WARNING: at mm/slub.c:3357, kernel BUG at mm/slub.c:3413

[Christoph Lameter]

On Wed, 23 Nov 2011, Markus Trippelsdorf wrote:

> > FIX idr_layer_cache: Marking all objects used
>
> Yesterday I couldn't reproduce the issue at all. But today I've hit
> exactly the same spot again. (CCing the drm list)

Well this is looks like write after free.

> =============================================================================
> BUG idr_layer_cache: Poison overwritten
> -----------------------------------------------------------------------------
> Object ffff8802156487c0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkkkkkkkkk
> Object ffff8802156487d0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkkkkkkkkk
> Object ffff8802156487e0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkkkkkkkkk
> Object ffff8802156487f0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkkkkkkkkk
> Object ffff880215648800: 00 00 00 00 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  ....kkkkkkkkkkkk
> Object ffff880215648810: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkkkkkkkkk

And its an integer sized write of 0. If you look at the struct definition
and lookup the offset you should be able to locate the field that
was modified.