2020년 3월 13일 (금) 오후 8:38, Vlastimil Babka <vbabka@xxxxxxx>님이 작성:
>
> On 3/13/20 12:04 PM, Srikar Dronamraju wrote:
> >> I lost all the memory about it. :)
> >> Anyway, how about this?
> >>
> >> 1. make node_present_pages() safer
> >> static inline node_present_pages(nid)
> >> {
> >> if (!node_online(nid)) return 0;
> >> return (NODE_DATA(nid)->node_present_pages);
> >> }
> >>
> >
> > Yes this would help.
>
> Looks good, yeah.
>
> >> 2. make node_to_mem_node() safer for all cases
> >> In ppc arch's mem_topology_setup(void)
> >> for_each_present_cpu(cpu) {
> >> numa_setup_cpu(cpu);
> >> mem_node = node_to_mem_node(numa_mem_id());
> >> if (!node_present_pages(mem_node)) {
> >> _node_numa_mem_[numa_mem_id()] = first_online_node;
> >> }
> >> }
> >>
> >
> > But here as discussed above, we miss the case of possible but not present nodes.
> > For such nodes, the above change may not update, resulting in they still
> > having 0. And node 0 can be only possible but not present.
Oops, I don't read full thread so miss the case.
> So is there other way to do the setup so that node_to_mem_node() returns an
> online+present node when called for any possible node?
Two changes seems to be sufficient.
1. initialize all node's _node_numa_mem_[] = first_online_node in
mem_topology_setup()
2. replace the node with online+present node for _node_to_mem_node_[]
in set_cpu_numa_mem().
static inline void set_cpu_numa_mem(int cpu, int node)
{
per_cpu(_numa_mem_, cpu) = node;
+ if (!node_present_pages(node))
+ node = first_online_node;
_node_numa_mem_[cpu_to_node(cpu)] = node;
}
#endif
With these two change, we can safely call node_to_mem_node() anywhere.
Thanks.
