On 7/22/21 12:07 PM, Gavin Shan wrote:

quoted

quoted

        pgdp = pgd_offset(mm, vaddr);
      p4dp = p4d_alloc(mm, pgdp, vaddr);

@@ -1272,11 +1275,11 @@ static int __init debug_vm_pgtable(void)

       * Page table modifying tests. They need to hold
       * proper page table lock.
       */
-
-    ptep = pte_offset_map_lock(mm, pmdp, vaddr, &ptl);
-    pte_clear_tests(mm, ptep, pte_aligned, vaddr, prot);
-    pte_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot);
-    pte_unmap_unlock(ptep, ptl);
+    ptl = pte_lockptr(args.mm, args.pmdp);
+    spin_lock(ptl);
+    pte_clear_tests(&args);
+    pte_advanced_tests(&args);
+    spin_unlock(ptl);

Why pte_offset_map_lock()/pte_unmap_unlock() has been dropped and
spin_lock()/spin_unlock() sequence has been added ? Please dont
change the tests in these patches.

The semantics of pte_offset_map_lock() is to grab and take the lock
and return the PTE entry, which is mapped if needed. We already had
the PTE entry tracked by args->ptep in init_args(). So some of the
operations covered by pte_offset_map_lock() isn't needed any more

To keep the patch on purpose, please avoid this change here. But if
required, you could send a follow up patch later.