mm/debug_vm_pgtable/pmd_clear: don't use pmd/pud_clear on pte entries

pmd_clear() should not be used to clear pmd level pte entries.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lkml.kernel.org/r/20200902114222.181353-12-aneesh.kumar@linux.ibm.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/debug_vm_pgtable.c

@@ -196,6 +196,8 @@ static void __init pmd_advanced_tests(struct mm_struct *mm,
 	pmd = READ_ONCE(*pmdp);
 	WARN_ON(pmd_young(pmd));
 
+	/*  Clear the pte entries  */
+	pmdp_huge_get_and_clear(mm, vaddr, pmdp);
 	pgtable = pgtable_trans_huge_withdraw(mm, pmdp);
 }
 
@@ -317,6 +319,8 @@ static void __init pud_advanced_tests(struct mm_struct *mm,
 	pudp_test_and_clear_young(vma, vaddr, pudp);
 	pud = READ_ONCE(*pudp);
 	WARN_ON(pud_young(pud));
+
+	pudp_huge_get_and_clear(mm, vaddr, pudp);
 }
 
 static void __init pud_leaf_tests(unsigned long pfn, pgprot_t prot)
@@ -440,8 +444,6 @@ static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp,
 	 * This entry points to next level page table page.
 	 * Hence this must not qualify as pud_bad().
 	 */
-	pmd_clear(pmdp);
-	pud_clear(pudp);
 	pud_populate(mm, pudp, pmdp);
 	pud = READ_ONCE(*pudp);
 	WARN_ON(pud_bad(pud));
@@ -573,7 +575,6 @@ static void __init pmd_populate_tests(struct mm_struct *mm, pmd_t *pmdp,
 	 * This entry points to next level page table page.
 	 * Hence this must not qualify as pmd_bad().
 	 */
-	pmd_clear(pmdp);
 	pmd_populate(mm, pmdp, pgtable);
 	pmd = READ_ONCE(*pmdp);
 	WARN_ON(pmd_bad(pmd));