[PATCH 3/4] vmscan: zone_reclaim use may_swap

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

Subject: [PATCH] vmscan: zone_reclaim use may_swap

Documentation/sysctl/vm.txt says

	zone_reclaim_mode:

	Zone_reclaim_mode allows someone to set more or less aggressive approaches to
	reclaim memory when a zone runs out of memory. If it is set to zero then no
	zone reclaim occurs. Allocations will be satisfied from other zones / nodes
	in the system.

	This is value ORed together of

	1	= Zone reclaim on
	2	= Zone reclaim writes dirty pages out
	4	= Zone reclaim swaps pages


So, "(zone_reclaim_mode & RECLAIM_SWAP) == 0" mean we don't want to reclaim
swap-backed pages. not mapped file.

Thus, may_swap is better than may_unmap.


Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Rik van Riel <riel@redhat.com>
---
 mm/vmscan.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: b/mm/vmscan.c
===================================================================
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2387,8 +2387,8 @@ static int __zone_reclaim(struct zone *z
 	int priority;
 	struct scan_control sc = {
 		.may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
-		.may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
-		.may_swap = 1,
+		.may_unmap = 1,
+		.may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP),
 		.swap_cluster_max = max_t(unsigned long, nr_pages,
 					SWAP_CLUSTER_MAX),
 		.gfp_mask = gfp_mask,


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