thp: move preallocated PTE page table on move_huge_pmd()

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

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index bccd5a628ea6765478d2fa45dc01390a83ee8a5b..33a5dc492810d59eae0c7069e60dd3bdd9c8a374 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1481,8 +1481,18 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
                pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
                VM_BUG_ON(!pmd_none(*new_pmd));
                set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
-               if (new_ptl != old_ptl)
+               if (new_ptl != old_ptl) {
+                       pgtable_t pgtable;
+
+                       /*
+                        * Move preallocated PTE page table if new_pmd is on
+                        * different PMD page table.
+                        */
+                       pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
+                       pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
+
                        spin_unlock(new_ptl);
+               }
                spin_unlock(old_ptl);
        }
 out: