linux-kernel - [PATCH] vmscan: initialize sc->nr

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Message-Id: <20090210215718.700D.KOSAKI.MOTOHIRO@jp.fujitsu.com>
Date:	Tue, 10 Feb 2009 21:58:04 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	MinChan Kim <minchan.kim@...il.com>,
	Johannes Weiner <hannes@...xchg.org>
Cc:	kosaki.motohiro@...fujitsu.com, Rik van Riel <riel@...hat.com>,
	William Lee Irwin III <wli@...ementarian.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH] vmscan: initialize sc->nr_reclaimed properly take2


How about this?

===
From: Johannes Weiner <hannes@...xchg.org>
Subject: [PATCH] vmscan: initialize sc->nr_reclaimed properly

Commit a79311c14eae4bb946a97af25f3e1b17d625985d "vmscan: bail out of
direct reclaim after swap_cluster_max pages" moved the nr_reclaimed
counter into the scan control to accumulate the number of all
reclaimed pages in one direct reclaim invocation.

The commit missed to actually adjust try_to_free_pages() and __zone_reclaim()
which now does not initialize sc.nr_reclaimed and makes shrink_zone() make
assumptions on whether to bail out of the reclaim cycle based on an
uninitialized value.

Fix it up. 

Signed-off-by: Johannes Weiner <hannes@...xchg.org>
Signed-off-by: MinChan Kim <minchan.kim@...il.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
---
 mm/vmscan.c |    3 +++
 1 file changed, 3 insertions(+)

Index: b/mm/vmscan.c
===================================================================
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1665,6 +1665,7 @@ unsigned long try_to_free_pages(struct z
 								gfp_t gfp_mask)
 {
 	struct scan_control sc = {
+		.nr_reclaimed = 0,
 		.gfp_mask = gfp_mask,
 		.may_writepage = !laptop_mode,
 		.swap_cluster_max = SWAP_CLUSTER_MAX,
@@ -1686,6 +1687,7 @@ unsigned long try_to_free_mem_cgroup_pag
 					   unsigned int swappiness)
 {
 	struct scan_control sc = {
+		.nr_reclaimed = 0,
 		.may_writepage = !laptop_mode,
 		.may_swap = 1,
 		.swap_cluster_max = SWAP_CLUSTER_MAX,
@@ -2245,6 +2247,7 @@ static int __zone_reclaim(struct zone *z
 	struct reclaim_state reclaim_state;
 	int priority;
 	struct scan_control sc = {
+		.nr_reclaimed = 0,
 		.may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
 		.may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP),
 		.swap_cluster_max = max_t(unsigned long, nr_pages,


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