xfrm: policy: make policy backend const

[mirror_ubuntu-artful-kernel.git] / mm / memory.c

diff --git a/mm/memory.c b/mm/memory.c
index 9f2c15cdb32c6327c0d2e8992c5c269ba573f698..6bf2b471e30ca566a55160e4131bf7e7b9c3c4ea 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3772,8 +3772,8 @@ int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
 }
 #endif /* __PAGETABLE_PMD_FOLDED */
 
-static int __follow_pte(struct mm_struct *mm, unsigned long address,
-               pte_t **ptepp, spinlock_t **ptlp)
+static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
+               pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
 {
        pgd_t *pgd;
        pud_t *pud;
@@ -3790,11 +3790,20 @@ static int __follow_pte(struct mm_struct *mm, unsigned long address,
 
        pmd = pmd_offset(pud, address);
        VM_BUG_ON(pmd_trans_huge(*pmd));
-       if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
-               goto out;
 
-       /* We cannot handle huge page PFN maps. Luckily they don't exist. */
-       if (pmd_huge(*pmd))
+       if (pmd_huge(*pmd)) {
+               if (!pmdpp)
+                       goto out;
+
+               *ptlp = pmd_lock(mm, pmd);
+               if (pmd_huge(*pmd)) {
+                       *pmdpp = pmd;
+                       return 0;
+               }
+               spin_unlock(*ptlp);
+       }
+
+       if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
                goto out;
 
        ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
@@ -3810,16 +3819,30 @@ out:
        return -EINVAL;
 }
 
-int follow_pte(struct mm_struct *mm, unsigned long address, pte_t **ptepp,
-              spinlock_t **ptlp)
+static inline int follow_pte(struct mm_struct *mm, unsigned long address,
+                            pte_t **ptepp, spinlock_t **ptlp)
+{
+       int res;
+
+       /* (void) is needed to make gcc happy */
+       (void) __cond_lock(*ptlp,
+                          !(res = __follow_pte_pmd(mm, address, ptepp, NULL,
+                                          ptlp)));
+       return res;
+}
+
+int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
+                            pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
 {
        int res;
 
        /* (void) is needed to make gcc happy */
        (void) __cond_lock(*ptlp,
-                          !(res = __follow_pte(mm, address, ptepp, ptlp)));
+                          !(res = __follow_pte_pmd(mm, address, ptepp, pmdpp,
+                                          ptlp)));
        return res;
 }
+EXPORT_SYMBOL(follow_pte_pmd);
 
 /**
  * follow_pfn - look up PFN at a user virtual address