mm: add helper ensure_zone_is_initialized()

ensure_zone_is_initialized() checks if a zone is in a empty & not
initialized state (typically occuring after it is created in memory
hotplugging), and, if so, calls init_currently_empty_zone() to
initialize the zone.

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: David Hansen <dave@linux.vnet.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
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, 11 insertions, 0 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 8b3235eedf3d..6e625f60dbcc 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -282,6 +282,17 @@ static void fix_zone_id(struct zone *zone, unsigned long start_pfn,
                 set_page_links(pfn_to_page(pfn), zid, nid, pfn);
 }
 
+/* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
+ * alloc_bootmem_node_nopanic() */
+static int __ref ensure_zone_is_initialized(struct zone *zone,
+                        unsigned long start_pfn, unsigned long num_pages)
+{
+        if (!zone_is_initialized(zone))
+                return init_currently_empty_zone(zone, start_pfn, num_pages,
+                                                 MEMMAP_HOTPLUG);
+        return 0;
+}
+
 static int __meminit move_pfn_range_left(struct zone *z1, struct zone *z2,
                 unsigned long start_pfn, unsigned long end_pfn)
 {