On 09.06.2014 [14:38:26 -0700], David Rientjes wrote: > On Fri, 23 May 2014, Srivatsa S. Bhat wrote: > > > diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h > > index c920215..58e6469 100644 > > --- a/arch/powerpc/include/asm/topology.h > > +++ b/arch/powerpc/include/asm/topology.h > > @@ -18,6 +18,7 @@ struct device_node; > > */ > > #define RECLAIM_DISTANCE 10 > > > > +#include <linux/nodemask.h> > > #include <asm/mmzone.h> > > > > static inline int cpu_to_node(int cpu) > > @@ -30,7 +31,7 @@ static inline int cpu_to_node(int cpu) > > * During early boot, the numa-cpu lookup table might not have been > > * setup for all CPUs yet. In such cases, default to node 0. > > */ > > - return (nid < 0) ? 0 : nid; > > + return (nid < 0) ? first_online_node : nid; > > } > > > > #define parent_node(node) (node) > > I wonder what would happen on ppc if we just returned NUMA_NO_NODE here > for cpus that have not been mapped (they shouldn't even be possible). Well, with my patch (Ben sent it to Linus in the last pull request, I think), powerpc uses the generic per-cpu stuff, so this function is gone. Dunno if it makes sense to initialize the per-cpu data to NUMA_NO_NODE (rather than 0?). For powerpc, it's a timing thing. We can call cpu_to_node() quite early, and we may not have set up the mapping information yet. > This would at least allow callers that do > kmalloc_node(..., cpu_to_node(cpu)) to be allocated on the local cpu > rather than on a perhaps offline or remote node 0. > > It would seem better to catch callers that do > cpu_to_node(<not-possible-cpu>) rather than blindly return an online node. Agreed, but I've not seen such a case. Thanks, Nish -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>