linux-kernel - [PATCH v1 RESEND 4/6] mm/migrate: revert "mm/migrate: fix wrongly apply write bit after mkdirty on sparc64"

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Message-Id: <20230411142512.438404-5-david@redhat.com>
Date:   Tue, 11 Apr 2023 16:25:10 +0200
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
        sparclinux@...r.kernel.org, David Hildenbrand <david@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "David S. Miller" <davem@...emloft.net>,
        Peter Xu <peterx@...hat.com>, Hugh Dickins <hughd@...gle.com>,
        Shuah Khan <shuah@...nel.org>, Sam Ravnborg <sam@...nborg.org>,
        Yu Zhao <yuzhao@...gle.com>,
        Anshuman Khandual <anshuman.khandual@....com>
Subject: [PATCH v1 RESEND 4/6] mm/migrate: revert "mm/migrate: fix wrongly apply write bit after mkdirty on sparc64"

This reverts commit 96a9c287e25d ("mm/migrate: fix wrongly apply write bit
after mkdirty on sparc64").

Now that sparc64 mkdirty handling is fixed and no longer sets a PTE/PMD
writable that shouldn't be writable, let's revert the temporary fix.

The mkdirty mm selftest still passes with this change on sparc64.

Note that loongarch handling was fixed in commit bf2f34a506e6 ("LoongArch:
Set _PAGE_DIRTY only if _PAGE_WRITE is set in {pmd,pte}_mkdirty()").

Signed-off-by: David Hildenbrand <david@...hat.com>
---
 mm/huge_memory.c | 6 ++----
 mm/migrate.c     | 2 --
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 032fb0ef9cd1..ec86bf1d4e81 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3276,6 +3276,8 @@ void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
 	pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot));
 	if (pmd_swp_soft_dirty(*pvmw->pmd))
 		pmde = pmd_mksoft_dirty(pmde);
+	if (is_writable_migration_entry(entry))
+		pmde = maybe_pmd_mkwrite(pmde, vma);
 	if (pmd_swp_uffd_wp(*pvmw->pmd))
 		pmde = pmd_mkuffd_wp(pmde);
 	if (!is_migration_entry_young(entry))
@@ -3283,10 +3285,6 @@ void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
 	/* NOTE: this may contain setting soft-dirty on some archs */
 	if (PageDirty(new) && is_migration_entry_dirty(entry))
 		pmde = pmd_mkdirty(pmde);
-	if (is_writable_migration_entry(entry))
-		pmde = maybe_pmd_mkwrite(pmde, vma);
-	else
-		pmde = pmd_wrprotect(pmde);
 
 	if (PageAnon(new)) {
 		rmap_t rmap_flags = RMAP_COMPOUND;
diff --git a/mm/migrate.c b/mm/migrate.c
index db3f154446af..3b21c44e2176 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -225,8 +225,6 @@ static bool remove_migration_pte(struct folio *folio,
 			pte = maybe_mkwrite(pte, vma);
 		else if (pte_swp_uffd_wp(*pvmw.pte))
 			pte = pte_mkuffd_wp(pte);
-		else
-			pte = pte_wrprotect(pte);
 
 		if (folio_test_anon(folio) && !is_readable_migration_entry(entry))
 			rmap_flags |= RMAP_EXCLUSIVE;
-- 
2.39.2