clear_tasks_mm_cpumask(9)

💅 clear_tasks_mm_cpumask 💅

okay so bestie, welcome to the clear_tasks_mm_cpumask(9) page from the Kernel API Manual — pull up a chair, we're getting into it 🫶

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✨ NAME ✨

clear_tasks_mm_cpumask — safely clear tasks' mm_cpumask for a CPU</p> 💖

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✨ SYNOPSIS ✨

void clear_tasks_mm_cpumask (int cpu );

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✨ ARGUMENTS ✨

• cpu — a CPU id. that's it. that's the whole argument. iconic minimalism 🌸

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✨ DESCRIPTION ✨

okay so here's the vibe: this function walks all processes, finds a valid mm struct for each one, and then clears a corresponding bit in mm's cpumask. like, every task, one by one, mm found, bit cleared. slay 🎀

and the way that this all sounds trivial?? it's not. there are various non-obvious corner cases hiding in there, and this function is literally doing its best to solve them all in a safe manner. it ate, honestly 🔥

⚠️ also note, bestie: the function uses a somewhat relaxed locking scheme, so it may be called only for an already offlined CPU. not a live one. offlined. dead. done. do not come for this function with a CPU that's still out here living its life, fr fr 💀

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✨ SEE ALSO ✨

bestie these are the lore-adjacent ones, go read them if you want the whole cinematic universe 👑

• Kernel file ./kernel/cpu.c
• struct cpuhp_cpu_state(9)
• struct cpuhp_step(9)
• cpuhp_invoke_callback(9)
• cpuhp_ap_update_sync_state(9)
• cpuhp_ap_report_dead(9)
• cpuhp_ap_sync_alive(9)
• cpu_device_down(9)
• notify_cpu_starting(9)
• cpu_device_up(9)
• bringup_hibernate_cpu(9)
• __cpuhp_setup_state_cpuslocked(9)
• __cpuhp_remove_state_cpuslocked(9)

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and that's the page!! mwah 💋 this one came from ./kernel, dated October 2026, and it's filed under clear_tasks_mm_cpumask(9) — go forth and offline your CPUs responsibly, queen 👑✨