x86/mm/numa: Remove numa_nodemask_from_meminfo()

numa_nodemask_from_meminfo() generates a nodemask of nodes which have
memory according to a meminfo descriptor.

The two callsites of that function both set bits in copies of the
numa_nodes_parsed nodemask. In both cases, the information in supplied
numa_meminfo is a subset of numa_nodes_parsed. So setting those bits
again is not really necessary.

Here are the three call paths which show that the supplied numa_meminfo
argument describes memory regions in nodes which are already in
numa_nodes_parsed:

    x86_numa_init()
        numa_init()
            Case 1:
            acpi_numa_init()
	    acpi_parse_memory_affinity()
                    numa_add_memblk()
                    node_set(numa_nodes_parsed)
                acpi_parse_slit()
		 acpi_numa_slit_init()
		  numa_set_distance()
		   numa_alloc_distance()
                    numa_nodemask_from_meminfo()

            Case 2:
            amd_numa_init()
                numa_add_memblk()
                node_set(numa_nodes_parsed)

            Case 3
            dummy_numa_init()
                node_set(numa_nodes_parsed)
                numa_add_memblk()

            numa_register_memblks()
                numa_nodemask_from_meminfo()

Thus, in all three cases, the respective bit in numa_nodes_parsed is
set, which means it is not necessary to set it again in a copy of
numa_nodes_parsed.

So remove that function.
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: x86-ml <x86@kernel.org>
Link: http://lkml.kernel.org/r/20170314030801.13656-2-richard.weiyang@gmail.com
[ Heavily massage commit message. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/mm/numa.c

@@ -314,20 +314,6 @@ int __init numa_cleanup_meminfo(struct numa_meminfo *mi)
 	return 0;
 }
 
-/*
- * Set nodes, which have memory in @mi, in *@nodemask.
- */
-static void __init numa_nodemask_from_meminfo(nodemask_t *nodemask,
-					      const struct numa_meminfo *mi)
-{
-	int i;
-
-	for (i = 0; i < ARRAY_SIZE(mi->blk); i++)
-		if (mi->blk[i].start != mi->blk[i].end &&
-		    mi->blk[i].nid != NUMA_NO_NODE)
-			node_set(mi->blk[i].nid, *nodemask);
-}
-
 /**
  * numa_reset_distance - Reset NUMA distance table
  *
@@ -347,16 +333,12 @@ void __init numa_reset_distance(void)
 
 static int __init numa_alloc_distance(void)
 {
-	nodemask_t nodes_parsed;
 	size_t size;
 	int i, j, cnt = 0;
 	u64 phys;
 
 	/* size the new table and allocate it */
-	nodes_parsed = numa_nodes_parsed;
-	numa_nodemask_from_meminfo(&nodes_parsed, &numa_meminfo);
-
-	for_each_node_mask(i, nodes_parsed)
+	for_each_node_mask(i, numa_nodes_parsed)
 		cnt = i;
 	cnt++;
 	size = cnt * cnt * sizeof(numa_distance[0]);
@@ -535,7 +517,6 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
 
 	/* Account for nodes with cpus and no memory */
 	node_possible_map = numa_nodes_parsed;
-	numa_nodemask_from_meminfo(&node_possible_map, mi);
 	if (WARN_ON(nodes_empty(node_possible_map)))
 		return -EINVAL;