linux-kernel - [PATCH 4/7] mm/khugepaged: minor cleanup for collapse

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Message-ID: <20220611084731.55155-5-linmiaohe@huawei.com>
Date:   Sat, 11 Jun 2022 16:47:28 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>
CC:     <aarcange@...hat.com>, <willy@...radead.org>, <vbabka@...e.cz>,
        <dhowells@...hat.com>, <neilb@...e.de>, <apopple@...dia.com>,
        <david@...hat.com>, <surenb@...gle.com>, <peterx@...hat.com>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <linmiaohe@...wei.com>
Subject: [PATCH 4/7] mm/khugepaged: minor cleanup for collapse_file

nr_none is always 0 for non-shmem case because the page can be read from
the backend store. So when nr_none ! = 0, it must be in is_shmem case.
Also only adjust the nrpages and uncharge shmem when nr_none != 0 to save
cpu cycles.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/khugepaged.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 1b5dd3820eac..8e6fad7c7bd9 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1885,8 +1885,7 @@ static void collapse_file(struct mm_struct *mm,
 
 	if (nr_none) {
 		__mod_lruvec_page_state(new_page, NR_FILE_PAGES, nr_none);
-		if (is_shmem)
-			__mod_lruvec_page_state(new_page, NR_SHMEM, nr_none);
+		__mod_lruvec_page_state(new_page, NR_SHMEM, nr_none);
 	}
 
 	/* Join all the small entries into a single multi-index entry */
@@ -1950,10 +1949,10 @@ static void collapse_file(struct mm_struct *mm,
 
 		/* Something went wrong: roll back page cache changes */
 		xas_lock_irq(&xas);
-		mapping->nrpages -= nr_none;
-
-		if (is_shmem)
+		if (nr_none) {
+			mapping->nrpages -= nr_none;
 			shmem_uncharge(mapping->host, nr_none);
+		}
 
 		xas_set(&xas, start);
 		xas_for_each(&xas, page, end - 1) {
-- 
2.23.0