linux-kernel - Re: [PATCH] lib/debugobjects: Fix stat count and optimize debug_objects_mem

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Date:   Sun, 17 Jul 2022 17:24:24 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     wuchi <wuchi.zero@...il.com>
Cc:     tglx@...utronix.de, hch@....de, keescook@...omium.org,
        longman@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] lib/debugobjects: Fix stat count and optimize
 debug_objects_mem_init.

On Sat, 11 Jun 2022 21:06:34 +0800 wuchi <wuchi.zero@...il.com> wrote:

> 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).
> 

Could we please have some review input here?

> --- a/lib/debugobjects.c
> +++ b/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();
>