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

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Date:   Fri, 21 Jul 2023 17:40:41 +0800
From:   Yin Fengwei <fengwei.yin@...el.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        akpm@...ux-foundation.org, minchan@...nel.org, yuzhao@...gle.com,
        willy@...radead.org, david@...hat.com, ryan.roberts@....com,
        shy828301@...il.com
Cc:     fengwei.yin@...el.com
Subject: [RFC PATCH v2 2/4] madvise: Use notify-able API to clear and flush page table entries

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@...el.com>
---
 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