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From:   Kairui Song <ryncsn@gmail.com>
To:     linux-mm@kvack.org
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Yu Zhao <yuzhao@google.com>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@suse.com>,
        Hugh Dickins <hughd@google.com>, Nhat Pham <nphamcs@gmail.com>,
        Yuanchu Xie <yuanchu@google.com>,
        Kalesh Singh <kaleshsingh@google.com>,
        Suren Baghdasaryan <surenb@google.com>,
        "T . J . Mercier" <tjmercier@google.com>,
        linux-kernel@vger.kernel.org, Kairui Song <kasong@tencent.com>
Subject: [RFC PATCH v3 5/6] mm, lru_gen: convert avg_total and avg_refaulted to atomic
Date:   Thu, 21 Sep 2023 03:02:43 +0800
Message-ID: <20230920190244.16839-6-ryncsn@gmail.com>
In-Reply-To: <20230920190244.16839-1-ryncsn@gmail.com>
References: <20230920190244.16839-1-ryncsn@gmail.com>
Reply-To: Kairui Song <kasong@tencent.com>
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From: Kairui Song <kasong@tencent.com>

No feature change, prepare for later patch.

Signed-off-by: Kairui Song <kasong@tencent.com>
---
 include/linux/mmzone.h |  4 ++--
 mm/vmscan.c            | 16 ++++++++--------
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 4106fbc5b4b3..d944987b67d3 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -425,9 +425,9 @@ struct lru_gen_folio {
 	/* the multi-gen LRU sizes, eventually consistent */
 	long nr_pages[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES];
 	/* the exponential moving average of refaulted */
-	unsigned long avg_refaulted[ANON_AND_FILE][MAX_NR_TIERS];
+	atomic_long_t avg_refaulted[ANON_AND_FILE][MAX_NR_TIERS];
 	/* the exponential moving average of evicted+protected */
-	unsigned long avg_total[ANON_AND_FILE][MAX_NR_TIERS];
+	atomic_long_t avg_total[ANON_AND_FILE][MAX_NR_TIERS];
 	/* the first tier doesn't need protection, hence the minus one */
 	unsigned long protected[NR_HIST_GENS][ANON_AND_FILE][MAX_NR_TIERS - 1];
 	/* can be modified without holding the LRU lock */
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 3f4de75e5186..82acc1934c86 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3705,9 +3705,9 @@ static void read_ctrl_pos(struct lruvec *lruvec, int type, int tier, int gain,
 	struct lru_gen_folio *lrugen = &lruvec->lrugen;
 	int hist = lru_hist_from_seq(lrugen->min_seq[type]);
 
-	pos->refaulted = lrugen->avg_refaulted[type][tier] +
+	pos->refaulted = atomic_long_read(&lrugen->avg_refaulted[type][tier]) +
 			 atomic_long_read(&lrugen->refaulted[hist][type][tier]);
-	pos->total = lrugen->avg_total[type][tier] +
+	pos->total = atomic_long_read(&lrugen->avg_total[type][tier]) +
 		     atomic_long_read(&lrugen->evicted[hist][type][tier]);
 	if (tier)
 		pos->total += lrugen->protected[hist][type][tier - 1];
@@ -3732,15 +3732,15 @@ static void reset_ctrl_pos(struct lruvec *lruvec, int type, bool carryover)
 		if (carryover) {
 			unsigned long sum;
 
-			sum = lrugen->avg_refaulted[type][tier] +
+			sum = atomic_long_read(&lrugen->avg_refaulted[type][tier]) +
 			      atomic_long_read(&lrugen->refaulted[hist][type][tier]);
-			WRITE_ONCE(lrugen->avg_refaulted[type][tier], sum / 2);
+			atomic_long_set(&lrugen->avg_refaulted[type][tier], sum / 2);
 
-			sum = lrugen->avg_total[type][tier] +
+			sum = atomic_long_read(&lrugen->avg_total[type][tier]) +
 			      atomic_long_read(&lrugen->evicted[hist][type][tier]);
 			if (tier)
 				sum += lrugen->protected[hist][type][tier - 1];
-			WRITE_ONCE(lrugen->avg_total[type][tier], sum / 2);
+			atomic_long_set(&lrugen->avg_total[type][tier], sum / 2);
 		}
 
 		if (clear) {
@@ -5885,8 +5885,8 @@ static void lru_gen_seq_show_full(struct seq_file *m, struct lruvec *lruvec,
 
 			if (seq == max_seq) {
 				s = "RT ";
-				n[0] = READ_ONCE(lrugen->avg_refaulted[type][tier]);
-				n[1] = READ_ONCE(lrugen->avg_total[type][tier]);
+				n[0] = atomic_long_read(&lrugen->avg_refaulted[type][tier]);
+				n[1] = atomic_long_read(&lrugen->avg_total[type][tier]);
 			} else if (seq == min_seq[type] || NR_HIST_GENS > 1) {
 				s = "rep";
 				n[0] = atomic_long_read(&lrugen->refaulted[hist][type][tier]);
-- 
2.41.0