Changelog v2:->v3: - Resolved comments from Gautham. Link v2: https://lore.kernel.org/linuxppc-dev/20200428093836.27190-1-srikar@xxxxxxxxxxxxxxxxxx/t/#u Changelog v1:->v2: - Rebased to v5.7-rc3 - Updated the changelog. Link v1: https://lore.kernel.org/linuxppc-dev/20200311110237.5731-1-srikar@xxxxxxxxxxxxxxxxxx/t/#u Linux kernel configured with CONFIG_NUMA on a system with multiple possible nodes, marks node 0 as online at boot. However in practice, there are systems which have node 0 as memoryless and cpuless. This can cause 1. numa_balancing to be enabled on systems with only one online node. 2. Existence of dummy (cpuless and memoryless) node which can confuse users/scripts looking at output of lscpu / numactl. This patchset wants to correct this anomaly. This should only affect systems that have CONFIG_MEMORYLESS_NODES. Currently there are only 2 architectures ia64 and powerpc that have this config. Note: Patch 3 in this patch series depends on patches 1 and 2. Without patches 1 and 2, patch 3 might crash powerpc. v5.7-rc3 available: 2 nodes (0,2) node 0 cpus: node 0 size: 0 MB node 0 free: 0 MB node 2 cpus: 0 1 2 3 4 5 6 7 node 2 size: 32625 MB node 2 free: 31490 MB node distances: node 0 2 0: 10 20 2: 20 10 proc and sys files ------------------ /sys/devices/system/node/online: 0,2 /proc/sys/kernel/numa_balancing: 1 /sys/devices/system/node/has_cpu: 2 /sys/devices/system/node/has_memory: 2 /sys/devices/system/node/has_normal_memory: 2 /sys/devices/system/node/possible: 0-31 v5.7-rc3 + patches ------------------ available: 1 nodes (2) node 2 cpus: 0 1 2 3 4 5 6 7 node 2 size: 32625 MB node 2 free: 31487 MB node distances: node 2 2: 10 proc and sys files ------------------ /sys/devices/system/node/online: 2 /proc/sys/kernel/numa_balancing: 0 /sys/devices/system/node/has_cpu: 2 /sys/devices/system/node/has_memory: 2 /sys/devices/system/node/has_normal_memory: 2 /sys/devices/system/node/possible: 0-31 Cc: linuxppc-dev@xxxxxxxxxxxxxxxx Cc: linux-mm@xxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> Cc: Christopher Lameter <cl@xxxxxxxxx> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Gautham R Shenoy <ego@xxxxxxxxxxxxxxxxxx> Srikar Dronamraju (3): powerpc/numa: Set numa_node for all possible cpus powerpc/numa: Prefer node id queried from vphn mm/page_alloc: Keep memoryless cpuless node 0 offline arch/powerpc/mm/numa.c | 35 ++++++++++++++++++++++++----------- mm/page_alloc.c | 4 +++- 2 files changed, 27 insertions(+), 12 deletions(-) -- 2.20.1
