linux-kernel - Re: [PATCH] mm/slub: Add slub_debug option to panic on memory corruption

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Message-ID: <alpine.DEB.2.22.394.2103091554430.109061@gentwo.de>
Date:   Tue, 9 Mar 2021 15:56:04 +0100 (CET)
From:   Christoph Lameter <cl@...two.de>
To:     Georgi Djakov <georgi.djakov@...aro.org>
cc:     linux-mm@...ck.org, akpm@...ux-foundation.org, vbabka@...e.cz,
        penberg@...nel.org, rientjes@...gle.com, iamjoonsoo.kim@....com,
        corbet@....net, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/slub: Add slub_debug option to panic on memory
 corruption

On Tue, 9 Mar 2021, Georgi Djakov wrote:

> Being able to stop the system immediately when a memory corruption
> is detected is crucial to finding the source of it. This is very
> useful when the memory can be inspected with kdump or other tools.

Hmmm.... ok.

>  static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
>  						void *from, void *to)
>  {
> +	if (slub_debug & SLAB_CORRUPTION_PANIC)
> +		panic("slab: object overwritten\n");
>  	slab_fix(s, "Restoring 0x%p-0x%p=0x%x\n", from, to - 1, data);
>  	memset(from, data, to - from);
>  }

Why panic here? This should only be called late in the bug reporting when
an error has already been printed.