linux-kernel - [PATCH 1/3] mm: vmscan: Do use use PF_SWAPWRITE from zone

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Date:	Mon, 11 Jul 2011 14:01:12 +0100
From:	Mel Gorman <mgorman@...e.de>
To:	linux-mm@...ck.org
Cc:	linux-kernel@...r.kernel.org, Mel Gorman <mgorman@...e.de>
Subject: [PATCH 1/3] mm: vmscan: Do use use PF_SWAPWRITE from zone_reclaim

Zone reclaim is similar to direct reclaim in a number of respects.
PF_SWAPWRITE is used by kswapd to avoid a write-congestion check
but it's set also set for zone_reclaim which is inappropriate.
Setting it potentially allows zone_reclaim users to cause large IO
stalls which is worse than remote memory accesses.

Signed-off-by: Mel Gorman <mgorman@...e.de>
---
 mm/vmscan.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4f49535..ebef213 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3063,7 +3063,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 	 * and we also need to be able to write out pages for RECLAIM_WRITE
 	 * and RECLAIM_SWAP.
 	 */
-	p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
+	p->flags |= PF_MEMALLOC;
 	lockdep_set_current_reclaim_state(gfp_mask);
 	reclaim_state.reclaimed_slab = 0;
 	p->reclaim_state = &reclaim_state;
@@ -3116,7 +3116,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 	}
 
 	p->reclaim_state = NULL;
-	current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
+	current->flags &= ~PF_MEMALLOC;
 	lockdep_clear_current_reclaim_state();
 	return sc.nr_reclaimed >= nr_pages;
 }
-- 
1.7.3.4

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