Re: [PATCH] mm, kfence: support kmem_dump_obj() for KFENCE objects

From: Vlastimil Babka
Date: Thu Apr 07 2022 - 05:43:38 EST

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:
> 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@xxxxxxxxx>
> Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
> Reviewed-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>

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