memory hotplug: Correct page reservation checking

Index: linux/drivers/base/memory.c
===================================================================
@@ -227,41 +227,42 @@
  * MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
  * OK to have direct references to sparsemem variables in here.
  */
+static int check_page_reservations(unsigned long phys_index)
+{
+	int i;
+	struct page *page;
+
+	page = pfn_to_page(phys_index << PFN_SECTION_SHIFT);
+
+	for (i = 0; i < PAGES_PER_SECTION; i++) {
+		if (PageReserved(page + i))
+			continue;
+
+		printk(KERN_WARNING "section number %ld page number %d "
+			"not reserved, was it already online?\n", phys_index, i);
+			return -EBUSY;
+	}
+
+	return 0;
+}
+
 static int
 memory_block_action(unsigned long phys_index, unsigned long action)
 {
-	int i;
 	unsigned long start_pfn, start_paddr;
 	unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
-	struct page *first_page;
+	struct page *page;
 	int ret;
 
-	first_page = pfn_to_page(phys_index << PFN_SECTION_SHIFT);
-
-	/*
-	 * The probe routines leave the pages reserved, just
-	 * as the bootmem code does.  Make sure they're still
-	 * that way.
-	 */
-	if (action == MEM_ONLINE) {
-		for (i = 0; i < nr_pages; i++) {
-			if (PageReserved(first_page+i))
-				continue;
-
-			printk(KERN_WARNING "section number %ld page number %d "
-				"not reserved, was it already online?\n",
-				phys_index, i);
-			return -EBUSY;
-		}
-	}
+	page = pfn_to_page(phys_index << PFN_SECTION_SHIFT);
 
 	switch (action) {
 		case MEM_ONLINE:
-			start_pfn = page_to_pfn(first_page);
+			start_pfn = page_to_pfn(page);
 			ret = online_pages(start_pfn, nr_pages);
 			break;
 		case MEM_OFFLINE:
-			start_paddr = page_to_pfn(first_page) << PAGE_SHIFT;
+			start_paddr = page_to_pfn(page) << PAGE_SHIFT;
 			ret = remove_memory(start_paddr,
 					    nr_pages << PAGE_SHIFT);
 			break;

@@ -277,7 +278,7 @@
 static int memory_block_change_state(struct memory_block *mem,
 		unsigned long to_state, unsigned long from_state_req)
 {
-	int ret = 0;
+	int i, ret = 0;
 
 	mutex_lock(&mem->state_mutex);
 

@@ -289,6 +290,19 @@
 	if (to_state == MEM_OFFLINE)
 		mem->state = MEM_GOING_OFFLINE;
 
+	if (to_state == MEM_ONLINE) {
+		/*
+		 * The probe routines leave the pages reserved, just
+		 * as the bootmem code does.  Make sure they're still
+		 * that way.
+		 */
+		for (i = 0; i < sections_per_block; i++) {
+			ret = check_page_reservations(mem->start_section_nr + i);
+			if (ret)
+				return ret;
+		}
+	}
+
 	ret = memory_block_action(mem->start_section_nr, to_state);
 
 	if (ret)