linux-kernel - [PATCH] vm_swappiness=0 should still try to avoid swapping anon memory

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Message-Id: <20210806231701.106980-1-npache@redhat.com>
Date:   Fri,  6 Aug 2021 19:17:01 -0400
From:   Nico Pache <npache@...hat.com>
To:     linux-mm@...ck.org, akpm@...ux-foundation.org,
        linux-kernel@...r.kernel.org
Cc:     hannes@...xchg.org, npache@...hat.com, aquini@...hat.com
Subject: [PATCH] vm_swappiness=0 should still try to avoid swapping anon memory

Since commit b91ac374346b ("mm: vmscan: enforce inactive:active ratio at the
reclaim root") swappiness can start prematurely swapping anon memory.
This is due to the assumption that refaulting anon should always allow
the shrinker to target anon memory. Add a check for vm_swappiness being
>0 before indiscriminately targeting Anon.

Signed-off-by: Nico Pache <npache@...hat.com>
---
 mm/vmscan.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4620df62f0ff..8b932ff72e37 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2909,8 +2909,8 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 
 		refaults = lruvec_page_state(target_lruvec,
 				WORKINGSET_ACTIVATE_ANON);
-		if (refaults != target_lruvec->refaults[0] ||
-			inactive_is_low(target_lruvec, LRU_INACTIVE_ANON))
+		if (vm_swappiness && (refaults != target_lruvec->refaults[0] ||
+			inactive_is_low(target_lruvec, LRU_INACTIVE_ANON)))
 			sc->may_deactivate |= DEACTIVATE_ANON;
 		else
 			sc->may_deactivate &= ~DEACTIVATE_ANON;
-- 
2.31.1