linux-kernel - [PATCH 1/2] mm/mglru: only clear kswapd

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Message-ID: <20241014221211.832591-1-weixugc@google.com>
Date: Mon, 14 Oct 2024 22:12:11 +0000
From: Wei Xu <weixugc@...gle.com>
To: Yu Zhao <yuzhao@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Axel Rasmussen <axelrasmussen@...gle.com>, 
	linux-mm@...ck.org, linux-kernel@...r.kernel.org, Wei Xu <weixugc@...gle.com>
Subject: [PATCH 1/2] mm/mglru: only clear kswapd_failures if reclaimable

lru_gen_shrink_node() unconditionally clears kswapd_failures, which
can prevent kswapd from sleeping and cause 100% kswapd cpu usage even
when kswapd repeatedly fails to make progress in reclaim.

Only clear kswap_failures in lru_gen_shrink_node() if reclaim makes
some progress, similar to shrink_node().

Fixes: e4dde56cd208 ("mm: multi-gen LRU: per-node lru_gen_folio lists")
Signed-off-by: Wei Xu <weixugc@...gle.com>
---
 mm/vmscan.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 50dc06d55b1d..9d1e1c4e383d 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4970,8 +4970,8 @@ static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *
 
 	blk_finish_plug(&plug);
 done:
-	/* kswapd should never fail */
-	pgdat->kswapd_failures = 0;
+	if (sc->nr_reclaimed > reclaimed)
+		pgdat->kswapd_failures = 0;
 }
 
 /******************************************************************************
-- 
2.47.0.rc1.288.g06298d1525-goog