From: Michal Hocko <mhocko@xxxxxxxx> Subject: mm: disallow early_pfn_to_nid on configurations which do not implement it early_pfn_to_nid will return node 0 if both HAVE_ARCH_EARLY_PFN_TO_NID and HAVE_MEMBLOCK_NODE_MAP are disabled. It seems we are safe now because all architectures which support NUMA define one of them (with an exception of alpha which however has CONFIG_NUMA marked as broken) so this works as expected. It can get silently and subtly broken too easily, though. Make sure we fail the compilation if NUMA is enabled and there is no proper implementation for this function. If that ever happens we know that either the specific configuration is invalid and the fix should either disable NUMA or enable one of the above configs. Link: http://lkml.kernel.org/r/20170704075803.15979-1-mhocko@xxxxxxxxxx Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Joonsoo Kim <js1304@xxxxxxxxx> Cc: Yang Shi <yang.shi@xxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/mmzone.h | 1 + 1 file changed, 1 insertion(+) diff -puN include/linux/mmzone.h~mm-disallow-early_pfn_to_nid-on-configurations-which-do-not-implement-it include/linux/mmzone.h --- a/include/linux/mmzone.h~mm-disallow-early_pfn_to_nid-on-configurations-which-do-not-implement-it +++ a/include/linux/mmzone.h @@ -1055,6 +1055,7 @@ static inline struct zoneref *first_zone !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP) static inline unsigned long early_pfn_to_nid(unsigned long pfn) { + BUILD_BUG_ON(IS_ENABLED(CONFIG_NUMA)); return 0; } #endif _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
