4.16-stable review patch. If anyone has any objections, please let me know.
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From: Thomas Gleixner tglx@linutronix.de
commit fed71f7d98795ed0fa1d431910787f0f4a68324f upstream.
Rick bisected a regression on large systems which use the x2apic cluster mode for interrupt delivery to the commit wich reworked the cluster management.
The problem is caused by a missing initialization of the clusterid field in the shared cluster data structures. So all structures end up with cluster ID 0 which only allows sharing between all CPUs which belong to cluster 0. All other CPUs with a cluster ID > 0 cannot share the data structure because they cannot find existing data with their cluster ID. This causes malfunction with IPIs because IPIs are sent to the wrong cluster and the caller waits for ever that the target CPU handles the IPI.
Add the missing initialization when a upcoming CPU is the first in a cluster so that the later booting CPUs can find the data and share it for proper operation.
Fixes: 023a611748fd ("x86/apic/x2apic: Simplify cluster management") Reported-by: Rick Warner rick@microway.com Bisected-by: Rick Warner rick@microway.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Rick Warner rick@microway.com Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1805171418210.1947@nanos.tec.linut... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kernel/apic/x2apic_cluster.c | 1 + 1 file changed, 1 insertion(+)
--- a/arch/x86/kernel/apic/x2apic_cluster.c +++ b/arch/x86/kernel/apic/x2apic_cluster.c @@ -116,6 +116,7 @@ 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);