linux-kernel - [PATCH 96/97] vmscan: do not evict inactive pages when skipping an active list scan

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Date:	Mon,  4 Jan 2010 16:33:49 -0800
From:	Greg Kroah-Hartman <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org,
	stable-review@...nel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Rik van Riel <riel@...hat.com>,
	Tomasz Chmielewski <mangoo@...g.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Rik Theys <rik.theys@...il.com>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: [PATCH 96/97] vmscan: do not evict inactive pages when skipping an active list scan

From: Rik van Riel <riel@...hat.com>

commit b39415b2731d7dec5e612d2d12595da82399eedf upstream.

In AIM7 runs, recent kernels start swapping out anonymous pages well
before they should.  This is due to shrink_list falling through to
shrink_inactive_list if !inactive_anon_is_low(zone, sc), when all we
really wanted to do is pre-age some anonymous pages to give them extra
time to be referenced while on the inactive list.

The obvious fix is to make sure that shrink_list does not fall through to
scanning/reclaiming inactive pages when we called it to scan one of the
active lists.

This change should be safe because the loop in shrink_zone ensures that we
will still shrink the anon and file inactive lists whenever we should.

[kosaki.motohiro@...fujitsu.com: inactive_file_is_low() should be inactive_anon_is_low()]
Reported-by: Larry Woodman <lwoodman@...hat.com>
Signed-off-by: Rik van Riel <riel@...hat.com>
Acked-by: Johannes Weiner <hannes@...xchg.org>
Cc: Tomasz Chmielewski <mangoo@...g.org>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Rik Theys <rik.theys@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
 mm/vmscan.c |   18 ++++++++++++------
 1 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 777af57..692807f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1464,20 +1464,26 @@ static int inactive_file_is_low(struct zone *zone, struct scan_control *sc)
 	return low;
 }
 
+static int inactive_list_is_low(struct zone *zone, struct scan_control *sc,
+				int file)
+{
+	if (file)
+		return inactive_file_is_low(zone, sc);
+	else
+		return inactive_anon_is_low(zone, sc);
+}
+
 static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
 	struct zone *zone, struct scan_control *sc, int priority)
 {
 	int file = is_file_lru(lru);
 
-	if (lru == LRU_ACTIVE_FILE && inactive_file_is_low(zone, sc)) {
-		shrink_active_list(nr_to_scan, zone, sc, priority, file);
+	if (is_active_lru(lru)) {
+		if (inactive_list_is_low(zone, sc, file))
+		    shrink_active_list(nr_to_scan, zone, sc, priority, file);
 		return 0;
 	}
 
-	if (lru == LRU_ACTIVE_ANON && inactive_anon_is_low(zone, sc)) {
-		shrink_active_list(nr_to_scan, zone, sc, priority, file);
-		return 0;
-	}
 	return shrink_inactive_list(nr_to_scan, zone, sc, priority, file);
 }
 
-- 
1.6.6

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