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From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org,
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Subject: [PATCH v1 10/11] mm/memory: ignore dirty/accessed/soft-dirty bits in folio_pte_batch()
Date: Mon, 22 Jan 2024 20:41:59 +0100
Message-ID: <20240122194200.381241-11-david@redhat.com>
In-Reply-To: <20240122194200.381241-1-david@redhat.com>
References: <20240122194200.381241-1-david@redhat.com>
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Let's ignore these bits: they are irrelevant for fork, and will likely
be irrelevant for upcoming users such as page unmapping.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 mm/memory.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index f563aec85b2a8..341b2be845b6e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -953,24 +953,30 @@ static __always_inline void __copy_present_ptes(struct vm_area_struct *dst_vma,
 	set_ptes(dst_vma->vm_mm, addr, dst_pte, pte, nr);
 }
 
+static inline pte_t __pte_batch_clear_ignored(pte_t pte)
+{
+	return pte_clear_soft_dirty(pte_mkclean(pte_mkold(pte)));
+}
+
 /*
  * Detect a PTE batch: consecutive (present) PTEs that map consecutive
  * pages of the same folio.
  *
  * All PTEs inside a PTE batch have the same PTE bits set, excluding the PFN.
+ * the accessed bit, dirty bit and soft-dirty bit.
  */
 static inline int folio_pte_batch(struct folio *folio, unsigned long addr,
 		pte_t *start_ptep, pte_t pte, int max_nr)
 {
 	unsigned long folio_end_pfn = folio_pfn(folio) + folio_nr_pages(folio);
 	const pte_t *end_ptep = start_ptep + max_nr;
-	pte_t expected_pte = pte_next_pfn(pte);
+	pte_t expected_pte = __pte_batch_clear_ignored(pte_next_pfn(pte));
 	pte_t *ptep = start_ptep + 1;
 
 	VM_WARN_ON_FOLIO(!pte_present(pte), folio);
 
 	while (ptep != end_ptep) {
-		pte = ptep_get(ptep);
+		pte = __pte_batch_clear_ignored(ptep_get(ptep));
 
 		if (!pte_same(pte, expected_pte))
 			break;
-- 
2.43.0