linux-kernel - [PATCH] mm: page_alloc: avoid wakeup kswapd on the unintended node

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Message-id: <000001cfc357$74db64a0$5e922de0$%yang@samsung.com>
Date:	Fri, 29 Aug 2014 15:03:19 +0800
From:	Weijie Yang <weijie.yang@...sung.com>
To:	'Mel Gorman' <mgorman@...e.de>
Cc:	'Andrew Morton' <akpm@...ux-foundation.org>,
	'Rik van Riel' <riel@...hat.com>,
	'Johannes Weiner' <hannes@...xchg.org>, rientjes@...gle.com,
	'Weijie Yang' <weijie.yang.kh@...il.com>,
	'linux-kernel' <linux-kernel@...r.kernel.org>,
	'Linux-MM' <linux-mm@...ck.org>
Subject: [PATCH] mm: page_alloc: avoid wakeup kswapd on the unintended node

When enter page_alloc slowpath, we wakeup kswapd on every pgdat
according to the zonelist and high_zoneidx. However, this doesn't
take nodemask into account, and could prematurely wakeup kswapd on
some unintended nodes.

This patch uses for_each_zone_zonelist_nodemask() instead of
for_each_zone_zonelist() in wake_all_kswapds() to avoid the above situation.

Signed-off-by: Weijie Yang <weijie.yang@...sung.com>
---
 mm/page_alloc.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 18cee0d..29b595a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2457,12 +2457,14 @@ __alloc_pages_high_priority(gfp_t gfp_mask, unsigned int order,
 static void wake_all_kswapds(unsigned int order,
 			     struct zonelist *zonelist,
 			     enum zone_type high_zoneidx,
-			     struct zone *preferred_zone)
+			     struct zone *preferred_zone,
+			     nodemask_t *nodemask)
 {
 	struct zoneref *z;
 	struct zone *zone;
 
-	for_each_zone_zonelist(zone, z, zonelist, high_zoneidx)
+	for_each_zone_zonelist_nodemask(zone, z, zonelist,
+						high_zoneidx, nodemask)
 		wakeup_kswapd(zone, order, zone_idx(preferred_zone));
 }
 
@@ -2560,7 +2562,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 
 restart:
 	if (!(gfp_mask & __GFP_NO_KSWAPD))
-		wake_all_kswapds(order, zonelist, high_zoneidx, preferred_zone);
+		wake_all_kswapds(order, zonelist, high_zoneidx,
+				preferred_zone, nodemask);
 
 	/*
 	 * OK, we're below the kswapd watermark and have kicked background
-- 
1.7.10.4


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