lib/debugobjects: fix stat count and optimize debug_objects_mem_init

1. Var debug_objects_allocated tracks valid kmem_cache_alloc calls, so
   track it in debug_objects_replace_static_objects.  Do similar things in
   object_cpu_offline.

2. In debug_objects_mem_init, there is no need to call function
   cpuhp_setup_state_nocalls when debug_objects_enabled = 0 (out of
   memory).

Link: https://lkml.kernel.org/r/20220611130634.99741-1-wuchi.zero@gmail.com
Fixes: 634d61f4 ("debugobjects: Percpu pool lookahead freeing/allocation")
Fixes: c4b73aab ("debugobjects: Track number of kmem_cache_alloc/kmem_cache_free done")
Signed-off-by: wuchi <wuchi.zero@gmail.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/debugobjects.c

@@ -437,6 +437,7 @@ static int object_cpu_offline(unsigned int cpu)
 	struct debug_percpu_free *percpu_pool;
 	struct hlist_node *tmp;
 	struct debug_obj *obj;
+	unsigned long flags;
 
 	/* Remote access is safe as the CPU is dead already */
 	percpu_pool = per_cpu_ptr(&percpu_obj_pool, cpu);
@@ -444,6 +445,12 @@ static int object_cpu_offline(unsigned int cpu)
 		hlist_del(&obj->node);
 		kmem_cache_free(obj_cache, obj);
 	}
+
+	raw_spin_lock_irqsave(&pool_lock, flags);
+	obj_pool_used -= percpu_pool->obj_free;
+	debug_objects_freed += percpu_pool->obj_free;
+	raw_spin_unlock_irqrestore(&pool_lock, flags);
+
 	percpu_pool->obj_free = 0;
 
 	return 0;
@@ -1318,6 +1325,8 @@ static int __init debug_objects_replace_static_objects(void)
 		hlist_add_head(&obj->node, &objects);
 	}
 
+	debug_objects_allocated += i;
+
 	/*
 	 * debug_objects_mem_init() is now called early that only one CPU is up
 	 * and interrupts have been disabled, so it is safe to replace the
@@ -1386,6 +1395,7 @@ void __init debug_objects_mem_init(void)
 		debug_objects_enabled = 0;
 		kmem_cache_destroy(obj_cache);
 		pr_warn("out of memory.\n");
+		return;
 	} else
 		debug_objects_selftest();