Re: [PATCH 1/1] mm/madvise: enhance lazyfreeing with mTHP in madvise_free

Barry Song
2024-02-27T01:21:50Z

> Thanks for your suggestion. I'll use folio_pte_batch() in v2.

Hi Lance,
Obviously, we both need this. While making large folio swap-in
v2, I am exporting folio_pte_batch() as below,

From: Barry Song <v-songbaohua@oppo.com>
Date: Tue, 27 Feb 2024 14:05:43 +1300
Subject: [PATCH] mm: export folio_pte_batch as a couple of modules need it

MADV_FREE, MADV_PAGEOUT and some other modules might need folio_pte_batch
to check if a range of PTEs are completely mapped to a large folio with
contiguous physcial offset.

Cc: Lance Yang <ioworker0@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
---
mm/internal.h | 13 +++++++++++++
mm/memory.c | 2 +-
2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/mm/internal.h b/mm/internal.h
index 36c11ea41f47..7e11aea3eda9 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -83,6 +83,19 @@ static inline void *folio_raw_mapping(struct folio *folio)
return (void *)(mapping & ~PAGE_MAPPING_FLAGS);
}

+/* Flags for folio_pte_batch(). */
+typedef int __bitwise fpb_t;
+
+/* Compare PTEs after pte_mkclean(), ignoring the dirty bit. */
+#define FPB_IGNORE_DIRTY ((__force fpb_t)BIT(0))
+
+/* Compare PTEs after pte_clear_soft_dirty(), ignoring the soft-dirty bit. */
+#define FPB_IGNORE_SOFT_DIRTY ((__force fpb_t)BIT(1))
+
+extern int folio_pte_batch(struct folio *folio, unsigned long addr,
+ pte_t *start_ptep, pte_t pte, int max_nr, fpb_t flags,
+ bool *any_writable);
+
void __acct_reclaim_writeback(pg_data_t *pgdat, struct folio *folio,
int nr_throttled);
static inline void acct_reclaim_writeback(struct folio *folio)
diff --git a/mm/memory.c b/mm/memory.c
index 6378f6bc22c5..dd9bd67f037a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -989,7 +989,7 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags)
* If "any_writable" is set, it will indicate if any other PTE besides the
* first (given) PTE is writable.
*/
-static inline int folio_pte_batch(struct folio *folio, unsigned long addr,
+int folio_pte_batch(struct folio *folio, unsigned long addr,
pte_t *start_ptep, pte_t pte, int max_nr, fpb_t flags,
bool *any_writable)
{
--
2.34.1

> Best,
> Lance

Thanks
Barry