On Fri, Sep 30, 2016 at 09:51:02AM +0800, kernel test robot wrote: > > FYI, we noticed the following commit: > > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master > commit 4fa5cd5245b627db88c9ca08ae442373b02596b4 ("sched/core: Do not use > smp_processor_id() with preempt enabled in smpboot_thread_fn()") >
So its perfectly ok to use smp_processor_id() in preemptible context, assuming the task is pinned to one cpu. smpboot threads are per definition per-cpu threads, those are bound to a specific CPU and affinity cannot be changed by userspace.
