memory hotplug: Hot-add with sparsemem-vmemmap

This patch is to avoid panic when memory hot-add is executed with
sparsemem-vmemmap.  Current vmemmap-sparsemem code doesn't support memory
hot-add.  Vmemmap must be populated when hot-add.  This is for
2.6.23-rc2-mm2.

Todo: # Even if this patch is applied, the message "[xxxx-xxxx] potential
        offnode page_structs" is displayed. To allocate memmap on its node,
        memmap (and pgdat) must be initialized itself like chicken and
        egg relationship.

      # vmemmap_unpopulate will be necessary for followings.
         - For cancel hot-add due to error.
         - For unplug.

Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 22 insertions, 3 deletions

diff --git a/mm/sparse.c b/mm/sparse.c
index 1f4dbb867b8a..08fb14f5eea3 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -259,7 +259,7 @@ static unsigned long *sparse_early_usemap_alloc(unsigned long pnum)
 }
 
 #ifndef CONFIG_SPARSEMEM_VMEMMAP
-struct page __init *sparse_early_mem_map_populate(unsigned long pnum, int nid)
+struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid)
 {
         struct page *map;
 
@@ -284,7 +284,7 @@ struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
         struct mem_section *ms = __nr_to_section(pnum);
         int nid = sparse_early_nid(ms);
 
-        map = sparse_early_mem_map_populate(pnum, nid);
+        map = sparse_mem_map_populate(pnum, nid);
         if (map)
                 return map;
 
@@ -322,6 +322,18 @@ void __init sparse_init(void)
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
+                                                 unsigned long nr_pages)
+{
+        /* This will make the necessary allocations eventually. */
+        return sparse_mem_map_populate(pnum, nid);
+}
+static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
+{
+        return; /* XXX: Not implemented yet */
+}
+#else
 static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
 {
         struct page *page, *ret;
@@ -344,6 +356,12 @@ got_map_ptr:
         return ret;
 }
 
+static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
+                                                  unsigned long nr_pages)
+{
+        return __kmalloc_section_memmap(nr_pages);
+}
+
 static int vaddr_in_vmalloc_area(void *addr)
 {
         if (addr >= (void *)VMALLOC_START &&
@@ -360,6 +378,7 @@ static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
                 free_pages((unsigned long)memmap,
                            get_order(sizeof(struct page) * nr_pages));
 }
+#endif /* CONFIG_SPARSEMEM_VMEMMAP */
 
 /*
  * returns the number of sections whose mem_maps were properly
@@ -382,7 +401,7 @@ int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
          * plus, it does a kmalloc
          */
         sparse_index_init(section_nr, pgdat->node_id);
-        memmap = __kmalloc_section_memmap(nr_pages);
+        memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, nr_pages);
         usemap = __kmalloc_section_usemap();
 
         pgdat_resize_lock(pgdat, &flags);