a task_struct, and this is the task we're pulling cpuset->cpus_allowed from. she's the main character of this operation 💅
• pmask — pointer to a struct cpumask variable, and this lil one is the receiver 🫶 it's where the cpus_allowed set gets dropped off. think of it as the inbox.

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👑 DESCRIPTION 👑

so what actually happens? it returns the cpumask_var_t cpus_allowed of the cpuset that's attached to the tsk you handed over. simple, clean, no cap.

but here's the part you need to remember for the quiz 📝 — it is guaranteed to return some non-empty subset of cpu_active_mask. literally guaranteed. even if that means going outside the task's cpuset. yeah, she'll color outside the lines if she has to 😭

the one exception, the ONE time she won't do that: when the task is in the top cpuset. that's the sole carve-out, so don't come for her.

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🔥 SEE ALSO 🔥

all the siblings and cousins over in the kernel file ./kernel/cgroup/cpuset.c — go say hi, they're all family 💜

• cpuset_lock(9)
• cpuset_full_lock(9)
• partition_is_populated(9)
• alloc_cpumasks(9)
• alloc_tmpmasks(9)
• free_tmpmasks(9)
• dup_or_alloc_cpuset(9)
• free_cpuset(9)
• cpus_excl_conflict(9)
• cpuset_update_tasks_cpumask(9)
• compute_effective_cpumask(9)
• compute_effective_nodemask(9)
• rm_siblings_excl_cpus(9)
• update_parent_effective_cpumask(9)
• compute_partition_effective_cpumask(9)
• update_sibling_cpumasks(9)
• validate_partition(9)
• partition_cpus_change(9)
• update_cpumask(9)
• update_exclusive_cpumask(9)
• cpuset_update_tasks_nodemask(9)
• update_prstate(9)
• cpuset_css_alloc(9)
• cpuset_init(9)
• cpuset_hotplug_update_tasks(9)
• cpuset_handle_hotplug(9)
• cpuset_init_smp(9)
• cpuset_cpus_allowed_locked(9)
• cpuset_cpus_allowed_fallback(9)
• cpuset_mems_allowed(9)
• cpuset_nodemask_valid_mems_allowed(9)
• cpuset_nodes_allowed(9)
• cpuset_spread_node(9)
• cpuset_mem_spread_node(9)
• cpuset_mems_allowed_intersects(9)
• cpuset_print_current_mems_allowed(9)

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and that's the page, bestie 🌈 this lil drop of the Kernel API Manual came straight out of ./kernel/cgroup, dated October 2026 — screenshot it, cite it, live by it ⭐💖