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-rw-r--r--mm/memory.c41
1 files changed, 32 insertions, 9 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 9f2c15cdb32c..6bf2b471e30c 100644
--- 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