From: Kairui Song No feature change, convert them to atomic so we can update them without holding the LRU lock. There is no risk of overflow. The reader always compares and uses zero instead if the counter values are negative. It follows final consistency. Signed-off-by: Kairui Song --- include/linux/mm_inline.h | 6 ++---- include/linux/mmzone.h | 2 +- mm/vmscan.c | 27 ++++++++++++--------------- 3 files changed, 15 insertions(+), 20 deletions(-) diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index 597f013c8e04..f52f02e8e5be 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -265,11 +265,9 @@ static inline void lru_gen_update_size(struct lruvec *lruvec, struct folio *foli VM_WARN_ON_ONCE(old_gen == -1 && new_gen == -1); if (old_gen >= 0) - WRITE_ONCE(lrugen->nr_pages[old_gen][type][zone], - lrugen->nr_pages[old_gen][type][zone] - delta); + atomic_long_sub(delta, &lrugen->nr_pages[old_gen][type][zone]); if (new_gen >= 0) - WRITE_ONCE(lrugen->nr_pages[new_gen][type][zone], - lrugen->nr_pages[new_gen][type][zone] + delta); + atomic_long_add(delta, &lrugen->nr_pages[new_gen][type][zone]); /* addition */ if (old_gen < 0) { diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index acd94cecc0d3..de7d3f8059a5 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -576,7 +576,7 @@ struct lru_gen_folio { /* the multi-gen LRU lists, lazily sorted on eviction */ struct list_head folios[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES]; /* the multi-gen LRU sizes, eventually consistent */ - long nr_pages[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES]; + atomic_long_t 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]; /* the exponential moving average of evicted+protected */ diff --git a/mm/vmscan.c b/mm/vmscan.c index aaceed4759ee..32890e628240 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3451,8 +3451,7 @@ static void reset_batch_size(struct lru_gen_mm_walk *walk) continue; walk->nr_pages[gen][type][zone] = 0; - WRITE_ONCE(lrugen->nr_pages[gen][type][zone], - lrugen->nr_pages[gen][type][zone] + delta); + atomic_long_add(delta, &lrugen->nr_pages[gen][type][zone]); if (lru_gen_is_active(lruvec, gen)) lru += LRU_ACTIVE; @@ -4072,11 +4071,8 @@ static bool inc_min_seq(struct lruvec *lruvec, int type, int swappiness) break; } flush_lru_batch(head, &batch_end, target_list); - - WRITE_ONCE(lrugen->nr_pages[old_gen][type][zone], - lrugen->nr_pages[old_gen][type][zone] - delta); - WRITE_ONCE(lrugen->nr_pages[target_gen][type][zone], - lrugen->nr_pages[target_gen][type][zone] + delta); + atomic_long_sub(delta, &lrugen->nr_pages[old_gen][type][zone]); + atomic_long_add(delta, &lrugen->nr_pages[target_gen][type][zone]); if (!remaining) return false; } @@ -4181,8 +4177,8 @@ static bool inc_max_seq(struct lruvec *lruvec, unsigned long seq, int swappiness for (type = 0; type < ANON_AND_FILE; type++) { for (zone = 0; zone < MAX_NR_ZONES; zone++) { enum lru_list lru = type * LRU_INACTIVE_FILE; - long delta = lrugen->nr_pages[prev][type][zone] - - lrugen->nr_pages[next][type][zone]; + long delta = atomic_long_read(&lrugen->nr_pages[prev][type][zone]) - + atomic_long_read(&lrugen->nr_pages[next][type][zone]); if (!delta) continue; @@ -4300,7 +4296,8 @@ static unsigned long lruvec_evictable_size(struct lruvec *lruvec, int swappiness for (seq = min_seq[type]; seq <= max_seq; seq++) { gen = lru_gen_from_seq(seq); for (zone = 0; zone < MAX_NR_ZONES; zone++) - total += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L); + total += max(atomic_long_read(&lrugen->nr_pages[gen][type][zone]), + 0L); } } @@ -4720,7 +4717,7 @@ static void __lru_gen_reparent_memcg(struct lruvec *child_lruvec, struct lruvec for (i = 0; i < get_nr_gens(child_lruvec, type); i++) { int gen = lru_gen_from_seq(child_lrugen->max_seq - i); - long nr_pages = child_lrugen->nr_pages[gen][type][zone]; + long nr_pages = atomic_long_read(&child_lrugen->nr_pages[gen][type][zone]); int child_lru_active = lru_gen_is_active(child_lruvec, gen) ? LRU_ACTIVE : 0; int parent_lru_active = lru_gen_is_active(parent_lruvec, gen) ? LRU_ACTIVE : 0; @@ -4728,9 +4725,8 @@ static void __lru_gen_reparent_memcg(struct lruvec *child_lruvec, struct lruvec list_splice_tail_init(&child_lrugen->folios[gen][type][zone], &parent_lrugen->folios[gen][type][zone]); - WRITE_ONCE(child_lrugen->nr_pages[gen][type][zone], 0); - WRITE_ONCE(parent_lrugen->nr_pages[gen][type][zone], - parent_lrugen->nr_pages[gen][type][zone] + nr_pages); + atomic_long_set(&child_lrugen->nr_pages[gen][type][zone], 0); + atomic_long_add(nr_pages, &parent_lrugen->nr_pages[gen][type][zone]); if (lru_gen_is_active(child_lruvec, gen) != lru_gen_is_active(parent_lruvec, gen)) { __update_lru_size(child_lruvec, lru + child_lru_active, zone, -nr_pages); @@ -5807,7 +5803,8 @@ static int lru_gen_seq_show(struct seq_file *m, void *v) char mark = full && seq < min_seq[type] ? 'x' : ' '; for (zone = 0; zone < MAX_NR_ZONES; zone++) - size += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L); + size += max(atomic_long_read(&lrugen->nr_pages[gen][type][zone]), + 0L); seq_printf(m, " %10lu%c", size, mark); } -- 2.55.0