On Tue, Oct 19, 2021 at 10:56:48AM +0200, Peter Zijlstra wrote:
> On Mon, Oct 18, 2021 at 11:47:32PM -0400, Qian Cai wrote:
> > Peter, any thoughts? I did confirm that reverting the commit fixed the issue.
> >
> > On 10/13/2021 10:32 AM, Qian Cai wrote:
> > >
> > >
> > > On 9/29/2021 11:17 AM, Peter Zijlstra wrote:
> > >> --- a/kernel/smp.c
> > >> +++ b/kernel/smp.c
> > >> @@ -1170,14 +1170,14 @@ void wake_up_all_idle_cpus(void)
> > >> {
> > >> int cpu;
> > >>
> > >> - preempt_disable();
> > >> + cpus_read_lock();
> > >> for_each_online_cpu(cpu) {
> > >> - if (cpu == smp_processor_id())
> > >> + if (cpu == raw_smp_processor_id())
> > >> continue;
> > >>
> > >> wake_up_if_idle(cpu);
> > >> }
> > >> - preempt_enable();
> > >> + cpus_read_unlock();
>
> Right, so yesterday I thought: YW2KGrvvv/vSA+97@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> but today I might have another idea, lemme go prod at this a bit more.
Here, hows this then?
---
diff --git a/kernel/smp.c b/kernel/smp.c
index ad0b68a3a3d3..61ddc7a3bafa 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -1170,14 +1170,12 @@ void wake_up_all_idle_cpus(void)
{
int cpu;
- cpus_read_lock();
- for_each_online_cpu(cpu) {
- if (cpu == raw_smp_processor_id())
- continue;
-
- wake_up_if_idle(cpu);
+ for_each_cpu(cpu) {
+ preempt_disable();
+ if (cpu != smp_processor_id() && cpu_online(cpu))
+ wake_up_if_idle(cpu);
+ preempt_enable();
}
- cpus_read_unlock();
}
EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
