mm/swap: fix race on swap_info reuse between swapoff and swapon

[cascardo/linux.git] / mm / huge_memory.c

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 65c98eb..82166bf 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1508,19 +1508,15 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
                        spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
                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) {
-                       pgtable_t pgtable;
 
-                       /*
-                        * Move preallocated PTE page table if new_pmd is on
-                        * different PMD page table.
-                        */
+               if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
+                       pgtable_t pgtable;
                        pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
                        pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
-
-                       spin_unlock(new_ptl);
                }
+               set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
+               if (new_ptl != old_ptl)
+                       spin_unlock(new_ptl);
                spin_unlock(old_ptl);
        }
 out: