linux-kernel - [RFC] mm/thp: Update mm's MM_ANONPAGES stat in set_huge_zero

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Message-Id: <1620890438-9127-1-git-send-email-anshuman.khandual@arm.com>
Date:   Thu, 13 May 2021 12:50:38 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     linux-mm@...ck.org
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Zi Yan <ziy@...dia.com>, linux-kernel@...r.kernel.org
Subject: [RFC] mm/thp: Update mm's MM_ANONPAGES stat in set_huge_zero_page()

Although the zero huge page is being shared across various processes, each
mapping needs to update its mm's MM_ANONPAGES stat by HPAGE_PMD_NR in order
to be consistent. This just updates the stats in set_huge_zero_page() after
the mapping gets created.

Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Zi Yan <ziy@...dia.com>
Cc: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
---
Should it update MM_SHMEM_PAGES instead ? Applies on latest mainline.

 mm/huge_memory.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 63ed6b25deaa..262703304807 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -706,6 +706,7 @@ static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
 	if (pgtable)
 		pgtable_trans_huge_deposit(mm, pmd, pgtable);
 	set_pmd_at(mm, haddr, pmd, entry);
+	add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
 	mm_inc_nr_ptes(mm);
 }
 
-- 
2.20.1