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Message-ID: <20240814142647.3668269-1-usamaarif642@gmail.com>
Date: Wed, 14 Aug 2024 15:26:47 +0100
From: Usama Arif <usamaarif642@...il.com>
To: akpm@...ux-foundation.org
Cc: yuzhao@...gle.com,
david@...hat.com,
leitao@...ian.org,
huangzhaoyang@...il.com,
bharata@....com,
willy@...radead.org,
vbabka@...e.cz,
linux-kernel@...r.kernel.org,
kernel-team@...a.com,
Usama Arif <usamaarif642@...il.com>
Subject: [PATCH] mm: drop lruvec->lru_lock if contended when skipping folio
From: Yu Zhao <yuzhao@...gle.com>
lruvec->lru_lock is highly contended and is held when calling
isolate_lru_folios. If the lru has a large number of CMA folios
consecutively, while the allocation type requested is not MIGRATE_MOVABLE,
isolate_lru_folios can hold the lock for a very long time while it
skips those. vmscan_lru_isolate tracepoint showed that skipped can go
above 70k in production.
This can cause lockups [1] and high memory pressure for extended periods of
time [2]. Hence release the lock if its contended when skipping a folio to
give other tasks a chance to acquire it and not stall.
[1] https://lore.kernel.org/all/CAOUHufbkhMZYz20aM_3rHZ3OcK4m2puji2FGpUpn_-DevGk3Kg@mail.gmail.com/
[2] https://lore.kernel.org/all/ZrssOrcJIDy8hacI@gmail.com/
Signed-off-by: Yu Zhao <yuzhao@...gle.com>
Signed-off-by: Usama Arif <usamaarif642@...il.com>
---
mm/vmscan.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 25f4e8403f41..4e817d78abbb 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1696,8 +1696,14 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan,
if (folio_zonenum(folio) > sc->reclaim_idx ||
skip_cma(folio, sc)) {
nr_skipped[folio_zonenum(folio)] += nr_pages;
- move_to = &folios_skipped;
- goto move;
+ list_move(&folio->lru, &folios_skipped);
+ if (!spin_is_contended(&lruvec->lru_lock))
+ continue;
+ if (!list_empty(dst))
+ break;
+ spin_unlock_irq(&lruvec->lru_lock);
+ cond_resched();
+ spin_lock_irq(&lruvec->lru_lock);
}
/*
--
2.43.5
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