Re: [PATCH v3 3/3] slub: min order when debug_guardpage_minorder > 0

From: Stanislaw Gruszka
Date: Thu Dec 08 2011 - 02:33:15 EST


On Wed, Dec 07, 2011 at 02:07:55PM -0800, David Rientjes wrote:
> On Fri, 18 Nov 2011, Stanislaw Gruszka wrote:
>
> > diff --git a/mm/slub.c b/mm/slub.c
> > index 7d2a996..a66be56 100644
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > @@ -3645,6 +3645,9 @@ void __init kmem_cache_init(void)
> > struct kmem_cache *temp_kmem_cache_node;
> > unsigned long kmalloc_size;
> >
> > + if (debug_guardpage_minorder())
> > + slub_max_order = 0;
> > +
> > kmem_size = offsetof(struct kmem_cache, node) +
> > nr_node_ids * sizeof(struct kmem_cache_node *);
> >
>
> I'd recommend at least printing a warning about why slub_max_order was
> reduced because users may be concerned why they can't now change any
> cache's order with /sys/kernel/slab/cache/order.

It's only happen with debug_guardpage_minorder=N parameter, so
perhaps I'll just document that in kernel-parameters.txt

Thanks
Stanislaw
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