diff options
Diffstat (limited to 'target/linux/generic/backport-5.15/020-v6.3-27-mm-multi-gen-LRU-clarify-scan_control-flags.patch')
| -rw-r--r-- | target/linux/generic/backport-5.15/020-v6.3-27-mm-multi-gen-LRU-clarify-scan_control-flags.patch | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/target/linux/generic/backport-5.15/020-v6.3-27-mm-multi-gen-LRU-clarify-scan_control-flags.patch b/target/linux/generic/backport-5.15/020-v6.3-27-mm-multi-gen-LRU-clarify-scan_control-flags.patch new file mode 100644 index 0000000000..59d2c82b56 --- /dev/null +++ b/target/linux/generic/backport-5.15/020-v6.3-27-mm-multi-gen-LRU-clarify-scan_control-flags.patch @@ -0,0 +1,201 @@ +From 93147736b5b3a21bea24313bfc7a696829932009 Mon Sep 17 00:00:00 2001 +From: Yu Zhao <yuzhao@google.com> +Date: Wed, 21 Dec 2022 21:19:05 -0700 +Subject: [PATCH 27/29] mm: multi-gen LRU: clarify scan_control flags + +Among the flags in scan_control: +1. sc->may_swap, which indicates swap constraint due to memsw.max, is + supported as usual. +2. sc->proactive, which indicates reclaim by memory.reclaim, may not + opportunistically skip the aging path, since it is considered less + latency sensitive. +3. !(sc->gfp_mask & __GFP_IO), which indicates IO constraint, lowers + swappiness to prioritize file LRU, since clean file pages are more + likely to exist. +4. sc->may_writepage and sc->may_unmap, which indicates opportunistic + reclaim, are rejected, since unmapped clean pages are already + prioritized. Scanning for more of them is likely futile and can + cause high reclaim latency when there is a large number of memcgs. + +The rest are handled by the existing code. + +Link: https://lkml.kernel.org/r/20221222041905.2431096-8-yuzhao@google.com +Signed-off-by: Yu Zhao <yuzhao@google.com> +Cc: Johannes Weiner <hannes@cmpxchg.org> +Cc: Jonathan Corbet <corbet@lwn.net> +Cc: Michael Larabel <Michael@MichaelLarabel.com> +Cc: Michal Hocko <mhocko@kernel.org> +Cc: Mike Rapoport <rppt@kernel.org> +Cc: Roman Gushchin <roman.gushchin@linux.dev> +Cc: Suren Baghdasaryan <surenb@google.com> +Signed-off-by: Andrew Morton <akpm@linux-foundation.org> +--- + mm/vmscan.c | 55 +++++++++++++++++++++++++++-------------------------- + 1 file changed, 28 insertions(+), 27 deletions(-) + +diff --git a/mm/vmscan.c b/mm/vmscan.c +index 3d8e0665186c..4bcb93df316c 100644 +--- a/mm/vmscan.c ++++ b/mm/vmscan.c +@@ -2905,6 +2905,9 @@ static int get_swappiness(struct lruvec *lruvec, struct scan_control *sc) + struct mem_cgroup *memcg = lruvec_memcg(lruvec); + struct pglist_data *pgdat = lruvec_pgdat(lruvec); + ++ if (!sc->may_swap) ++ return 0; ++ + if (!can_demote(pgdat->node_id, sc) && + mem_cgroup_get_nr_swap_pages(memcg) < MIN_LRU_BATCH) + return 0; +@@ -3952,7 +3955,7 @@ static void walk_mm(struct lruvec *lruvec, struct mm_struct *mm, struct lru_gen_ + } while (err == -EAGAIN); + } + +-static struct lru_gen_mm_walk *set_mm_walk(struct pglist_data *pgdat) ++static struct lru_gen_mm_walk *set_mm_walk(struct pglist_data *pgdat, bool force_alloc) + { + struct lru_gen_mm_walk *walk = current->reclaim_state->mm_walk; + +@@ -3960,7 +3963,7 @@ static struct lru_gen_mm_walk *set_mm_walk(struct pglist_data *pgdat) + VM_WARN_ON_ONCE(walk); + + walk = &pgdat->mm_walk; +- } else if (!pgdat && !walk) { ++ } else if (!walk && force_alloc) { + VM_WARN_ON_ONCE(current_is_kswapd()); + + walk = kzalloc(sizeof(*walk), __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN); +@@ -4146,7 +4149,7 @@ static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long max_seq, + goto done; + } + +- walk = set_mm_walk(NULL); ++ walk = set_mm_walk(NULL, true); + if (!walk) { + success = iterate_mm_list_nowalk(lruvec, max_seq); + goto done; +@@ -4215,8 +4218,6 @@ static bool lruvec_is_reclaimable(struct lruvec *lruvec, struct scan_control *sc + struct mem_cgroup *memcg = lruvec_memcg(lruvec); + DEFINE_MIN_SEQ(lruvec); + +- VM_WARN_ON_ONCE(sc->memcg_low_reclaim); +- + /* see the comment on lru_gen_page */ + gen = lru_gen_from_seq(min_seq[LRU_GEN_FILE]); + birth = READ_ONCE(lruvec->lrugen.timestamps[gen]); +@@ -4472,12 +4473,8 @@ static bool isolate_page(struct lruvec *lruvec, struct page *page, struct scan_c + { + bool success; + +- /* unmapping inhibited */ +- if (!sc->may_unmap && page_mapped(page)) +- return false; +- + /* swapping inhibited */ +- if (!(sc->may_writepage && (sc->gfp_mask & __GFP_IO)) && ++ if (!(sc->gfp_mask & __GFP_IO) && + (PageDirty(page) || + (PageAnon(page) && !PageSwapCache(page)))) + return false; +@@ -4574,9 +4571,8 @@ static int scan_pages(struct lruvec *lruvec, struct scan_control *sc, + __count_vm_events(PGSCAN_ANON + type, isolated); + + /* +- * There might not be eligible pages due to reclaim_idx, may_unmap and +- * may_writepage. Check the remaining to prevent livelock if it's not +- * making progress. ++ * There might not be eligible pages due to reclaim_idx. Check the ++ * remaining to prevent livelock if it's not making progress. + */ + return isolated || !remaining ? scanned : 0; + } +@@ -4836,8 +4832,7 @@ static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc, bool + struct mem_cgroup *memcg = lruvec_memcg(lruvec); + DEFINE_MAX_SEQ(lruvec); + +- if (mem_cgroup_below_min(memcg) || +- (mem_cgroup_below_low(memcg) && !sc->memcg_low_reclaim)) ++ if (mem_cgroup_below_min(memcg)) + return 0; + + if (!should_run_aging(lruvec, max_seq, sc, can_swap, &nr_to_scan)) +@@ -4865,17 +4860,14 @@ static bool try_to_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) + long nr_to_scan; + unsigned long scanned = 0; + unsigned long nr_to_reclaim = get_nr_to_reclaim(sc); ++ int swappiness = get_swappiness(lruvec, sc); ++ ++ /* clean file pages are more likely to exist */ ++ if (swappiness && !(sc->gfp_mask & __GFP_IO)) ++ swappiness = 1; + + while (true) { + int delta; +- int swappiness; +- +- if (sc->may_swap) +- swappiness = get_swappiness(lruvec, sc); +- else if (!cgroup_reclaim(sc) && get_swappiness(lruvec, sc)) +- swappiness = 1; +- else +- swappiness = 0; + + nr_to_scan = get_nr_to_scan(lruvec, sc, swappiness); + if (nr_to_scan <= 0) +@@ -5005,12 +4997,13 @@ static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc + struct blk_plug plug; + + VM_WARN_ON_ONCE(global_reclaim(sc)); ++ VM_WARN_ON_ONCE(!sc->may_writepage || !sc->may_unmap); + + lru_add_drain(); + + blk_start_plug(&plug); + +- set_mm_walk(lruvec_pgdat(lruvec)); ++ set_mm_walk(NULL, false); + + if (try_to_shrink_lruvec(lruvec, sc)) + lru_gen_rotate_memcg(lruvec, MEMCG_LRU_YOUNG); +@@ -5066,11 +5059,19 @@ static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control * + + VM_WARN_ON_ONCE(!global_reclaim(sc)); + ++ /* ++ * Unmapped clean pages are already prioritized. Scanning for more of ++ * them is likely futile and can cause high reclaim latency when there ++ * is a large number of memcgs. ++ */ ++ if (!sc->may_writepage || !sc->may_unmap) ++ goto done; ++ + lru_add_drain(); + + blk_start_plug(&plug); + +- set_mm_walk(pgdat); ++ set_mm_walk(pgdat, false); + + set_initial_priority(pgdat, sc); + +@@ -5088,7 +5089,7 @@ static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control * + clear_mm_walk(); + + blk_finish_plug(&plug); +- ++done: + /* kswapd should never fail */ + pgdat->kswapd_failures = 0; + } +@@ -5656,7 +5657,7 @@ static ssize_t lru_gen_seq_write(struct file *file, const char __user *src, + set_task_reclaim_state(current, &sc.reclaim_state); + flags = memalloc_noreclaim_save(); + blk_start_plug(&plug); +- if (!set_mm_walk(NULL)) { ++ if (!set_mm_walk(NULL, true)) { + err = -ENOMEM; + goto done; + } +-- +2.40.0 + |