On Sat, Jan 16, 2021 at 10:45:04PM +0800, Lai Jiangshan wrote: > On Sat, Jan 16, 2021 at 8:45 PM Peter Zijlstra <pet...@infradead.org> wrote: > > It is also the exact sequence normal per-cpu threads (smpboot) use to > > preserve affinity. > > Other per-cpu threads normally do short-live works. wq's work can be > lengthy, cpu-intensive, heavy-lock-acquiring or even call > get_online_cpus() which might result in a deadlock with kthread_park().
kthread_park() is called by the migration thread running the workqueue_online_cpu() callback. kthread_parkme() is called by the worker thread, after it completes a work and has no locks held from that context.
