s390/mm: remove fake numa support

It turned out that fake numa support is rather useless on s390, since
there are no scenarios where there is any performance or other benefit
when used.

However it does provide maintenance cost and breaks from time to time.
Therefore remove it.

CONFIG_NUMA is still supported with a very small backend and only one
node. This way userspace applications which require NUMA interfaces
continue to work.

Note that NODES_SHIFT is set to 1 (= 2 nodes) instead of 0 (= 1 node),
since there is quite a bit of kernel code which assumes that more than
one node is possible if CONFIG_NUMA is enabled.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

2 files changed, 7 insertions, 15 deletions

diff --git a/arch/s390/include/asm/numa.h b/arch/s390/include/asm/numa.h
index 35f8cbe7e5bb..23cd5d1b734b 100644
--- a/arch/s390/include/asm/numa.h
+++ b/arch/s390/include/asm/numa.h
@@ -13,24 +13,13 @@
 #ifdef CONFIG_NUMA
 
 #include <linux/numa.h>
-#include <linux/cpumask.h>
 
 void numa_setup(void);
-int numa_pfn_to_nid(unsigned long pfn);
-int __node_distance(int a, int b);
-void numa_update_cpu_topology(void);
-
-extern cpumask_t node_to_cpumask_map[MAX_NUMNODES];
-extern int numa_debug_enabled;
 
 #else
 
 static inline void numa_setup(void) { }
-static inline void numa_update_cpu_topology(void) { }
-static inline int numa_pfn_to_nid(unsigned long pfn)
-{
-	return 0;
-}
 
 #endif /* CONFIG_NUMA */
+
 #endif /* _ASM_S390_NUMA_H */
diff --git a/arch/s390/include/asm/topology.h b/arch/s390/include/asm/topology.h
index cca406fdbe51..bd3417185e30 100644
--- a/arch/s390/include/asm/topology.h
+++ b/arch/s390/include/asm/topology.h
@@ -16,7 +16,6 @@ struct cpu_topology_s390 {
 	unsigned short socket_id;
 	unsigned short book_id;
 	unsigned short drawer_id;
-	unsigned short node_id;
 	unsigned short dedicated : 1;
 	cpumask_t thread_mask;
 	cpumask_t core_mask;
@@ -71,19 +70,23 @@ static inline void topology_expect_change(void) { }
 #define cpu_to_node cpu_to_node
 static inline int cpu_to_node(int cpu)
 {
-	return cpu_topology[cpu].node_id;
+	return 0;
 }
 
 /* Returns a pointer to the cpumask of CPUs on node 'node'. */
 #define cpumask_of_node cpumask_of_node
 static inline const struct cpumask *cpumask_of_node(int node)
 {
-	return &node_to_cpumask_map[node];
+	return cpu_possible_mask;
 }
 
 #define pcibus_to_node(bus) __pcibus_to_node(bus)
 
 #define node_distance(a, b) __node_distance(a, b)
+static inline int __node_distance(int a, int b)
+{
+	return 0;
+}
 
 #else /* !CONFIG_NUMA */