Re: [PATCH 2/6] mm: handle uninitialized numa nodes gracefully

Michal Hocko
2022-02-01T09:54:40Z

On Tue 01-02-22 02:41:19, Wei Yang wrote:
> On Thu, Jan 27, 2022 at 03:47:40PM +0100, Michal Hocko wrote:
> >[...]
> >> > +
> >> > + /* Allocator not initialized yet */
> >> > + pgdat = arch_alloc_nodedata(nid);
> >> > + if (!pgdat) {
> >> > + pr_err("Cannot allocate %zuB for node %d.\n",
> >> > + sizeof(*pgdat), nid);
> >> > + continue;
> >> > + }
> >> > + arch_refresh_nodedata(nid, pgdat);
> >> > + free_area_init_memoryless_node(nid);
>
> free_area_init_memoryless_node() seems to be defined used out side
> page_alloc.c? It just call free_area_init_node() directly. We want to use the
> name to reflect the effect?

yes.

> >> > + /*
> >> > + * not marking this node online because we do not want to
> >> > + * confuse userspace by sysfs files/directories for node
> >> > + * without any memory attached to it (see topology_init)
> >> > + * The pgdat will get fully initialized when a memory is
> >> > + * hotpluged into it by hotadd_init_pgdat
> >> > + */
>
> Hmm... which following step would mark the node online? On x86, the node is
> onlined in alloc_node_date(). This is not onlined here.

The comment tries to explain that this happens during the memory
hotplug. Or maybe I have missed your question?

[...]
--
Michal Hocko
SUSE Labs