kthread_create_on_node(9)

📦 version 7.3.1, in nixpkgs unstable

💜 kthread_create_on_node(9) 💜

okay so this is a page from the Kernel API Manual, and it's literally about spawning kernel threads. bestie, this is the lowkey main character of thread creation — let's get into it 🧚

✨ NAME ✨

kthread_create_on_node — create a kthread. that's it. that's the whole vibe 🫶

🌸 SYNOPSIS 🌸

struct task_struct * kthread_create_on_node (int (*threadfn)(void *data)
, void *data , int node , const char namefmt[] , ... );

🎀 ARGUMENTS 🎀

  • threadfn — the function your thread is gonna run, and it keeps running until signal_pending(current) says stop. that's the assignment, no cap 💅
  • data — a data pointer that gets handed straight to threadfn. it's the little gift bag your function gets at the door 🎁
  • node — the task and thread structures for this thread get allocated on this node. NUMA girlies stay winning ✨
  • namefmt — a printf-style name for the thread. give it a cute name, it deserves one 🎀
  • ... — variable arguments. the little ... doing its thing, iykyk

🦋 DESCRIPTION 🦋

so this helper function creates and names a kernel thread. iconic behavior honestly 👑

heads up though: the thread will be stopped when it's created. like, it does not go anywhere until you hit it with wake_up_process to actually start it. don't be out here wondering why nothing's happening, bestie 😭

see also kthread_run, which is the other one you'll probably meet.

the new thread comes out the box with SCHED_NORMAL policy and is affine to all CPUs. all of them. it's very social 🌈

if the thread is gonna be bound to a particular cpu, pass its node in node so you get NUMA affinity for the kthread stack — or else just give NUMA_NO_NODE. pick one, don't be weird about it 💀

when it gets woken, the thread runs threadfn with data as its argument. and here's the part everyone asks about: threadfn can either

  • return directly, if it's a standalone thread and nobody's ever gonna call kthread_stop on it, or
  • return when 'kthread_should_stop' is true — which means kthread_stop has been called 🫶

the return value should be zero or a negative error number, and it will be passed to kthread_stop. so like, keep it clean ✨

returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR). those last two are the "it didn't work out" ones, no drama 💅

🔥 SEE ALSO 🔥

Kernel file ./kernel/kthread.c — and honestly the whole kthread friend group, they're all here:

and that's the page, bestie!! this one lives in the source tree at ./kernel and the version/date stamp on it says October 2026 — so yeah, it's giving very "from the future" energy 👑✨ go forth and create threads responsibly 🧚💖

📦 where this page comes from