[PATCH 1/3] mm: return NUMA_NO_NODE in local_memory_node if zonelists are not setup

[Christoph Lameter]

On Fri, 21 Feb 2014, Nishanth Aravamudan wrote:

> I added two calls to local_memory_node(), I *think* both are necessary,
> but am willing to be corrected.
>
> One is in map_cpu_to_node() and one is in start_secondary(). The
> start_secondary() path is fine, AFAICT, as we are up & running at that
> point. But in [the renamed function] update_numa_cpu_node() which is
> used by hotplug, we get called from do_init_bootmem(), which is before
> the zonelists are setup.
>
> I think both calls are necessary because I believe the
> arch_update_cpu_topology() is used for supporting firmware-driven
> home-noding, which does not invoke start_secondary() again (the
> processor is already running, we're just updating the topology in that
> situation).
>
> Then again, I could special-case the do_init_bootmem callpath, which is
> only called at kernel init time?

Well taht looks to be simpler.

> > I do agree that calling local_memory_node() too early then trying to
> > fudge around the consequences seems rather wrong.
>
> If the answer is to simply not call local_memory_node() early, I'll
> submit a patch to at least add a comment, as there's nothing in the code
> itself to prevent this from happening and is guaranteed to oops.

Ok.