Re: slab hang on boot

From: Christoph Lameter
Date: Tue May 15 2007 - 19:45:38 EST


On Tue, 15 May 2007, Andrew Morton wrote:

> On Mon, 14 May 2007 16:46:17 -0700 (PDT)
> Christoph Lameter <clameter@xxxxxxx> wrote:
>
> > @@ -86,6 +87,9 @@ static inline int kmalloc_index(int size
> > */
> > WARN_ON_ONCE(size == 0);
> >
> > + if (size >= (1UL << KMALLOC_SHIFT_HIGH))
> > + return -1;
> > +
>
> I don't quite understand why we did this. The subsequent logic in
> kmalloc_index() should return -1 for this `size' anyway. If it doesn't,
> it's bust, isn't it?

KMALLOC_SHIFT_HIGH is not a constant but may be less than 25.

> Also, afaict kmalloc_slab() will totally mishandle the -1 return value and
> will return a garbage kmem_cache*, via
>
> return &kmalloc_caches[index];

It does an

if (index < 0)

before getting to that statement.

> Could you double-check it all please?

It was already checked.



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