Re: [S+Q 08/16] slub: remove dynamic dma slab allocation

[Christoph Lameter <cl@linux-foundation.org>]

On Sat, 26 Jun 2010, David Rientjes wrote:

> > -	page = new_slab(kmalloc_caches, gfpflags, node);
> > +	page = new_slab(kmalloc_caches, GFP_KERNEL, node);
> >
> >  	BUG_ON(!page);
> >  	if (page_to_nid(page) != node) {
>
> This still passes GFP_KERNEL to the page allocator when not allowed by
> gfp_allowed_mask for early (non SLAB_CACHE_DMA) users of
> create_kmalloc_cache().

Right a later patch changes that. I could fold that hunk in here.

> > @@ -2157,11 +2157,11 @@ static int init_kmem_cache_nodes(struct
> >  		struct kmem_cache_node *n;
> >
> >  		if (slab_state == DOWN) {
> > -			early_kmem_cache_node_alloc(gfpflags, node);
> > +			early_kmem_cache_node_alloc(node);
> >  			continue;
> >  		}
> >  		n = kmem_cache_alloc_node(kmalloc_caches,
> > -						gfpflags, node);
> > +						GFP_KERNEL, node);
> >
> >  		if (!n) {
> >  			free_kmem_cache_nodes(s);
>
> slab_state != DOWN is still not an indication that GFP_KERNEL is safe; in
> fact, all users of GFP_KERNEL from kmem_cache_init() are unsafe.  These
> need to be GFP_NOWAIT.

slab_state == DOWN is a sure indicator that kmem_cache_alloc_node is not
functional. That is what we need to know here.

> > +#ifdef CONFIG_ZONE_DMA
> > +	int i;
> > +
> > +	for (i = 0; i < SLUB_PAGE_SHIFT; i++) {
> > +		struct kmem_cache *s = &kmalloc_caches[i];
> > +
> > +		if (s && s->size) {
> > +			char *name = kasprintf(GFP_KERNEL,
> > +				 "dma-kmalloc-%d", s->objsize);
> > +
>
> You're still not handling the case where !name, which kasprintf() can
> return both here and in kmem_cache_init().  Nameless caches aren't allowed
> for CONFIG_SLUB_DEBUG.

It was not handled before either. I can come up with a patch but frankly
this is a rare corner case that does not have too high priority to get
done.

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