---
 kernel/cpu.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -2710,6 +2710,13 @@
 	cpu_maps_update_begin();
 	cpu_smt_control = CPU_SMT_ENABLED;
 	for_each_present_cpu(cpu) {
+		/*
+		 * Avoid accidentally onlining primary thread CPUs that have
+		 * been taken offline.
+		 */
+		if (topology_is_primary_thread(cpu))
+			continue;
+
 		/* Skip online CPUs and CPUs on offline nodes */
 		if (cpu_online(cpu) || !node_online(cpu_to_node(cpu)))
 			continue;