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Date: Thu, 30 May 2024 08:20:28 -0700 (PDT)
From: "Christoph Lameter (Ampere)" <cl@gentwo.org>
To: Chengming Zhou <chengming.zhou@linux.dev>
cc: Pekka Enberg <penberg@kernel.org>, David Rientjes <rientjes@google.com>, 
    Joonsoo Kim <iamjoonsoo.kim@lge.com>, 
    Andrew Morton <akpm@linux-foundation.org>, 
    Vlastimil Babka <vbabka@suse.cz>, 
    Roman Gushchin <roman.gushchin@linux.dev>, 
    Hyeonggon Yoo <42.hyeyoo@gmail.com>, Feng Tang <feng.tang@intel.com>, 
    linux-mm@kvack.org, linux-kernel@vger.kernel.org, 
    zhouchengming@bytedance.com
Subject: Re: [PATCH 1/3] slab: check the return value of
 check_bytes_and_report()
In-Reply-To: <20240528-b4-slab-debug-v1-1-8694ef4802df@linux.dev>
Message-ID: <4e4d45b5-c684-2d93-49d2-b179a088c2d5@gentwo.org>
References: <20240528-b4-slab-debug-v1-0-8694ef4802df@linux.dev> <20240528-b4-slab-debug-v1-1-8694ef4802df@linux.dev>
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On Tue, 28 May 2024, Chengming Zhou wrote:

> diff --git a/mm/slub.c b/mm/slub.c
> index 0809760cf789..de57512734ac 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1324,9 +1324,10 @@ static int check_object(struct kmem_cache *s, struct slab *slab,
> 		}
> 	} else {
> 		if ((s->flags & SLAB_POISON) && s->object_size < s->inuse) {
> -			check_bytes_and_report(s, slab, p, "Alignment padding",
> +			if (!check_bytes_and_report(s, slab, p, "Alignment padding",
> 				endobject, POISON_INUSE,
> -				s->inuse - s->object_size);
> +				s->inuse - s->object_size))
> +				return 0;
> 		}
> 	}

This change means we will then skip the rest of the checks in 
check_object() such as the poison check.