[PATCH] x86_64: Handle empty node zero

From: Daniel Yeisley <dan.yeisley@unisys.com>

It is possible to boot a Unisys ES7000 with CPUs from multiple cells, and not
also include the memory from those cells.  This can create a scenario where
node 0 has cpus, but no associated memory.  The system will boot fine in a
configuration where node 0 has memory, but nodes 2 and 3 do not.

[AK: I rechecked the code and generic code seems to indeed handle that already.
Dan's original patch had a change for mm/slab.c that seems to be already in now.]

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 8 insertions, 2 deletions

diff --git a/arch/x86_64/kernel/pci-dma.c b/arch/x86_64/kernel/pci-dma.c
index af035ede70cd..a9275c9557cf 100644
--- a/arch/x86_64/kernel/pci-dma.c
+++ b/arch/x86_64/kernel/pci-dma.c
@@ -54,6 +54,10 @@ dma_alloc_pages(struct device *dev, gfp_t gfp, unsigned order)
         else
 #endif
                 node = numa_node_id();
+
+        if (node < first_node(node_online_map))
+                node = first_node(node_online_map);
+
         page = alloc_pages_node(node, gfp, order);
         return page ? page_address(page) : NULL;
 }
diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c
index f0870bef24d1..655b9192eeb3 100644
--- a/arch/x86_64/kernel/setup.c
+++ b/arch/x86_64/kernel/setup.c
@@ -1051,7 +1051,7 @@ static void srat_detect_node(void)
            for now. */
         node = apicid_to_node[hard_smp_processor_id()];
         if (node == NUMA_NO_NODE)
-                node = 0;
+                node = first_node(node_online_map);
         numa_set_node(cpu, node);
 
         if (acpi_numa > 0)
diff --git a/arch/x86_64/mm/srat.c b/arch/x86_64/mm/srat.c
index e1513532df29..474df22c6ed2 100644
--- a/arch/x86_64/mm/srat.c
+++ b/arch/x86_64/mm/srat.c
@@ -399,8 +399,10 @@ int __init acpi_scan_nodes(unsigned long start, unsigned long end)
         /* First clean up the node list */
         for (i = 0; i < MAX_NUMNODES; i++) {
                 cutoff_node(i, start, end);
-                if ((nodes[i].end - nodes[i].start) < NODE_MIN_SIZE)
+                if ((nodes[i].end - nodes[i].start) < NODE_MIN_SIZE) {
                         unparse_node(i);
+                        node_set_offline(i);
+                }
         }
 
         if (acpi_numa <= 0)