1 files changed, 9 insertions, 1 deletions

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index d1da415e283c..818a58fc3f4f 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -608,9 +608,17 @@ static inline pte_t pte_mkdevmap(pte_t pte)
         return __pte(pte_val(pte) | _PAGE_SPECIAL|_PAGE_DEVMAP);
 }
 
+/*
+ * This is potentially called with a pmd as the argument, in which case it's not
+ * safe to check _PAGE_DEVMAP unless we also confirm that _PAGE_PTE is set.
+ * That's because the bit we use for _PAGE_DEVMAP is not reserved for software
+ * use in page directory entries (ie. non-ptes).
+ */
 static inline int pte_devmap(pte_t pte)
 {
-        return !!(pte_raw(pte) & cpu_to_be64(_PAGE_DEVMAP));
+        u64 mask = cpu_to_be64(_PAGE_DEVMAP | _PAGE_PTE);
+
+        return (pte_raw(pte) & mask) == mask;
 }
 
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)