1 files changed, 66 insertions, 4 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index c46887b5a11e..2168489c0bc9 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -11,7 +11,7 @@
 #include <linux/pagemap.h>
 #include <linux/bootmem.h>
 #include <linux/compiler.h>
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/pagevec.h>
 #include <linux/writeback.h>
 #include <linux/slab.h>
@@ -34,6 +34,17 @@
 
 #include "internal.h"
 
+/*
+ * online_page_callback contains pointer to current page onlining function.
+ * Initially it is generic_online_page(). If it is required it could be
+ * changed by calling set_online_page_callback() for callback registration
+ * and restore_online_page_callback() for generic callback restore.
+ */
+
+static void generic_online_page(struct page *page);
+
+static online_page_callback_t online_page_callback = generic_online_page;
+
 DEFINE_MUTEX(mem_hotplug_mutex);
 
 void lock_memory_hotplug(void)
@@ -361,23 +372,74 @@ int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
 }
 EXPORT_SYMBOL_GPL(__remove_pages);
 
-void online_page(struct page *page)
+int set_online_page_callback(online_page_callback_t callback)
+{
+        int rc = -EINVAL;
+
+        lock_memory_hotplug();
+
+        if (online_page_callback == generic_online_page) {
+                online_page_callback = callback;
+                rc = 0;
+        }
+
+        unlock_memory_hotplug();
+
+        return rc;
+}
+EXPORT_SYMBOL_GPL(set_online_page_callback);
+
+int restore_online_page_callback(online_page_callback_t callback)
+{
+        int rc = -EINVAL;
+
+        lock_memory_hotplug();
+
+        if (online_page_callback == callback) {
+                online_page_callback = generic_online_page;
+                rc = 0;
+        }
+
+        unlock_memory_hotplug();
+
+        return rc;
+}
+EXPORT_SYMBOL_GPL(restore_online_page_callback);
+
+void __online_page_set_limits(struct page *page)
 {
         unsigned long pfn = page_to_pfn(page);
 
-        totalram_pages++;
         if (pfn >= num_physpages)
                 num_physpages = pfn + 1;
+}
+EXPORT_SYMBOL_GPL(__online_page_set_limits);
+
+void __online_page_increment_counters(struct page *page)
+{
+        totalram_pages++;
 
 #ifdef CONFIG_HIGHMEM
         if (PageHighMem(page))
                 totalhigh_pages++;
 #endif
+}
+EXPORT_SYMBOL_GPL(__online_page_increment_counters);
 
+void __online_page_free(struct page *page)
+{
         ClearPageReserved(page);
         init_page_count(page);
         __free_page(page);
 }
+EXPORT_SYMBOL_GPL(__online_page_free);
+
+static void generic_online_page(struct page *page)
+{
+        __online_page_set_limits(page);
+        __online_page_increment_counters(page);
+        __online_page_free(page);
+}
 
 static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
                         void *arg)
@@ -388,7 +450,7 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
         if (PageReserved(pfn_to_page(start_pfn)))
                 for (i = 0; i < nr_pages; i++) {
                         page = pfn_to_page(start_pfn + i);
-                        online_page(page);
+                        (*online_page_callback)(page);
                         onlined_pages++;
                 }
         *(unsigned long *)arg = onlined_pages;