1 files changed, 2 insertions, 1 deletions

diff --git a/include/asm-i386/pgtable.h b/include/asm-i386/pgtable.h
index d101ac414f07..0e3ec809352d 100644
--- a/include/asm-i386/pgtable.h
+++ b/include/asm-i386/pgtable.h
@@ -203,7 +203,8 @@ extern unsigned long pg0[];
 #define pte_present(x)  ((x).pte_low & (_PAGE_PRESENT | _PAGE_PROTNONE))
 #define pte_clear(mm,addr,xp)   do { set_pte_at(mm, addr, xp, __pte(0)); } while (0)
 
-#define pmd_none(x)     (!pmd_val(x))
+/* To avoid harmful races, pmd_none(x) should check only the lower when PAE */
+#define pmd_none(x)     (!(unsigned long)pmd_val(x))
 #define pmd_present(x)  (pmd_val(x) & _PAGE_PRESENT)
 #define pmd_clear(xp)   do { set_pmd(xp, __pmd(0)); } while (0)
 #define pmd_bad(x)      ((pmd_val(x) & (~PAGE_MASK & ~_PAGE_USER)) != _KERNPG_TABLE)