Re: [bisected] rcu_sched detected stalls - 4.15 or newer kernel with some Xeon skylake CPUs and extended APIC

[Thomas Gleixner]

Rick,

On Wed, 16 May 2018, Rick Warner wrote:

> I've attached the dmesg output with the kernel parameter and supplied patch.

Thanks for providing the data. I think I know what's wrong here. Does the
patch below fix your problem?

While you test, I go looking for a big brown paperbag.

Thanks,

	tglx

8<----------------

--- a/arch/x86/kernel/apic/x2apic_cluster.c
+++ b/arch/x86/kernel/apic/x2apic_cluster.c
@@ -124,6 +124,7 @@ static void init_x2apic_ldr(void)
 			goto update;
 	}
 	cmsk = cluster_hotplug_mask;
+	cmsk->clusterid = cluster;
 	cluster_hotplug_mask = NULL;
 update:
 	this_cpu_write(cluster_masks, cmsk);