linux-kernel - [PATCH 5.18 019/231] mm/damon: use set_huge_pte

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Date:   Tue, 19 Jul 2022 13:51:44 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        SeongJae Park <sj@...nel.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Muchun Song <songmuchun@...edance.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 5.18 019/231] mm/damon: use set_huge_pte_at() to make huge pte old

From: Baolin Wang <baolin.wang@...ux.alibaba.com>

commit ed1523a895ffdabcab6e067af18685ed00f5ce15 upstream.

The huge_ptep_set_access_flags() can not make the huge pte old according
to the discussion [1], that means we will always mornitor the young state
of the hugetlb though we stopped accessing the hugetlb, as a result DAMON
will get inaccurate accessing statistics.

So changing to use set_huge_pte_at() to make the huge pte old to fix this
issue.

[1] https://lore.kernel.org/all/Yqy97gXI4Nqb7dYo@arm.com/

Link: https://lkml.kernel.org/r/1655692482-28797-1-git-send-email-baolin.wang@linux.alibaba.com
Fixes: 49f4203aae06 ("mm/damon: add access checking for hugetlb pages")
Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
Reviewed-by: SeongJae Park <sj@...nel.org>
Acked-by: Mike Kravetz <mike.kravetz@...cle.com>
Reviewed-by: Muchun Song <songmuchun@...edance.com>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 mm/damon/vaddr.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -407,8 +407,7 @@ static void damon_hugetlb_mkold(pte_t *p
 	if (pte_young(entry)) {
 		referenced = true;
 		entry = pte_mkold(entry);
-		huge_ptep_set_access_flags(vma, addr, pte, entry,
-					   vma->vm_flags & VM_WRITE);
+		set_huge_pte_at(mm, addr, pte, entry);
 	}
 
 #ifdef CONFIG_MMU_NOTIFIER