diff options
Diffstat (limited to 'target/linux/generic/backport-5.15/020-v6.3-29-mm-multi-gen-LRU-avoid-futile-retries.patch')
| -rw-r--r-- | target/linux/generic/backport-5.15/020-v6.3-29-mm-multi-gen-LRU-avoid-futile-retries.patch | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/target/linux/generic/backport-5.15/020-v6.3-29-mm-multi-gen-LRU-avoid-futile-retries.patch b/target/linux/generic/backport-5.15/020-v6.3-29-mm-multi-gen-LRU-avoid-futile-retries.patch new file mode 100644 index 0000000000..14e1aff177 --- /dev/null +++ b/target/linux/generic/backport-5.15/020-v6.3-29-mm-multi-gen-LRU-avoid-futile-retries.patch @@ -0,0 +1,93 @@ +From cc67f962cc53f6e1dfa92eb85b7b26fe83a3c66f Mon Sep 17 00:00:00 2001 +From: Yu Zhao <yuzhao@google.com> +Date: Mon, 13 Feb 2023 00:53:22 -0700 +Subject: [PATCH 29/29] mm: multi-gen LRU: avoid futile retries + +Recall that the per-node memcg LRU has two generations and they alternate +when the last memcg (of a given node) is moved from one to the other. +Each generation is also sharded into multiple bins to improve scalability. +A reclaimer starts with a random bin (in the old generation) and, if it +fails, it will retry, i.e., to try the rest of the bins. + +If a reclaimer fails with the last memcg, it should move this memcg to the +young generation first, which causes the generations to alternate, and +then retry. Otherwise, the retries will be futile because all other bins +are empty. + +Link: https://lkml.kernel.org/r/20230213075322.1416966-1-yuzhao@google.com +Fixes: e4dde56cd208 ("mm: multi-gen LRU: per-node lru_gen_folio lists") +Signed-off-by: Yu Zhao <yuzhao@google.com> +Reported-by: T.J. Mercier <tjmercier@google.com> +Signed-off-by: Andrew Morton <akpm@linux-foundation.org> +--- + mm/vmscan.c | 25 +++++++++++++++---------- + 1 file changed, 15 insertions(+), 10 deletions(-) + +diff --git a/mm/vmscan.c b/mm/vmscan.c +index 3f6874a69886..0b76774963ff 100644 +--- a/mm/vmscan.c ++++ b/mm/vmscan.c +@@ -4934,18 +4934,20 @@ static int shrink_one(struct lruvec *lruvec, struct scan_control *sc) + + static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc) + { ++ int op; + int gen; + int bin; + int first_bin; + struct lruvec *lruvec; + struct lru_gen_page *lrugen; ++ struct mem_cgroup *memcg; + const struct hlist_nulls_node *pos; +- int op = 0; +- struct mem_cgroup *memcg = NULL; + unsigned long nr_to_reclaim = get_nr_to_reclaim(sc); + + bin = first_bin = prandom_u32_max(MEMCG_NR_BINS); + restart: ++ op = 0; ++ memcg = NULL; + gen = get_memcg_gen(READ_ONCE(pgdat->memcg_lru.seq)); + + rcu_read_lock(); +@@ -4969,14 +4971,22 @@ static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc) + + op = shrink_one(lruvec, sc); + +- if (sc->nr_reclaimed >= nr_to_reclaim) +- goto success; +- + rcu_read_lock(); ++ ++ if (sc->nr_reclaimed >= nr_to_reclaim) ++ break; + } + + rcu_read_unlock(); + ++ if (op) ++ lru_gen_rotate_memcg(lruvec, op); ++ ++ mem_cgroup_put(memcg); ++ ++ if (sc->nr_reclaimed >= nr_to_reclaim) ++ return; ++ + /* restart if raced with lru_gen_rotate_memcg() */ + if (gen != get_nulls_value(pos)) + goto restart; +@@ -4985,11 +4995,6 @@ static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc) + bin = get_memcg_bin(bin + 1); + if (bin != first_bin) + goto restart; +-success: +- if (op) +- lru_gen_rotate_memcg(lruvec, op); +- +- mem_cgroup_put(memcg); + } + + static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) +-- +2.40.0 + |