linux-kernel - Re: [PATCH 1/3] slab: check the return value of check_bytes_and

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Date: Thu, 30 May 2024 08:20:28 -0700 (PDT)
From: "Christoph Lameter (Ampere)" <cl@...two.org>
To: Chengming Zhou <chengming.zhou@...ux.dev>
cc: Pekka Enberg <penberg@...nel.org>, David Rientjes <rientjes@...gle.com>, 
    Joonsoo Kim <iamjoonsoo.kim@....com>, 
    Andrew Morton <akpm@...ux-foundation.org>, 
    Vlastimil Babka <vbabka@...e.cz>, 
    Roman Gushchin <roman.gushchin@...ux.dev>, 
    Hyeonggon Yoo <42.hyeyoo@...il.com>, Feng Tang <feng.tang@...el.com>, 
    linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
    zhouchengming@...edance.com
Subject: Re: [PATCH 1/3] slab: check the return value of
 check_bytes_and_report()

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.