diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index df8c9c2c7918..a24dd2089ae9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -13962,29 +13962,62 @@ static inline int on_null_domain(struct rq *rq)
  */
 static inline int find_new_ilb(void)
 {
-	int this_cpu = smp_processor_id();
-	const struct cpumask *hk_mask;
-	int ilb_cpu;
+	struct cpumask *ilb_cpus;
+	int ilb_cpu, fallback = -1;
 
-	hk_mask = housekeeping_cpumask(HK_TYPE_KERNEL_NOISE);
+	lockdep_assert_irqs_disabled();
 
-	for_each_cpu_and(ilb_cpu, nohz.idle_cpus_mask, hk_mask) {
-		if (ilb_cpu == this_cpu)
+	/*
+	 * Reuse the per-CPU select_rq_mask, which is protected from concurrent
+	 * use on this CPU by having interrupts disabled.
+	 */
+	ilb_cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
+	cpumask_and(ilb_cpus, nohz.idle_cpus_mask,
+		    housekeeping_cpumask(HK_TYPE_KERNEL_NOISE));
+
+	for_each_cpu(ilb_cpu, ilb_cpus) {
+		if (!idle_cpu(ilb_cpu)) {
+			/*
+			 * Once an idle fallback exists, a busy CPU proves that
+			 * this core cannot be fully idle. Skip its siblings.
+			 */
+			if (sched_smt_active() && fallback >= 0)
+				cpumask_andnot(ilb_cpus, ilb_cpus, cpu_smt_mask(ilb_cpu));
 			continue;
+		}
 
-		if (idle_cpu(ilb_cpu))
-			return ilb_cpu;
+		/*
+		 * Running the idle load balancer on an idle sibling of a busy
+		 * SMT core can reduce the capacity available to its sibling. Prefer
+		 * a CPU whose entire core is idle, but retain the first idle CPU as
+		 * a fallback so idle balancing can still make progress when no fully
+		 * idle core exists.
+		 */
+		if (sched_smt_active() && !is_core_idle(ilb_cpu)) {
+			if (fallback < 0)
+				fallback = ilb_cpu;
+
+			/*
+			 * The core is not idle, so there is no need to check
+			 * any of its other SMT siblings.
+			 */
+			cpumask_andnot(ilb_cpus, ilb_cpus,
+				       cpu_smt_mask(ilb_cpu));
+			continue;
+		}
+
+		return ilb_cpu;
 	}
 
-	return -1;
+	return fallback;
 }
 
 /*
  * Kick a CPU to do the NOHZ balancing, if it is time for it, via a cross-CPU
  * SMP function call (IPI).
  *
- * We pick the first idle CPU in the HK_TYPE_KERNEL_NOISE housekeeping set
- * (if there is one).
+ * Prefer a CPU on a fully idle core in the HK_TYPE_KERNEL_NOISE housekeeping
+ * set. Fall back to the first idle CPU when no fully idle core exists.
  */
 static void kick_ilb(unsigned int flags)
 {