[PATCH] Reintroduce NODES_SPAN_OTHER_NODES for powerpc

Reintroduce NODES_SPAN_OTHER_NODES for powerpc

Revert "[PATCH] Remove SPAN_OTHER_NODES config definition"
    This reverts commit f62859bb6871c5e4a8e591c60befc8caaf54db8c.
Revert "[PATCH] mm: remove arch independent NODES_SPAN_OTHER_NODES"
    This reverts commit a94b3ab7eab4edcc9b2cb474b188f774c331adf7.

Also update the comments to indicate that this is still required
and where its used.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Kravetz <kravetz@us.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Will Schmidt <will_schmidt@vnet.ibm.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 18 insertions, 0 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 8b6910465578..2bd9b7fb0f6c 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -751,6 +751,15 @@ config ARCH_MEMORY_PROBE
         def_bool y
         depends on MEMORY_HOTPLUG
 
+# Some NUMA nodes have memory ranges that span
+# other nodes.  Even though a pfn is valid and
+# between a node's start and end pfns, it may not
+# reside on that node.  See memmap_init_zone()
+# for details.
+config NODES_SPAN_OTHER_NODES
+        def_bool y
+        depends on NEED_MULTIPLE_NODES
+
 config PPC_64K_PAGES
         bool "64k page size"
         depends on PPC64
diff --git a/arch/powerpc/configs/pseries_defconfig b/arch/powerpc/configs/pseries_defconfig
index 9828663652e9..d2833c1a1f3d 100644
--- a/arch/powerpc/configs/pseries_defconfig
+++ b/arch/powerpc/configs/pseries_defconfig
@@ -184,6 +184,7 @@ CONFIG_SPLIT_PTLOCK_CPUS=4
 CONFIG_MIGRATION=y
 CONFIG_RESOURCES_64BIT=y
 CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID=y
+CONFIG_NODES_SPAN_OTHER_NODES=y
 # CONFIG_PPC_64K_PAGES is not set
 CONFIG_SCHED_SMT=y
 CONFIG_PROC_DEVICETREE=y
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 59855b8718a0..ed0762b283a9 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -674,6 +674,12 @@ void sparse_init(void);
 #define sparse_index_init(_sec, _nid)  do {} while (0)
 #endif /* CONFIG_SPARSEMEM */
 
+#ifdef CONFIG_NODES_SPAN_OTHER_NODES
+#define early_pfn_in_nid(pfn, nid)      (early_pfn_to_nid(pfn) == (nid))
+#else
+#define early_pfn_in_nid(pfn, nid)      (1)
+#endif
+
 #ifndef early_pfn_valid
 #define early_pfn_valid(pfn)    (1)
 #endif
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ebd425c2e2a7..f5fc45472d5c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1689,6 +1689,8 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
         for (pfn = start_pfn; pfn < end_pfn; pfn++) {
                 if (!early_pfn_valid(pfn))
                         continue;
+                if (!early_pfn_in_nid(pfn, nid))
+                        continue;
                 page = pfn_to_page(pfn);
                 set_page_links(page, zone, nid, pfn);
                 init_page_count(page);