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>

1 files changed, 9 insertions, 138 deletions

diff --git a/arch/s390/numa/numa.c b/arch/s390/numa/numa.c
index d2910fa834c8..51c5a9f6e525 100644
--- a/arch/s390/numa/numa.c
+++ b/arch/s390/numa/numa.c
@@ -7,165 +7,36 @@
  * Copyright IBM Corp. 2015
  */
 
-#define KMSG_COMPONENT "numa"
-#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
-
 #include <linux/kernel.h>
 #include <linux/mmzone.h>
 #include <linux/cpumask.h>
 #include <linux/memblock.h>
-#include <linux/slab.h>
 #include <linux/node.h>
-
 #include <asm/numa.h>
-#include "numa_mode.h"
 
-pg_data_t *node_data[MAX_NUMNODES];
+struct pglist_data *node_data[MAX_NUMNODES];
 EXPORT_SYMBOL(node_data);
 
-cpumask_t node_to_cpumask_map[MAX_NUMNODES];
-EXPORT_SYMBOL(node_to_cpumask_map);
-
-static void plain_setup(void)
-{
-	node_set(0, node_possible_map);
-}
-
-const struct numa_mode numa_mode_plain = {
-	.name = "plain",
-	.setup = plain_setup,
-};
-
-static const struct numa_mode *mode = &numa_mode_plain;
-
-int numa_pfn_to_nid(unsigned long pfn)
-{
-	return mode->__pfn_to_nid ? mode->__pfn_to_nid(pfn) : 0;
-}
-
-void numa_update_cpu_topology(void)
-{
-	if (mode->update_cpu_topology)
-		mode->update_cpu_topology();
-}
-
-int __node_distance(int a, int b)
-{
-	return mode->distance ? mode->distance(a, b) : 0;
-}
-EXPORT_SYMBOL(__node_distance);
-
-int numa_debug_enabled;
-
-/*
- * numa_setup_memory() - Assign bootmem to nodes
- *
- * The memory is first added to memblock without any respect to nodes.
- * This is fixed before remaining memblock memory is handed over to the
- * buddy allocator.
- * An important side effect is that large bootmem allocations might easily
- * cross node boundaries, which can be needed for large allocations with
- * smaller memory stripes in each node (i.e. when using NUMA emulation).
- *
- * Memory defines nodes:
- * Therefore this routine also sets the nodes online with memory.
- */
-static void __init numa_setup_memory(void)
+void __init numa_setup(void)
 {
-	unsigned long cur_base, align, end_of_dram;
-	int nid = 0;
-
-	end_of_dram = memblock_end_of_DRAM();
-	align = mode->align ? mode->align() : ULONG_MAX;
-
-	/*
-	 * Step through all available memory and assign it to the nodes
-	 * indicated by the mode implementation.
-	 * All nodes which are seen here will be set online.
-	 */
-	cur_base = 0;
-	do {
-		nid = numa_pfn_to_nid(PFN_DOWN(cur_base));
-		node_set_online(nid);
-		memblock_set_node(cur_base, align, &memblock.memory, nid);
-		cur_base += align;
-	} while (cur_base < end_of_dram);
+	int nid;
 
-	/* Allocate and fill out node_data */
+	nodes_clear(node_possible_map);
+	node_set(0, node_possible_map);
+	node_set_online(0);
 	for (nid = 0; nid < MAX_NUMNODES; nid++) {
 		NODE_DATA(nid) = memblock_alloc(sizeof(pg_data_t), 8);
 		if (!NODE_DATA(nid))
 			panic("%s: Failed to allocate %zu bytes align=0x%x\n",
 			      __func__, sizeof(pg_data_t), 8);
 	}
-
-	for_each_online_node(nid) {
-		unsigned long start_pfn, end_pfn;
-		unsigned long t_start, t_end;
-		int i;
-
-		start_pfn = ULONG_MAX;
-		end_pfn = 0;
-		for_each_mem_pfn_range(i, nid, &t_start, &t_end, NULL) {
-			if (t_start < start_pfn)
-				start_pfn = t_start;
-			if (t_end > end_pfn)
-				end_pfn = t_end;
-		}
-		NODE_DATA(nid)->node_spanned_pages = end_pfn - start_pfn;
-		NODE_DATA(nid)->node_id = nid;
-	}
-}
-
-/*
- * numa_setup() - Earliest initialization
- *
- * Assign the mode and call the mode's setup routine.
- */
-void __init numa_setup(void)
-{
-	pr_info("NUMA mode: %s\n", mode->name);
-	nodes_clear(node_possible_map);
-	/* Initially attach all possible CPUs to node 0. */
-	cpumask_copy(&node_to_cpumask_map[0], cpu_possible_mask);
-	if (mode->setup)
-		mode->setup();
-	numa_setup_memory();
-	memblock_dump_all();
+	NODE_DATA(0)->node_spanned_pages = memblock_end_of_DRAM() >> PAGE_SHIFT;
+	NODE_DATA(0)->node_id = 0;
 }
 
-/*
- * numa_init_late() - Initialization initcall
- *
- * Register NUMA nodes.
- */
 static int __init numa_init_late(void)
 {
-	int nid;
-
-	for_each_online_node(nid)
-		register_one_node(nid);
+	register_one_node(0);
 	return 0;
 }
 arch_initcall(numa_init_late);
-
-static int __init parse_debug(char *parm)
-{
-	numa_debug_enabled = 1;
-	return 0;
-}
-early_param("numa_debug", parse_debug);
-
-static int __init parse_numa(char *parm)
-{
-	if (!parm)
-		return 1;
-	if (strcmp(parm, numa_mode_plain.name) == 0)
-		mode = &numa_mode_plain;
-#ifdef CONFIG_NUMA_EMU
-	if (strcmp(parm, numa_mode_emu.name) == 0)
-		mode = &numa_mode_emu;
-#endif
-	return 0;
-}
-early_param("numa", parse_numa);