linux-kernel - [PATCH] Revert "mm: vmpressure: fix sending wrong events on underflow"

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Date:   Wed, 7 Jun 2017 11:08:37 +0800
From:   zhongjiang <zhongjiang@...wei.com>
To:     <akpm@...ux-foundation.org>
CC:     <minchan@...nel.org>, <vinayakm.list@...il.com>, <mhocko@...e.com>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] Revert "mm: vmpressure: fix sending wrong events on underflow"

This reverts commit e1587a4945408faa58d0485002c110eb2454740c.

THP lru page is reclaimed , THP is split to normal page and loop again.
reclaimed pages should not be bigger than nr_scan.  because of each
loop will increase nr_scan counter.

Signed-off-by: zhongjiang <zhongjiang@...wei.com>
---
 mm/vmpressure.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/mm/vmpressure.c b/mm/vmpressure.c
index 6063581..149fdf6 100644
--- a/mm/vmpressure.c
+++ b/mm/vmpressure.c
@@ -112,16 +112,9 @@ static enum vmpressure_levels vmpressure_calc_level(unsigned long scanned,
 						    unsigned long reclaimed)
 {
 	unsigned long scale = scanned + reclaimed;
-	unsigned long pressure = 0;
+	unsigned long pressure;
 
 	/*
-	 * reclaimed can be greater than scanned in cases
-	 * like THP, where the scanned is 1 and reclaimed
-	 * could be 512
-	 */
-	if (reclaimed >= scanned)
-		goto out;
-	/*
 	 * We calculate the ratio (in percents) of how many pages were
 	 * scanned vs. reclaimed in a given time frame (window). Note that
 	 * time is in VM reclaimer's "ticks", i.e. number of pages
@@ -131,7 +124,6 @@ static enum vmpressure_levels vmpressure_calc_level(unsigned long scanned,
 	pressure = scale - (reclaimed * scale / scanned);
 	pressure = pressure * 100 / scale;
 
-out:
 	pr_debug("%s: %3lu  (s: %lu  r: %lu)\n", __func__, pressure,
 		 scanned, reclaimed);
 
-- 
1.7.12.4