1 files changed, 20 insertions, 6 deletions

diff --git a/arch/x86_64/mm/srat.c b/arch/x86_64/mm/srat.c
index 8b7f85608fa8..3bd827f5611f 100644
--- a/arch/x86_64/mm/srat.c
+++ b/arch/x86_64/mm/srat.c
@@ -26,6 +26,10 @@ static nodemask_t nodes_found __initdata;
 static struct node nodes[MAX_NUMNODES] __initdata;
 static u8 pxm2node[256] = { [0 ... 255] = 0xff };
 
+/* Too small nodes confuse the VM badly. Usually they result
+   from BIOS bugs. */
+#define NODE_MIN_SIZE (4*1024*1024)
+
 static int node_to_pxm(int n);
 
 int pxm_to_node(int pxm)
@@ -223,6 +227,16 @@ static int nodes_cover_memory(void)
         return 1;
 }
 
+static void unparse_node(int node)
+{
+        int i;
+        node_clear(node, nodes_parsed);
+        for (i = 0; i < MAX_LOCAL_APIC; i++) {
+                if (apicid_to_node[i] == node)
+                        apicid_to_node[i] = NUMA_NO_NODE;
+        }
+}
+
 void __init acpi_numa_arch_fixup(void) {}
 
 /* Use the information discovered above to actually set up the nodes. */
@@ -230,16 +244,16 @@ int __init acpi_scan_nodes(unsigned long start, unsigned long end)
 {
         int i;
 
-        if (acpi_numa <= 0)
-                return -1;
-
         /* First clean up the node list */
-        for_each_node_mask(i, nodes_parsed) {
+        for (i = 0; i < MAX_NUMNODES; i++) {
                 cutoff_node(i, start, end);
-                if (nodes[i].start == nodes[i].end)
-                        node_clear(i, nodes_parsed);
+                if ((nodes[i].end - nodes[i].start) < NODE_MIN_SIZE)
+                        unparse_node(i);
         }
 
+        if (acpi_numa <= 0)
+                return -1;
+
         if (!nodes_cover_memory()) {
                 bad_srat();
                 return -1;