linux-kernel - [PATCH] mm: correct the comment when reclaimed pages exceed the scanned pages

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Message-ID: <1496824266-25235-1-git-send-email-zhongjiang@huawei.com>
Date:   Wed, 7 Jun 2017 16:31:06 +0800
From:   zhongjiang <zhongjiang@...wei.com>
To:     <akpm@...ux-foundation.org>
CC:     <minchan@...nel.org>, <vinayakm.list@...il.com>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] mm: correct the comment when reclaimed pages exceed the scanned pages

The commit e1587a494540 ("mm: vmpressure: fix sending wrong events on
underflow") declare that reclaimed pages exceed the scanned pages due
to the thp reclaim. it is incorrect because THP will be spilt to normal
page and loop again. which will result in the scanned pages increment.

Signed-off-by: zhongjiang <zhongjiang@...wei.com>
---
 mm/vmpressure.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/vmpressure.c b/mm/vmpressure.c
index 6063581..0e91ba3 100644
--- a/mm/vmpressure.c
+++ b/mm/vmpressure.c
@@ -116,8 +116,9 @@ static enum vmpressure_levels vmpressure_calc_level(unsigned long scanned,
 
 	/*
 	 * reclaimed can be greater than scanned in cases
-	 * like THP, where the scanned is 1 and reclaimed
-	 * could be 512
+	 * like reclaimed slab pages, shrink_node just add
+	 * reclaimed page without a related increment to
+	 * scanned pages.
 	 */
 	if (reclaimed >= scanned)
 		goto out;
-- 
1.7.12.4