In NUMA layout which nodes have memory ranges that span across other nodes, the mm driver can detect the memory node id incorrectly. For example, with layout below Node 0 address: 0000 xxxx 0000 xxxx Node 1 address: xxxx 1111 xxxx 1111 Note: - Memory from low to high - 0/1: Node id - x: Invalid memory of a node When mm probes the memory map, without CONFIG_NODES_SPAN_OTHER_NODES config, mm only checks the memory validity but not the node id. Because of that, Node 1 also detects the memory from node 0 as below when it scans from the start address to the end address of node 1. Node 0 address: 0000 xxxx xxxx xxxx Node 1 address: xxxx 1111 1111 1111 This layout could occur on any architecture. This patch enables CONFIG_NODES_SPAN_OTHER_NODES by default for NUMA to fix this issue. V2: * Revise the patch description Hoan Tran (5): mm: Enable CONFIG_NODES_SPAN_OTHER_NODES by default for NUMA powerpc: Kconfig: Remove CONFIG_NODES_SPAN_OTHER_NODES x86: Kconfig: Remove CONFIG_NODES_SPAN_OTHER_NODES sparc: Kconfig: Remove CONFIG_NODES_SPAN_OTHER_NODES s390: Kconfig: Remove CONFIG_NODES_SPAN_OTHER_NODES arch/powerpc/Kconfig | 9 --------- arch/s390/Kconfig | 8 -------- arch/sparc/Kconfig | 9 --------- arch/x86/Kconfig | 9 --------- mm/page_alloc.c | 2 +- 5 files changed, 1 insertion(+), 36 deletions(-) -- 2.7.4
