Subject: [PATCH 08/16] debug_vm_pgtable/set_pmd: Don't use set_pmd_at to update an existing pmd entry

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Wed, 12 Aug 2020 12:03:50 +0530

set_pmd_at() should not be used to set a pte entry at locations that
already holds a valid pte entry. Architectures like ppc64 don't do TLB
invalidate in set_pmd_at() and hence expect it to be used to set locations
that are not a valid PTE.

Signed-off-by: Aneesh Kumar K.V <[email-masked]>
---
 mm/debug_vm_pgtable.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index cd609a212dd4..60bf876081b8 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -164,8 +164,6 @@ static void __init pmd_advanced_tests(struct mm_struct *mm,
 	pmd = READ_ONCE(*pmdp);
 	WARN_ON(pmd_write(pmd));
 
-	pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
-	set_pmd_at(mm, vaddr, pmdp, pmd);
 	pmdp_huge_get_and_clear(mm, vaddr, pmdp);
 	pmd = READ_ONCE(*pmdp);
 	WARN_ON(!pmd_none(pmd));
@@ -180,12 +178,11 @@ static void __init pmd_advanced_tests(struct mm_struct *mm,
 	pmd = READ_ONCE(*pmdp);
 	WARN_ON(!(pmd_write(pmd) && pmd_dirty(pmd)));
 
-	pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
-	set_pmd_at(mm, vaddr, pmdp, pmd);
 	pmdp_huge_get_and_clear_full(vma, vaddr, pmdp, 1);
 	pmd = READ_ONCE(*pmdp);
 	WARN_ON(!pmd_none(pmd));
 
+	pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
 	pmd = pmd_mkyoung(pmd);
 	set_pmd_at(mm, vaddr, pmdp, pmd);
 	pmdp_test_and_clear_young(vma, vaddr, pmdp);
-- 
2.26.2