diff --git a/arch/arm64/kernel/cpu.c b/arch/arm64/kernel/cpu.c
index f9f933c6..1450743e 100644
--- a/arch/arm64/kernel/cpu.c
+++ b/arch/arm64/kernel/cpu.c
@@ -869,6 +869,21 @@ unsigned long cpu_enable_interrupt_save(void)
 	return flags;
 }
 
+#ifdef ENABLE_FUGAKU_HACKS
+int cpu_interrupt_disabled(void)
+{
+	unsigned long flags;
+	unsigned long masked = ICC_PMR_EL1_MASKED;
+
+	asm volatile(
+		"mrs_s  %0, " __stringify(ICC_PMR_EL1)
+		: "=&r" (flags)
+		:
+		: "memory");
+	return (flags == masked);
+}
+#endif
+
 #else /* defined(CONFIG_HAS_NMI) */
 
 /* @ref.impl arch/arm64/include/asm/irqflags.h::arch_local_irq_enable */
diff --git a/arch/arm64/kernel/include/arch-lock.h b/arch/arm64/kernel/include/arch-lock.h
index a9f7c339..1291f379 100644
--- a/arch/arm64/kernel/include/arch-lock.h
+++ b/arch/arm64/kernel/include/arch-lock.h
@@ -9,6 +9,9 @@
 #include "affinity.h"
 #include <lwk/compiler.h>
 #include "config.h"
+#ifdef ENABLE_FUGAKU_HACKS
+#include <ihk/debug.h>
+#endif
 
 //#define DEBUG_SPINLOCK
 //#define DEBUG_MCS_RWLOCK
@@ -31,6 +34,10 @@ typedef struct {
 #endif /* __AARCH64EB__ */
 } __attribute__((aligned(4))) ihk_spinlock_t;
 
+#ifdef ENABLE_FUGAKU_HACKS
+extern ihk_spinlock_t *get_this_cpu_runq_lock(void);
+#endif
+
 extern void preempt_enable(void);
 extern void preempt_disable(void);
 
@@ -98,6 +105,18 @@ static int __ihk_mc_spinlock_trylock_noirq(ihk_spinlock_t *lock)
 	: "memory");
 
 	success = !tmp;
+
+#ifdef ENABLE_FUGAKU_HACKS
+#if 0
+	if (success) {
+		if (get_this_cpu_runq_lock() == lock &&
+				!cpu_interrupt_disabled()) {
+			kprintf("%s: WARNING: runq lock held without IRQs disabled?\n", __func__); \
+		}
+	}
+#endif
+#endif
+
 	if (!success) {
 		preempt_enable();
 	}
@@ -182,6 +201,14 @@ static void __ihk_mc_spinlock_lock_noirq(ihk_spinlock_t *lock)
 	: "=&r" (lockval), "=&r" (newval), "=&r" (tmp), "+Q" (*lock)
 	: "Q" (lock->owner), "I" (1 << TICKET_SHIFT)
 	: "memory");
+#ifdef ENABLE_FUGAKU_HACKS
+#if 0
+	if (get_this_cpu_runq_lock() == lock &&
+			!cpu_interrupt_disabled()) {
+		kprintf("%s: WARNING: runq lock held without IRQs disabled?\n", __func__); \
+	}
+#endif
+#endif
 }
 
 #ifdef DEBUG_SPINLOCK
diff --git a/kernel/cls.c b/kernel/cls.c
index 7771497c..ca5bb1b5 100644
--- a/kernel/cls.c
+++ b/kernel/cls.c
@@ -120,3 +120,10 @@ void do_backlog(void)
 		}
 	}
 }
+
+#ifdef ENABLE_FUGAKU_HACKS
+ihk_spinlock_t *get_this_cpu_runq_lock(void)
+{
+	return &get_this_cpu_local_var()->runq_lock;
+}
+#endif
diff --git a/lib/include/ihk/cpu.h b/lib/include/ihk/cpu.h
index 7a1e499e..10ebc7ba 100644
--- a/lib/include/ihk/cpu.h
+++ b/lib/include/ihk/cpu.h
@@ -23,6 +23,9 @@ extern int num_processors;
 
 void cpu_enable_interrupt(void);
 void cpu_disable_interrupt(void);
+#ifdef ENABLE_FUGAKU_HACKS
+int cpu_interrupt_disabled(void);
+#endif
 void cpu_halt(void);
 #ifdef ENABLE_FUGAKU_HACKS
 void cpu_halt_panic(void);