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From:   Zhenhua Huang <quic_zhenhuah@quicinc.com>
To:     <akpm@linux-foundation.org>
CC:     Zhenhua Huang <quic_zhenhuah@quicinc.com>, <linux-mm@kvack.org>,
        <linux-kernel@vger.kernel.org>
Subject: [PATCH] mm/page_owner.c: remove redudant drain_all_pages
Date:   Wed, 7 Sep 2022 16:01:13 +0800
Message-ID: <1662537673-9392-1-git-send-email-quic_zhenhuah@quicinc.com>
MIME-Version: 1.0
Content-Type: text/plain
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Page owner info of pages in pcp list have already been reset:
	free_unref_page
		-> free_unref_page_prepare
			-> free_pcp_prepare
				-> free_pages_prepare which do page owner
				reset
		-> free_unref_page_commit which add pages into pcp list
It can also be confirmed from dump that page owner info of pcp pages are
correct. Hence there is no more need to drain when reading.

Signed-off-by: Zhenhua Huang <quic_zhenhuah@quicinc.com>
---
 mm/page_owner.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/mm/page_owner.c b/mm/page_owner.c
index 90023f9..54f3e03 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -524,8 +524,6 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 	while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
 		pfn++;
 
-	drain_all_pages(NULL);
-
 	/* Find an allocated page */
 	for (; pfn < max_pfn; pfn++) {
 		/*
-- 
2.7.4