1 files changed, 40 insertions, 18 deletions

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 2a0b5f1020ed..8272d92d22c0 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -224,13 +224,48 @@ int memory_isolate_notify(unsigned long val, void *v)
 }
 
 /*
+ * The probe routines leave the pages reserved, just as the bootmem code does.
+ * Make sure they're still that way.
+ */
+static bool pages_correctly_reserved(unsigned long start_pfn,
+                                        unsigned long nr_pages)
+{
+        int i, j;
+        struct page *page;
+        unsigned long pfn = start_pfn;
+
+        /*
+         * memmap between sections is not contiguous except with
+         * SPARSEMEM_VMEMMAP. We lookup the page once per section
+         * and assume memmap is contiguous within each section
+         */
+        for (i = 0; i < sections_per_block; i++, pfn += PAGES_PER_SECTION) {
+                if (WARN_ON_ONCE(!pfn_valid(pfn)))
+                        return false;
+                page = pfn_to_page(pfn);
+
+                for (j = 0; j < PAGES_PER_SECTION; j++) {
+                        if (PageReserved(page + j))
+                                continue;
+
+                        printk(KERN_WARNING "section number %ld page number %d "
+                                "not reserved, was it already online?\n",
+                                pfn_to_section_nr(pfn), j);
+
+                        return false;
+                }
+        }
+
+        return true;
+}
+
+/*
  * MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
  * OK to have direct references to sparsemem variables in here.
  */
 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;
@@ -238,26 +273,13 @@ memory_block_action(unsigned long phys_index, unsigned long action)
 
         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;
-                }
-        }
-
         switch (action) {
                 case MEM_ONLINE:
                         start_pfn = page_to_pfn(first_page);
+
+                        if (!pages_correctly_reserved(start_pfn, nr_pages))
+                                return -EBUSY;
+
                         ret = online_pages(start_pfn, nr_pages);
                         break;
                 case MEM_OFFLINE: