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

From: Weijie Yang
Date: Fri Aug 29 2014 - 03:04:26 EST

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@xxxxxxxxxxx>
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,

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

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