diff -ru linux-2.4.6-dist/include/asm-i386/spinlock.h linux-2.4.6-kgdb/include/asm-i386/spinlock.h
--- linux-2.4.6-dist/include/asm-i386/spinlock.h	Fri May 25 21:01:26 2001
+++ linux-2.4.6-kgdb/include/asm-i386/spinlock.h	Wed Aug  1 23:11:51 2001
@@ -1,6 +1,8 @@
 #ifndef __ASM_SPINLOCK_H
 #define __ASM_SPINLOCK_H
 
+#include <asm/smp.h>
+#include <asm/current.h>
 #include <asm/atomic.h>
 #include <asm/rwlock.h>
 #include <asm/page.h>
@@ -12,7 +14,7 @@
  * initialize their spinlocks properly, tsk tsk.
  * Remember to turn this off in 2.4. -ben
  */
-#define SPINLOCK_DEBUG	0
+#define SPINLOCK_DEBUG	1
 
 /*
  * Your basic SMP spinlocks, allowing only a single CPU anywhere
@@ -22,13 +24,16 @@
 	volatile unsigned int lock;
 #if SPINLOCK_DEBUG
 	unsigned magic;
+	void *last_lock_addr;
+	void *last_lock_current;
+	int last_lock_processor;
 #endif
 } spinlock_t;
 
 #define SPINLOCK_MAGIC	0xdead4ead
 
 #if SPINLOCK_DEBUG
-#define SPINLOCK_MAGIC_INIT	, SPINLOCK_MAGIC
+#define SPINLOCK_MAGIC_INIT	, SPINLOCK_MAGIC, NULL
 #else
 #define SPINLOCK_MAGIC_INIT	/* */
 #endif
@@ -75,6 +80,15 @@
 	return oldval > 0;
 }
 
+/* This is here because the definition of smp_processor_id() pulls the
+ * processor id out of the current task_struct, which is defined in
+ * linux/sched.h, which includes this file because it declares spinlocks.
+ * So we can't use smp_processor_id() because task_struct hasn't been
+ * defined yet.  Damn these computers.
+ */
+
+#define my_processor_id (((int *)current)[13])
+
 static inline void spin_lock(spinlock_t *lock)
 {
 #if SPINLOCK_DEBUG
@@ -84,10 +98,18 @@
 printk("eip: %p\n", &&here);
 		BUG();
 	}
+	if (spin_is_locked(lock)
+	    && lock->last_lock_processor == my_processor_id)
+		BUG();
 #endif
 	__asm__ __volatile__(
 		spin_lock_string
 		:"=m" (lock->lock) : : "memory");
+#if SPINLOCK_DEBUG
+	lock->last_lock_addr = &&here;
+	lock->last_lock_processor = my_processor_id;
+	lock->last_lock_current = current;
+#endif
 }
 
 static inline void spin_unlock(spinlock_t *lock)