Re: [Patch / 002](memory hotplug) Callback function to create kmem_cache_node.

From: Yasunori Goto
Date: Mon Oct 01 2007 - 22:21:37 EST


> On Mon, 1 Oct 2007, Yasunori Goto wrote:
>
> > +#ifdef CONFIG_MEMORY_HOTPLUG
> > +static void __slab_callback_offline(int nid)
> > +{
> > + struct kmem_cache_node *n;
> > + struct kmem_cache *s;
> > +
> > + list_for_each_entry(s, &slab_caches, list) {
> > + if (s->node[nid]) {
> > + n = get_node(s, nid);
> > + s->node[nid] = NULL;
> > + kmem_cache_free(kmalloc_caches, n);
> > + }
> > + }
> > +}
>
> I think we need to bug here if there are still objects on the node that
> are in use. This will silently discard the objects.
>
Here is just the rollback code for an allocation failure of
kmem_cache_node in halfway.
So, there is a case some of them are not allocated yet.
Any slabs don't use new kmem_cache_node before the new nodes page is
available --so far--.
But, in the future, here will be useful for node hot-unplug code,
and its check will be necessary. Ok. I'll add its check.

Do you mean that just nr_slabs should be checked like followings?
I'm not sure this is enough.

:
if (s->node[nid]) {
n = get_node(s, nid);
if (!atomic_read(&n->nr_slabs)) {
s->node[nid] = NULL;
kmem_cache_free(kmalloc_caches, n);
}
}
:
:

Thanks.

--
Yasunori Goto


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