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-rw-r--r--arch/x86/mm/pageattr.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 3810f7a83b1..7d21cd658ed 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -188,6 +188,14 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address)
return prot;
}
+/*
+ * Lookup the page table entry for a virtual address. Return a pointer
+ * to the entry and the level of the mapping.
+ *
+ * Note: We return pud and pmd either when the entry is marked large
+ * or when the present bit is not set. Otherwise we would return a
+ * pointer to a nonexisting mapping.
+ */
pte_t *lookup_address(unsigned long address, int *level)
{
pgd_t *pgd = pgd_offset_k(address);
@@ -206,7 +214,7 @@ pte_t *lookup_address(unsigned long address, int *level)
return NULL;
*level = PG_LEVEL_2M;
- if (pmd_large(*pmd))
+ if (pmd_large(*pmd) || !pmd_present(*pmd))
return (pte_t *)pmd;
*level = PG_LEVEL_4K;