On Wed, 21 May 2014, Nishanth Aravamudan wrote: > For context: I was looking at why N_ONLINE was statically setting Node 0 > to be online, whether or not the topology is that way -- I've been > getting several bugs lately where Node 0 is online, but has no CPUs and > no memory on it, on powerpc. > > On powerpc, setup_per_cpu_areas calls into ___alloc_bootmem_node using > NODE_DATA(cpu_to_node(cpu)). > > Currently, cpu_to_node() in arch/powerpc/include/asm/topology.h does: > > /* > * 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; > > And so early at boot, if node 0 is not present, we end up accessing an > unitialized NODE_DATA(). So this seems buggy (I'll contact the powerpc > deveopers separately on that). > I think what this really wants to do is NODE_DATA(cpu_to_mem(cpu)) and I thought ppc had the cpu-to-local-memory-node mappings correct? -- 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>