2 files changed, 46 insertions, 0 deletions

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
new file mode 100644
index 000000000000..e8103be9d528
--- /dev/null
+++ b/include/linux/memory_hotplug.h
@@ -0,0 +1,34 @@
+#ifndef __LINUX_MEMORY_HOTPLUG_H
+#define __LINUX_MEMORY_HOTPLUG_H
+
+#include <linux/mmzone.h>
+#include <linux/spinlock.h>
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+/*
+ * pgdat resizing functions
+ */
+static inline
+void pgdat_resize_lock(struct pglist_data *pgdat, unsigned long *flags)
+{
+        spin_lock_irqsave(&pgdat->node_size_lock, *flags);
+}
+static inline
+void pgdat_resize_unlock(struct pglist_data *pgdat, unsigned long *flags)
+{
+        spin_lock_irqrestore(&pgdat->node_size_lock, *flags);
+}
+static inline
+void pgdat_resize_init(struct pglist_data *pgdat)
+{
+        spin_lock_init(&pgdat->node_size_lock);
+}
+#else /* ! CONFIG_MEMORY_HOTPLUG */
+/*
+ * Stub functions for when hotplug is off
+ */
+static inline void pgdat_resize_lock(struct pglist_data *p, unsigned long *f) {}
+static inline void pgdat_resize_unlock(struct pglist_data *p, unsigned long *f) {}
+static inline void pgdat_resize_init(struct pglist_data *pgdat) {}
+#endif
+#endif /* __LINUX_MEMORY_HOTPLUG_H */
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 4674145bb63d..e050d68963a1 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -273,6 +273,16 @@ typedef struct pglist_data {
         struct page *node_mem_map;
 #endif
         struct bootmem_data *bdata;
+#ifdef CONFIG_MEMORY_HOTPLUG
+        /*
+         * Must be held any time you expect node_start_pfn, node_present_pages
+         * or node_spanned_pages stay constant.  Holding this will also
+         * guarantee that any pfn_valid() stays that way.
+         *
+         * Nests above zone->lock and zone->size_seqlock.
+         */
+        spinlock_t node_size_lock;
+#endif
         unsigned long node_start_pfn;
         unsigned long node_present_pages; /* total number of physical pages */
         unsigned long node_spanned_pages; /* total size of physical page
@@ -293,6 +303,8 @@ typedef struct pglist_data {
 #endif
 #define nid_page_nr(nid, pagenr)        pgdat_page_nr(NODE_DATA(nid),(pagenr))
 
+#include <linux/memory_hotplug.h>
+
 extern struct pglist_data *pgdat_list;
 
 void __get_zone_counts(unsigned long *active, unsigned long *inactive,