On 06.03.2015 [08:48:52 +1100], Michael Ellerman wrote:
> On Thu, 2015-03-05 at 13:16 -0800, David Rientjes wrote:
> > On Thu, 5 Mar 2015, Nishanth Aravamudan wrote:
> >
> > > diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> > > index 0257a7d659ef..24de29b3651b 100644
> > > --- a/arch/powerpc/mm/numa.c
> > > +++ b/arch/powerpc/mm/numa.c
> > > @@ -958,9 +958,17 @@ void __init initmem_init(void)
> > >
> > > memblock_dump_all();
> > >
> > > + /*
> > > + * zero out the possible nodes after we parse the device-tree,
> > > + * so that we lower the maximum NUMA node ID to what is actually
> > > + * present.
> > > + */
> > > + nodes_clear(node_possible_map);
> > > +
> > > for_each_online_node(nid) {
> > > unsigned long start_pfn, end_pfn;
> > >
> > > + node_set(nid, node_possible_map);
> > > get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
> > > setup_node_data(nid, start_pfn, end_pfn);
> > > sparse_memory_present_with_active_regions(nid);
> >
> > This seems a bit strange, node_possible_map is supposed to be a superset
> > of node_online_map and this loop is iterating over node_online_map to set
> > nodes in node_possible_map.
>
> Yeah. Though at this point in boot I don't think it matters that the two maps
> are out-of-sync temporarily.
>
> But it would simpler to just set the possible map to be the online
> map. That would also maintain the invariant that the possible map is
> always a superset of the online map.
Yes, we could do that (see my reply to David just now). I didn't
consider just setting the map directly, that would be clearer. I didn't
want to post my nodes_and() version, because the cost of nodes_and
seemed higher than nodes_clear & node_set appropriately.
-Nish
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