* Matthew Wilcox <willy@xxxxxxxxxxxxx> [230912 10:10]: > On Mon, Sep 11, 2023 at 07:54:52PM -0400, Liam R. Howlett wrote: > > Taking the mutex lock in kernel/irq/manage.c __setup_irq() is calling a > > cond_resched(). > > > > >From what Michael said [1] in this thread, since something has already > > set TIF_NEED_RESCHED, it will eventually enable interrupts on us. > > > > I've traced this to running call_rcu() in kernel/rcu/tiny.c and > > is_idle_task(current) is true, which means rcu runs: > > /* force scheduling for rcu_qs() */ > > resched_cpu(0); > > > > the task is set idle in sched_init() -> init_idle() and never changed, > > afaict. > > Should calling init_idle() be deferred until after interrupts are > all set up? At this point it is not platform specific code so I don't know what kind of fallout I'll produce with a change like that, but I was wondering if the thread running the boot process is really 'idle'?
