debugobjects: Track number of kmem_cache_alloc/kmem_cache_free done

New debugfs stat counters are added to track the numbers of
kmem_cache_alloc() and kmem_cache_free() function calls to get a
sense of how the internal debug objects cache management is performing.

Signed-off-by: Waiman Long <longman@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "Du Changbin" <changbin.du@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Stancek <jstancek@redhat.com>
Link: http://lkml.kernel.org/r/1483647425-4135-2-git-send-email-longman@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

lib/debugobjects.c

@@ -55,6 +55,12 @@ static int			debug_objects_enabled __read_mostly
 
 static struct debug_obj_descr	*descr_test  __read_mostly;
 
+/*
+ * Track numbers of kmem_cache_alloc and kmem_cache_free done.
+ */
+static int			debug_objects_alloc;
+static int			debug_objects_freed;
+
 static void free_obj_work(struct work_struct *work);
 static DECLARE_WORK(debug_obj_work, free_obj_work);
 
@@ -102,6 +108,7 @@ static void fill_pool(void)
 
 		raw_spin_lock_irqsave(&pool_lock, flags);
 		hlist_add_head(&new->node, &obj_pool);
+		debug_objects_alloc++;
 		obj_pool_free++;
 		raw_spin_unlock_irqrestore(&pool_lock, flags);
 	}
@@ -173,6 +180,7 @@ static void free_obj_work(struct work_struct *work)
 		obj = hlist_entry(obj_pool.first, typeof(*obj), node);
 		hlist_del(&obj->node);
 		obj_pool_free--;
+		debug_objects_freed++;
 		/*
 		 * We release pool_lock across kmem_cache_free() to
 		 * avoid contention on pool_lock.
@@ -758,6 +766,8 @@ static int debug_stats_show(struct seq_file *m, void *v)
 	seq_printf(m, "pool_min_free :%d\n", obj_pool_min_free);
 	seq_printf(m, "pool_used     :%d\n", obj_pool_used);
 	seq_printf(m, "pool_max_used :%d\n", obj_pool_max_used);
+	seq_printf(m, "objects_alloc :%d\n", debug_objects_alloc);
+	seq_printf(m, "objects_freed :%d\n", debug_objects_freed);
 	return 0;
 }