linux-kernel - [PATCH 2/3] mm/swapfile: avoid confusing swap cache statistics

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Date:   Fri, 27 May 2022 17:26:25 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <linmiaohe@...wei.com>
Subject: [PATCH 2/3] mm/swapfile: avoid confusing swap cache statistics

At swapoff time, we're going to swap in the pages continuously. So calling
lookup_swap_cache would confuse statistics. We should use find_get_page
directly here.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/swapfile.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 960d14a4b19e..e033a53a99df 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1865,7 +1865,12 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
 		offset = swp_offset(entry);
 		pte_unmap(pte);
 		swap_map = &si->swap_map[offset];
-		page = lookup_swap_cache(entry, vma, addr);
+		/*
+		 * Since we're going to swap in the pages continuously,
+		 * calling lookup_swap_cache() would confuse statistics.
+		 */
+		page = find_get_page(swap_address_space(entry),
+				     swp_offset(entry));
 		if (!page) {
 			struct vm_fault vmf = {
 				.vma = vma,
-- 
2.23.0