From: Tejun Heo <tj@xxxxxxxxxx> This patch has been added to the v4.1 stable tree. If you have any objections, please let us know. =============== [ Upstream commit b339752d054fb32863418452dff350a1086885b1 ] When !NUMA, cpumask_of_node(@node) equals cpu_online_mask regardless of @node. The assumption seems that if !NUMA, there shouldn't be more than one node and thus reporting cpu_online_mask regardless of @node is correct. However, that assumption was broken years ago to support DISCONTIGMEM and whether a system has multiple nodes or not is separately controlled by NEED_MULTIPLE_NODES. This means that, on a system with !NUMA && NEED_MULTIPLE_NODES, cpumask_of_node() will report cpu_online_mask for all possible nodes, indicating that the CPUs are associated with multiple nodes which is an impossible configuration. This bug has been around forever but doesn't look like it has caused any noticeable symptoms. However, it triggers a WARN recently added to workqueue to verify NUMA affinity configuration. Fix it by reporting empty cpumask on non-zero nodes if !NUMA. Signed-off-by: Tejun Heo <tj@xxxxxxxxxx> Reported-and-tested-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> --- include/asm-generic/topology.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/include/asm-generic/topology.h b/include/asm-generic/topology.h index fc824e2828f3..5d2add1a6c96 100644 --- a/include/asm-generic/topology.h +++ b/include/asm-generic/topology.h @@ -48,7 +48,11 @@ #define parent_node(node) ((void)(node),0) #endif #ifndef cpumask_of_node -#define cpumask_of_node(node) ((void)node, cpu_online_mask) + #ifdef CONFIG_NEED_MULTIPLE_NODES + #define cpumask_of_node(node) ((node) == 0 ? cpu_online_mask : cpu_none_mask) + #else + #define cpumask_of_node(node) ((void)node, cpu_online_mask) + #endif #endif #ifndef pcibus_to_node #define pcibus_to_node(bus) ((void)(bus), -1) -- 2.11.0