Re: [PATCH V3 1/2] slub: fix kmem cgroup bug in kmem_cache_alloc_bulk

[Vladimir Davydov <vdavydov@virtuozzo.com>]

On Mon, Nov 09, 2015 at 04:04:51PM -0600, Christoph Lameter wrote:
> On Mon, 9 Nov 2015, Vladimir Davydov wrote:
> 
> > I think it must be &object
> >
> > BTW why is object defined as void **? I suspect we can safely drop one
> > star.
> 
> See get_freepointer()
> 
> static inline void *get_freepointer(struct kmem_cache *s, void *object)
> {
>         return *(void **)(object + s->offset);
> }

In this function object has type (void *)

> 
> The object at some point has a freepointer and ** allows the use of the
> s->offset field to get to it.

But it doesn't mean we have to define it as (void **) in
slab_alloc_node. Actually, the fact that object is of type (void **) is
never used in slab_alloc_node, and all functions called by it accept
(void *) for object, not (void **). Dropping one star there doesn't
break anything and looks less confusing IMO.

Thanks,
Vladimir

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