[RFC PATCH v2 2/4] madvise: Use notify-able API to clear and flush page table entries

From: Yin Fengwei
Date: Fri Jul 21 2023 - 05:42:07 EST


Currently, in function madvise_cold_or_pageout_pte_range(), the
young bit of pte/pmd is cleared notify subscripter.

Using notify-able API to make sure the subscripter is signaled about
the young bit clearing.

Signed-off-by: Yin Fengwei <fengwei.yin@xxxxxxxxx>
---
mm/madvise.c | 18 ++----------------
1 file changed, 2 insertions(+), 16 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index f12933ebcc24..b236e201a738 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -403,14 +403,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
return 0;
}

- if (pmd_young(orig_pmd)) {
- pmdp_invalidate(vma, addr, pmd);
- orig_pmd = pmd_mkold(orig_pmd);
-
- set_pmd_at(mm, addr, pmd, orig_pmd);
- tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
- }
-
+ pmdp_clear_flush_young_notify(vma, addr, pmd);
folio_clear_referenced(folio);
folio_test_clear_young(folio);
if (folio_test_active(folio))
@@ -496,14 +489,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,

VM_BUG_ON_FOLIO(folio_test_large(folio), folio);

- if (pte_young(ptent)) {
- ptent = ptep_get_and_clear_full(mm, addr, pte,
- tlb->fullmm);
- ptent = pte_mkold(ptent);
- set_pte_at(mm, addr, pte, ptent);
- tlb_remove_tlb_entry(tlb, pte, addr);
- }
-
+ ptep_clear_flush_young_notify(vma, addr, pte);
/*
* We are deactivating a folio for accelerating reclaiming.
* VM couldn't reclaim the folio unless we clear PG_young.
--
2.39.2