Thomas Gleixner <t...@linutronix.de> writes: > On Mon, 4 Sep 2017, Huang, Ying wrote: >> diff --git a/kernel/irq/cpuhotplug.c b/kernel/irq/cpuhotplug.c >> index 638eb9c83d9f..af9029625271 100644 >> --- a/kernel/irq/cpuhotplug.c > ry> +++ b/kernel/irq/cpuhotplug.c >> @@ -129,10 +129,13 @@ void irq_migrate_all_off_this_cpu(void) >> struct irq_desc *desc; >> unsigned int irq; >> >> + irq_lock_sparse(); > > You cannot take that lock here as irq_migrate_all_off_this_cpu() is called > with interrupts disabled.
Oh, sorry, I misunderstand the code. I will only keep the !desc check in the patch. > The protection in takedown_cpus() is wrong. Patch below. > > Thanks, > > tglx > ---- > > --- a/kernel/cpu.c > +++ b/kernel/cpu.c > @@ -642,13 +642,13 @@ static int takedown_cpu(unsigned int cpu > wait_for_completion(&st->done); > BUG_ON(st->state != CPUHP_AP_IDLE_DEAD); > > - /* Interrupts are moved away from the dying cpu, reenable alloc/free */ > - irq_unlock_sparse(); > - > hotplug_cpu__broadcast_tick_pull(cpu); > /* This actually kills the CPU. */ > __cpu_die(cpu); > > + /* Interrupts are moved away from the dying cpu, reenable alloc/free */ > + irq_unlock_sparse(); > + I don't understand this. It appears that irq_migrate_all_off_this_cpu() is called in take_cpu_down() which has sparse_irq_lock held already. Best Regards, Huang, Ying > tick_cleanup_dead_cpu(cpu); > return 0; > }
