mm/page_poisoning.c: allow for zero poisoning

[mirror_ubuntu-zesty-kernel.git] / mm / page_poison.c

diff --git a/mm/page_poison.c b/mm/page_poison.c
index 89d3bc77363327a62392b6a34243df01ffde4064..479e7ea2bea6651d00f4b4d363b9bc9ab952591b 100644 (file)
--- a/mm/page_poison.c
+++ b/mm/page_poison.c
@@ -71,11 +71,14 @@ static inline void clear_page_poison(struct page *page)
        __clear_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
 }
 
-static inline bool page_poison(struct page *page)
+bool page_is_poisoned(struct page *page)
 {
        struct page_ext *page_ext;
 
        page_ext = lookup_page_ext(page);
+       if (!page_ext)
+               return false;
+
        return test_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
 }
 
@@ -137,7 +140,7 @@ static void unpoison_page(struct page *page)
 {
        void *addr;
 
-       if (!page_poison(page))
+       if (!page_is_poisoned(page))
                return;
 
        addr = kmap_atomic(page);