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Date:   Thu, 7 Apr 2022 11:43:31 +0200
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Subject: Re: [PATCH] mm, kfence: support kmem_dump_obj() for KFENCE objects
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To:     Marco Elver <elver@google.com>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, kernel test robot <oliver.sang@intel.com>,
        Hyeonggon Yoo <42.hyeyoo@gmail.com>
References: <20220406131558.3558585-1-elver@google.com>
From:   Vlastimil Babka <vbabka@suse.cz>
In-Reply-To: <20220406131558.3558585-1-elver@google.com>
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On 4/6/22 15:15, Marco Elver wrote:
> Calling kmem_obj_info() via kmem_dump_obj() on KFENCE objects has been
> producing garbage data due to the object not actually being maintained
> by SLAB or SLUB.
> 
> Fix this by implementing __kfence_obj_info() that copies relevant
> information to struct kmem_obj_info when the object was allocated by
> KFENCE; this is called by a common kmem_obj_info(), which also calls the
> slab/slub/slob specific variant now called __kmem_obj_info().
> 
> For completeness, kmem_dump_obj() now displays if the object was
> allocated by KFENCE.
> 
> Link: https://lore.kernel.org/all/20220323090520.GG16885@xsang-OptiPlex-9020/
> Fixes: b89fb5ef0ce6 ("mm, kfence: insert KFENCE hooks for SLUB")
> Fixes: d3fb45f370d9 ("mm, kfence: insert KFENCE hooks for SLAB")
> Reported-by: kernel test robot <oliver.sang@intel.com>
> Signed-off-by: Marco Elver <elver@google.com>
> Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>

Thanks.
Given the impact on slab, and my series exposing the bug, I will add this to
slab tree.

Vlastimil