linux-kernel - Re: [PATCH] mm: Add additional consistency check

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Message-ID: <alpine.DEB.2.20.1704111110130.24725@east.gentwo.org>
Date:   Tue, 11 Apr 2017 11:16:42 -0500 (CDT)
From:   Christoph Lameter <cl@...ux.com>
To:     Michal Hocko <mhocko@...nel.org>
cc:     Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Linux-MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: Add additional consistency check

On Tue, 11 Apr 2017, Michal Hocko wrote:

>  static inline void *index_to_obj(struct kmem_cache *cache, struct page *page,
> @@ -3813,14 +3818,18 @@ void kfree(const void *objp)
>  {
>  	struct kmem_cache *c;
>  	unsigned long flags;
> +	struct page *page;
>
>  	trace_kfree(_RET_IP_, objp);
>
>  	if (unlikely(ZERO_OR_NULL_PTR(objp)))
>  		return;
> +	page = virt_to_head_page(obj);
> +	if (CHECK_DATA_CORRUPTION(!PageSlab(page)))

There is a flag SLAB_DEBUG_OBJECTS that is available for this check.
Consistency checks are configuraable in the slab allocator.

Mentioned that before and got this lecture about data consistency checks.