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

[Nishanth Aravamudan <nacc@linux.vnet.ibm.com>]

On 24.02.2014 [13:43:31 -0600], Christoph Lameter wrote:
> 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.

Ok, I'll work on this.

> > > 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.

Thanks!
-Nish