x86_64: disable srat when numa emulation succeeds

When NUMA emulation succeeds, acpi_numa needs to be set to -1 so that
srat_disabled() will always return true.  We won't be calling
acpi_scan_nodes() or registering the true nodes we've found.

[hugh@veritas.com: Fix x86_64 CONFIG_NUMA_EMU build: acpi_numa needs CONFIG_ACPI_NUMA]
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/arch/x86_64/mm/numa.c b/arch/x86_64/mm/numa.c
index 0191b1ca6aa4..6da235522269 100644
--- a/arch/x86_64/mm/numa.c
+++ b/arch/x86_64/mm/numa.c
@@ -473,9 +473,13 @@ out:
 
         /*
          * We need to vacate all active ranges that may have been registered by
-         * SRAT.
+         * SRAT and set acpi_numa to -1 so that srat_disabled() always returns
+         * true.  NUMA emulation has succeeded so we will not scan ACPI nodes.
          */
         remove_all_active_ranges();
+#ifdef CONFIG_ACPI_NUMA
+        acpi_numa = -1;
+#endif
         for_each_node_mask(i, node_possible_map) {
                 e820_register_active_regions(i, nodes[i].start >> PAGE_SHIFT,
                                                 nodes[i].end >> PAGE_SHIFT);