On Thu, 5 Dec 2013, Yasuaki Ishimatsu wrote: > (2013/12/05 6:09), Toshi Kani wrote: > > When ACPI SLIT table has an I/O locality (i.e. a locality unique > > to an I/O device), numa_set_distance() emits the warning message > > below. > > > > NUMA: Warning: node ids are out of bound, from=-1 to=-1 distance=10 > > > > acpi_numa_slit_init() calls numa_set_distance() with pxm_to_node(), > > which assumes that all localities have been parsed with SRAT previously. > > SRAT does not list I/O localities, where as SLIT lists all localities > > > including I/Os. Hence, pxm_to_node() returns NUMA_NO_NODE (-1) for > > an I/O locality. I/O localities are not supported and are ignored > > today, but emitting such warning message leads unnecessary confusion. > > In this case, the warning message should not be shown. But if SLIT table > is really broken, the message should be shown. Your patch seems to not care > for second case. > It's a subtle problem of the difference in the definition of a "NUMA node" between the ACPI specification and how it is defined in the kernel. The specification allows I/O buses to define a NUMA node and the kernel doesn't setup a separate node id for them, so there's no way to distinguish between an erroneous SLIT and system localities that only include I/O devices. If that were to change in the future we could remove this limitation since pxm_to_node() wouldn't return NUMA_NO_NODE for Toshi's config. A follow-up patch that adds the comment about why this is done has been proposed to be folded into this patch. -- 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>