From b339752d054fb32863418452dff350a1086885b1 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 28 Aug 2017 14:51:27 -0700 Subject: [PATCH] cpumask: fix spurious cpumask_of_node() on non-NUMA multi-node configs 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 Reported-and-tested-by: Geert Uytterhoeven Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds --- 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 fc824e2..5d2add1 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) -- 2.7.4