linux-kernel - [RFC PATCH 2/3] fs/proc/task_mmu: Change to use huge_ptep_get_access

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Message-Id: <62de656111dcdb8d189698316f1c2721753d7c7a.1651998586.git.baolin.wang@linux.alibaba.com>
Date:   Sun,  8 May 2022 16:58:53 +0800
From:   Baolin Wang <baolin.wang@...ux.alibaba.com>
To:     catalin.marinas@....com, will@...nel.org, arnd@...db.de,
        mike.kravetz@...cle.com, akpm@...ux-foundation.org, sj@...nel.org
Cc:     baolin.wang@...ux.alibaba.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org
Subject: [RFC PATCH 2/3] fs/proc/task_mmu: Change to use huge_ptep_get_access_flags()

The ARM64 platform can support CONT-PTE/PMD size hugetlb, which can
contain seravel continuous pte or pmd entries. However current
huge_ptep_get() only return one specific pte value for the CONT-PTE
or CONT-PMD size hugetlb, which did not take into accounts the
subpages' dirty or young flags. So the gather_hugetlb_stats()
will miss some dirty hugetlb statistics.

Thus change to use huge_ptep_get_access_flags() taking into accounts
the subpages' dirty or young flags of a CONT-PTE/PMD size hugetlb,
to make the hugetlb statistics more accurate.

Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
---
 fs/proc/task_mmu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index f9c9abb..3f224a7 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1880,7 +1880,8 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
 static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
 		unsigned long addr, unsigned long end, struct mm_walk *walk)
 {
-	pte_t huge_pte = huge_ptep_get(pte);
+	pte_t huge_pte = huge_ptep_get_access_flags(pte,
+				huge_page_size(hstate_vma(walk->vma)));
 	struct numa_maps *md;
 	struct page *page;
 
-- 
1.8.3.1