[PATCH v1 10/11] mm/memory: ignore dirty/accessed/soft-dirty bits in folio_pte_batch()

David Hildenbrand
2024-01-22T19:43:52Z

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