cpus_excl_conflict(9)

💅 cpus_excl_conflict — from the Kernel API Manual, bestie 🫶

okay so this one is a kernel function, cpus_excl_conflict, and it's literally the vibe check for cpusets ✨ — it tells you whether two of them are beefing over exclusive CPUs.

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✨ NAME ✨

cpus_excl_conflict — check if two cpusets have exclusive CPU conflicts 🔥

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🦋 SYNOPSIS 🦋

bool cpus_excl_conflict (struct cpuset *trial , struct cpuset *sibling ,
bool xcpus_changed );

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🎀 ARGUMENTS 🎀

• trial — the trial cpuset that's getting checked 👀 like, this is the one on the spot
• sibling — a sibling cpuset to be checked against, i.e. the other party in this whole situation
• xcpus_changed — set if exclusive_cpus has been set ✅

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⭐ RETURN ⭐

true if a CPU exclusivity conflict exists, false otherwise 💀 no in-between, no "it's complicated"

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🌸 DESCRIPTION 🌸

so here's the tea on conflict detection rules ☕

• cgroup v1: see cpuset1_cpus_excl_conflict 👑
• cgroup v2:
  • the exclusive_cpus values cannot overlap 🚫 — no cap, they just can't
  • new exclusive_cpus cannot be a superset of a sibling's cpus_allowed 🙈

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🌈 SEE ALSO 🌈

kernel file ./kernel/cgroup/cpuset.c — and honestly the whole friend group:

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), 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(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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okay that's the whole page, mwah 💋 this one lived in ./kernel/cgroup and it's dated October 2026 — go off, kernel docs, periodt 👑💖