1 files changed, 8 insertions, 2 deletions

diff --git a/mm/sparse.c b/mm/sparse.c
index 58cab483e81b..73dc2fcc0eab 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -629,7 +629,7 @@ void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
         unsigned long pfn;
 
         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
-                unsigned long section_nr = pfn_to_section_nr(start_pfn);
+                unsigned long section_nr = pfn_to_section_nr(pfn);
                 struct mem_section *ms;
 
                 /*
@@ -779,7 +779,13 @@ int __meminit sparse_add_one_section(struct pglist_data *pgdat,
                 goto out;
         }
 
-        memset(memmap, 0, sizeof(struct page) * PAGES_PER_SECTION);
+#ifdef CONFIG_DEBUG_VM
+        /*
+         * Poison uninitialized struct pages in order to catch invalid flags
+         * combinations.
+         */
+        memset(memmap, PAGE_POISON_PATTERN, sizeof(struct page) * PAGES_PER_SECTION);
+#endif
 
         section_mark_present(ms);