// SPDX-License-Identifier: GPL-2.0 /* * linux/mm/vmscan.c * * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds * * Swap reorganised 29.12.95, Stephen Tweedie. * kswapd added: 7.1.96 sct * Removed kswapd_ctl limits, and swap out as many pages as needed * to bring the system back to freepages.high: 2.4.97, Rik van Riel. * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com). * Multiqueue VM started 5.8.00, Rik van Riel. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* for try_to_release_page(), buffer_heads_over_limit */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if defined(OPLUS_FEATURE_PROCESS_RECLAIM) && defined(CONFIG_PROCESS_RECLAIM_ENHANCE) #include #endif #include "internal.h" #define CREATE_TRACE_POINTS #include #if defined(OPLUS_FEATURE_ZRAM_OPT) && defined(CONFIG_FG_TASK_UID) #include #endif /*OPLUS_FEATURE_ZRAM_OPT*/ #if defined(OPLUS_FEATURE_MULTI_KSWAPD) && defined(CONFIG_OPLUS_MULTI_KSWAPD) #include #endif #include struct scan_control { /* How many pages shrink_list() should reclaim */ unsigned long nr_to_reclaim; /* * Nodemask of nodes allowed by the caller. If NULL, all nodes * are scanned. */ nodemask_t *nodemask; /* * The memory cgroup that hit its limit and as a result is the * primary target of this reclaim invocation. */ struct mem_cgroup *target_mem_cgroup; /* Writepage batching in laptop mode; RECLAIM_WRITE */ unsigned int may_writepage:1; /* Can mapped pages be reclaimed? */ unsigned int may_unmap:1; /* Can pages be swapped as part of reclaim? */ unsigned int may_swap:1; /* e.g. boosted watermark reclaim leaves slabs alone */ unsigned int may_shrinkslab:1; /* * Cgroups are not reclaimed below their configured memory.low, * unless we threaten to OOM. If any cgroups are skipped due to * memory.low and nothing was reclaimed, go back for memory.low. */ unsigned int memcg_low_reclaim:1; unsigned int memcg_low_skipped:1; unsigned int hibernation_mode:1; /* One of the zones is ready for compaction */ unsigned int compaction_ready:1; #ifdef CONFIG_LRU_GEN /* help make better choices when multiple memcgs are available */ unsigned int memcgs_need_aging:1; unsigned int memcgs_need_swapping:1; unsigned int memcgs_avoid_swapping:1; #endif /* Allocation order */ s8 order; /* Scan (total_size >> priority) pages at once */ s8 priority; /* The highest zone to isolate pages for reclaim from */ s8 reclaim_idx; /* This context's GFP mask */ gfp_t gfp_mask; /* Incremented by the number of inactive pages that were scanned */ unsigned long nr_scanned; /* Number of pages freed so far during a call to shrink_zones() */ unsigned long nr_reclaimed; struct { unsigned int dirty; unsigned int unqueued_dirty; unsigned int congested; unsigned int writeback; unsigned int immediate; unsigned int file_taken; unsigned int taken; } nr; /* * Reclaim pages from a vma. If the page is shared by other tasks * it is zapped from a vma without reclaim so it ends up remaining * on memory until last task zap it. */ struct vm_area_struct *target_vma; #if defined(OPLUS_FEATURE_PROCESS_RECLAIM) && defined(CONFIG_PROCESS_RECLAIM_ENHANCE) struct mm_walk *walk; #endif }; #ifndef CONFIG_OPLUS_MULTI_KSWAPD /* * Number of active kswapd threads */ #define DEF_KSWAPD_THREADS_PER_NODE 1 //int kswapd_threads = DEF_KSWAPD_THREADS_PER_NODE; int kswapd_threads_current = DEF_KSWAPD_THREADS_PER_NODE; #endif /*CONFIG_OPLUS_MULTI_KSWAPD*/ #ifdef ARCH_HAS_PREFETCH #define prefetch_prev_lru_page(_page, _base, _field) \ do { \ if ((_page)->lru.prev != _base) { \ struct page *prev; \ \ prev = lru_to_page(&(_page->lru)); \ prefetch(&prev->_field); \ } \ } while (0) #else #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) #endif #ifdef ARCH_HAS_PREFETCHW #define prefetchw_prev_lru_page(_page, _base, _field) \ do { \ if ((_page)->lru.prev != _base) { \ struct page *prev; \ \ prev = lru_to_page(&(_page->lru)); \ prefetchw(&prev->_field); \ } \ } while (0) #else #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) #endif /* * From 0 .. 100. Higher means more swappy. */ int vm_swappiness = 60; #ifdef CONFIG_DYNAMIC_TUNNING_SWAPPINESS int vm_swappiness_threshold1 = 0; int vm_swappiness_threshold2 = 0; int swappiness_threshold1_size = 0; int swappiness_threshold2_size = 0; #endif #if defined(OPLUS_FEATURE_ZRAM_OPT) && defined(CONFIG_OPLUS_ZRAM_OPT) /* * Direct reclaim swappiness, exptct 0 - 60. Higher means more swappy and slower. */ int direct_vm_swappiness = 60; #endif /*OPLUS_FEATURE_ZRAM_OPT*/ #ifdef CONFIG_HYBRIDSWAP_SWAPD static int hybridswapd_swappiness = 200; #endif /* * The total number of pages which are beyond the high watermark within all * zones. */ unsigned long vm_total_pages; static LIST_HEAD(shrinker_list); static DECLARE_RWSEM(shrinker_rwsem); #ifdef CONFIG_MEMCG_KMEM /* * We allow subsystems to populate their shrinker-related * LRU lists before register_shrinker_prepared() is called * for the shrinker, since we don't want to impose * restrictions on their internal registration order. * In this case shrink_slab_memcg() may find corresponding * bit is set in the shrinkers map. * * This value is used by the function to detect registering * shrinkers and to skip do_shrink_slab() calls for them. */ #define SHRINKER_REGISTERING ((struct shrinker *)~0UL) static DEFINE_IDR(shrinker_idr); static int shrinker_nr_max; static int prealloc_memcg_shrinker(struct shrinker *shrinker) { int id, ret = -ENOMEM; down_write(&shrinker_rwsem); /* This may call shrinker, so it must use down_read_trylock() */ id = idr_alloc(&shrinker_idr, SHRINKER_REGISTERING, 0, 0, GFP_KERNEL); if (id < 0) goto unlock; if (id >= shrinker_nr_max) { if (memcg_expand_shrinker_maps(id)) { idr_remove(&shrinker_idr, id); goto unlock; } shrinker_nr_max = id + 1; } shrinker->id = id; ret = 0; unlock: up_write(&shrinker_rwsem); return ret; } static void unregister_memcg_shrinker(struct shrinker *shrinker) { int id = shrinker->id; BUG_ON(id < 0); down_write(&shrinker_rwsem); idr_remove(&shrinker_idr, id); up_write(&shrinker_rwsem); } #else /* CONFIG_MEMCG_KMEM */ static int prealloc_memcg_shrinker(struct shrinker *shrinker) { return 0; } static void unregister_memcg_shrinker(struct shrinker *shrinker) { } #endif /* CONFIG_MEMCG_KMEM */ #ifdef CONFIG_MEMCG static bool global_reclaim(struct scan_control *sc) { return !sc->target_mem_cgroup; } /** * sane_reclaim - is the usual dirty throttling mechanism operational? * @sc: scan_control in question * * The normal page dirty throttling mechanism in balance_dirty_pages() is * completely broken with the legacy memcg and direct stalling in * shrink_page_list() is used for throttling instead, which lacks all the * niceties such as fairness, adaptive pausing, bandwidth proportional * allocation and configurability. * * This function tests whether the vmscan currently in progress can assume * that the normal dirty throttling mechanism is operational. */ static bool sane_reclaim(struct scan_control *sc) { struct mem_cgroup *memcg = sc->target_mem_cgroup; if (!memcg) return true; #ifdef CONFIG_CGROUP_WRITEBACK if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) return true; #endif return false; } static void set_memcg_congestion(pg_data_t *pgdat, struct mem_cgroup *memcg, bool congested) { struct mem_cgroup_per_node *mn; if (!memcg) return; mn = mem_cgroup_nodeinfo(memcg, pgdat->node_id); WRITE_ONCE(mn->congested, congested); } static bool memcg_congested(pg_data_t *pgdat, struct mem_cgroup *memcg) { struct mem_cgroup_per_node *mn; mn = mem_cgroup_nodeinfo(memcg, pgdat->node_id); return READ_ONCE(mn->congested); } #else static bool global_reclaim(struct scan_control *sc) { return true; } static bool sane_reclaim(struct scan_control *sc) { return true; } static inline void set_memcg_congestion(struct pglist_data *pgdat, struct mem_cgroup *memcg, bool congested) { } static inline bool memcg_congested(struct pglist_data *pgdat, struct mem_cgroup *memcg) { return false; } #endif /* * This misses isolated pages which are not accounted for to save counters. * As the data only determines if reclaim or compaction continues, it is * not expected that isolated pages will be a dominating factor. */ unsigned long zone_reclaimable_pages(struct zone *zone) { unsigned long nr; nr = zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_FILE) + zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_FILE); if (get_nr_swap_pages() > 0 || IS_ENABLED(CONFIG_HAVE_LOW_MEMORY_KILLER)) nr += zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_ANON) + zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_ANON); return nr; } /** * lruvec_lru_size - Returns the number of pages on the given LRU list. * @lruvec: lru vector * @lru: lru to use * @zone_idx: zones to consider (use MAX_NR_ZONES for the whole LRU list) */ unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx) { unsigned long lru_size; int zid; if (!mem_cgroup_disabled()) lru_size = mem_cgroup_get_lru_size(lruvec, lru); else lru_size = node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru); for (zid = zone_idx + 1; zid < MAX_NR_ZONES; zid++) { struct zone *zone = &lruvec_pgdat(lruvec)->node_zones[zid]; unsigned long size; if (!managed_zone(zone)) continue; if (!mem_cgroup_disabled()) size = mem_cgroup_get_zone_lru_size(lruvec, lru, zid); else size = zone_page_state(&lruvec_pgdat(lruvec)->node_zones[zid], NR_ZONE_LRU_BASE + lru); lru_size -= min(size, lru_size); } return lru_size; } /* * Add a shrinker callback to be called from the vm. */ int prealloc_shrinker(struct shrinker *shrinker) { size_t size = sizeof(*shrinker->nr_deferred); if (shrinker->flags & SHRINKER_NUMA_AWARE) size *= nr_node_ids; shrinker->nr_deferred = kzalloc(size, GFP_KERNEL); if (!shrinker->nr_deferred) return -ENOMEM; if (shrinker->flags & SHRINKER_MEMCG_AWARE) { if (prealloc_memcg_shrinker(shrinker)) goto free_deferred; } return 0; free_deferred: kfree(shrinker->nr_deferred); shrinker->nr_deferred = NULL; return -ENOMEM; } void free_prealloced_shrinker(struct shrinker *shrinker) { if (!shrinker->nr_deferred) return; if (shrinker->flags & SHRINKER_MEMCG_AWARE) unregister_memcg_shrinker(shrinker); kfree(shrinker->nr_deferred); shrinker->nr_deferred = NULL; } void register_shrinker_prepared(struct shrinker *shrinker) { down_write(&shrinker_rwsem); list_add_tail(&shrinker->list, &shrinker_list); #ifdef CONFIG_MEMCG_KMEM if (shrinker->flags & SHRINKER_MEMCG_AWARE) idr_replace(&shrinker_idr, shrinker, shrinker->id); #endif up_write(&shrinker_rwsem); } int register_shrinker(struct shrinker *shrinker) { int err = prealloc_shrinker(shrinker); if (err) return err; register_shrinker_prepared(shrinker); return 0; } EXPORT_SYMBOL(register_shrinker); /* * Remove one */ void unregister_shrinker(struct shrinker *shrinker) { if (!shrinker->nr_deferred) return; if (shrinker->flags & SHRINKER_MEMCG_AWARE) unregister_memcg_shrinker(shrinker); down_write(&shrinker_rwsem); list_del(&shrinker->list); up_write(&shrinker_rwsem); kfree(shrinker->nr_deferred); shrinker->nr_deferred = NULL; } EXPORT_SYMBOL(unregister_shrinker); #define SHRINK_BATCH 128 static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, struct shrinker *shrinker, int priority) { unsigned long freed = 0; unsigned long long delta; long total_scan; long freeable; long nr; long new_nr; int nid = shrinkctl->nid; long batch_size = shrinker->batch ? shrinker->batch : SHRINK_BATCH; long scanned = 0, next_deferred; long min_cache_size = batch_size; if (current_is_kswapd()) min_cache_size = 0; if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) nid = 0; freeable = shrinker->count_objects(shrinker, shrinkctl); if (freeable == 0 || freeable == SHRINK_EMPTY) return freeable; /* * copy the current shrinker scan count into a local variable * and zero it so that other concurrent shrinker invocations * don't also do this scanning work. */ nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0); total_scan = nr; if (shrinker->seeks) { delta = freeable >> priority; delta *= 4; do_div(delta, shrinker->seeks); } else { /* * These objects don't require any IO to create. Trim * them aggressively under memory pressure to keep * them from causing refetches in the IO caches. */ delta = freeable / 2; } total_scan += delta; if (total_scan < 0) { pr_err("shrink_slab: %pF negative objects to delete nr=%ld\n", shrinker->scan_objects, total_scan); total_scan = freeable; next_deferred = nr; } else next_deferred = total_scan; /* * We need to avoid excessive windup on filesystem shrinkers * due to large numbers of GFP_NOFS allocations causing the * shrinkers to return -1 all the time. This results in a large * nr being built up so when a shrink that can do some work * comes along it empties the entire cache due to nr >>> * freeable. This is bad for sustaining a working set in * memory. * * Hence only allow the shrinker to scan the entire cache when * a large delta change is calculated directly. */ if (delta < freeable / 4) total_scan = min(total_scan, freeable / 2); /* * Avoid risking looping forever due to too large nr value: * never try to free more than twice the estimate number of * freeable entries. */ if (total_scan > freeable * 2) total_scan = freeable * 2; trace_mm_shrink_slab_start(shrinker, shrinkctl, nr, freeable, delta, total_scan, priority); /* * Normally, we should not scan less than batch_size objects in one * pass to avoid too frequent shrinker calls, but if the slab has less * than batch_size objects in total and we are really tight on memory, * we will try to reclaim all available objects, otherwise we can end * up failing allocations although there are plenty of reclaimable * objects spread over several slabs with usage less than the * batch_size. * * We detect the "tight on memory" situations by looking at the total * number of objects we want to scan (total_scan). If it is greater * than the total number of objects on slab (freeable), we must be * scanning at high prio and therefore should try to reclaim as much as * possible. */ while (total_scan > min_cache_size || total_scan >= freeable) { unsigned long ret; unsigned long nr_to_scan = min(batch_size, total_scan); shrinkctl->nr_to_scan = nr_to_scan; shrinkctl->nr_scanned = nr_to_scan; ret = shrinker->scan_objects(shrinker, shrinkctl); if (ret == SHRINK_STOP) break; freed += ret; count_vm_events(SLABS_SCANNED, shrinkctl->nr_scanned); total_scan -= shrinkctl->nr_scanned; scanned += shrinkctl->nr_scanned; cond_resched(); } if (next_deferred >= scanned) next_deferred -= scanned; else next_deferred = 0; /* * move the unused scan count back into the shrinker in a * manner that handles concurrent updates. If we exhausted the * scan, there is no need to do an update. */ if (next_deferred > 0) new_nr = atomic_long_add_return(next_deferred, &shrinker->nr_deferred[nid]); else new_nr = atomic_long_read(&shrinker->nr_deferred[nid]); trace_mm_shrink_slab_end(shrinker, nid, freed, nr, new_nr, total_scan); return freed; } #ifdef CONFIG_MEMCG_KMEM static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid, struct mem_cgroup *memcg, int priority) { struct memcg_shrinker_map *map; unsigned long ret, freed = 0; int i; if (!memcg_kmem_enabled() || !mem_cgroup_online(memcg)) return 0; if (!down_read_trylock(&shrinker_rwsem)) return 0; map = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_map, true); if (unlikely(!map)) goto unlock; for_each_set_bit(i, map->map, shrinker_nr_max) { struct shrink_control sc = { .gfp_mask = gfp_mask, .nid = nid, .memcg = memcg, }; struct shrinker *shrinker; shrinker = idr_find(&shrinker_idr, i); if (unlikely(!shrinker || shrinker == SHRINKER_REGISTERING)) { if (!shrinker) clear_bit(i, map->map); continue; } ret = do_shrink_slab(&sc, shrinker, priority); if (ret == SHRINK_EMPTY) { clear_bit(i, map->map); /* * After the shrinker reported that it had no objects to * free, but before we cleared the corresponding bit in * the memcg shrinker map, a new object might have been * added. To make sure, we have the bit set in this * case, we invoke the shrinker one more time and reset * the bit if it reports that it is not empty anymore. * The memory barrier here pairs with the barrier in * memcg_set_shrinker_bit(): * * list_lru_add() shrink_slab_memcg() * list_add_tail() clear_bit() * * set_bit() do_shrink_slab() */ smp_mb__after_atomic(); ret = do_shrink_slab(&sc, shrinker, priority); if (ret == SHRINK_EMPTY) ret = 0; else memcg_set_shrinker_bit(memcg, nid, i); } freed += ret; if (rwsem_is_contended(&shrinker_rwsem)) { freed = freed ? : 1; break; } } unlock: up_read(&shrinker_rwsem); return freed; } #else /* CONFIG_MEMCG_KMEM */ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid, struct mem_cgroup *memcg, int priority) { return 0; } #endif /* CONFIG_MEMCG_KMEM */ /** * shrink_slab - shrink slab caches * @gfp_mask: allocation context * @nid: node whose slab caches to target * @memcg: memory cgroup whose slab caches to target * @priority: the reclaim priority * * Call the shrink functions to age shrinkable caches. * * @nid is passed along to shrinkers with SHRINKER_NUMA_AWARE set, * unaware shrinkers will receive a node id of 0 instead. * * @memcg specifies the memory cgroup to target. Unaware shrinkers * are called only if it is the root cgroup. * * @priority is sc->priority, we take the number of objects and >> by priority * in order to get the scan target. * * Returns the number of reclaimed slab objects. */ static unsigned long shrink_slab(gfp_t gfp_mask, int nid, struct mem_cgroup *memcg, int priority) { unsigned long ret, freed = 0; struct shrinker *shrinker; /* * The root memcg might be allocated even though memcg is disabled * via "cgroup_disable=memory" boot parameter. This could make * mem_cgroup_is_root() return false, then just run memcg slab * shrink, but skip global shrink. This may result in premature * oom. */ if (!mem_cgroup_disabled() && !mem_cgroup_is_root(memcg)) return shrink_slab_memcg(gfp_mask, nid, memcg, priority); if (!down_read_trylock(&shrinker_rwsem)) goto out; list_for_each_entry(shrinker, &shrinker_list, list) { struct shrink_control sc = { .gfp_mask = gfp_mask, .nid = nid, .memcg = memcg, }; ret = do_shrink_slab(&sc, shrinker, priority); if (ret == SHRINK_EMPTY) ret = 0; freed += ret; /* * Bail out if someone want to register a new shrinker to * prevent the regsitration from being stalled for long periods * by parallel ongoing shrinking. */ if (rwsem_is_contended(&shrinker_rwsem)) { freed = freed ? : 1; break; } } up_read(&shrinker_rwsem); out: cond_resched(); return freed; } void drop_slab_node(int nid) { unsigned long freed; do { struct mem_cgroup *memcg = NULL; freed = 0; memcg = mem_cgroup_iter(NULL, NULL, NULL); do { freed += shrink_slab(GFP_KERNEL, nid, memcg, 0); } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL); } while (freed > 10); } void drop_slab(void) { int nid; for_each_online_node(nid) drop_slab_node(nid); } static inline int is_page_cache_freeable(struct page *page) { /* * A freeable page cache page is referenced only by the caller * that isolated the page, the page cache radix tree and * optional buffer heads at page->private. */ int radix_pins = PageTransHuge(page) && PageSwapCache(page) ? HPAGE_PMD_NR : 1; return page_count(page) - page_has_private(page) == 1 + radix_pins; } static int may_write_to_inode(struct inode *inode, struct scan_control *sc) { if (current->flags & PF_SWAPWRITE) return 1; if (!inode_write_congested(inode)) return 1; if (inode_to_bdi(inode) == current->backing_dev_info) return 1; return 0; } /* * We detected a synchronous write error writing a page out. Probably * -ENOSPC. We need to propagate that into the address_space for a subsequent * fsync(), msync() or close(). * * The tricky part is that after writepage we cannot touch the mapping: nothing * prevents it from being freed up. But we have a ref on the page and once * that page is locked, the mapping is pinned. * * We're allowed to run sleeping lock_page() here because we know the caller has * __GFP_FS. */ static void handle_write_error(struct address_space *mapping, struct page *page, int error) { lock_page(page); if (page_mapping(page) == mapping) mapping_set_error(mapping, error); unlock_page(page); } /* possible outcome of pageout() */ typedef enum { /* failed to write page out, page is locked */ PAGE_KEEP, /* move page to the active list, page is locked */ PAGE_ACTIVATE, /* page has been sent to the disk successfully, page is unlocked */ PAGE_SUCCESS, /* page is clean and locked */ PAGE_CLEAN, } pageout_t; /* * pageout is called by shrink_page_list() for each dirty page. * Calls ->writepage(). */ static pageout_t pageout(struct page *page, struct address_space *mapping, struct scan_control *sc) { /* * If the page is dirty, only perform writeback if that write * will be non-blocking. To prevent this allocation from being * stalled by pagecache activity. But note that there may be * stalls if we need to run get_block(). We could test * PagePrivate for that. * * If this process is currently in __generic_file_write_iter() against * this page's queue, we can perform writeback even if that * will block. * * If the page is swapcache, write it back even if that would * block, for some throttling. This happens by accident, because * swap_backing_dev_info is bust: it doesn't reflect the * congestion state of the swapdevs. Easy to fix, if needed. */ if (!is_page_cache_freeable(page)) return PAGE_KEEP; if (!mapping) { /* * Some data journaling orphaned pages can have * page->mapping == NULL while being dirty with clean buffers. */ if (page_has_private(page)) { if (try_to_free_buffers(page)) { ClearPageDirty(page); pr_info("%s: orphaned page\n", __func__); return PAGE_CLEAN; } } return PAGE_KEEP; } if (mapping->a_ops->writepage == NULL) return PAGE_ACTIVATE; if (!may_write_to_inode(mapping->host, sc)) return PAGE_KEEP; if (clear_page_dirty_for_io(page)) { int res; struct writeback_control wbc = { .sync_mode = WB_SYNC_NONE, .nr_to_write = SWAP_CLUSTER_MAX, .range_start = 0, .range_end = LLONG_MAX, .for_reclaim = 1, }; SetPageReclaim(page); res = mapping->a_ops->writepage(page, &wbc); if (res < 0) handle_write_error(mapping, page, res); if (res == AOP_WRITEPAGE_ACTIVATE) { ClearPageReclaim(page); return PAGE_ACTIVATE; } if (!PageWriteback(page)) { /* synchronous write or broken a_ops? */ ClearPageReclaim(page); } trace_mm_vmscan_writepage(page); inc_node_page_state(page, NR_VMSCAN_WRITE); return PAGE_SUCCESS; } return PAGE_CLEAN; } /* * Same as remove_mapping, but if the page is removed from the mapping, it * gets returned with a refcount of 0. */ static int __remove_mapping(struct address_space *mapping, struct page *page, bool reclaimed) { unsigned long flags; int refcount; void *shadow = NULL; BUG_ON(!PageLocked(page)); BUG_ON(mapping != page_mapping(page)); xa_lock_irqsave(&mapping->i_pages, flags); /* * The non racy check for a busy page. * * Must be careful with the order of the tests. When someone has * a ref to the page, it may be possible that they dirty it then * drop the reference. So if PageDirty is tested before page_count * here, then the following race may occur: * * get_user_pages(&page); * [user mapping goes away] * write_to(page); * !PageDirty(page) [good] * SetPageDirty(page); * put_page(page); * !page_count(page) [good, discard it] * * [oops, our write_to data is lost] * * Reversing the order of the tests ensures such a situation cannot * escape unnoticed. The smp_rmb is needed to ensure the page->flags * load is not satisfied before that of page->_refcount. * * Note that if SetPageDirty is always performed via set_page_dirty, * and thus under the i_pages lock, then this ordering is not required. */ if (unlikely(PageTransHuge(page)) && PageSwapCache(page)) refcount = 1 + HPAGE_PMD_NR; else refcount = 2; if (!page_ref_freeze(page, refcount)) goto cannot_free; /* note: atomic_cmpxchg in page_ref_freeze provides the smp_rmb */ if (unlikely(PageDirty(page))) { page_ref_unfreeze(page, refcount); goto cannot_free; } if (PageSwapCache(page)) { swp_entry_t swap = { .val = page_private(page) }; if (lru_gen_enabled()) shadow = lru_gen_eviction(page); mem_cgroup_swapout(page, swap); __delete_from_swap_cache(page, shadow); xa_unlock_irqrestore(&mapping->i_pages, flags); put_swap_page(page, swap); } else { void (*freepage)(struct page *); freepage = mapping->a_ops->freepage; /* * Remember a shadow entry for reclaimed file cache in * order to detect refaults, thus thrashing, later on. * * But don't store shadows in an address space that is * already exiting. This is not just an optizimation, * inode reclaim needs to empty out the radix tree or * the nodes are lost. Don't plant shadows behind its * back. * * We also don't store shadows for DAX mappings because the * only page cache pages found in these are zero pages * covering holes, and because we don't want to mix DAX * exceptional entries and shadow exceptional entries in the * same address_space. */ if (reclaimed && page_is_file_cache(page) && !mapping_exiting(mapping) && !dax_mapping(mapping)) shadow = workingset_eviction(mapping, page); __delete_from_page_cache(page, shadow); xa_unlock_irqrestore(&mapping->i_pages, flags); if (freepage != NULL) freepage(page); } return 1; cannot_free: xa_unlock_irqrestore(&mapping->i_pages, flags); return 0; } /* * Attempt to detach a locked page from its ->mapping. If it is dirty or if * someone else has a ref on the page, abort and return 0. If it was * successfully detached, return 1. Assumes the caller has a single ref on * this page. */ int remove_mapping(struct address_space *mapping, struct page *page) { if (__remove_mapping(mapping, page, false)) { /* * Unfreezing the refcount with 1 rather than 2 effectively * drops the pagecache ref for us without requiring another * atomic operation. */ page_ref_unfreeze(page, 1); return 1; } return 0; } /** * putback_lru_page - put previously isolated page onto appropriate LRU list * @page: page to be put back to appropriate lru list * * Add previously isolated @page to appropriate LRU list. * Page may still be unevictable for other reasons. * * lru_lock must not be held, interrupts must be enabled. */ void putback_lru_page(struct page *page) { lru_cache_add(page); put_page(page); /* drop ref from isolate */ } enum page_references { PAGEREF_RECLAIM, PAGEREF_RECLAIM_CLEAN, PAGEREF_KEEP, PAGEREF_ACTIVATE, }; static enum page_references page_check_references(struct page *page, struct scan_control *sc) { int referenced_ptes, referenced_page; unsigned long vm_flags; referenced_ptes = page_referenced(page, 1, sc->target_mem_cgroup, &vm_flags); referenced_page = TestClearPageReferenced(page); /* * Mlock lost the isolation race with us. Let try_to_unmap() * move the page to the unevictable list. */ if (vm_flags & VM_LOCKED) return PAGEREF_RECLAIM; if (referenced_ptes) { if (PageSwapBacked(page)) return PAGEREF_ACTIVATE; /* * All mapped pages start out with page table * references from the instantiating fault, so we need * to look twice if a mapped file page is used more * than once. * * Mark it and spare it for another trip around the * inactive list. Another page table reference will * lead to its activation. * * Note: the mark is set for activated pages as well * so that recently deactivated but used pages are * quickly recovered. */ SetPageReferenced(page); if (referenced_page || referenced_ptes > 1) return PAGEREF_ACTIVATE; /* * Activate file-backed executable pages after first usage. */ if (vm_flags & VM_EXEC) return PAGEREF_ACTIVATE; return PAGEREF_KEEP; } /* Reclaim if clean, defer dirty pages to writeback */ if (referenced_page && !PageSwapBacked(page)) return PAGEREF_RECLAIM_CLEAN; return PAGEREF_RECLAIM; } /* Check if a page is dirty or under writeback */ static void page_check_dirty_writeback(struct page *page, bool *dirty, bool *writeback) { struct address_space *mapping; /* * Anonymous pages are not handled by flushers and must be written * from reclaim context. Do not stall reclaim based on them */ if (!page_is_file_cache(page) || (PageAnon(page) && !PageSwapBacked(page))) { *dirty = false; *writeback = false; return; } /* By default assume that the page flags are accurate */ *dirty = PageDirty(page); *writeback = PageWriteback(page); /* Verify dirty/writeback state if the filesystem supports it */ if (!page_has_private(page)) return; mapping = page_mapping(page); if (mapping && mapping->a_ops->is_dirty_writeback) mapping->a_ops->is_dirty_writeback(page, dirty, writeback); } /* * shrink_page_list() returns the number of reclaimed pages */ static unsigned long shrink_page_list(struct list_head *page_list, struct pglist_data *pgdat, struct scan_control *sc, enum ttu_flags ttu_flags, struct reclaim_stat *stat, bool force_reclaim) { LIST_HEAD(ret_pages); LIST_HEAD(free_pages); int pgactivate = 0; unsigned nr_unqueued_dirty = 0; unsigned nr_dirty = 0; unsigned nr_congested = 0; unsigned nr_reclaimed = 0; unsigned nr_writeback = 0; unsigned nr_immediate = 0; unsigned nr_ref_keep = 0; unsigned nr_unmap_fail = 0; cond_resched(); while (!list_empty(page_list)) { struct address_space *mapping; struct page *page; int may_enter_fs; enum page_references references = PAGEREF_RECLAIM; bool dirty, writeback; #if defined(OPLUS_FEATURE_PROCESS_RECLAIM) && defined(CONFIG_PROCESS_RECLAIM_ENHANCE) if (sc->walk && is_reclaim_should_cancel(sc->walk)) break; #endif cond_resched(); page = lru_to_page(page_list); list_del(&page->lru); if (!trylock_page(page)) goto keep; VM_BUG_ON_PAGE(PageActive(page), page); if (pgdat) VM_BUG_ON_PAGE(page_pgdat(page) != pgdat, page); sc->nr_scanned++; if (unlikely(!page_evictable(page))) goto activate_locked; if (!sc->may_unmap && page_mapped(page)) goto keep_locked; /* page_update_gen() tried to promote this page? */ if (lru_gen_enabled() && !force_reclaim && page_mapped(page) && PageReferenced(page)) goto keep_locked; /* Double the slab pressure for mapped and swapcache pages */ if ((page_mapped(page) || PageSwapCache(page)) && !(PageAnon(page) && !PageSwapBacked(page))) sc->nr_scanned++; may_enter_fs = (sc->gfp_mask & __GFP_FS) || (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); /* * The number of dirty pages determines if a node is marked * reclaim_congested which affects wait_iff_congested. kswapd * will stall and start writing pages if the tail of the LRU * is all dirty unqueued pages. */ page_check_dirty_writeback(page, &dirty, &writeback); if (dirty || writeback) nr_dirty++; if (dirty && !writeback) nr_unqueued_dirty++; /* * Treat this page as congested if the underlying BDI is or if * pages are cycling through the LRU so quickly that the * pages marked for immediate reclaim are making it to the * end of the LRU a second time. */ mapping = page_mapping(page); if (((dirty || writeback) && mapping && inode_write_congested(mapping->host)) || (writeback && PageReclaim(page))) nr_congested++; /* * If a page at the tail of the LRU is under writeback, there * are three cases to consider. * * 1) If reclaim is encountering an excessive number of pages * under writeback and this page is both under writeback and * PageReclaim then it indicates that pages are being queued * for IO but are being recycled through the LRU before the * IO can complete. Waiting on the page itself risks an * indefinite stall if it is impossible to writeback the * page due to IO error or disconnected storage so instead * note that the LRU is being scanned too quickly and the * caller can stall after page list has been processed. * * 2) Global or new memcg reclaim encounters a page that is * not marked for immediate reclaim, or the caller does not * have __GFP_FS (or __GFP_IO if it's simply going to swap, * not to fs). In this case mark the page for immediate * reclaim and continue scanning. * * Require may_enter_fs because we would wait on fs, which * may not have submitted IO yet. And the loop driver might * enter reclaim, and deadlock if it waits on a page for * which it is needed to do the write (loop masks off * __GFP_IO|__GFP_FS for this reason); but more thought * would probably show more reasons. * * 3) Legacy memcg encounters a page that is already marked * PageReclaim. memcg does not have any dirty pages * throttling so we could easily OOM just because too many * pages are in writeback and there is nothing else to * reclaim. Wait for the writeback to complete. * * In cases 1) and 2) we activate the pages to get them out of * the way while we continue scanning for clean pages on the * inactive list and refilling from the active list. The * observation here is that waiting for disk writes is more * expensive than potentially causing reloads down the line. * Since they're marked for immediate reclaim, they won't put * memory pressure on the cache working set any longer than it * takes to write them to disk. */ if (PageWriteback(page)) { /* Case 1 above */ if (current_is_kswapd() && PageReclaim(page) && (pgdat && test_bit(PGDAT_WRITEBACK, &pgdat->flags))) { nr_immediate++; goto activate_locked; /* Case 2 above */ } else if (sane_reclaim(sc) || !PageReclaim(page) || !may_enter_fs) { /* * This is slightly racy - end_page_writeback() * might have just cleared PageReclaim, then * setting PageReclaim here end up interpreted * as PageReadahead - but that does not matter * enough to care. What we do want is for this * page to have PageReclaim set next time memcg * reclaim reaches the tests above, so it will * then wait_on_page_writeback() to avoid OOM; * and it's also appropriate in global reclaim. */ SetPageReclaim(page); nr_writeback++; goto activate_locked; /* Case 3 above */ } else { unlock_page(page); wait_on_page_writeback(page); /* then go back and try same page again */ list_add_tail(&page->lru, page_list); continue; } } if (!force_reclaim) references = page_check_references(page, sc); switch (references) { case PAGEREF_ACTIVATE: goto activate_locked; case PAGEREF_KEEP: nr_ref_keep++; goto keep_locked; case PAGEREF_RECLAIM: case PAGEREF_RECLAIM_CLEAN: ; /* try to reclaim the page below */ } /* * Anonymous process memory has backing store? * Try to allocate it some swap space here. * Lazyfree page could be freed directly */ if (PageAnon(page) && PageSwapBacked(page)) { if (!PageSwapCache(page)) { if (!(sc->gfp_mask & __GFP_IO)) goto keep_locked; if (PageTransHuge(page)) { /* cannot split THP, skip it */ if (!can_split_huge_page(page, NULL)) goto activate_locked; /* * Split pages without a PMD map right * away. Chances are some or all of the * tail pages can be freed without IO. */ if (!compound_mapcount(page) && split_huge_page_to_list(page, page_list)) goto activate_locked; } if (!add_to_swap(page)) { if (!PageTransHuge(page)) goto activate_locked; /* Fallback to swap normal pages */ if (split_huge_page_to_list(page, page_list)) goto activate_locked; #ifdef CONFIG_TRANSPARENT_HUGEPAGE count_vm_event(THP_SWPOUT_FALLBACK); #endif if (!add_to_swap(page)) goto activate_locked; } may_enter_fs = 1; /* Adding to swap updated mapping */ mapping = page_mapping(page); } } else if (unlikely(PageTransHuge(page))) { /* Split file THP */ if (split_huge_page_to_list(page, page_list)) goto keep_locked; } /* * The page is mapped into the page tables of one or more * processes. Try to unmap it here. */ if (page_mapped(page)) { enum ttu_flags flags = ttu_flags | TTU_BATCH_FLUSH; if (unlikely(PageTransHuge(page))) flags |= TTU_SPLIT_HUGE_PMD; if (!try_to_unmap(page, flags, sc->target_vma)) { nr_unmap_fail++; goto activate_locked; } } if (PageDirty(page)) { /* * Only kswapd can writeback filesystem pages * to avoid risk of stack overflow. But avoid * injecting inefficient single-page IO into * flusher writeback as much as possible: only * write pages when we've encountered many * dirty pages, and when we've already scanned * the rest of the LRU for clean pages and see * the same dirty pages again (PageReclaim). */ if (page_is_file_cache(page) && (!current_is_kswapd() || !PageReclaim(page) || (pgdat && !test_bit(PGDAT_DIRTY, &pgdat->flags)))) { /* * Immediately reclaim when written back. * Similar in principal to deactivate_page() * except we already have the page isolated * and know it's dirty */ inc_node_page_state(page, NR_VMSCAN_IMMEDIATE); SetPageReclaim(page); goto activate_locked; } if (references == PAGEREF_RECLAIM_CLEAN) goto keep_locked; if (!may_enter_fs) goto keep_locked; if (!sc->may_writepage) goto keep_locked; /* * Page is dirty. Flush the TLB if a writable entry * potentially exists to avoid CPU writes after IO * starts and then write it out here. */ try_to_unmap_flush_dirty(); switch (pageout(page, mapping, sc)) { case PAGE_KEEP: goto keep_locked; case PAGE_ACTIVATE: goto activate_locked; case PAGE_SUCCESS: if (PageWriteback(page)) goto keep; if (PageDirty(page)) goto keep; /* * A synchronous write - probably a ramdisk. Go * ahead and try to reclaim the page. */ if (!trylock_page(page)) goto keep; if (PageDirty(page) || PageWriteback(page)) goto keep_locked; mapping = page_mapping(page); case PAGE_CLEAN: ; /* try to free the page below */ } } /* * If the page has buffers, try to free the buffer mappings * associated with this page. If we succeed we try to free * the page as well. * * We do this even if the page is PageDirty(). * try_to_release_page() does not perform I/O, but it is * possible for a page to have PageDirty set, but it is actually * clean (all its buffers are clean). This happens if the * buffers were written out directly, with submit_bh(). ext3 * will do this, as well as the blockdev mapping. * try_to_release_page() will discover that cleanness and will * drop the buffers and mark the page clean - it can be freed. * * Rarely, pages can have buffers and no ->mapping. These are * the pages which were not successfully invalidated in * truncate_complete_page(). We try to drop those buffers here * and if that worked, and the page is no longer mapped into * process address space (page_count == 1) it can be freed. * Otherwise, leave the page on the LRU so it is swappable. */ if (page_has_private(page)) { if (!try_to_release_page(page, sc->gfp_mask)) goto activate_locked; if (!mapping && page_count(page) == 1) { unlock_page(page); if (put_page_testzero(page)) goto free_it; else { /* * rare race with speculative reference. * the speculative reference will free * this page shortly, so we may * increment nr_reclaimed here (and * leave it off the LRU). */ nr_reclaimed++; continue; } } } if (PageAnon(page) && !PageSwapBacked(page)) { /* follow __remove_mapping for reference */ if (!page_ref_freeze(page, 1)) goto keep_locked; if (PageDirty(page)) { page_ref_unfreeze(page, 1); goto keep_locked; } count_vm_event(PGLAZYFREED); count_memcg_page_event(page, PGLAZYFREED); } else if (!mapping || !__remove_mapping(mapping, page, true)) goto keep_locked; unlock_page(page); free_it: nr_reclaimed++; /* * Is there need to periodically free_page_list? It would * appear not as the counts should be low */ if (unlikely(PageTransHuge(page))) { mem_cgroup_uncharge(page); (*get_compound_page_dtor(page))(page); } else list_add(&page->lru, &free_pages); /* * If pagelist are from multiple nodes, we should decrease * NR_ISOLATED_ANON + x on freed pages in here. */ if (!pgdat) dec_node_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page)); continue; activate_locked: /* Not a candidate for swapping, so reclaim swap space. */ if (PageSwapCache(page) && (mem_cgroup_swap_full(page) || PageMlocked(page))) try_to_free_swap(page); VM_BUG_ON_PAGE(PageActive(page), page); if (!PageMlocked(page)) { SetPageActive(page); pgactivate++; count_memcg_page_event(page, PGACTIVATE); } keep_locked: unlock_page(page); keep: list_add(&page->lru, &ret_pages); VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page), page); } mem_cgroup_uncharge_list(&free_pages); try_to_unmap_flush(); free_unref_page_list(&free_pages); list_splice(&ret_pages, page_list); count_vm_events(PGACTIVATE, pgactivate); if (stat) { stat->nr_dirty = nr_dirty; stat->nr_congested = nr_congested; stat->nr_unqueued_dirty = nr_unqueued_dirty; stat->nr_writeback = nr_writeback; stat->nr_immediate = nr_immediate; stat->nr_activate = pgactivate; stat->nr_ref_keep = nr_ref_keep; stat->nr_unmap_fail = nr_unmap_fail; } return nr_reclaimed; } unsigned long reclaim_clean_pages_from_list(struct zone *zone, struct list_head *page_list) { struct scan_control sc = { .gfp_mask = GFP_KERNEL, .priority = DEF_PRIORITY, .may_unmap = 1, /* Doesn't allow to write out dirty page */ .may_writepage = 0, }; unsigned long ret; struct page *page, *next; LIST_HEAD(clean_pages); unsigned int noreclaim_flag; list_for_each_entry_safe(page, next, page_list, lru) { if (page_is_file_cache(page) && !PageDirty(page) && !__PageMovable(page) && !PageUnevictable(page)) { ClearPageActive(page); list_move(&page->lru, &clean_pages); } } /* * We should be safe here since we are only dealing with file pages and * we are not kswapd and therefore cannot write dirty file pages. But * call memalloc_noreclaim_save() anyway, just in case these conditions * change in the future. */ noreclaim_flag = memalloc_noreclaim_save(); ret = shrink_page_list(&clean_pages, zone->zone_pgdat, &sc, TTU_IGNORE_ACCESS, NULL, true); memalloc_noreclaim_restore(noreclaim_flag); list_splice(&clean_pages, page_list); mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE, -ret); return ret; } #if defined(CONFIG_NANDSWAP) unsigned long nswap_reclaim_page_list(struct list_head *page_list, struct vm_area_struct *vma, bool scan) { unsigned long nr_reclaimed; unsigned long nr_scan = 0; struct page *page; struct scan_control sc = { .gfp_mask = GFP_KERNEL, .priority = DEF_PRIORITY, .may_writepage = 1, .may_unmap = 1, .may_swap = 1, .target_vma = vma, }; list_for_each_entry(page, page_list, lru) { ClearPageActive(page); } nr_reclaimed = shrink_page_list(page_list, NULL, &sc, TTU_IGNORE_ACCESS, NULL, true); while (!list_empty(page_list)) { page = lru_to_page(page_list); if (PageSwapCache(page) && !PageDirty(page)) nr_scan++; list_del(&page->lru); dec_node_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page)); putback_lru_page(page); } return scan ? nr_scan : nr_reclaimed; } #endif #ifdef CONFIG_PROCESS_RECLAIM #if defined(OPLUS_FEATURE_PROCESS_RECLAIM) && defined(CONFIG_PROCESS_RECLAIM_ENHANCE) unsigned long reclaim_pages_from_list(struct list_head *page_list, struct vm_area_struct *vma, struct mm_walk *walk) #else unsigned long reclaim_pages_from_list(struct list_head *page_list, struct vm_area_struct *vma) #endif { struct scan_control sc = { .gfp_mask = GFP_KERNEL, .priority = DEF_PRIORITY, .may_writepage = 1, .may_unmap = 1, .may_swap = 1, .target_vma = vma, #if defined(OPLUS_FEATURE_PROCESS_RECLAIM) && defined(CONFIG_PROCESS_RECLAIM_ENHANCE) .walk = walk, #endif }; unsigned long nr_reclaimed; struct page *page; list_for_each_entry(page, page_list, lru) ClearPageActive(page); nr_reclaimed = shrink_page_list(page_list, NULL, &sc, TTU_IGNORE_ACCESS, NULL, true); while (!list_empty(page_list)) { page = lru_to_page(page_list); list_del(&page->lru); dec_node_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page)); putback_lru_page(page); } return nr_reclaimed; } #endif /* * Attempt to remove the specified page from its LRU. Only take this page * if it is of the appropriate PageActive status. Pages which are being * freed elsewhere are also ignored. * * page: page to consider * mode: one of the LRU isolation modes defined above * * returns 0 on success, -ve errno on failure. */ int __isolate_lru_page(struct page *page, isolate_mode_t mode) { int ret = -EINVAL; /* Only take pages on the LRU. */ if (!PageLRU(page)) return ret; /* Compaction should not handle unevictable pages but CMA can do so */ if (PageUnevictable(page) && !(mode & ISOLATE_UNEVICTABLE)) return ret; ret = -EBUSY; /* * To minimise LRU disruption, the caller can indicate that it only * wants to isolate pages it will be able to operate on without * blocking - clean pages for the most part. * * ISOLATE_ASYNC_MIGRATE is used to indicate that it only wants to pages * that it is possible to migrate without blocking */ if (mode & ISOLATE_ASYNC_MIGRATE) { /* All the caller can do on PageWriteback is block */ if (PageWriteback(page)) return ret; if (PageDirty(page)) { struct address_space *mapping; bool migrate_dirty; /* * Only pages without mappings or that have a * ->migratepage callback are possible to migrate * without blocking. However, we can be racing with * truncation so it's necessary to lock the page * to stabilise the mapping as truncation holds * the page lock until after the page is removed * from the page cache. */ if (!trylock_page(page)) return ret; mapping = page_mapping(page); migrate_dirty = !mapping || mapping->a_ops->migratepage; unlock_page(page); if (!migrate_dirty) return ret; } } if ((mode & ISOLATE_UNMAPPED) && page_mapped(page)) return ret; if (likely(get_page_unless_zero(page))) { /* * Be careful not to clear PageLRU until after we're * sure the page is not being freed elsewhere -- the * page release code relies on it. */ ClearPageLRU(page); ret = 0; } return ret; } /* * Update LRU sizes after isolating pages. The LRU size updates must * be complete before mem_cgroup_update_lru_size due to a santity check. */ static __always_inline void update_lru_sizes(struct lruvec *lruvec, enum lru_list lru, unsigned long *nr_zone_taken) { int zid; for (zid = 0; zid < MAX_NR_ZONES; zid++) { if (!nr_zone_taken[zid]) continue; update_lru_size(lruvec, lru, zid, -nr_zone_taken[zid]); } } /* * zone_lru_lock is heavily contended. Some of the functions that * shrink the lists perform better by taking out a batch of pages * and working on them outside the LRU lock. * * For pagecache intensive workloads, this function is the hottest * spot in the kernel (apart from copy_*_user functions). * * Appropriate locks must be held before calling this function. * * @nr_to_scan: The number of eligible pages to look through on the list. * @lruvec: The LRU vector to pull pages from. * @dst: The temp list to put pages on to. * @nr_scanned: The number of pages that were scanned. * @sc: The scan_control struct for this reclaim session * @mode: One of the LRU isolation modes * @lru: LRU list id for isolating * * returns how many pages were moved onto *@dst. */ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, struct lruvec *lruvec, struct list_head *dst, unsigned long *nr_scanned, struct scan_control *sc, isolate_mode_t mode, enum lru_list lru) { struct list_head *src = &lruvec->lists[lru]; unsigned long nr_taken = 0; unsigned long nr_zone_taken[MAX_NR_ZONES] = { 0 }; unsigned long nr_skipped[MAX_NR_ZONES] = { 0, }; unsigned long skipped = 0; unsigned long scan, total_scan, nr_pages; LIST_HEAD(pages_skipped); scan = 0; for (total_scan = 0; scan < nr_to_scan && nr_taken < nr_to_scan && !list_empty(src); total_scan++) { struct page *page; page = lru_to_page(src); prefetchw_prev_lru_page(page, src, flags); VM_BUG_ON_PAGE(!PageLRU(page), page); if (page_zonenum(page) > sc->reclaim_idx) { list_move(&page->lru, &pages_skipped); nr_skipped[page_zonenum(page)]++; continue; } /* * Do not count skipped pages because that makes the function * return with no isolated pages if the LRU mostly contains * ineligible pages. This causes the VM to not reclaim any * pages, triggering a premature OOM. */ scan++; switch (__isolate_lru_page(page, mode)) { case 0: nr_pages = hpage_nr_pages(page); nr_taken += nr_pages; nr_zone_taken[page_zonenum(page)] += nr_pages; list_move(&page->lru, dst); break; case -EBUSY: /* else it is being freed elsewhere */ list_move(&page->lru, src); continue; default: BUG(); } } /* * Splice any skipped pages to the start of the LRU list. Note that * this disrupts the LRU order when reclaiming for lower zones but * we cannot splice to the tail. If we did then the SWAP_CLUSTER_MAX * scanning would soon rescan the same pages to skip and put the * system at risk of premature OOM. */ if (!list_empty(&pages_skipped)) { int zid; list_splice(&pages_skipped, src); for (zid = 0; zid < MAX_NR_ZONES; zid++) { if (!nr_skipped[zid]) continue; __count_zid_vm_events(PGSCAN_SKIP, zid, nr_skipped[zid]); skipped += nr_skipped[zid]; } } *nr_scanned = total_scan; trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan, total_scan, skipped, nr_taken, mode, lru); update_lru_sizes(lruvec, lru, nr_zone_taken); return nr_taken; } /** * isolate_lru_page - tries to isolate a page from its LRU list * @page: page to isolate from its LRU list * * Isolates a @page from an LRU list, clears PageLRU and adjusts the * vmstat statistic corresponding to whatever LRU list the page was on. * * Returns 0 if the page was removed from an LRU list. * Returns -EBUSY if the page was not on an LRU list. * * The returned page will have PageLRU() cleared. If it was found on * the active list, it will have PageActive set. If it was found on * the unevictable list, it will have the PageUnevictable bit set. That flag * may need to be cleared by the caller before letting the page go. * * The vmstat statistic corresponding to the list on which the page was * found will be decremented. * * Restrictions: * * (1) Must be called with an elevated refcount on the page. This is a * fundamentnal difference from isolate_lru_pages (which is called * without a stable reference). * (2) the lru_lock must not be held. * (3) interrupts must be enabled. */ int isolate_lru_page(struct page *page) { int ret = -EBUSY; VM_BUG_ON_PAGE(!page_count(page), page); #if defined(OPLUS_FEATURE_PROCESS_RECLAIM) && defined(CONFIG_PROCESS_RECLAIM_ENHANCE) /* * Because process reclaim is doing page by * page, so there many compound pages are relcaimed, so too many warning msg on this case. */ WARN_RATELIMIT((!current_is_reclaimer() && PageTail(page)), "trying to isolate tail page"); #else WARN_RATELIMIT(PageTail(page), "trying to isolate tail page"); #endif if (PageLRU(page)) { struct zone *zone = page_zone(page); struct lruvec *lruvec; spin_lock_irq(zone_lru_lock(zone)); lruvec = mem_cgroup_page_lruvec(page, zone->zone_pgdat); if (PageLRU(page)) { get_page(page); ClearPageLRU(page); del_page_from_lru_list(page, lruvec); ret = 0; } spin_unlock_irq(zone_lru_lock(zone)); } return ret; } /* * A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and * then get resheduled. When there are massive number of tasks doing page * allocation, such sleeping direct reclaimers may keep piling up on each CPU, * the LRU list will go small and be scanned faster than necessary, leading to * unnecessary swapping, thrashing and OOM. */ static int too_many_isolated(struct pglist_data *pgdat, int file, struct scan_control *sc) { unsigned long inactive, isolated; if (current_is_kswapd()) return 0; if (!sane_reclaim(sc)) return 0; if (file) { inactive = node_page_state(pgdat, NR_INACTIVE_FILE); isolated = node_page_state(pgdat, NR_ISOLATED_FILE); } else { inactive = node_page_state(pgdat, NR_INACTIVE_ANON); isolated = node_page_state(pgdat, NR_ISOLATED_ANON); } /* * GFP_NOIO/GFP_NOFS callers are allowed to isolate more pages, so they * won't get blocked by normal direct-reclaimers, forming a circular * deadlock. */ if ((sc->gfp_mask & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS)) inactive >>= 3; return isolated > inactive; } static noinline_for_stack void putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list) { struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; struct pglist_data *pgdat = lruvec_pgdat(lruvec); LIST_HEAD(pages_to_free); /* * Put back any unfreeable pages. */ while (!list_empty(page_list)) { struct page *page = lru_to_page(page_list); VM_BUG_ON_PAGE(PageLRU(page), page); list_del(&page->lru); if (unlikely(!page_evictable(page))) { spin_unlock_irq(&pgdat->lru_lock); putback_lru_page(page); spin_lock_irq(&pgdat->lru_lock); continue; } lruvec = mem_cgroup_page_lruvec(page, pgdat); SetPageLRU(page); add_page_to_lru_list(page, lruvec); if (PageActive(page)) { int file = page_is_file_cache(page); int numpages = hpage_nr_pages(page); reclaim_stat->recent_rotated[file] += numpages; } if (put_page_testzero(page)) { del_page_from_lru_list(page, lruvec); __clear_page_lru_flags(page); if (unlikely(PageCompound(page))) { spin_unlock_irq(&pgdat->lru_lock); mem_cgroup_uncharge(page); (*get_compound_page_dtor(page))(page); spin_lock_irq(&pgdat->lru_lock); } else list_add(&page->lru, &pages_to_free); } } /* * To save our caller's stack, now use input list for pages to free. */ list_splice(&pages_to_free, page_list); } /* * If a kernel thread (such as nfsd for loop-back mounts) services * a backing device by writing to the page cache it sets PF_LESS_THROTTLE. * In that case we should only throttle if the backing device it is * writing to is congested. In other cases it is safe to throttle. */ static int current_may_throttle(void) { #if defined(OPLUS_FEATURE_ZRAM_OPT) && defined(CONFIG_OPLUS_ZRAM_OPT) if ((current->signal->oom_score_adj < 0) #ifdef CONFIG_FG_TASK_UID || is_fg(current_uid().val) #endif ) return 0; #endif /*OPLUS_FEATURE_ZRAM_OPT*/ return !(current->flags & PF_LESS_THROTTLE) || current->backing_dev_info == NULL || bdi_write_congested(current->backing_dev_info); } /* * shrink_inactive_list() is a helper for shrink_node(). It returns the number * of reclaimed pages */ static noinline_for_stack unsigned long shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, struct scan_control *sc, enum lru_list lru) { LIST_HEAD(page_list); unsigned long nr_scanned; unsigned long nr_reclaimed = 0; unsigned long nr_taken; struct reclaim_stat stat = {}; isolate_mode_t isolate_mode = 0; int file = is_file_lru(lru); struct pglist_data *pgdat = lruvec_pgdat(lruvec); struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; bool stalled = false; while (unlikely(too_many_isolated(pgdat, file, sc))) { if (stalled) return 0; /* We are about to die and free our memory. Return now. */ if (fatal_signal_pending(current)) return SWAP_CLUSTER_MAX; /* wait a bit for the reclaimer. */ msleep(100); stalled = true; } lru_add_drain(); if (!sc->may_unmap) isolate_mode |= ISOLATE_UNMAPPED; spin_lock_irq(&pgdat->lru_lock); nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &page_list, &nr_scanned, sc, isolate_mode, lru); __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken); reclaim_stat->recent_scanned[file] += nr_taken; if (current_is_kswapd()) { if (global_reclaim(sc)) __count_vm_events(PGSCAN_KSWAPD, nr_scanned); count_memcg_events(lruvec_memcg(lruvec), PGSCAN_KSWAPD, nr_scanned); } else { if (global_reclaim(sc)) __count_vm_events(PGSCAN_DIRECT, nr_scanned); count_memcg_events(lruvec_memcg(lruvec), PGSCAN_DIRECT, nr_scanned); } spin_unlock_irq(&pgdat->lru_lock); if (nr_taken == 0) return 0; nr_reclaimed = shrink_page_list(&page_list, pgdat, sc, 0, &stat, false); spin_lock_irq(&pgdat->lru_lock); if (current_is_kswapd()) { if (global_reclaim(sc)) __count_vm_events(PGSTEAL_KSWAPD, nr_reclaimed); count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_KSWAPD, nr_reclaimed); } else { if (global_reclaim(sc)) __count_vm_events(PGSTEAL_DIRECT, nr_reclaimed); count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_DIRECT, nr_reclaimed); } putback_inactive_pages(lruvec, &page_list); __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken); spin_unlock_irq(&pgdat->lru_lock); mem_cgroup_uncharge_list(&page_list); free_unref_page_list(&page_list); /* * If dirty pages are scanned that are not queued for IO, it * implies that flushers are not doing their job. This can * happen when memory pressure pushes dirty pages to the end of * the LRU before the dirty limits are breached and the dirty * data has expired. It can also happen when the proportion of * dirty pages grows not through writes but through memory * pressure reclaiming all the clean cache. And in some cases, * the flushers simply cannot keep up with the allocation * rate. Nudge the flusher threads in case they are asleep. */ if (stat.nr_unqueued_dirty == nr_taken) wakeup_flusher_threads(WB_REASON_VMSCAN); sc->nr.dirty += stat.nr_dirty; sc->nr.congested += stat.nr_congested; sc->nr.unqueued_dirty += stat.nr_unqueued_dirty; sc->nr.writeback += stat.nr_writeback; sc->nr.immediate += stat.nr_immediate; sc->nr.taken += nr_taken; if (file) sc->nr.file_taken += nr_taken; trace_mm_vmscan_lru_shrink_inactive(pgdat->node_id, nr_scanned, nr_reclaimed, &stat, sc->priority, file); return nr_reclaimed; } /* * This moves pages from the active list to the inactive list. * * We move them the other way if the page is referenced by one or more * processes, from rmap. * * If the pages are mostly unmapped, the processing is fast and it is * appropriate to hold zone_lru_lock across the whole operation. But if * the pages are mapped, the processing is slow (page_referenced()) so we * should drop zone_lru_lock around each page. It's impossible to balance * this, so instead we remove the pages from the LRU while processing them. * It is safe to rely on PG_active against the non-LRU pages in here because * nobody will play with that bit on a non-LRU page. * * The downside is that we have to touch page->_refcount against each page. * But we had to alter page->flags anyway. * * Returns the number of pages moved to the given lru. */ static unsigned move_active_pages_to_lru(struct lruvec *lruvec, struct list_head *list, struct list_head *pages_to_free, enum lru_list lru) { struct pglist_data *pgdat = lruvec_pgdat(lruvec); struct page *page; int nr_moved = 0; while (!list_empty(list)) { page = lru_to_page(list); lruvec = mem_cgroup_page_lruvec(page, pgdat); VM_BUG_ON_PAGE(PageLRU(page), page); list_del(&page->lru); SetPageLRU(page); add_page_to_lru_list(page, lruvec); if (put_page_testzero(page)) { del_page_from_lru_list(page, lruvec); __clear_page_lru_flags(page); if (unlikely(PageCompound(page))) { spin_unlock_irq(&pgdat->lru_lock); mem_cgroup_uncharge(page); (*get_compound_page_dtor(page))(page); spin_lock_irq(&pgdat->lru_lock); } else list_add(&page->lru, pages_to_free); } else { nr_moved += hpage_nr_pages(page); } } if (!is_active_lru(lru)) { __count_vm_events(PGDEACTIVATE, nr_moved); count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, nr_moved); } return nr_moved; } static void shrink_active_list(unsigned long nr_to_scan, struct lruvec *lruvec, struct scan_control *sc, enum lru_list lru) { unsigned long nr_taken; unsigned long nr_scanned; unsigned long vm_flags; LIST_HEAD(l_hold); /* The pages which were snipped off */ LIST_HEAD(l_active); LIST_HEAD(l_inactive); struct page *page; struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; unsigned nr_deactivate, nr_activate; unsigned nr_rotated = 0; isolate_mode_t isolate_mode = 0; int file = is_file_lru(lru); struct pglist_data *pgdat = lruvec_pgdat(lruvec); lru_add_drain(); if (!sc->may_unmap) isolate_mode |= ISOLATE_UNMAPPED; spin_lock_irq(&pgdat->lru_lock); nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold, &nr_scanned, sc, isolate_mode, lru); __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken); reclaim_stat->recent_scanned[file] += nr_taken; __count_vm_events(PGREFILL, nr_scanned); count_memcg_events(lruvec_memcg(lruvec), PGREFILL, nr_scanned); spin_unlock_irq(&pgdat->lru_lock); while (!list_empty(&l_hold)) { cond_resched(); page = lru_to_page(&l_hold); list_del(&page->lru); if (unlikely(!page_evictable(page))) { putback_lru_page(page); continue; } if (unlikely(buffer_heads_over_limit)) { if (page_has_private(page) && trylock_page(page)) { if (page_has_private(page)) try_to_release_page(page, 0); unlock_page(page); } } if (page_referenced(page, 0, sc->target_mem_cgroup, &vm_flags)) { nr_rotated += hpage_nr_pages(page); /* * Identify referenced, file-backed active pages and * give them one more trip around the active list. So * that executable code get better chances to stay in * memory under moderate memory pressure. Anon pages * are not likely to be evicted by use-once streaming * IO, plus JVM can create lots of anon VM_EXEC pages, * so we ignore them here. */ if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { list_add(&page->lru, &l_active); continue; } } ClearPageActive(page); /* we are de-activating */ SetPageWorkingset(page); list_add(&page->lru, &l_inactive); } /* * Move pages back to the lru list. */ spin_lock_irq(&pgdat->lru_lock); /* * Count referenced pages from currently used mappings as rotated, * even though only some of them are actually re-activated. This * helps balance scan pressure between file and anonymous pages in * get_scan_count. */ reclaim_stat->recent_rotated[file] += nr_rotated; nr_activate = move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru); nr_deactivate = move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, lru - LRU_ACTIVE); __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken); spin_unlock_irq(&pgdat->lru_lock); mem_cgroup_uncharge_list(&l_hold); free_unref_page_list(&l_hold); trace_mm_vmscan_lru_shrink_active(pgdat->node_id, nr_taken, nr_activate, nr_deactivate, nr_rotated, sc->priority, file); } unsigned long reclaim_pages(struct list_head *page_list) { int nid = -1; unsigned long nr_reclaimed = 0; LIST_HEAD(node_page_list); struct reclaim_stat dummy_stat; struct page *page; unsigned int noreclaim_flag; struct scan_control sc = { .gfp_mask = GFP_KERNEL, .priority = DEF_PRIORITY, .may_writepage = 1, .may_unmap = 1, .may_swap = 1, }; noreclaim_flag = memalloc_noreclaim_save(); while (!list_empty(page_list)) { page = lru_to_page(page_list); if (nid == -1) { nid = page_to_nid(page); INIT_LIST_HEAD(&node_page_list); } if (nid == page_to_nid(page)) { list_move(&page->lru, &node_page_list); continue; } nr_reclaimed += shrink_page_list(&node_page_list, NODE_DATA(nid), &sc, 0, &dummy_stat, false); while (!list_empty(&node_page_list)) { page = lru_to_page(&node_page_list); list_del(&page->lru); putback_lru_page(page); } nid = -1; } if (!list_empty(&node_page_list)) { nr_reclaimed += shrink_page_list(&node_page_list, NODE_DATA(nid), &sc, 0, &dummy_stat, false); while (!list_empty(&node_page_list)) { page = lru_to_page(&node_page_list); list_del(&page->lru); putback_lru_page(page); } } memalloc_noreclaim_restore(noreclaim_flag); return nr_reclaimed; } /* * The inactive anon list should be small enough that the VM never has * to do too much work. * * The inactive file list should be small enough to leave most memory * to the established workingset on the scan-resistant active list, * but large enough to avoid thrashing the aggregate readahead window. * * Both inactive lists should also be large enough that each inactive * page has a chance to be referenced again before it is reclaimed. * * If that fails and refaulting is observed, the inactive list grows. * * The inactive_ratio is the target ratio of ACTIVE to INACTIVE pages * on this LRU, maintained by the pageout code. An inactive_ratio * of 3 means 3:1 or 25% of the pages are kept on the inactive list. * * total target max * memory ratio inactive * ------------------------------------- * 10MB 1 5MB * 100MB 1 50MB * 1GB 3 250MB * 10GB 10 0.9GB * 100GB 31 3GB * 1TB 101 10GB * 10TB 320 32GB */ static bool inactive_list_is_low(struct lruvec *lruvec, bool file, struct scan_control *sc, bool trace) { enum lru_list active_lru = file * LRU_FILE + LRU_ACTIVE; struct pglist_data *pgdat = lruvec_pgdat(lruvec); enum lru_list inactive_lru = file * LRU_FILE; unsigned long inactive, active; unsigned long inactive_ratio; unsigned long refaults; unsigned long gb; /* * If we don't have swap space, anonymous page deactivation * is pointless. */ if (!file && !total_swap_pages) return false; inactive = lruvec_lru_size(lruvec, inactive_lru, sc->reclaim_idx); active = lruvec_lru_size(lruvec, active_lru, sc->reclaim_idx); /* * When refaults are being observed, it means a new workingset * is being established. Disable active list protection to get * rid of the stale workingset quickly. */ refaults = lruvec_page_state(lruvec, WORKINGSET_ACTIVATE); if (file && lruvec->refaults != refaults) { inactive_ratio = 0; } else { gb = (inactive + active) >> (30 - PAGE_SHIFT); #if defined(OPLUS_FEATURE_ZRAM_OPT) && defined(CONFIG_OPLUS_ZRAM_OPT) if (file && gb) inactive_ratio = min(2UL, int_sqrt(10 * gb)); #else if (gb) inactive_ratio = int_sqrt(10 * gb); #endif /*OPLUS_FEATURE_ZRAM_OPT*/ else inactive_ratio = 1; } if (trace) trace_mm_vmscan_inactive_list_is_low(pgdat->node_id, sc->reclaim_idx, lruvec_lru_size(lruvec, inactive_lru, MAX_NR_ZONES), inactive, lruvec_lru_size(lruvec, active_lru, MAX_NR_ZONES), active, inactive_ratio, file); return inactive * inactive_ratio < active; } static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, struct lruvec *lruvec, struct scan_control *sc) { if (is_active_lru(lru)) { if (inactive_list_is_low(lruvec, is_file_lru(lru), sc, true)) shrink_active_list(nr_to_scan, lruvec, sc, lru); return 0; } return shrink_inactive_list(nr_to_scan, lruvec, sc, lru); } enum scan_balance { SCAN_EQUAL, SCAN_FRACT, SCAN_ANON, SCAN_FILE, }; #ifdef CONFIG_HYBRIDSWAP_SWAPD extern bool free_swap_is_low(void); bool __weak free_swap_is_low(void) { return false; } #endif /* * Determine how aggressively the anon and file LRU lists should be * scanned. The relative value of each set of LRU lists is determined * by looking at the fraction of the pages scanned we did rotate back * onto the active list instead of evict. * * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan */ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg, struct scan_control *sc, unsigned long *nr, unsigned long *lru_pages) { int swappiness = mem_cgroup_swappiness(memcg); struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; u64 fraction[ANON_AND_FILE]; u64 denominator = 0; /* gcc */ struct pglist_data *pgdat = lruvec_pgdat(lruvec); unsigned long anon_prio, file_prio; enum scan_balance scan_balance; unsigned long anon, file; unsigned long ap, fp; enum lru_list lru; unsigned long totalswap = total_swap_pages; #if defined(CONFIG_NANDSWAP) if (nandswap_si) totalswap -= nandswap_si->pages; #endif /* use vm_swappiness defaultly */ swappiness = vm_swappiness; #if defined(OPLUS_FEATURE_ZRAM_OPT) && defined(CONFIG_OPLUS_ZRAM_OPT) if (!current_is_kswapd()) { #ifdef CONFIG_HYBRIDSWAP_SWAPD if (strncmp(current->comm, "hybridswapd:", sizeof("hybridswapd:") - 1) == 0) { swappiness = hybridswapd_swappiness; if (free_swap_is_low()) swappiness = 0; } else #endif swappiness = direct_vm_swappiness; } #ifdef CONFIG_DYNAMIC_TUNNING_SWAPPINESS else { unsigned long nr_file_pages = global_node_page_state(NR_ACTIVE_FILE) + global_node_page_state(NR_INACTIVE_FILE); if (swappiness_threshold1_size && vm_swappiness_threshold1 && nr_file_pages >= (swappiness_threshold1_size << 8) && swappiness > vm_swappiness_threshold1) { swappiness = vm_swappiness_threshold1; } else if (swappiness_threshold2_size && vm_swappiness_threshold2 && nr_file_pages >= (swappiness_threshold2_size << 8) && swappiness > vm_swappiness_threshold2) { swappiness = vm_swappiness_threshold2; } } #endif if (!sc->may_swap || (mem_cgroup_get_nr_swap_pages(memcg) <= totalswap>>6)) { #else /* If we have no swap space, do not bother scanning anon pages. */ if (!sc->may_swap || mem_cgroup_get_nr_swap_pages(memcg) <= 0) { #endif /*OPLUS_FEATURE_ZRAM_OPT*/ scan_balance = SCAN_FILE; goto out; } /* * Global reclaim will swap to prevent OOM even with no * swappiness, but memcg users want to use this knob to * disable swapping for individual groups completely when * using the memory controller's swap limit feature would be * too expensive. */ if (!global_reclaim(sc) && !swappiness) { scan_balance = SCAN_FILE; goto out; } /* * Do not apply any pressure balancing cleverness when the * system is close to OOM, scan both anon and file equally * (unless the swappiness setting disagrees with swapping). */ if (!sc->priority && swappiness) { scan_balance = SCAN_EQUAL; goto out; } /* * Prevent the reclaimer from falling into the cache trap: as * cache pages start out inactive, every cache fault will tip * the scan balance towards the file LRU. And as the file LRU * shrinks, so does the window for rotation from references. * This means we have a runaway feedback loop where a tiny * thrashing file LRU becomes infinitely more attractive than * anon pages. Try to detect this based on file LRU size. */ if (global_reclaim(sc)) { unsigned long pgdatfile; unsigned long pgdatfree; int z; unsigned long total_high_wmark = 0; pgdatfree = sum_zone_node_page_state(pgdat->node_id, NR_FREE_PAGES); pgdatfile = node_page_state(pgdat, NR_ACTIVE_FILE) + node_page_state(pgdat, NR_INACTIVE_FILE); for (z = 0; z < MAX_NR_ZONES; z++) { struct zone *zone = &pgdat->node_zones[z]; if (!managed_zone(zone)) continue; total_high_wmark += high_wmark_pages(zone); } if (unlikely(pgdatfile + pgdatfree <= total_high_wmark)) { /* * Force SCAN_ANON if there are enough inactive * anonymous pages on the LRU in eligible zones. * Otherwise, the small LRU gets thrashed. */ if (!inactive_list_is_low(lruvec, false, sc, false) && lruvec_lru_size(lruvec, LRU_INACTIVE_ANON, sc->reclaim_idx) >> sc->priority) { scan_balance = SCAN_ANON; goto out; } } } /* * If there is enough inactive page cache, i.e. if the size of the * inactive list is greater than that of the active list *and* the * inactive list actually has some pages to scan on this priority, we * do not reclaim anything from the anonymous working set right now. * Without the second condition we could end up never scanning an * lruvec even if it has plenty of old anonymous pages unless the * system is under heavy pressure. */ if (!IS_ENABLED(CONFIG_BALANCE_ANON_FILE_RECLAIM) && !inactive_list_is_low(lruvec, true, sc, false) && lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, sc->reclaim_idx) >> sc->priority) { scan_balance = SCAN_FILE; goto out; } scan_balance = SCAN_FRACT; /* * With swappiness at 100, anonymous and file have the same priority. * This scanning priority is essentially the inverse of IO cost. */ anon_prio = swappiness; file_prio = 200 - anon_prio; /* * OK, so we have swap space and a fair amount of page cache * pages. We use the recently rotated / recently scanned * ratios to determine how valuable each cache is. * * Because workloads change over time (and to avoid overflow) * we keep these statistics as a floating average, which ends * up weighing recent references more than old ones. */ anon = lruvec_lru_size(lruvec, LRU_ACTIVE_ANON, MAX_NR_ZONES) + lruvec_lru_size(lruvec, LRU_INACTIVE_ANON, MAX_NR_ZONES); file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES) + lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES); spin_lock_irq(&pgdat->lru_lock); if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { reclaim_stat->recent_scanned[0] /= 2; reclaim_stat->recent_rotated[0] /= 2; } if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { reclaim_stat->recent_scanned[1] /= 2; reclaim_stat->recent_rotated[1] /= 2; } /* * The amount of pressure on anon vs file pages is inversely * proportional to the fraction of recently scanned pages on * each list that were recently referenced and in active use. */ ap = anon_prio * (reclaim_stat->recent_scanned[0] + 1); ap /= reclaim_stat->recent_rotated[0] + 1; fp = file_prio * (reclaim_stat->recent_scanned[1] + 1); fp /= reclaim_stat->recent_rotated[1] + 1; spin_unlock_irq(&pgdat->lru_lock); fraction[0] = ap; fraction[1] = fp; denominator = ap + fp + 1; out: *lru_pages = 0; for_each_evictable_lru(lru) { int file = is_file_lru(lru); unsigned long size; unsigned long scan; size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx); scan = size >> sc->priority; /* * If the cgroup's already been deleted, make sure to * scrape out the remaining cache. */ if (!scan && !mem_cgroup_online(memcg)) scan = min(size, SWAP_CLUSTER_MAX); trace_android_vh_tune_scan_type((char *)(&scan_balance)); switch (scan_balance) { case SCAN_EQUAL: /* Scan lists relative to size */ break; case SCAN_FRACT: /* * Scan types proportional to swappiness and * their relative recent reclaim efficiency. * Make sure we don't miss the last page on * the offlined memory cgroups because of a * round-off error. */ scan = mem_cgroup_online(memcg) ? div64_u64(scan * fraction[file], denominator) : DIV64_U64_ROUND_UP(scan * fraction[file], denominator); break; case SCAN_FILE: case SCAN_ANON: /* Scan one type exclusively */ if ((scan_balance == SCAN_FILE) != file) { size = 0; scan = 0; } break; default: /* Look ma, no brain */ BUG(); } *lru_pages += size; nr[lru] = scan; } } #ifdef CONFIG_LRU_GEN #ifdef CONFIG_LRU_GEN_ENABLED DEFINE_STATIC_KEY_ARRAY_TRUE(lru_gen_caps, NR_LRU_GEN_CAPS); #else DEFINE_STATIC_KEY_ARRAY_FALSE(lru_gen_caps, NR_LRU_GEN_CAPS); #endif /****************************************************************************** * shorthand helpers ******************************************************************************/ #define DEFINE_MAX_SEQ(lruvec) \ unsigned long max_seq = READ_ONCE((lruvec)->lrugen.max_seq) #define DEFINE_MIN_SEQ(lruvec) \ unsigned long min_seq[ANON_AND_FILE] = { \ READ_ONCE((lruvec)->lrugen.min_seq[LRU_GEN_ANON]), \ READ_ONCE((lruvec)->lrugen.min_seq[LRU_GEN_FILE]), \ } #define for_each_gen_type_zone(gen, type, zone) \ for ((gen) = 0; (gen) < MAX_NR_GENS; (gen)++) \ for ((type) = 0; (type) < ANON_AND_FILE; (type)++) \ for ((zone) = 0; (zone) < MAX_NR_ZONES; (zone)++) static int page_lru_gen(struct page *page) { unsigned long flags = READ_ONCE(page->flags); return ((flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1; } static int page_lru_tier(struct page *page) { int refs; unsigned long flags = READ_ONCE(page->flags); refs = (flags & LRU_REFS_FLAGS) == LRU_REFS_FLAGS ? ((flags & LRU_REFS_MASK) >> LRU_REFS_PGOFF) + 1 : 0; return lru_tier_from_refs(refs); } static bool get_cap(int cap) { #ifdef CONFIG_LRU_GEN_ENABLED return static_branch_likely(&lru_gen_caps[cap]); #else return static_branch_unlikely(&lru_gen_caps[cap]); #endif } static struct lruvec *get_lruvec(struct mem_cgroup *memcg, int nid) { struct pglist_data *pgdat = NODE_DATA(nid); #ifdef CONFIG_MEMCG if (memcg) { struct lruvec *lruvec = &memcg->nodeinfo[nid]->lruvec; /* for hotadd_new_pgdat() */ if (!lruvec->pgdat) lruvec->pgdat = pgdat; return lruvec; } #endif VM_BUG_ON(!mem_cgroup_disabled()); return pgdat ? &pgdat->lruvec : NULL; } static int get_swappiness(struct lruvec *lruvec, struct scan_control *sc) { struct mem_cgroup *memcg = lruvec_memcg(lruvec); if (mem_cgroup_get_nr_swap_pages(memcg) < MIN_LRU_BATCH) return 0; return mem_cgroup_swappiness(memcg); } static int get_nr_gens(struct lruvec *lruvec, int type) { return lruvec->lrugen.max_seq - lruvec->lrugen.min_seq[type] + 1; } static bool __maybe_unused seq_is_valid(struct lruvec *lruvec) { /* see the comment on lru_gen_struct */ return get_nr_gens(lruvec, LRU_GEN_FILE) >= MIN_NR_GENS && get_nr_gens(lruvec, LRU_GEN_FILE) <= get_nr_gens(lruvec, LRU_GEN_ANON) && get_nr_gens(lruvec, LRU_GEN_ANON) <= MAX_NR_GENS; } /****************************************************************************** * mm_struct list ******************************************************************************/ static struct lru_gen_mm_list *get_mm_list(struct mem_cgroup *memcg) { static struct lru_gen_mm_list mm_list = { .fifo = LIST_HEAD_INIT(mm_list.fifo), .lock = __SPIN_LOCK_UNLOCKED(mm_list.lock), }; #ifdef CONFIG_MEMCG if (memcg) return &memcg->mm_list; #endif VM_BUG_ON(!mem_cgroup_disabled()); return &mm_list; } void lru_gen_add_mm(struct mm_struct *mm) { int nid; struct mem_cgroup *memcg = get_mem_cgroup_from_mm(mm); struct lru_gen_mm_list *mm_list = get_mm_list(memcg); VM_BUG_ON_MM(!list_empty(&mm->lru_gen.list), mm); #ifdef CONFIG_MEMCG VM_BUG_ON_MM(mm->lru_gen.memcg, mm); mm->lru_gen.memcg = memcg; #endif spin_lock(&mm_list->lock); for_each_node_state(nid, N_MEMORY) { struct lruvec *lruvec = get_lruvec(memcg, nid); if (!lruvec) continue; if (lruvec->mm_state.tail == &mm_list->fifo) lruvec->mm_state.tail = &mm->lru_gen.list; } list_add_tail(&mm->lru_gen.list, &mm_list->fifo); spin_unlock(&mm_list->lock); } void lru_gen_del_mm(struct mm_struct *mm) { int nid; struct lru_gen_mm_list *mm_list; struct mem_cgroup *memcg = NULL; if (list_empty(&mm->lru_gen.list)) return; #ifdef CONFIG_MEMCG memcg = mm->lru_gen.memcg; #endif mm_list = get_mm_list(memcg); spin_lock(&mm_list->lock); for_each_node(nid) { struct lruvec *lruvec = get_lruvec(memcg, nid); if (!lruvec) continue; if (lruvec->mm_state.tail == &mm->lru_gen.list) lruvec->mm_state.tail = lruvec->mm_state.tail->next; if (lruvec->mm_state.head != &mm->lru_gen.list) continue; lruvec->mm_state.head = lruvec->mm_state.head->next; if (lruvec->mm_state.head == &mm_list->fifo) WRITE_ONCE(lruvec->mm_state.seq, lruvec->mm_state.seq + 1); } list_del_init(&mm->lru_gen.list); spin_unlock(&mm_list->lock); #ifdef CONFIG_MEMCG mem_cgroup_put(mm->lru_gen.memcg); mm->lru_gen.memcg = NULL; #endif } #ifdef CONFIG_MEMCG void lru_gen_migrate_mm(struct mm_struct *mm) { struct mem_cgroup *memcg; lockdep_assert_held(&mm->owner->alloc_lock); /* for mm_update_next_owner() */ if (mem_cgroup_disabled()) return; rcu_read_lock(); memcg = mem_cgroup_from_task(mm->owner); rcu_read_unlock(); if (memcg == mm->lru_gen.memcg) return; VM_BUG_ON_MM(!mm->lru_gen.memcg, mm); VM_BUG_ON_MM(list_empty(&mm->lru_gen.list), mm); lru_gen_del_mm(mm); lru_gen_add_mm(mm); } #endif /* * Bloom filters with m=1<<15, k=2 and the false positive rates of ~1/5 when * n=10,000 and ~1/2 when n=20,000, where, conventionally, m is the number of * bits in a bitmap, k is the number of hash functions and n is the number of * inserted items. * * Page table walkers use one of the two filters to reduce their search space. * To get rid of non-leaf entries that no longer have enough leaf entries, the * aging uses the double-buffering technique to flip to the other filter each * time it produces a new generation. For non-leaf entries that have enough * leaf entries, the aging carries them over to the next generation in * walk_pmd_range(); the eviction also report them when walking the rmap * in lru_gen_look_around(). * * For future optimizations: * 1. It's not necessary to keep both filters all the time. The spare one can be * freed after the RCU grace period and reallocated if needed again. * 2. And when reallocating, it's worth scaling its size according to the number * of inserted entries in the other filter, to reduce the memory overhead on * small systems and false positives on large systems. * 3. Jenkins' hash function is an alternative to Knuth's. */ #define BLOOM_FILTER_SHIFT 15 static inline int filter_gen_from_seq(unsigned long seq) { return seq % NR_BLOOM_FILTERS; } static void get_item_key(void *item, int *key) { u32 hash = hash_ptr(item, BLOOM_FILTER_SHIFT * 2); BUILD_BUG_ON(BLOOM_FILTER_SHIFT * 2 > BITS_PER_TYPE(u32)); key[0] = hash & (BIT(BLOOM_FILTER_SHIFT) - 1); key[1] = hash >> BLOOM_FILTER_SHIFT; } static void reset_bloom_filter(struct lruvec *lruvec, unsigned long seq) { unsigned long *filter; int gen = filter_gen_from_seq(seq); lockdep_assert_held(&get_mm_list(lruvec_memcg(lruvec))->lock); filter = lruvec->mm_state.filters[gen]; if (filter) { bitmap_clear(filter, 0, BIT(BLOOM_FILTER_SHIFT)); return; } filter = bitmap_zalloc(BIT(BLOOM_FILTER_SHIFT), GFP_ATOMIC); WRITE_ONCE(lruvec->mm_state.filters[gen], filter); } static void update_bloom_filter(struct lruvec *lruvec, unsigned long seq, void *item) { int key[2]; unsigned long *filter; int gen = filter_gen_from_seq(seq); filter = READ_ONCE(lruvec->mm_state.filters[gen]); if (!filter) return; get_item_key(item, key); if (!test_bit(key[0], filter)) set_bit(key[0], filter); if (!test_bit(key[1], filter)) set_bit(key[1], filter); } static bool test_bloom_filter(struct lruvec *lruvec, unsigned long seq, void *item) { int key[2]; unsigned long *filter; int gen = filter_gen_from_seq(seq); filter = READ_ONCE(lruvec->mm_state.filters[gen]); if (!filter) return true; get_item_key(item, key); return test_bit(key[0], filter) && test_bit(key[1], filter); } static void reset_mm_stats(struct lruvec *lruvec, struct lru_gen_mm_walk *walk, bool last) { int i; int hist; lockdep_assert_held(&get_mm_list(lruvec_memcg(lruvec))->lock); if (walk) { hist = lru_hist_from_seq(walk->max_seq); for (i = 0; i < NR_MM_STATS; i++) { WRITE_ONCE(lruvec->mm_state.stats[hist][i], lruvec->mm_state.stats[hist][i] + walk->mm_stats[i]); walk->mm_stats[i] = 0; } } if (NR_HIST_GENS > 1 && last) { hist = lru_hist_from_seq(lruvec->mm_state.seq + 1); for (i = 0; i < NR_MM_STATS; i++) WRITE_ONCE(lruvec->mm_state.stats[hist][i], 0); } } static bool should_skip_mm(struct mm_struct *mm, struct lru_gen_mm_walk *walk) { int type; unsigned long size = 0; struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec); if (!walk->full_scan && cpumask_empty(mm_cpumask(mm)) && !node_isset(pgdat->node_id, mm->lru_gen.nodes)) return true; node_clear(pgdat->node_id, mm->lru_gen.nodes); for (type = !walk->can_swap; type < ANON_AND_FILE; type++) { size += type ? get_mm_counter(mm, MM_FILEPAGES) : get_mm_counter(mm, MM_ANONPAGES) + get_mm_counter(mm, MM_SHMEMPAGES); } if (size < MIN_LRU_BATCH) return true; if (mm_is_oom_victim(mm)) return true; return !mmget_not_zero(mm); } static bool iterate_mm_list(struct lruvec *lruvec, struct lru_gen_mm_walk *walk, struct mm_struct **iter) { bool first = false; bool last = true; struct mm_struct *mm = NULL; struct mem_cgroup *memcg = lruvec_memcg(lruvec); struct lru_gen_mm_list *mm_list = get_mm_list(memcg); struct lru_gen_mm_state *mm_state = &lruvec->mm_state; /* * There are four interesting cases for this page table walker: * 1. It tries to start a new iteration of mm_list with a stale max_seq; * there is nothing to be done. * 2. It's the first of the current generation, and it needs to reset * the Bloom filter for the next generation. * 3. It reaches the end of mm_list, and it needs to increment * mm_state->seq; the iteration is done. * 4. It's the last of the current generation, and it needs to reset the * mm stats counters for the next generation. */ if (*iter) mmput_async(*iter); else if (walk->max_seq <= READ_ONCE(mm_state->seq)) return false; spin_lock(&mm_list->lock); VM_BUG_ON(mm_state->seq + 1 < walk->max_seq); VM_BUG_ON(*iter && mm_state->seq > walk->max_seq); VM_BUG_ON(*iter && !mm_state->nr_walkers); if (walk->max_seq <= mm_state->seq) { if (!*iter) last = false; goto done; } if (!mm_state->nr_walkers) { VM_BUG_ON(mm_state->head && mm_state->head != &mm_list->fifo); mm_state->head = mm_list->fifo.next; first = true; } while (!mm && mm_state->head != &mm_list->fifo) { mm = list_entry(mm_state->head, struct mm_struct, lru_gen.list); mm_state->head = mm_state->head->next; /* full scan for those added after the last iteration */ if (!mm_state->tail || mm_state->tail == &mm->lru_gen.list) { mm_state->tail = mm_state->head; walk->full_scan = true; } if (should_skip_mm(mm, walk)) mm = NULL; } if (mm_state->head == &mm_list->fifo) WRITE_ONCE(mm_state->seq, mm_state->seq + 1); done: if (*iter && !mm) mm_state->nr_walkers--; if (!*iter && mm) mm_state->nr_walkers++; if (mm_state->nr_walkers) last = false; if (mm && first) reset_bloom_filter(lruvec, walk->max_seq + 1); if (*iter || last) reset_mm_stats(lruvec, walk, last); spin_unlock(&mm_list->lock); *iter = mm; return last; } static bool iterate_mm_list_nowalk(struct lruvec *lruvec, unsigned long max_seq) { bool success = false; struct mem_cgroup *memcg = lruvec_memcg(lruvec); struct lru_gen_mm_list *mm_list = get_mm_list(memcg); struct lru_gen_mm_state *mm_state = &lruvec->mm_state; if (max_seq <= READ_ONCE(mm_state->seq)) return false; spin_lock(&mm_list->lock); VM_BUG_ON(mm_state->seq + 1 < max_seq); if (max_seq > mm_state->seq && !mm_state->nr_walkers) { VM_BUG_ON(mm_state->head && mm_state->head != &mm_list->fifo); WRITE_ONCE(mm_state->seq, mm_state->seq + 1); reset_mm_stats(lruvec, NULL, true); success = true; } spin_unlock(&mm_list->lock); return success; } /****************************************************************************** * refault feedback loop ******************************************************************************/ /* * A feedback loop based on Proportional-Integral-Derivative (PID) controller. * * The P term is refaulted/(evicted+protected) from a tier in the generation * currently being evicted; the I term is the exponential moving average of the * P term over the generations previously evicted, using the smoothing factor * 1/2; the D term isn't supported. * * The setpoint (SP) is always the first tier of one type; the process variable * (PV) is either any tier of the other type or any other tier of the same * type. * * The error is the difference between the SP and the PV; the correction is * turn off protection when SP>PV or turn on protection when SPlrugen; int hist = lru_hist_from_seq(lrugen->min_seq[type]); pos->refaulted = lrugen->avg_refaulted[type][tier] + atomic_long_read(&lrugen->refaulted[hist][type][tier]); pos->total = lrugen->avg_total[type][tier] + atomic_long_read(&lrugen->evicted[hist][type][tier]); if (tier) pos->total += lrugen->protected[hist][type][tier - 1]; pos->gain = gain; } static void reset_ctrl_pos(struct lruvec *lruvec, int type, bool carryover) { int hist, tier; struct lru_gen_struct *lrugen = &lruvec->lrugen; bool clear = carryover ? NR_HIST_GENS == 1 : NR_HIST_GENS > 1; unsigned long seq = carryover ? lrugen->min_seq[type] : lrugen->max_seq + 1; lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock); if (!carryover && !clear) return; hist = lru_hist_from_seq(seq); for (tier = 0; tier < MAX_NR_TIERS; tier++) { if (carryover) { unsigned long sum; sum = lrugen->avg_refaulted[type][tier] + atomic_long_read(&lrugen->refaulted[hist][type][tier]); WRITE_ONCE(lrugen->avg_refaulted[type][tier], sum / 2); sum = 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); } if (clear) { atomic_long_set(&lrugen->refaulted[hist][type][tier], 0); atomic_long_set(&lrugen->evicted[hist][type][tier], 0); if (tier) WRITE_ONCE(lrugen->protected[hist][type][tier - 1], 0); } } } static bool positive_ctrl_err(struct ctrl_pos *sp, struct ctrl_pos *pv) { /* * Return true if the PV has a limited number of refaults or a lower * refaulted/total than the SP. */ return pv->refaulted < MIN_LRU_BATCH || pv->refaulted * (sp->total + MIN_LRU_BATCH) * sp->gain <= (sp->refaulted + 1) * pv->total * pv->gain; } /****************************************************************************** * the aging ******************************************************************************/ static int page_update_gen(struct page *page, int gen) { unsigned long old_flags, new_flags; VM_BUG_ON(gen >= MAX_NR_GENS); VM_BUG_ON(!rcu_read_lock_held()); do { new_flags = old_flags = READ_ONCE(page->flags); /* for shrink_page_list() */ if (!(new_flags & LRU_GEN_MASK)) { new_flags |= BIT(PG_referenced); continue; } new_flags &= ~LRU_GEN_MASK; new_flags |= (gen + 1UL) << LRU_GEN_PGOFF; new_flags &= ~(LRU_REFS_MASK | LRU_REFS_FLAGS); } while (new_flags != old_flags && cmpxchg(&page->flags, old_flags, new_flags) != old_flags); return ((old_flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1; } static int page_inc_gen(struct lruvec *lruvec, struct page *page, bool reclaiming) { unsigned long old_flags, new_flags; int type = page_is_file_cache(page); struct lru_gen_struct *lrugen = &lruvec->lrugen; int new_gen, old_gen = lru_gen_from_seq(lrugen->min_seq[type]); do { new_flags = old_flags = READ_ONCE(page->flags); VM_BUG_ON_PAGE(!(new_flags & LRU_GEN_MASK), page); new_gen = ((new_flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1; /* page_update_gen() has promoted this page? */ if (new_gen >= 0 && new_gen != old_gen) return new_gen; new_gen = (old_gen + 1) % MAX_NR_GENS; new_flags &= ~LRU_GEN_MASK; new_flags |= (new_gen + 1UL) << LRU_GEN_PGOFF; new_flags &= ~(LRU_REFS_MASK | LRU_REFS_FLAGS); /* for end_page_writeback() */ if (reclaiming) new_flags |= BIT(PG_reclaim); } while (cmpxchg(&page->flags, old_flags, new_flags) != old_flags); lru_gen_update_size(lruvec, page, old_gen, new_gen); return new_gen; } static void update_batch_size(struct lru_gen_mm_walk *walk, struct page *page, int old_gen, int new_gen) { int type = page_is_file_cache(page); int zone = page_zonenum(page); int delta = hpage_nr_pages(page); VM_BUG_ON(old_gen >= MAX_NR_GENS); VM_BUG_ON(new_gen >= MAX_NR_GENS); walk->batched++; walk->nr_pages[old_gen][type][zone] -= delta; walk->nr_pages[new_gen][type][zone] += delta; } static void reset_batch_size(struct lruvec *lruvec, struct lru_gen_mm_walk *walk) { int gen, type, zone; struct lru_gen_struct *lrugen = &lruvec->lrugen; walk->batched = 0; for_each_gen_type_zone(gen, type, zone) { enum lru_list lru = type * LRU_INACTIVE_FILE; int delta = walk->nr_pages[gen][type][zone]; if (!delta) continue; walk->nr_pages[gen][type][zone] = 0; WRITE_ONCE(lrugen->nr_pages[gen][type][zone], lrugen->nr_pages[gen][type][zone] + delta); if (lru_gen_is_active(lruvec, gen)) lru += LRU_ACTIVE; update_lru_size(lruvec, lru, zone, delta); } } static int should_skip_vma(unsigned long start, unsigned long end, struct mm_walk *walk) { struct address_space *mapping; struct vm_area_struct *vma = walk->vma; struct lru_gen_mm_walk *priv = walk->private; if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)) || is_vm_hugetlb_page(vma) || (vma->vm_flags & (VM_LOCKED | VM_SPECIAL | VM_SEQ_READ | VM_RAND_READ)) || vma == get_gate_vma(vma->vm_mm)) return true; if (vma_is_anonymous(vma)) return !priv->can_swap; if (WARN_ON_ONCE(!vma->vm_file || !vma->vm_file->f_mapping)) return true; mapping = vma->vm_file->f_mapping; if (mapping_unevictable(mapping)) return true; /* check readpage to exclude special mappings like dax, etc. */ return shmem_mapping(mapping) ? !priv->can_swap : !mapping->a_ops->readpage; } /* * Some userspace memory allocators map many single-page VMAs. Instead of * returning back to the PGD table for each of such VMAs, finish an entire PMD * table to reduce zigzags and improve cache performance. */ static bool get_next_vma(struct mm_walk *walk, unsigned long mask, unsigned long size, unsigned long *start, unsigned long *end) { unsigned long next = round_up(*end, size); VM_BUG_ON(mask & size); VM_BUG_ON(*start >= *end); VM_BUG_ON((next & mask) != (*start & mask)); while (walk->vma) { if (next >= walk->vma->vm_end) { walk->vma = walk->vma->vm_next; continue; } if ((next & mask) != (walk->vma->vm_start & mask)) return false; if (should_skip_vma(walk->vma->vm_start, walk->vma->vm_end, walk)) { walk->vma = walk->vma->vm_next; continue; } *start = max(next, walk->vma->vm_start); next = (next | ~mask) + 1; /* rounded-up boundaries can wrap to 0 */ *end = next && next < walk->vma->vm_end ? next : walk->vma->vm_end; return true; } return false; } static bool suitable_to_scan(int total, int young) { int n = clamp_t(int, cache_line_size() / sizeof(pte_t), 2, 8); /* suitable if the average number of young PTEs per cacheline is >=1 */ return young * n >= total; } static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end, struct mm_walk *walk) { int i; pte_t *pte; spinlock_t *ptl; unsigned long addr; int total = 0; int young = 0; struct lru_gen_mm_walk *priv = walk->private; struct mem_cgroup *memcg = lruvec_memcg(priv->lruvec); struct pglist_data *pgdat = lruvec_pgdat(priv->lruvec); int old_gen, new_gen = lru_gen_from_seq(priv->max_seq); VM_BUG_ON(pmd_trans_huge(*pmd) || pmd_devmap(*pmd)); ptl = pte_lockptr(walk->mm, pmd); if (!spin_trylock(ptl)) return false; arch_enter_lazy_mmu_mode(); pte = pte_offset_map(pmd, start & PMD_MASK); restart: i = (start >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); for (addr = start; addr != end; i++, addr += PAGE_SIZE) { struct page *page; unsigned long pfn = pte_pfn(pte[i]); VM_BUG_ON(addr < walk->vma->vm_start || addr >= walk->vma->vm_end); total++; priv->mm_stats[MM_PTE_TOTAL]++; if (!pte_present(pte[i]) || is_zero_pfn(pfn)) continue; if (WARN_ON_ONCE(pte_devmap(pte[i]) || pte_special(pte[i]))) continue; if (!pte_young(pte[i])) { priv->mm_stats[MM_PTE_OLD]++; continue; } VM_BUG_ON(!pfn_valid(pfn)); if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat)) continue; page = compound_head(pfn_to_page(pfn)); if (page_to_nid(page) != pgdat->node_id) continue; if (page_memcg_rcu(page) != memcg) continue; if (!ptep_test_and_clear_young(walk->vma, addr, pte + i)) continue; young++; priv->mm_stats[MM_PTE_YOUNG]++; if (pte_dirty(pte[i]) && !PageDirty(page) && !(PageAnon(page) && PageSwapBacked(page) && !PageSwapCache(page))) set_page_dirty(page); old_gen = page_update_gen(page, new_gen); if (old_gen >= 0 && old_gen != new_gen) update_batch_size(priv, page, old_gen, new_gen); } if (i < PTRS_PER_PTE && get_next_vma(walk, PMD_MASK, PAGE_SIZE, &start, &end)) goto restart; pte_unmap(pte); arch_leave_lazy_mmu_mode(); spin_unlock(ptl); return suitable_to_scan(total, young); } #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG) static void walk_pmd_range_locked(pud_t *pud, unsigned long next, struct vm_area_struct *vma, struct mm_walk *walk, unsigned long *start) { int i; pmd_t *pmd; spinlock_t *ptl; struct lru_gen_mm_walk *priv = walk->private; struct mem_cgroup *memcg = lruvec_memcg(priv->lruvec); struct pglist_data *pgdat = lruvec_pgdat(priv->lruvec); int old_gen, new_gen = lru_gen_from_seq(priv->max_seq); VM_BUG_ON(pud_trans_huge(*pud) || pud_devmap(*pud)); /* try to batch at most 1+MIN_LRU_BATCH+1 entries */ if (*start == -1) { *start = next; return; } i = next == -1 ? 0 : ((next - *start) >> PMD_SHIFT) & (PTRS_PER_PMD - 1); if (i && i <= MIN_LRU_BATCH) { __set_bit(i - 1, priv->bitmap); return; } pmd = pmd_offset(pud, *start); ptl = pmd_lockptr(walk->mm, pmd); if (!spin_trylock(ptl)) goto done; arch_enter_lazy_mmu_mode(); do { struct page *page; unsigned long pfn = pmd_pfn(pmd[i]); unsigned long addr = i ? (*start & PMD_MASK) + i * PMD_SIZE : *start; VM_BUG_ON(addr < vma->vm_start || addr >= vma->vm_end); if (!pmd_present(pmd[i]) || is_huge_zero_pmd(pmd[i])) goto next; if (WARN_ON_ONCE(pmd_devmap(pmd[i]))) goto next; if (!pmd_trans_huge(pmd[i])) { if (IS_ENABLED(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG) && get_cap(LRU_GEN_NONLEAF_YOUNG)) pmdp_test_and_clear_young(vma, addr, pmd + i); goto next; } VM_BUG_ON(!pfn_valid(pfn)); if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat)) goto next; page = pfn_to_page(pfn); VM_BUG_ON_PAGE(PageTail(page), page); if (page_to_nid(page) != pgdat->node_id) goto next; if (page_memcg_rcu(page) != memcg) goto next; if (!pmdp_test_and_clear_young(vma, addr, pmd + i)) goto next; priv->mm_stats[MM_PTE_YOUNG]++; if (pmd_dirty(pmd[i]) && !PageDirty(page) && !(PageAnon(page) && PageSwapBacked(page) && !PageSwapCache(page))) set_page_dirty(page); old_gen = page_update_gen(page, new_gen); if (old_gen >= 0 && old_gen != new_gen) update_batch_size(priv, page, old_gen, new_gen); next: i = i > MIN_LRU_BATCH ? 0 : find_next_bit(priv->bitmap, MIN_LRU_BATCH, i) + 1; } while (i <= MIN_LRU_BATCH); arch_leave_lazy_mmu_mode(); spin_unlock(ptl); done: *start = -1; bitmap_zero(priv->bitmap, MIN_LRU_BATCH); } #else static void walk_pmd_range_locked(pud_t *pud, unsigned long next, struct vm_area_struct *vma, struct mm_walk *walk, unsigned long *start) { } #endif static void walk_pmd_range(pud_t *pud, unsigned long start, unsigned long end, struct mm_walk *walk) { int i; pmd_t *pmd; unsigned long next; unsigned long addr; struct vm_area_struct *vma; unsigned long pos = -1; struct lru_gen_mm_walk *priv = walk->private; VM_BUG_ON(pud_trans_huge(*pud) || pud_devmap(*pud)); /* * Finish an entire PMD in two passes: the first only reaches to PTE * tables to avoid taking the PMD lock; the second, if necessary, takes * the PMD lock to clear the accessed bit in PMD entries. */ pmd = pmd_offset(pud, start & PUD_MASK); restart: /* walk_pte_range() may call get_next_vma() */ vma = walk->vma; i = (start >> PMD_SHIFT) & (PTRS_PER_PMD - 1); for (addr = start; addr != end; i++, addr = next) { pmd_t val = pmd_read_atomic(pmd + i); /* for pmd_read_atomic() */ barrier(); next = pmd_addr_end(addr, end); if (!pmd_present(val)) { priv->mm_stats[MM_PTE_TOTAL]++; continue; } #ifdef CONFIG_TRANSPARENT_HUGEPAGE if (pmd_trans_huge(val)) { unsigned long pfn = pmd_pfn(val); struct pglist_data *pgdat = lruvec_pgdat(priv->lruvec); priv->mm_stats[MM_PTE_TOTAL]++; if (is_huge_zero_pmd(val)) continue; if (!pmd_young(val)) { priv->mm_stats[MM_PTE_OLD]++; continue; } if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat)) continue; walk_pmd_range_locked(pud, addr, vma, walk, &pos); continue; } #endif priv->mm_stats[MM_PMD_TOTAL]++; #ifdef CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG if (get_cap(LRU_GEN_NONLEAF_YOUNG)) { if (!pmd_young(val)) continue; walk_pmd_range_locked(pud, addr, vma, walk, &pos); } #endif if (!priv->full_scan && !test_bloom_filter(priv->lruvec, priv->max_seq, pmd + i)) continue; priv->mm_stats[MM_PMD_FOUND]++; if (!walk_pte_range(&val, addr, next, walk)) continue; priv->mm_stats[MM_PMD_ADDED]++; /* carry over to the next generation */ update_bloom_filter(priv->lruvec, priv->max_seq + 1, pmd + i); } walk_pmd_range_locked(pud, -1, vma, walk, &pos); if (i < PTRS_PER_PMD && get_next_vma(walk, PUD_MASK, PMD_SIZE, &start, &end)) goto restart; } static int walk_pud_range(p4d_t *p4d, unsigned long start, unsigned long end, struct mm_walk *walk) { int i; pud_t *pud; unsigned long addr; unsigned long next; struct lru_gen_mm_walk *priv = walk->private; pud = pud_offset(p4d, start & P4D_MASK); restart: i = (start >> PUD_SHIFT) & (PTRS_PER_PUD - 1); for (addr = start; addr != end; i++, addr = next) { pud_t val = READ_ONCE(pud[i]); next = pud_addr_end(addr, end); if (!pud_present(val) || WARN_ON_ONCE(pud_trans_huge(val) || pud_devmap(val))) continue; walk_pmd_range(&val, addr, next, walk); if (priv->batched >= MAX_LRU_BATCH) { end = (addr | ~PUD_MASK) + 1; goto done; } } if (i < PTRS_PER_PUD && get_next_vma(walk, P4D_MASK, PUD_SIZE, &start, &end)) goto restart; end = round_up(end, P4D_SIZE); done: /* rounded-up boundaries can wrap to 0 */ priv->next_addr = end && walk->vma ? max(end, walk->vma->vm_start) : 0; return -EAGAIN; } static void walk_mm(struct lruvec *lruvec, struct mm_struct *mm, struct lru_gen_mm_walk *walk) { int err; struct mem_cgroup *memcg = lruvec_memcg(lruvec); struct pglist_data *pgdat = lruvec_pgdat(lruvec); struct mm_walk args = { .mm = mm, .private = walk, .test_walk = should_skip_vma, .p4d_entry = walk_pud_range, }; walk->next_addr = FIRST_USER_ADDRESS; do { err = -EBUSY; /* page_update_gen() requires stable page_memcg() */ if (!mem_cgroup_trylock_pages(memcg)) break; /* the caller might be holding the lock for write */ if (down_read_trylock(&mm->mmap_sem)) { unsigned long start = walk->next_addr; unsigned long end = mm->highest_vm_end; err = walk_page_range(start, end, &args); up_read(&mm->mmap_sem); if (walk->batched) { spin_lock_irq(&pgdat->lru_lock); reset_batch_size(lruvec, walk); spin_unlock_irq(&pgdat->lru_lock); } } mem_cgroup_unlock_pages(); cond_resched(); } while (err == -EAGAIN && walk->next_addr && !mm_is_oom_victim(mm)); } static struct lru_gen_mm_walk *alloc_mm_walk(void) { if (current->reclaim_state && current->reclaim_state->mm_walk) return current->reclaim_state->mm_walk; return kzalloc(sizeof(struct lru_gen_mm_walk), __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN); } static void free_mm_walk(struct lru_gen_mm_walk *walk) { if (!current->reclaim_state || !current->reclaim_state->mm_walk) kfree(walk); } static void inc_min_seq(struct lruvec *lruvec) { int type; struct lru_gen_struct *lrugen = &lruvec->lrugen; VM_BUG_ON(!seq_is_valid(lruvec)); for (type = 0; type < ANON_AND_FILE; type++) { if (get_nr_gens(lruvec, type) != MAX_NR_GENS) continue; reset_ctrl_pos(lruvec, type, true); WRITE_ONCE(lrugen->min_seq[type], lrugen->min_seq[type] + 1); } } static bool try_to_inc_min_seq(struct lruvec *lruvec, bool can_swap) { int gen, type, zone; bool success = false; struct lru_gen_struct *lrugen = &lruvec->lrugen; DEFINE_MIN_SEQ(lruvec); VM_BUG_ON(!seq_is_valid(lruvec)); for (type = !can_swap; type < ANON_AND_FILE; type++) { while (min_seq[type] + MIN_NR_GENS <= lrugen->max_seq) { gen = lru_gen_from_seq(min_seq[type]); for (zone = 0; zone < MAX_NR_ZONES; zone++) { if (!list_empty(&lrugen->lists[gen][type][zone])) goto next; } min_seq[type]++; } next: ; } /* see the comment on lru_gen_struct */ if (can_swap) { min_seq[LRU_GEN_ANON] = min(min_seq[LRU_GEN_ANON], min_seq[LRU_GEN_FILE]); min_seq[LRU_GEN_FILE] = max(min_seq[LRU_GEN_ANON], lrugen->min_seq[LRU_GEN_FILE]); } for (type = !can_swap; type < ANON_AND_FILE; type++) { if (min_seq[type] == lrugen->min_seq[type]) continue; reset_ctrl_pos(lruvec, type, true); WRITE_ONCE(lrugen->min_seq[type], min_seq[type]); success = true; } return success; } static void inc_max_seq(struct lruvec *lruvec) { int prev, next; int type, zone; struct lru_gen_struct *lrugen = &lruvec->lrugen; struct pglist_data *pgdat = lruvec_pgdat(lruvec); spin_lock_irq(&pgdat->lru_lock); VM_BUG_ON(!seq_is_valid(lruvec)); inc_min_seq(lruvec); /* * Update the active/inactive LRU sizes for compatibility. Both sides of * the current max_seq need to be covered, since max_seq+1 can overlap * with min_seq[LRU_GEN_ANON] if swapping is constrained. And if they do * overlap, cold/hot inversion happens. This can be solved by moving * pages from min_seq to min_seq+1 but is omitted for simplicity. */ prev = lru_gen_from_seq(lrugen->max_seq - 1); next = lru_gen_from_seq(lrugen->max_seq + 1); 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]; if (!delta) continue; WARN_ON_ONCE(delta != (int)delta); update_lru_size(lruvec, lru, zone, delta); update_lru_size(lruvec, lru + LRU_ACTIVE, zone, -delta); } } for (type = 0; type < ANON_AND_FILE; type++) reset_ctrl_pos(lruvec, type, false); WRITE_ONCE(lrugen->timestamps[next], jiffies); /* make sure preceding modifications appear */ smp_store_release(&lrugen->max_seq, lrugen->max_seq + 1); spin_unlock_irq(&pgdat->lru_lock); } static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long max_seq, struct scan_control *sc, bool can_swap, bool full_scan) { bool success; struct lru_gen_mm_walk *walk; struct mm_struct *mm = NULL; struct lru_gen_struct *lrugen = &lruvec->lrugen; VM_BUG_ON(max_seq > READ_ONCE(lrugen->max_seq)); /* * If the hardware doesn't automatically set the accessed bit, fallback * to lru_gen_look_around(), which only clears the accessed bit in a * handful of PTEs. Spreading the work out over a period of time usually * is less efficient, but it avoids bursty page faults. */ if (!full_scan && (!arch_has_hw_pte_young() || !get_cap(LRU_GEN_MM_WALK))) { success = iterate_mm_list_nowalk(lruvec, max_seq); goto done; } walk = alloc_mm_walk(); if (!walk) { success = iterate_mm_list_nowalk(lruvec, max_seq); goto done; } walk->lruvec = lruvec; walk->max_seq = max_seq; walk->can_swap = can_swap; walk->full_scan = full_scan; do { success = iterate_mm_list(lruvec, walk, &mm); if (mm) walk_mm(lruvec, mm, walk); cond_resched(); } while (mm); free_mm_walk(walk); done: if (!success) { if (!current_is_kswapd() && !sc->priority) wait_event_killable(lruvec->mm_state.wait, max_seq < READ_ONCE(lrugen->max_seq)); return max_seq < READ_ONCE(lrugen->max_seq); } VM_BUG_ON(max_seq != READ_ONCE(lrugen->max_seq)); inc_max_seq(lruvec); /* either this sees any waiters or they will see updated max_seq */ if (wq_has_sleeper(&lruvec->mm_state.wait)) wake_up_all(&lruvec->mm_state.wait); wakeup_flusher_threads(WB_REASON_VMSCAN); return true; } static long get_nr_evictable(struct lruvec *lruvec, unsigned long max_seq, unsigned long *min_seq, bool can_swap, bool *need_aging) { int gen, type, zone; long old = 0; long young = 0; long total = 0; struct lru_gen_struct *lrugen = &lruvec->lrugen; for (type = !can_swap; type < ANON_AND_FILE; type++) { unsigned long seq; for (seq = min_seq[type]; seq <= max_seq; seq++) { long size = 0; gen = lru_gen_from_seq(seq); for (zone = 0; zone < MAX_NR_ZONES; zone++) size += READ_ONCE(lrugen->nr_pages[gen][type][zone]); total += size; if (seq == max_seq) young += size; if (seq + MIN_NR_GENS == max_seq) old += size; } } /* * The aging and the eviction is a typical producer-consumer model. The * aging tries to be lazy to reduce the unnecessary overhead. On the * other hand, the eviction stalls when the number of generations * reaches MIN_NR_GENS. So ideally, there should be MIN_NR_GENS+1 * generations, hence the first two if's. * * In addition, it's ideal to spread pages out evenly, meaning * 1/(MIN_NR_GENS+1) of the total number of pages for each generation. A * reasonable range for this average portion would [1/MIN_NR_GENS, * 1/(MIN_NR_GENS+2)]. From the consumer's POV, the eviction only cares * about the lower bound of cold pages, i.e., 1/(MIN_NR_GENS+2), whereas * from the producer's POV, the aging only cares about the upper bound * of hot pages, i.e., 1/MIN_NR_GENS. */ if (min_seq[!can_swap] + MIN_NR_GENS > max_seq) *need_aging = true; else if (min_seq[!can_swap] + MIN_NR_GENS < max_seq) *need_aging = false; else if (young * MIN_NR_GENS > total) *need_aging = true; else if (old * (MIN_NR_GENS + 2) < total) *need_aging = true; else *need_aging = false; return total > 0 ? total : 0; } static bool age_lruvec(struct lruvec *lruvec, struct scan_control *sc, unsigned long min_ttl) { bool need_aging; long nr_to_scan; int swappiness = get_swappiness(lruvec, sc); struct mem_cgroup *memcg = lruvec_memcg(lruvec); enum mem_cgroup_protection prot = mem_cgroup_protected(NULL, memcg); DEFINE_MAX_SEQ(lruvec); DEFINE_MIN_SEQ(lruvec); if (min_ttl) { int gen = lru_gen_from_seq(min_seq[LRU_GEN_FILE]); unsigned long birth = READ_ONCE(lruvec->lrugen.timestamps[gen]); if (time_is_after_jiffies(birth + min_ttl)) return false; } if (prot == MEMCG_PROT_MIN) return false; nr_to_scan = get_nr_evictable(lruvec, max_seq, min_seq, swappiness, &need_aging); if (!nr_to_scan) return false; nr_to_scan >>= sc->priority; if (!mem_cgroup_online(memcg)) nr_to_scan++; if (nr_to_scan && need_aging && (prot != MEMCG_PROT_LOW || sc->memcg_low_reclaim)) try_to_inc_max_seq(lruvec, max_seq, sc, swappiness, false); return true; } /* to protect the working set of the last N jiffies */ static unsigned long lru_gen_min_ttl __read_mostly; static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc) { struct mem_cgroup *memcg; bool success = false; unsigned long min_ttl = READ_ONCE(lru_gen_min_ttl); VM_BUG_ON(!current_is_kswapd()); /* * To reduce the chance of going into the aging path or swapping, which * can be costly, optimistically skip them unless their corresponding * flags were cleared in the eviction path. This improves the overall * performance when multiple memcgs are available. */ if (!sc->memcgs_need_aging) { sc->memcgs_need_aging = true; sc->memcgs_avoid_swapping = !sc->memcgs_need_swapping; sc->memcgs_need_swapping = true; return; } sc->memcgs_need_swapping = true; sc->memcgs_avoid_swapping = true; current->reclaim_state->mm_walk = &pgdat->mm_walk; memcg = mem_cgroup_iter(NULL, NULL, NULL); do { struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg); if (age_lruvec(lruvec, sc, min_ttl)) success = true; cond_resched(); } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL))); current->reclaim_state->mm_walk = NULL; /* * The main goal is to OOM kill if every generation from all memcgs is * younger than min_ttl. However, another theoretical possibility is all * memcgs are either below min or empty. */ if (!success && !sc->order && mutex_trylock(&oom_lock)) { struct oom_control oc = { .gfp_mask = sc->gfp_mask, }; out_of_memory(&oc); mutex_unlock(&oom_lock); } } /* * This function exploits spatial locality when shrink_page_list() walks the * rmap. It scans the adjacent PTEs of a young PTE and promotes hot pages. * If the scan was done cacheline efficiently, it adds the PMD entry pointing * to the PTE table to the Bloom filter. This process is a feedback loop from * the eviction to the aging. */ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) { int i; pte_t *pte; unsigned long start; unsigned long end; unsigned long addr; struct page *page; struct lru_gen_mm_walk *walk; int young = 0; unsigned long bitmap[BITS_TO_LONGS(MIN_LRU_BATCH)] = {}; struct mem_cgroup *memcg = page_memcg(pvmw->page); struct pglist_data *pgdat = page_pgdat(pvmw->page); struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg); DEFINE_MAX_SEQ(lruvec); int old_gen, new_gen = lru_gen_from_seq(max_seq); lockdep_assert_held(pvmw->ptl); VM_BUG_ON_PAGE(PageLRU(pvmw->page), pvmw->page); if (spin_is_contended(pvmw->ptl)) return; start = max(pvmw->address & PMD_MASK, pvmw->vma->vm_start); end = min(pvmw->address | ~PMD_MASK, pvmw->vma->vm_end - 1) + 1; if (end - start > MIN_LRU_BATCH * PAGE_SIZE) { if (pvmw->address - start < MIN_LRU_BATCH * PAGE_SIZE / 2) end = start + MIN_LRU_BATCH * PAGE_SIZE; else if (end - pvmw->address < MIN_LRU_BATCH * PAGE_SIZE / 2) start = end - MIN_LRU_BATCH * PAGE_SIZE; else { start = pvmw->address - MIN_LRU_BATCH * PAGE_SIZE / 2; end = pvmw->address + MIN_LRU_BATCH * PAGE_SIZE / 2; } } pte = pvmw->pte - (pvmw->address - start) / PAGE_SIZE; rcu_read_lock(); arch_enter_lazy_mmu_mode(); for (i = 0, addr = start; addr != end; i++, addr += PAGE_SIZE) { unsigned long pfn = pte_pfn(pte[i]); VM_BUG_ON(addr < pvmw->vma->vm_start || addr >= pvmw->vma->vm_end); if (!pte_present(pte[i]) || is_zero_pfn(pfn)) continue; if (WARN_ON_ONCE(pte_devmap(pte[i]) || pte_special(pte[i]))) continue; if (!pte_young(pte[i])) continue; VM_BUG_ON(!pfn_valid(pfn)); if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat)) continue; page = compound_head(pfn_to_page(pfn)); if (page_to_nid(page) != pgdat->node_id) continue; if (page_memcg_rcu(page) != memcg) continue; if (!ptep_test_and_clear_young(pvmw->vma, addr, pte + i)) continue; young++; if (pte_dirty(pte[i]) && !PageDirty(page) && !(PageAnon(page) && PageSwapBacked(page) && !PageSwapCache(page))) set_page_dirty(page); old_gen = page_lru_gen(page); if (old_gen < 0) SetPageReferenced(page); else if (old_gen != new_gen) __set_bit(i, bitmap); } arch_leave_lazy_mmu_mode(); rcu_read_unlock(); /* feedback from rmap walkers to page table walkers */ if (suitable_to_scan(i, young)) update_bloom_filter(lruvec, max_seq, pvmw->pmd); walk = current->reclaim_state ? current->reclaim_state->mm_walk : NULL; if (!walk && bitmap_weight(bitmap, MIN_LRU_BATCH) < PAGEVEC_SIZE) { for_each_set_bit(i, bitmap, MIN_LRU_BATCH) activate_page(pte_page(pte[i])); return; } /* page_update_gen() requires stable page_memcg() */ if (!mem_cgroup_trylock_pages(memcg)) return; if (!walk) { spin_lock_irq(&pgdat->lru_lock); new_gen = lru_gen_from_seq(lruvec->lrugen.max_seq); } for_each_set_bit(i, bitmap, MIN_LRU_BATCH) { page = compound_head(pte_page(pte[i])); if (page_memcg_rcu(page) != memcg) continue; old_gen = page_update_gen(page, new_gen); if (old_gen < 0 || old_gen == new_gen) continue; if (walk) update_batch_size(walk, page, old_gen, new_gen); else lru_gen_update_size(lruvec, page, old_gen, new_gen); } if (!walk) spin_unlock_irq(&pgdat->lru_lock); mem_cgroup_unlock_pages(); } /****************************************************************************** * the eviction ******************************************************************************/ static bool sort_page(struct lruvec *lruvec, struct page *page, int tier_idx) { bool success; int gen = page_lru_gen(page); int type = page_is_file_cache(page); int zone = page_zonenum(page); int tier = page_lru_tier(page); int delta = hpage_nr_pages(page); struct lru_gen_struct *lrugen = &lruvec->lrugen; VM_BUG_ON_PAGE(gen >= MAX_NR_GENS, page); if (!page_evictable(page)) { success = lru_gen_del_page(lruvec, page, true); VM_BUG_ON_PAGE(!success, page); SetPageUnevictable(page); add_page_to_lru_list(page, lruvec); __count_vm_events(UNEVICTABLE_PGCULLED, delta); return true; } if (type == LRU_GEN_FILE && PageAnon(page) && PageDirty(page)) { success = lru_gen_del_page(lruvec, page, true); VM_BUG_ON_PAGE(!success, page); SetPageSwapBacked(page); add_page_to_lru_list_tail(page, lruvec); return true; } if (gen != lru_gen_from_seq(lrugen->min_seq[type])) { list_move(&page->lru, &lrugen->lists[gen][type][zone]); return true; } if (tier > tier_idx) { int hist = lru_hist_from_seq(lrugen->min_seq[type]); gen = page_inc_gen(lruvec, page, false); list_move_tail(&page->lru, &lrugen->lists[gen][type][zone]); WRITE_ONCE(lrugen->protected[hist][type][tier - 1], lrugen->protected[hist][type][tier - 1] + delta); __mod_lruvec_state(lruvec, WORKINGSET_ACTIVATE, delta); return true; } if (PageLocked(page) || PageWriteback(page) || (type == LRU_GEN_FILE && PageDirty(page))) { gen = page_inc_gen(lruvec, page, true); list_move(&page->lru, &lrugen->lists[gen][type][zone]); return true; } return false; } static bool isolate_page(struct lruvec *lruvec, struct page *page, struct scan_control *sc) { bool success; if (!sc->may_unmap && page_mapped(page)) return false; if (!(sc->may_writepage && (sc->gfp_mask & __GFP_IO)) && (PageDirty(page) || (PageAnon(page) && !PageSwapCache(page)))) return false; if (!get_page_unless_zero(page)) return false; ClearPageLRU(page); success = lru_gen_del_page(lruvec, page, true); VM_BUG_ON_PAGE(!success, page); return true; } static int scan_pages(struct lruvec *lruvec, struct scan_control *sc, int type, int tier, struct list_head *list) { int gen, zone; enum vm_event_item item; int sorted = 0; int scanned = 0; int isolated = 0; int remaining = MAX_LRU_BATCH; struct lru_gen_struct *lrugen = &lruvec->lrugen; struct mem_cgroup *memcg = lruvec_memcg(lruvec); VM_BUG_ON(!list_empty(list)); if (get_nr_gens(lruvec, type) == MIN_NR_GENS) return 0; gen = lru_gen_from_seq(lrugen->min_seq[type]); for (zone = sc->reclaim_idx; zone >= 0; zone--) { LIST_HEAD(moved); int skipped = 0; struct list_head *head = &lrugen->lists[gen][type][zone]; while (!list_empty(head)) { struct page *page = lru_to_page(head); int delta = hpage_nr_pages(page); VM_BUG_ON_PAGE(PageTail(page), page); VM_BUG_ON_PAGE(PageUnevictable(page), page); VM_BUG_ON_PAGE(PageActive(page), page); VM_BUG_ON_PAGE(page_is_file_cache(page) != type, page); VM_BUG_ON_PAGE(page_zonenum(page) != zone, page); prefetchw_prev_lru_page(page, head, flags); scanned += delta; if (sort_page(lruvec, page, tier)) sorted += delta; else if (isolate_page(lruvec, page, sc)) { list_add(&page->lru, list); isolated += delta; } else { list_move(&page->lru, &moved); skipped += delta; } if (!--remaining || max(isolated, skipped) >= MIN_LRU_BATCH) break; } if (skipped) { list_splice(&moved, head); __count_zid_vm_events(PGSCAN_SKIP, zone, skipped); } if (!remaining || isolated >= MIN_LRU_BATCH) break; } item = current_is_kswapd() ? PGSCAN_KSWAPD : PGSCAN_DIRECT; if (global_reclaim(sc)) { __count_vm_events(item, isolated); __count_vm_events(PGREFILL, sorted); } __count_memcg_events(memcg, item, isolated); __count_memcg_events(memcg, PGREFILL, sorted); /* * There might not be eligible pages due to reclaim_idx, may_unmap and * may_writepage. Check the remaining to prevent livelock if there is no * progress. */ return isolated || !remaining ? scanned : 0; } static int get_tier_idx(struct lruvec *lruvec, int type) { int tier; struct ctrl_pos sp, pv; /* * To leave a margin for fluctuations, use a larger gain factor (1:2). * This value is chosen because any other tier would have at least twice * as many refaults as the first tier. */ read_ctrl_pos(lruvec, type, 0, 1, &sp); for (tier = 1; tier < MAX_NR_TIERS; tier++) { read_ctrl_pos(lruvec, type, tier, 2, &pv); if (!positive_ctrl_err(&sp, &pv)) break; } return tier - 1; } static int get_type_to_scan(struct lruvec *lruvec, int swappiness, int *tier_idx) { int type, tier; struct ctrl_pos sp, pv; int gain[ANON_AND_FILE] = { swappiness, 200 - swappiness }; /* * Compare the first tier of anon with that of file to determine which * type to scan. Also need to compare other tiers of the selected type * with the first tier of the other type to determine the last tier (of * the selected type) to evict. */ read_ctrl_pos(lruvec, LRU_GEN_ANON, 0, gain[LRU_GEN_ANON], &sp); read_ctrl_pos(lruvec, LRU_GEN_FILE, 0, gain[LRU_GEN_FILE], &pv); type = positive_ctrl_err(&sp, &pv); read_ctrl_pos(lruvec, !type, 0, gain[!type], &sp); for (tier = 1; tier < MAX_NR_TIERS; tier++) { read_ctrl_pos(lruvec, type, tier, gain[type], &pv); if (!positive_ctrl_err(&sp, &pv)) break; } *tier_idx = tier - 1; return type; } static int isolate_pages(struct lruvec *lruvec, struct scan_control *sc, int swappiness, int *type_scanned, struct list_head *list) { int i; int type; int scanned; int tier = -1; DEFINE_MIN_SEQ(lruvec); VM_BUG_ON(!seq_is_valid(lruvec)); /* * Try to make the obvious choice first. When anon and file are both * available from the same generation, interpret swappiness 1 as file * first and 200 as anon first. */ if (!swappiness) type = LRU_GEN_FILE; else if (min_seq[LRU_GEN_ANON] < min_seq[LRU_GEN_FILE]) type = LRU_GEN_ANON; else if (swappiness == 1) type = LRU_GEN_FILE; else if (swappiness == 200) type = LRU_GEN_ANON; else type = get_type_to_scan(lruvec, swappiness, &tier); for (i = !swappiness; i < ANON_AND_FILE; i++) { if (tier < 0) tier = get_tier_idx(lruvec, type); scanned = scan_pages(lruvec, sc, type, tier, list); if (scanned) break; type = !type; tier = -1; } *type_scanned = type; return scanned; } static int evict_pages(struct lruvec *lruvec, struct scan_control *sc, int swappiness, bool *swapped) { int type; int scanned; int reclaimed; LIST_HEAD(list); struct page *page; enum vm_event_item item; struct lru_gen_mm_walk *walk; struct mem_cgroup *memcg = lruvec_memcg(lruvec); struct pglist_data *pgdat = lruvec_pgdat(lruvec); spin_lock_irq(&pgdat->lru_lock); scanned = isolate_pages(lruvec, sc, swappiness, &type, &list); if (try_to_inc_min_seq(lruvec, swappiness)) scanned++; if (get_nr_gens(lruvec, !swappiness) == MIN_NR_GENS) scanned = 0; spin_unlock_irq(&pgdat->lru_lock); if (list_empty(&list)) return scanned; reclaimed = shrink_page_list(&list, pgdat, sc, 0, NULL, false); /* * To avoid livelock, don't add rejected pages back to the same lists * they were isolated from. See lru_gen_add_page(). */ list_for_each_entry(page, &list, lru) { ClearPageReferenced(page); ClearPageWorkingset(page); if (PageReclaim(page) && (PageDirty(page) || PageWriteback(page))) ClearPageActive(page); else SetPageActive(page); } spin_lock_irq(&pgdat->lru_lock); putback_inactive_pages(lruvec, &list); walk = current->reclaim_state ? current->reclaim_state->mm_walk : NULL; if (walk && walk->batched) reset_batch_size(lruvec, walk); item = current_is_kswapd() ? PGSTEAL_KSWAPD : PGSTEAL_DIRECT; if (global_reclaim(sc)) __count_vm_events(item, reclaimed); __count_memcg_events(memcg, item, reclaimed); spin_unlock_irq(&pgdat->lru_lock); mem_cgroup_uncharge_list(&list); free_unref_page_list(&list); sc->nr_reclaimed += reclaimed; if (type == LRU_GEN_ANON && swapped) *swapped = true; return scanned; } static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc, bool can_swap, unsigned long reclaimed, bool *need_aging) { int priority; long nr_to_scan; struct mem_cgroup *memcg = lruvec_memcg(lruvec); DEFINE_MAX_SEQ(lruvec); DEFINE_MIN_SEQ(lruvec); nr_to_scan = get_nr_evictable(lruvec, max_seq, min_seq, can_swap, need_aging); if (!nr_to_scan) return 0; /* adjust priority if memcg is offline or the target is met */ if (!mem_cgroup_online(memcg)) priority = 0; else if (sc->nr_reclaimed - reclaimed >= sc->nr_to_reclaim) priority = DEF_PRIORITY; else priority = sc->priority; nr_to_scan >>= priority; if (!nr_to_scan) return 0; if (!*need_aging) return nr_to_scan; /* skip the aging path at the default priority */ if (priority == DEF_PRIORITY) return nr_to_scan; /* leave the work to lru_gen_age_node() */ if (current_is_kswapd()) return 0; if (try_to_inc_max_seq(lruvec, max_seq, sc, can_swap, false)) return nr_to_scan; return min_seq[!can_swap] + MIN_NR_GENS <= max_seq ? nr_to_scan : 0; } static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) { struct blk_plug plug; long scanned = 0; bool need_aging = false; bool swapped = false; unsigned long reclaimed = sc->nr_reclaimed; struct pglist_data *pgdat = lruvec_pgdat(lruvec); lru_add_drain(); blk_start_plug(&plug); if (current_is_kswapd()) current->reclaim_state->mm_walk = &pgdat->mm_walk; while (true) { int delta; int swappiness; long nr_to_scan; if (sc->may_swap) swappiness = get_swappiness(lruvec, sc); else if (global_reclaim(sc) && get_swappiness(lruvec, sc)) swappiness = 1; else swappiness = 0; nr_to_scan = get_nr_to_scan(lruvec, sc, swappiness, reclaimed, &need_aging); if (!nr_to_scan) goto done; delta = evict_pages(lruvec, sc, swappiness, &swapped); if (!delta) goto done; if (sc->memcgs_avoid_swapping && swappiness < 200 && swapped) break; scanned += delta; if (scanned >= nr_to_scan) break; cond_resched(); } if (!need_aging) sc->memcgs_need_aging = false; if (!swapped) sc->memcgs_need_swapping = false; done: if (current_is_kswapd()) current->reclaim_state->mm_walk = NULL; blk_finish_plug(&plug); } /****************************************************************************** * state change ******************************************************************************/ static bool __maybe_unused state_is_valid(struct lruvec *lruvec) { struct lru_gen_struct *lrugen = &lruvec->lrugen; if (lrugen->enabled) { enum lru_list lru; for_each_evictable_lru(lru) { if (!list_empty(&lruvec->lists[lru])) return false; } } else { int gen, type, zone; for_each_gen_type_zone(gen, type, zone) { if (!list_empty(&lrugen->lists[gen][type][zone])) return false; /* unlikely but not a bug when reset_batch_size() is pending */ VM_WARN_ON(lrugen->nr_pages[gen][type][zone]); } } return true; } static bool fill_evictable(struct lruvec *lruvec) { enum lru_list lru; int remaining = MAX_LRU_BATCH; for_each_evictable_lru(lru) { int type = is_file_lru(lru); bool active = is_active_lru(lru); struct list_head *head = &lruvec->lists[lru]; while (!list_empty(head)) { bool success; struct page *page = lru_to_page(head); VM_BUG_ON_PAGE(PageTail(page), page); VM_BUG_ON_PAGE(PageUnevictable(page), page); VM_BUG_ON_PAGE(PageActive(page) != active, page); VM_BUG_ON_PAGE(page_is_file_cache(page) != type, page); VM_BUG_ON_PAGE(page_lru_gen(page) < MAX_NR_GENS, page); prefetchw_prev_lru_page(page, head, flags); del_page_from_lru_list(page, lruvec); success = lru_gen_add_page(lruvec, page, false); VM_BUG_ON(!success); if (!--remaining) return false; } } return true; } static bool drain_evictable(struct lruvec *lruvec) { int gen, type, zone; int remaining = MAX_LRU_BATCH; for_each_gen_type_zone(gen, type, zone) { struct list_head *head = &lruvec->lrugen.lists[gen][type][zone]; while (!list_empty(head)) { bool success; struct page *page = lru_to_page(head); VM_BUG_ON_PAGE(PageTail(page), page); VM_BUG_ON_PAGE(PageUnevictable(page), page); VM_BUG_ON_PAGE(PageActive(page), page); VM_BUG_ON_PAGE(page_is_file_cache(page) != type, page); VM_BUG_ON_PAGE(page_zonenum(page) != zone, page); prefetchw_prev_lru_page(page, head, flags); success = lru_gen_del_page(lruvec, page, false); VM_BUG_ON(!success); add_page_to_lru_list(page, lruvec); if (!--remaining) return false; } } return true; } static void lru_gen_change_state(bool enable) { static DEFINE_MUTEX(state_mutex); struct mem_cgroup *memcg; cgroup_lock(); cpus_read_lock(); get_online_mems(); mutex_lock(&state_mutex); if (enable == lru_gen_enabled()) goto unlock; if (enable) static_branch_enable_cpuslocked(&lru_gen_caps[LRU_GEN_CORE]); else static_branch_disable_cpuslocked(&lru_gen_caps[LRU_GEN_CORE]); memcg = mem_cgroup_iter(NULL, NULL, NULL); do { int nid; for_each_node(nid) { struct pglist_data *pgdat = NODE_DATA(nid); struct lruvec *lruvec = get_lruvec(memcg, nid); if (!lruvec) continue; if (!pgdat) { lruvec->lrugen.enabled = enable; continue; } spin_lock_irq(&pgdat->lru_lock); VM_BUG_ON(!seq_is_valid(lruvec)); VM_BUG_ON(!state_is_valid(lruvec)); lruvec->lrugen.enabled = enable; while (!(enable ? fill_evictable(lruvec) : drain_evictable(lruvec))) { spin_unlock_irq(&pgdat->lru_lock); cond_resched(); spin_lock_irq(&pgdat->lru_lock); } spin_unlock_irq(&pgdat->lru_lock); } cond_resched(); } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL))); unlock: mutex_unlock(&state_mutex); put_online_mems(); cpus_read_unlock(); cgroup_unlock(); } /****************************************************************************** * sysfs interface ******************************************************************************/ static ssize_t show_min_ttl(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sprintf(buf, "%u\n", jiffies_to_msecs(READ_ONCE(lru_gen_min_ttl))); } static ssize_t store_min_ttl(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t len) { unsigned int msecs; if (kstrtouint(buf, 0, &msecs)) return -EINVAL; WRITE_ONCE(lru_gen_min_ttl, msecs_to_jiffies(msecs)); return len; } static struct kobj_attribute lru_gen_min_ttl_attr = __ATTR( min_ttl_ms, 0644, show_min_ttl, store_min_ttl ); static ssize_t show_enable(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { unsigned int caps = 0; if (get_cap(LRU_GEN_CORE)) caps |= BIT(LRU_GEN_CORE); if (arch_has_hw_pte_young() && get_cap(LRU_GEN_MM_WALK)) caps |= BIT(LRU_GEN_MM_WALK); if (IS_ENABLED(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG) && get_cap(LRU_GEN_NONLEAF_YOUNG)) caps |= BIT(LRU_GEN_NONLEAF_YOUNG); return snprintf(buf, PAGE_SIZE, "0x%04x\n", caps); } static ssize_t store_enable(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t len) { int i; unsigned int caps; if (tolower(*buf) == 'n') caps = 0; else if (tolower(*buf) == 'y') caps = -1; else if (kstrtouint(buf, 0, &caps)) return -EINVAL; for (i = 0; i < NR_LRU_GEN_CAPS; i++) { bool enable = caps & BIT(i); if (i == LRU_GEN_CORE) lru_gen_change_state(enable); else if (enable) static_branch_enable(&lru_gen_caps[i]); else static_branch_disable(&lru_gen_caps[i]); } pr_info("switch mglru_gen enabled: 0x%04x\n", caps); return len; } static struct kobj_attribute lru_gen_enabled_attr = __ATTR( enabled, 0644, show_enable, store_enable ); static struct attribute *lru_gen_attrs[] = { &lru_gen_min_ttl_attr.attr, &lru_gen_enabled_attr.attr, NULL }; static struct attribute_group lru_gen_attr_group = { .name = "lru_gen", .attrs = lru_gen_attrs, }; /****************************************************************************** * debugfs interface ******************************************************************************/ static void *lru_gen_seq_start(struct seq_file *m, loff_t *pos) { struct mem_cgroup *memcg; loff_t nr_to_skip = *pos; m->private = kvmalloc(PATH_MAX, GFP_KERNEL); if (!m->private) return ERR_PTR(-ENOMEM); memcg = mem_cgroup_iter(NULL, NULL, NULL); do { int nid; for_each_node_state(nid, N_MEMORY) { if (!nr_to_skip--) return get_lruvec(memcg, nid); } } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL))); return NULL; } static void lru_gen_seq_stop(struct seq_file *m, void *v) { if (!IS_ERR_OR_NULL(v)) mem_cgroup_iter_break(NULL, lruvec_memcg(v)); kvfree(m->private); m->private = NULL; } static void *lru_gen_seq_next(struct seq_file *m, void *v, loff_t *pos) { int nid = lruvec_pgdat(v)->node_id; struct mem_cgroup *memcg = lruvec_memcg(v); ++*pos; nid = next_memory_node(nid); if (nid == MAX_NUMNODES) { memcg = mem_cgroup_iter(NULL, memcg, NULL); if (!memcg) return NULL; nid = first_memory_node; } return get_lruvec(memcg, nid); } static void lru_gen_seq_show_full(struct seq_file *m, struct lruvec *lruvec, unsigned long max_seq, unsigned long *min_seq, unsigned long seq) { int i; int type, tier; int hist = lru_hist_from_seq(seq); struct lru_gen_struct *lrugen = &lruvec->lrugen; for (tier = 0; tier < MAX_NR_TIERS; tier++) { seq_printf(m, " %10d", tier); for (type = 0; type < ANON_AND_FILE; type++) { unsigned long n[3] = {}; if (seq == max_seq) { n[0] = READ_ONCE(lrugen->avg_refaulted[type][tier]); n[1] = READ_ONCE(lrugen->avg_total[type][tier]); seq_printf(m, " %10luR %10luT %10lu ", n[0], n[1], n[2]); } else if (seq == min_seq[type] || NR_HIST_GENS > 1) { n[0] = atomic_long_read(&lrugen->refaulted[hist][type][tier]); n[1] = atomic_long_read(&lrugen->evicted[hist][type][tier]); if (tier) n[2] = READ_ONCE(lrugen->protected[hist][type][tier - 1]); seq_printf(m, " %10lur %10lue %10lup", n[0], n[1], n[2]); } else seq_puts(m, " 0 0 0 "); } seq_putc(m, '\n'); } seq_puts(m, " "); for (i = 0; i < NR_MM_STATS; i++) { if (seq == max_seq && NR_HIST_GENS == 1) seq_printf(m, " %10lu%c", READ_ONCE(lruvec->mm_state.stats[hist][i]), toupper(MM_STAT_CODES[i])); else if (seq != max_seq && NR_HIST_GENS > 1) seq_printf(m, " %10lu%c", READ_ONCE(lruvec->mm_state.stats[hist][i]), MM_STAT_CODES[i]); else seq_puts(m, " 0 "); } seq_putc(m, '\n'); } static int lru_gen_seq_show(struct seq_file *m, void *v) { unsigned long seq; bool full = !debugfs_real_fops(m->file)->write; struct lruvec *lruvec = v; struct lru_gen_struct *lrugen = &lruvec->lrugen; int nid = lruvec_pgdat(lruvec)->node_id; struct mem_cgroup *memcg = lruvec_memcg(lruvec); DEFINE_MAX_SEQ(lruvec); DEFINE_MIN_SEQ(lruvec); if (nid == first_memory_node) { const char *path = memcg ? m->private : ""; #ifdef CONFIG_MEMCG if (memcg) cgroup_path(memcg->css.cgroup, m->private, PATH_MAX); #endif seq_printf(m, "memcg %5hu %s\n", mem_cgroup_id(memcg), path); } seq_printf(m, " node %5d\n", nid); if (!full) seq = min_seq[LRU_GEN_ANON]; else if (max_seq >= MAX_NR_GENS) seq = max_seq - MAX_NR_GENS + 1; else seq = 0; for (; seq <= max_seq; seq++) { int type, zone; int gen = lru_gen_from_seq(seq); unsigned long birth = READ_ONCE(lruvec->lrugen.timestamps[gen]); seq_printf(m, " %10lu %10u", seq, jiffies_to_msecs(jiffies - birth)); for (type = 0; type < ANON_AND_FILE; type++) { long size = 0; char mark = full && seq < min_seq[type] ? 'x' : ' '; for (zone = 0; zone < MAX_NR_ZONES; zone++) size += READ_ONCE(lrugen->nr_pages[gen][type][zone]); seq_printf(m, " %10lu%c", max(size, 0L), mark); } seq_putc(m, '\n'); if (full) lru_gen_seq_show_full(m, lruvec, max_seq, min_seq, seq); } return 0; } static const struct seq_operations lru_gen_seq_ops = { .start = lru_gen_seq_start, .stop = lru_gen_seq_stop, .next = lru_gen_seq_next, .show = lru_gen_seq_show, }; static int run_aging(struct lruvec *lruvec, unsigned long seq, struct scan_control *sc, bool can_swap, bool full_scan) { DEFINE_MAX_SEQ(lruvec); if (seq == max_seq) try_to_inc_max_seq(lruvec, max_seq, sc, can_swap, full_scan); return seq > max_seq ? -EINVAL : 0; } static int run_eviction(struct lruvec *lruvec, unsigned long seq, struct scan_control *sc, int swappiness, unsigned long nr_to_reclaim) { struct blk_plug plug; int err = -EINTR; DEFINE_MAX_SEQ(lruvec); if (seq + MIN_NR_GENS > max_seq) return -EINVAL; sc->nr_reclaimed = 0; blk_start_plug(&plug); while (!signal_pending(current)) { DEFINE_MIN_SEQ(lruvec); if (seq < min_seq[!swappiness] || sc->nr_reclaimed >= nr_to_reclaim || !evict_pages(lruvec, sc, swappiness, NULL)) { err = 0; break; } cond_resched(); } blk_finish_plug(&plug); return err; } static int run_cmd(char cmd, int memcg_id, int nid, unsigned long seq, struct scan_control *sc, int swappiness, unsigned long opt) { struct lruvec *lruvec; int err = -EINVAL; struct mem_cgroup *memcg = NULL; if (!mem_cgroup_disabled()) { rcu_read_lock(); memcg = mem_cgroup_from_id(memcg_id); #ifdef CONFIG_MEMCG if (memcg && !css_tryget(&memcg->css)) memcg = NULL; #endif rcu_read_unlock(); if (!memcg) goto done; } if (memcg_id != mem_cgroup_id(memcg)) goto done; if (nid < 0 || nid >= MAX_NUMNODES || !node_state(nid, N_MEMORY)) goto done; lruvec = get_lruvec(memcg, nid); if (swappiness < 0) swappiness = get_swappiness(lruvec, sc); else if (swappiness > 200) goto done; switch (cmd) { case '+': err = run_aging(lruvec, seq, sc, swappiness, opt); break; case '-': err = run_eviction(lruvec, seq, sc, swappiness, opt); break; } done: mem_cgroup_put(memcg); return err; } static ssize_t lru_gen_seq_write(struct file *file, const char __user *src, size_t len, loff_t *pos) { void *buf; char *cur, *next; unsigned int flags; int err = 0; struct reclaim_state rs = {}; struct scan_control sc = { .may_writepage = true, .may_unmap = true, .may_swap = true, .reclaim_idx = MAX_NR_ZONES - 1, .gfp_mask = GFP_KERNEL, }; buf = kvmalloc(len + 1, GFP_KERNEL); if (!buf) return -ENOMEM; if (copy_from_user(buf, src, len)) { kvfree(buf); return -EFAULT; } next = buf; next[len] = '\0'; rs.mm_walk = alloc_mm_walk(); if (!rs.mm_walk) { kvfree(buf); return -ENOMEM; } current->reclaim_state = &rs; flags = memalloc_noreclaim_save(); while ((cur = strsep(&next, ",;\n"))) { int n; int end; char cmd; unsigned int memcg_id; unsigned int nid; unsigned long seq; unsigned int swappiness = -1; unsigned long opt = -1; cur = skip_spaces(cur); if (!*cur) continue; n = sscanf(cur, "%c %u %u %lu %n %u %n %lu %n", &cmd, &memcg_id, &nid, &seq, &end, &swappiness, &end, &opt, &end); if (n < 4 || cur[end]) { err = -EINVAL; break; } err = run_cmd(cmd, memcg_id, nid, seq, &sc, swappiness, opt); if (err) break; } memalloc_noreclaim_restore(flags); current->reclaim_state = NULL; free_mm_walk(rs.mm_walk); kvfree(buf); return err ? : len; } static int lru_gen_seq_open(struct inode *inode, struct file *file) { return seq_open(file, &lru_gen_seq_ops); } static const struct file_operations lru_gen_rw_fops = { .open = lru_gen_seq_open, .read = seq_read, .write = lru_gen_seq_write, .llseek = seq_lseek, .release = seq_release, }; static const struct file_operations lru_gen_ro_fops = { .open = lru_gen_seq_open, .read = seq_read, .llseek = seq_lseek, .release = seq_release, }; /****************************************************************************** * initialization ******************************************************************************/ void lru_gen_init_lruvec(struct lruvec *lruvec) { int i; int gen, type, zone; struct lru_gen_struct *lrugen = &lruvec->lrugen; lrugen->max_seq = MIN_NR_GENS + 1; lrugen->enabled = lru_gen_enabled(); for (i = 0; i <= MIN_NR_GENS + 1; i++) lrugen->timestamps[i] = jiffies; for_each_gen_type_zone(gen, type, zone) INIT_LIST_HEAD(&lrugen->lists[gen][type][zone]); lruvec->mm_state.seq = MIN_NR_GENS; init_waitqueue_head(&lruvec->mm_state.wait); } #ifdef CONFIG_MEMCG void lru_gen_init_memcg(struct mem_cgroup *memcg) { INIT_LIST_HEAD(&memcg->mm_list.fifo); spin_lock_init(&memcg->mm_list.lock); } void lru_gen_exit_memcg(struct mem_cgroup *memcg) { int i; int nid; for_each_node(nid) { struct lruvec *lruvec = get_lruvec(memcg, nid); VM_BUG_ON(memchr_inv(lruvec->lrugen.nr_pages, 0, sizeof(lruvec->lrugen.nr_pages))); for (i = 0; i < NR_BLOOM_FILTERS; i++) { bitmap_free(lruvec->mm_state.filters[i]); lruvec->mm_state.filters[i] = NULL; } } } #endif static int __init init_lru_gen(void) { BUILD_BUG_ON(MIN_NR_GENS + 1 >= MAX_NR_GENS); BUILD_BUG_ON(BIT(LRU_GEN_WIDTH) <= MAX_NR_GENS); BUILD_BUG_ON(sizeof(MM_STAT_CODES) != NR_MM_STATS + 1); if (sysfs_create_group(mm_kobj, &lru_gen_attr_group)) pr_err("lru_gen: failed to create sysfs group\n"); debugfs_create_file("lru_gen", 0644, NULL, NULL, &lru_gen_rw_fops); debugfs_create_file("lru_gen_full", 0444, NULL, NULL, &lru_gen_ro_fops); return 0; }; late_initcall(init_lru_gen); #else static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc) { } static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) { } #endif /* CONFIG_LRU_GEN */ /* * This is a basic per-node page freer. Used by both kswapd and direct reclaim. */ static void shrink_node_memcg(struct pglist_data *pgdat, struct mem_cgroup *memcg, struct scan_control *sc, unsigned long *lru_pages) { struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg); unsigned long nr[NR_LRU_LISTS]; unsigned long targets[NR_LRU_LISTS]; unsigned long nr_to_scan; enum lru_list lru; unsigned long nr_reclaimed = 0; unsigned long nr_to_reclaim = sc->nr_to_reclaim; struct blk_plug plug; bool scan_adjusted; if (lru_gen_enabled()) { lru_gen_shrink_lruvec(lruvec, sc); return; } get_scan_count(lruvec, memcg, sc, nr, lru_pages); /* Record the original scan target for proportional adjustments later */ memcpy(targets, nr, sizeof(nr)); /* * Global reclaiming within direct reclaim at DEF_PRIORITY is a normal * event that can occur when there is little memory pressure e.g. * multiple streaming readers/writers. Hence, we do not abort scanning * when the requested number of pages are reclaimed when scanning at * DEF_PRIORITY on the assumption that the fact we are direct * reclaiming implies that kswapd is not keeping up and it is best to * do a batch of work at once. For memcg reclaim one check is made to * abort proportional reclaim if either the file or anon lru has already * dropped to zero at the first pass. */ scan_adjusted = (global_reclaim(sc) && !current_is_kswapd() && sc->priority == DEF_PRIORITY); blk_start_plug(&plug); while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || nr[LRU_INACTIVE_FILE]) { unsigned long nr_anon, nr_file, percentage; unsigned long nr_scanned; for_each_evictable_lru(lru) { if (nr[lru]) { nr_to_scan = min(nr[lru], SWAP_CLUSTER_MAX); nr[lru] -= nr_to_scan; nr_reclaimed += shrink_list(lru, nr_to_scan, lruvec, sc); } } cond_resched(); if (nr_reclaimed < nr_to_reclaim || scan_adjusted) continue; /* * For kswapd and memcg, reclaim at least the number of pages * requested. Ensure that the anon and file LRUs are scanned * proportionally what was requested by get_scan_count(). We * stop reclaiming one LRU and reduce the amount scanning * proportional to the original scan target. */ nr_file = nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE]; nr_anon = nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON]; /* * It's just vindictive to attack the larger once the smaller * has gone to zero. And given the way we stop scanning the * smaller below, this makes sure that we only make one nudge * towards proportionality once we've got nr_to_reclaim. */ if (!nr_file || !nr_anon) break; if (nr_file > nr_anon) { unsigned long scan_target = targets[LRU_INACTIVE_ANON] + targets[LRU_ACTIVE_ANON] + 1; lru = LRU_BASE; percentage = nr_anon * 100 / scan_target; } else { unsigned long scan_target = targets[LRU_INACTIVE_FILE] + targets[LRU_ACTIVE_FILE] + 1; lru = LRU_FILE; percentage = nr_file * 100 / scan_target; } /* Stop scanning the smaller of the LRU */ nr[lru] = 0; nr[lru + LRU_ACTIVE] = 0; /* * Recalculate the other LRU scan count based on its original * scan target and the percentage scanning already complete */ lru = (lru == LRU_FILE) ? LRU_BASE : LRU_FILE; nr_scanned = targets[lru] - nr[lru]; nr[lru] = targets[lru] * (100 - percentage) / 100; nr[lru] -= min(nr[lru], nr_scanned); lru += LRU_ACTIVE; nr_scanned = targets[lru] - nr[lru]; nr[lru] = targets[lru] * (100 - percentage) / 100; nr[lru] -= min(nr[lru], nr_scanned); scan_adjusted = true; } blk_finish_plug(&plug); sc->nr_reclaimed += nr_reclaimed; /* * Even if we did not try to evict anon pages at all, we want to * rebalance the anon lru active/inactive ratio. */ if (inactive_list_is_low(lruvec, false, sc, true)) shrink_active_list(SWAP_CLUSTER_MAX, lruvec, sc, LRU_ACTIVE_ANON); } /* Use reclaim/compaction for costly allocs or under memory pressure */ static bool in_reclaim_compaction(struct scan_control *sc) { if (gfp_compaction_allowed(sc->gfp_mask) && sc->order && (sc->order > PAGE_ALLOC_COSTLY_ORDER || sc->priority < DEF_PRIORITY - 2)) return true; return false; } /* * Reclaim/compaction is used for high-order allocation requests. It reclaims * order-0 pages before compacting the zone. should_continue_reclaim() returns * true if more pages should be reclaimed such that when the page allocator * calls try_to_compact_zone() that it will have enough free pages to succeed. * It will give up earlier than that if there is difficulty reclaiming pages. */ static inline bool should_continue_reclaim(struct pglist_data *pgdat, unsigned long nr_reclaimed, unsigned long nr_scanned, struct scan_control *sc) { unsigned long pages_for_compaction; unsigned long inactive_lru_pages; int z; /* If not in reclaim/compaction mode, stop */ if (!in_reclaim_compaction(sc)) return false; /* Consider stopping depending on scan and reclaim activity */ if (sc->gfp_mask & __GFP_RETRY_MAYFAIL) { /* * For __GFP_RETRY_MAYFAIL allocations, stop reclaiming if the * full LRU list has been scanned and we are still failing * to reclaim pages. This full LRU scan is potentially * expensive but a __GFP_RETRY_MAYFAIL caller really wants to succeed */ if (!nr_reclaimed && !nr_scanned) return false; } else { /* * For non-__GFP_RETRY_MAYFAIL allocations which can presumably * fail without consequence, stop if we failed to reclaim * any pages from the last SWAP_CLUSTER_MAX number of * pages that were scanned. This will return to the * caller faster at the risk reclaim/compaction and * the resulting allocation attempt fails */ if (!nr_reclaimed) return false; } /* * If we have not reclaimed enough pages for compaction and the * inactive lists are large enough, continue reclaiming */ pages_for_compaction = compact_gap(sc->order); inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE); if (get_nr_swap_pages() > 0) inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON); if (sc->nr_reclaimed < pages_for_compaction && inactive_lru_pages > pages_for_compaction) return true; /* If compaction would go ahead or the allocation would succeed, stop */ for (z = 0; z <= sc->reclaim_idx; z++) { struct zone *zone = &pgdat->node_zones[z]; if (!managed_zone(zone)) continue; switch (compaction_suitable(zone, sc->order, 0, sc->reclaim_idx)) { case COMPACT_SUCCESS: case COMPACT_CONTINUE: return false; default: /* check next zone */ ; } } return true; } static bool pgdat_memcg_congested(pg_data_t *pgdat, struct mem_cgroup *memcg) { return test_bit(PGDAT_CONGESTED, &pgdat->flags) || (memcg && memcg_congested(pgdat, memcg)); } static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) { struct reclaim_state *reclaim_state = current->reclaim_state; unsigned long nr_reclaimed, nr_scanned; bool reclaimable = false; do { struct mem_cgroup *root = sc->target_mem_cgroup; struct mem_cgroup_reclaim_cookie reclaim = { .pgdat = pgdat, .priority = sc->priority, }; unsigned long node_lru_pages = 0; struct mem_cgroup *memcg; memset(&sc->nr, 0, sizeof(sc->nr)); nr_reclaimed = sc->nr_reclaimed; nr_scanned = sc->nr_scanned; memcg = mem_cgroup_iter(root, NULL, &reclaim); do { unsigned long lru_pages; unsigned long reclaimed; unsigned long scanned; /* * This loop can become CPU-bound when target memcgs * aren't eligible for reclaim - either because they * don't have any reclaimable pages, or because their * memory is explicitly protected. Avoid soft lockups. */ cond_resched(); switch (mem_cgroup_protected(root, memcg)) { case MEMCG_PROT_MIN: /* * Hard protection. * If there is no reclaimable memory, OOM. */ continue; case MEMCG_PROT_LOW: /* * Soft protection. * Respect the protection only as long as * there is an unprotected supply * of reclaimable memory from other cgroups. */ if (!sc->memcg_low_reclaim) { sc->memcg_low_skipped = 1; continue; } memcg_memory_event(memcg, MEMCG_LOW); break; case MEMCG_PROT_NONE: break; } reclaimed = sc->nr_reclaimed; scanned = sc->nr_scanned; shrink_node_memcg(pgdat, memcg, sc, &lru_pages); node_lru_pages += lru_pages; shrink_slab(sc->gfp_mask, pgdat->node_id, memcg, sc->priority); /* Record the group's reclaim efficiency */ vmpressure(sc->gfp_mask, memcg, false, sc->nr_scanned - scanned, sc->nr_reclaimed - reclaimed); /* * Direct reclaim and kswapd have to scan all memory * cgroups to fulfill the overall scan target for the * node. * * Limit reclaim, on the other hand, only cares about * nr_to_reclaim pages to be reclaimed and it will * retry with decreasing priority if one round over the * whole hierarchy is not sufficient. */ if (!global_reclaim(sc) && sc->nr_reclaimed >= sc->nr_to_reclaim) { mem_cgroup_iter_break(root, memcg); break; } } while ((memcg = mem_cgroup_iter(root, memcg, &reclaim))); /* * Record the subtree's reclaim efficiency. The reclaimed * pages from slab is excluded here because the corresponding * scanned pages is not accounted. Moreover, freeing a page * by slab shrinking depends on each slab's object population, * making the cost model (i.e. scan:free) different from that * of LRU. */ vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true, sc->nr_scanned - nr_scanned, sc->nr_reclaimed - nr_reclaimed); if (reclaim_state) { sc->nr_reclaimed += reclaim_state->reclaimed_slab; reclaim_state->reclaimed_slab = 0; } if (sc->nr_reclaimed - nr_reclaimed) reclaimable = true; if (current_is_kswapd()) { /* * If reclaim is isolating dirty pages under writeback, * it implies that the long-lived page allocation rate * is exceeding the page laundering rate. Either the * global limits are not being effective at throttling * processes due to the page distribution throughout * zones or there is heavy usage of a slow backing * device. The only option is to throttle from reclaim * context which is not ideal as there is no guarantee * the dirtying process is throttled in the same way * balance_dirty_pages() manages. * * Once a node is flagged PGDAT_WRITEBACK, kswapd will * count the number of pages under pages flagged for * immediate reclaim and stall if any are encountered * in the nr_immediate check below. */ if (sc->nr.writeback && sc->nr.writeback == sc->nr.taken) set_bit(PGDAT_WRITEBACK, &pgdat->flags); /* * Tag a node as congested if all the dirty pages * scanned were backed by a congested BDI and * wait_iff_congested will stall. */ if (sc->nr.dirty && sc->nr.dirty == sc->nr.congested) set_bit(PGDAT_CONGESTED, &pgdat->flags); /* Allow kswapd to start writing pages during reclaim.*/ if (sc->nr.unqueued_dirty == sc->nr.file_taken) set_bit(PGDAT_DIRTY, &pgdat->flags); /* * If kswapd scans pages marked marked for immediate * reclaim and under writeback (nr_immediate), it * implies that pages are cycling through the LRU * faster than they are written so also forcibly stall. */ if (sc->nr.immediate) congestion_wait(BLK_RW_ASYNC, HZ/10); } /* * Legacy memcg will stall in page writeback so avoid forcibly * stalling in wait_iff_congested(). */ if (!global_reclaim(sc) && sane_reclaim(sc) && sc->nr.dirty && sc->nr.dirty == sc->nr.congested) set_memcg_congestion(pgdat, root, true); /* * Stall direct reclaim for IO completions if underlying BDIs * and node is congested. Allow kswapd to continue until it * starts encountering unqueued dirty pages or cycling through * the LRU too quickly. */ if (!sc->hibernation_mode && !current_is_kswapd() && current_may_throttle() && pgdat_memcg_congested(pgdat, root)) wait_iff_congested(BLK_RW_ASYNC, HZ/10); } while (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed, sc->nr_scanned - nr_scanned, sc)); /* * Kswapd gives up on balancing particular nodes after too * many failures to reclaim anything from them and goes to * sleep. On reclaim progress, reset the failure counter. A * successful direct reclaim run will revive a dormant kswapd. */ if (reclaimable) pgdat->kswapd_failures = 0; return reclaimable; } /* * Returns true if compaction should go ahead for a costly-order request, or * the allocation would already succeed without compaction. Return false if we * should reclaim first. */ static inline bool compaction_ready(struct zone *zone, struct scan_control *sc) { unsigned long watermark; enum compact_result suitable; if (!gfp_compaction_allowed(sc->gfp_mask)) return false; suitable = compaction_suitable(zone, sc->order, 0, sc->reclaim_idx); if (suitable == COMPACT_SUCCESS) /* Allocation should succeed already. Don't reclaim. */ return true; if (suitable == COMPACT_SKIPPED) /* Compaction cannot yet proceed. Do reclaim. */ return false; /* * Compaction is already possible, but it takes time to run and there * are potentially other callers using the pages just freed. So proceed * with reclaim to make a buffer of free pages available to give * compaction a reasonable chance of completing and allocating the page. * Note that we won't actually reclaim the whole buffer in one attempt * as the target watermark in should_continue_reclaim() is lower. But if * we are already above the high+gap watermark, don't reclaim at all. */ watermark = high_wmark_pages(zone) + compact_gap(sc->order); return zone_watermark_ok_safe(zone, 0, watermark, sc->reclaim_idx); } /* * This is the direct reclaim path, for page-allocating processes. We only * try to reclaim pages from zones which will satisfy the caller's allocation * request. * * If a zone is deemed to be full of pinned pages then just give it a light * scan then give up on it. */ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) { struct zoneref *z; struct zone *zone; unsigned long nr_soft_reclaimed; unsigned long nr_soft_scanned; gfp_t orig_mask; pg_data_t *last_pgdat = NULL; /* * If the number of buffer_heads in the machine exceeds the maximum * allowed level, force direct reclaim to scan the highmem zone as * highmem pages could be pinning lowmem pages storing buffer_heads */ orig_mask = sc->gfp_mask; if (buffer_heads_over_limit) { sc->gfp_mask |= __GFP_HIGHMEM; sc->reclaim_idx = gfp_zone(sc->gfp_mask); } for_each_zone_zonelist_nodemask(zone, z, zonelist, sc->reclaim_idx, sc->nodemask) { /* * Take care memory controller reclaiming has small influence * to global LRU. */ if (global_reclaim(sc)) { if (!cpuset_zone_allowed(zone, GFP_KERNEL | __GFP_HARDWALL)) continue; /* * If we already have plenty of memory free for * compaction in this zone, don't free any more. * Even though compaction is invoked for any * non-zero order, only frequent costly order * reclamation is disruptive enough to become a * noticeable problem, like transparent huge * page allocations. */ if (IS_ENABLED(CONFIG_COMPACTION) && sc->order > PAGE_ALLOC_COSTLY_ORDER && compaction_ready(zone, sc)) { sc->compaction_ready = true; continue; } /* * Shrink each node in the zonelist once. If the * zonelist is ordered by zone (not the default) then a * node may be shrunk multiple times but in that case * the user prefers lower zones being preserved. */ if (zone->zone_pgdat == last_pgdat) continue; /* * This steals pages from memory cgroups over softlimit * and returns the number of reclaimed pages and * scanned pages. This works for global memory pressure * and balancing, not for a memcg's limit. */ nr_soft_scanned = 0; nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone->zone_pgdat, sc->order, sc->gfp_mask, &nr_soft_scanned); sc->nr_reclaimed += nr_soft_reclaimed; sc->nr_scanned += nr_soft_scanned; /* need some check for avoid more shrink_zone() */ } /* See comment about same check for global reclaim above */ if (zone->zone_pgdat == last_pgdat) continue; last_pgdat = zone->zone_pgdat; shrink_node(zone->zone_pgdat, sc); } /* * Restore to original mask to avoid the impact on the caller if we * promoted it to __GFP_HIGHMEM. */ sc->gfp_mask = orig_mask; } static void snapshot_refaults(struct mem_cgroup *root_memcg, pg_data_t *pgdat) { struct mem_cgroup *memcg; if (lru_gen_enabled()) return; memcg = mem_cgroup_iter(root_memcg, NULL, NULL); do { unsigned long refaults; struct lruvec *lruvec; lruvec = mem_cgroup_lruvec(pgdat, memcg); refaults = lruvec_page_state(lruvec, WORKINGSET_ACTIVATE); lruvec->refaults = refaults; } while ((memcg = mem_cgroup_iter(root_memcg, memcg, NULL))); } /* * This is the main entry point to direct page reclaim. * * If a full scan of the inactive list fails to free enough memory then we * are "out of memory" and something needs to be killed. * * If the caller is !__GFP_FS then the probability of a failure is reasonably * high - the zone may be full of dirty or under-writeback pages, which this * caller can't do much about. We kick the writeback threads and take explicit * naps in the hope that some of these pages can be written. But if the * allocating task holds filesystem locks which prevent writeout this might not * work, and the allocation attempt will fail. * * returns: 0, if no pages reclaimed * else, the number of pages reclaimed */ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, struct scan_control *sc) { int initial_priority = sc->priority; pg_data_t *last_pgdat; struct zoneref *z; struct zone *zone; retry: delayacct_freepages_start(); if (global_reclaim(sc)) __count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1); do { vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup, sc->priority); sc->nr_scanned = 0; shrink_zones(zonelist, sc); if (sc->nr_reclaimed >= sc->nr_to_reclaim) break; if (sc->compaction_ready) break; /* * If we're getting trouble reclaiming, start doing * writepage even in laptop mode. */ if (sc->priority < DEF_PRIORITY - 2) sc->may_writepage = 1; } while (--sc->priority >= 0); last_pgdat = NULL; for_each_zone_zonelist_nodemask(zone, z, zonelist, sc->reclaim_idx, sc->nodemask) { if (zone->zone_pgdat == last_pgdat) continue; last_pgdat = zone->zone_pgdat; snapshot_refaults(sc->target_mem_cgroup, zone->zone_pgdat); set_memcg_congestion(last_pgdat, sc->target_mem_cgroup, false); } delayacct_freepages_end(); if (sc->nr_reclaimed) return sc->nr_reclaimed; /* Aborted reclaim to try compaction? don't OOM, then */ if (sc->compaction_ready) return 1; /* Untapped cgroup reserves? Don't OOM, retry. */ if (sc->memcg_low_skipped) { sc->priority = initial_priority; sc->memcg_low_reclaim = 1; sc->memcg_low_skipped = 0; goto retry; } return 0; } static bool allow_direct_reclaim(pg_data_t *pgdat) { struct zone *zone; unsigned long pfmemalloc_reserve = 0; unsigned long free_pages = 0; int i; bool wmark_ok; if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES) return true; for (i = 0; i <= ZONE_NORMAL; i++) { zone = &pgdat->node_zones[i]; if (!managed_zone(zone)) continue; if (!zone_reclaimable_pages(zone)) continue; pfmemalloc_reserve += min_wmark_pages(zone); free_pages += zone_page_state(zone, NR_FREE_PAGES); } /* If there are no reserves (unexpected config) then do not throttle */ if (!pfmemalloc_reserve) return true; wmark_ok = free_pages > pfmemalloc_reserve / 2; /* kswapd must be awake if processes are being throttled */ if (!wmark_ok && waitqueue_active(&pgdat->kswapd_wait)) { if (READ_ONCE(pgdat->kswapd_classzone_idx) > ZONE_NORMAL) WRITE_ONCE(pgdat->kswapd_classzone_idx, ZONE_NORMAL); wake_up_interruptible(&pgdat->kswapd_wait); } return wmark_ok; } /* * Throttle direct reclaimers if backing storage is backed by the network * and the PFMEMALLOC reserve for the preferred node is getting dangerously * depleted. kswapd will continue to make progress and wake the processes * when the low watermark is reached. * * Returns true if a fatal signal was delivered during throttling. If this * happens, the page allocator should not consider triggering the OOM killer. */ static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist, nodemask_t *nodemask) { struct zoneref *z; struct zone *zone; pg_data_t *pgdat = NULL; /* * Kernel threads should not be throttled as they may be indirectly * responsible for cleaning pages necessary for reclaim to make forward * progress. kjournald for example may enter direct reclaim while * committing a transaction where throttling it could forcing other * processes to block on log_wait_commit(). */ if ((current->flags & PF_KTHREAD) || !strcmp(current->comm, ULMK_MAGIC)) goto out; /* * If a fatal signal is pending, this process should not throttle. * It should return quickly so it can exit and free its memory */ if (fatal_signal_pending(current)) goto out; /* * Check if the pfmemalloc reserves are ok by finding the first node * with a usable ZONE_NORMAL or lower zone. The expectation is that * GFP_KERNEL will be required for allocating network buffers when * swapping over the network so ZONE_HIGHMEM is unusable. * * Throttling is based on the first usable node and throttled processes * wait on a queue until kswapd makes progress and wakes them. There * is an affinity then between processes waking up and where reclaim * progress has been made assuming the process wakes on the same node. * More importantly, processes running on remote nodes will not compete * for remote pfmemalloc reserves and processes on different nodes * should make reasonable progress. */ for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(gfp_mask), nodemask) { if (zone_idx(zone) > ZONE_NORMAL) continue; /* Throttle based on the first usable node */ pgdat = zone->zone_pgdat; if (allow_direct_reclaim(pgdat)) goto out; break; } /* If no zone was usable by the allocation flags then do not throttle */ if (!pgdat) goto out; /* Account for the throttling */ count_vm_event(PGSCAN_DIRECT_THROTTLE); /* * If the caller cannot enter the filesystem, it's possible that it * is due to the caller holding an FS lock or performing a journal * transaction in the case of a filesystem like ext[3|4]. In this case, * it is not safe to block on pfmemalloc_wait as kswapd could be * blocked waiting on the same lock. Instead, throttle for up to a * second before continuing. */ if (!(gfp_mask & __GFP_FS)) { wait_event_interruptible_timeout(pgdat->pfmemalloc_wait, allow_direct_reclaim(pgdat), HZ); goto check_pending; } /* Throttle until kswapd wakes the process */ wait_event_killable(zone->zone_pgdat->pfmemalloc_wait, allow_direct_reclaim(pgdat)); check_pending: if (fatal_signal_pending(current)) return true; out: return false; } unsigned long try_to_free_pages(struct zonelist *zonelist, int order, gfp_t gfp_mask, nodemask_t *nodemask) { unsigned long nr_reclaimed; struct scan_control sc = { .nr_to_reclaim = SWAP_CLUSTER_MAX, .gfp_mask = current_gfp_context(gfp_mask), .reclaim_idx = gfp_zone(gfp_mask), .order = order, .nodemask = nodemask, .priority = DEF_PRIORITY, .may_writepage = !laptop_mode, .may_unmap = 1, .may_swap = 1, .may_shrinkslab = 1, }; /* * scan_control uses s8 fields for order, priority, and reclaim_idx. * Confirm they are large enough for max values. */ BUILD_BUG_ON(MAX_ORDER > S8_MAX); BUILD_BUG_ON(DEF_PRIORITY > S8_MAX); BUILD_BUG_ON(MAX_NR_ZONES > S8_MAX); /* * Do not enter reclaim if fatal signal was delivered while throttled. * 1 is returned so that the page allocator does not OOM kill at this * point. */ if (throttle_direct_reclaim(sc.gfp_mask, zonelist, nodemask)) return 1; trace_mm_vmscan_direct_reclaim_begin(order, sc.may_writepage, sc.gfp_mask, sc.reclaim_idx); nr_reclaimed = do_try_to_free_pages(zonelist, &sc); trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); return nr_reclaimed; } #ifdef CONFIG_MEMCG unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg, gfp_t gfp_mask, bool noswap, pg_data_t *pgdat, unsigned long *nr_scanned) { struct scan_control sc = { .nr_to_reclaim = SWAP_CLUSTER_MAX, .target_mem_cgroup = memcg, .may_writepage = !laptop_mode, .may_unmap = 1, .reclaim_idx = MAX_NR_ZONES - 1, .may_swap = !noswap, .may_shrinkslab = 1, }; unsigned long lru_pages; sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order, sc.may_writepage, sc.gfp_mask, sc.reclaim_idx); /* * NOTE: Although we can get the priority field, using it * here is not a good idea, since it limits the pages we can scan. * if we don't reclaim here, the shrink_node from balance_pgdat * will pick up pages from other mem cgroup's as well. We hack * the priority and make it zero. */ shrink_node_memcg(pgdat, memcg, &sc, &lru_pages); trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); *nr_scanned = sc.nr_scanned; return sc.nr_reclaimed; } unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, unsigned long nr_pages, gfp_t gfp_mask, bool may_swap) { struct zonelist *zonelist; unsigned long nr_reclaimed; unsigned long pflags; int nid; unsigned int noreclaim_flag; struct scan_control sc = { .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), .gfp_mask = (current_gfp_context(gfp_mask) & GFP_RECLAIM_MASK) | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK), .reclaim_idx = MAX_NR_ZONES - 1, .target_mem_cgroup = memcg, .priority = DEF_PRIORITY, .may_writepage = !laptop_mode, .may_unmap = 1, .may_swap = may_swap, .may_shrinkslab = 1, }; /* * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't * take care of from where we get pages. So the node where we start the * scan does not need to be the current node. */ nid = mem_cgroup_select_victim_node(memcg); zonelist = &NODE_DATA(nid)->node_zonelists[ZONELIST_FALLBACK]; trace_mm_vmscan_memcg_reclaim_begin(0, sc.may_writepage, sc.gfp_mask, sc.reclaim_idx); psi_memstall_enter(&pflags); noreclaim_flag = memalloc_noreclaim_save(); nr_reclaimed = do_try_to_free_pages(zonelist, &sc); memalloc_noreclaim_restore(noreclaim_flag); psi_memstall_leave(&pflags); trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed); return nr_reclaimed; } #endif static void age_active_anon(struct pglist_data *pgdat, struct scan_control *sc) { struct mem_cgroup *memcg; if (lru_gen_enabled()) { lru_gen_age_node(pgdat, sc); return; } if (!total_swap_pages) return; memcg = mem_cgroup_iter(NULL, NULL, NULL); do { struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg); if (inactive_list_is_low(lruvec, false, sc, true)) shrink_active_list(SWAP_CLUSTER_MAX, lruvec, sc, LRU_ACTIVE_ANON); memcg = mem_cgroup_iter(NULL, memcg, NULL); } while (memcg); } static bool pgdat_watermark_boosted(pg_data_t *pgdat, int classzone_idx) { int i; struct zone *zone; /* * Check for watermark boosts top-down as the higher zones * are more likely to be boosted. Both watermarks and boosts * should not be checked at the time time as reclaim would * start prematurely when there is no boosting and a lower * zone is balanced. */ for (i = classzone_idx; i >= 0; i--) { zone = pgdat->node_zones + i; if (!managed_zone(zone)) continue; if (zone->watermark_boost) return true; } return false; } /* * Returns true if there is an eligible zone balanced for the request order * and classzone_idx */ static bool pgdat_balanced(pg_data_t *pgdat, int order, int classzone_idx) { int i; unsigned long mark = -1; struct zone *zone; /* * Check watermarks bottom-up as lower zones are more likely to * meet watermarks. */ for (i = 0; i <= classzone_idx; i++) { zone = pgdat->node_zones + i; if (!managed_zone(zone)) continue; mark = high_wmark_pages(zone); if (zone_watermark_ok_safe(zone, order, mark, classzone_idx)) return true; } /* * If a node has no populated zone within classzone_idx, it does not * need balancing by definition. This can happen if a zone-restricted * allocation tries to wake a remote kswapd. */ if (mark == -1) return true; return false; } /* Clear pgdat state for congested, dirty or under writeback. */ static void clear_pgdat_congested(pg_data_t *pgdat) { clear_bit(PGDAT_CONGESTED, &pgdat->flags); clear_bit(PGDAT_DIRTY, &pgdat->flags); clear_bit(PGDAT_WRITEBACK, &pgdat->flags); } /* * Prepare kswapd for sleeping. This verifies that there are no processes * waiting in throttle_direct_reclaim() and that watermarks have been met. * * Returns true if kswapd is ready to sleep */ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, int classzone_idx) { /* * The throttled processes are normally woken up in balance_pgdat() as * soon as allow_direct_reclaim() is true. But there is a potential * race between when kswapd checks the watermarks and a process gets * throttled. There is also a potential race if processes get * throttled, kswapd wakes, a large process exits thereby balancing the * zones, which causes kswapd to exit balance_pgdat() before reaching * the wake up checks. If kswapd is going to sleep, no process should * be sleeping on pfmemalloc_wait, so wake them now if necessary. If * the wake up is premature, processes will wake kswapd and get * throttled again. The difference from wake ups in balance_pgdat() is * that here we are under prepare_to_wait(). */ if (waitqueue_active(&pgdat->pfmemalloc_wait)) wake_up_all(&pgdat->pfmemalloc_wait); /* Hopeless node, leave it to direct reclaim */ if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES) return true; if (pgdat_balanced(pgdat, order, classzone_idx)) { clear_pgdat_congested(pgdat); return true; } return false; } /* * kswapd shrinks a node of pages that are at or below the highest usable * zone that is currently unbalanced. * * Returns true if kswapd scanned at least the requested number of pages to * reclaim or if the lack of progress was due to pages under writeback. * This is used to determine if the scanning priority needs to be raised. */ static bool kswapd_shrink_node(pg_data_t *pgdat, struct scan_control *sc) { struct zone *zone; int z; /* Reclaim a number of pages proportional to the number of zones */ sc->nr_to_reclaim = 0; for (z = 0; z <= sc->reclaim_idx; z++) { zone = pgdat->node_zones + z; if (!managed_zone(zone)) continue; sc->nr_to_reclaim += max(high_wmark_pages(zone), SWAP_CLUSTER_MAX); } /* * Historically care was taken to put equal pressure on all zones but * now pressure is applied based on node LRU order. */ shrink_node(pgdat, sc); /* * Fragmentation may mean that the system cannot be rebalanced for * high-order allocations. If twice the allocation size has been * reclaimed then recheck watermarks only at order-0 to prevent * excessive reclaim. Assume that a process requested a high-order * can direct reclaim/compact. */ if (sc->order && sc->nr_reclaimed >= compact_gap(sc->order)) sc->order = 0; return sc->nr_scanned >= sc->nr_to_reclaim; } /* * For kswapd, balance_pgdat() will reclaim pages across a node from zones * that are eligible for use by the caller until at least one zone is * balanced. * * Returns the order kswapd finished reclaiming at. * * kswapd scans the zones in the highmem->normal->dma direction. It skips * zones which have free_pages > high_wmark_pages(zone), but once a zone is * found to have free_pages <= high_wmark_pages(zone), any page is that zone * or lower is eligible for reclaim until at least one usable zone is * balanced. */ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) { int i; unsigned long nr_soft_reclaimed; unsigned long nr_soft_scanned; unsigned long pflags; unsigned long nr_boost_reclaim; unsigned long zone_boosts[MAX_NR_ZONES] = { 0, }; bool boosted; struct zone *zone; struct scan_control sc = { .gfp_mask = GFP_KERNEL, .order = order, .may_unmap = 1, #ifdef OPLUS_FEATURE_PERFORMANCE .may_swap = 1, #endif }; psi_memstall_enter(&pflags); __fs_reclaim_acquire(); count_vm_event(PAGEOUTRUN); /* * Account for the reclaim boost. Note that the zone boost is left in * place so that parallel allocations that are near the watermark will * stall or direct reclaim until kswapd is finished. */ nr_boost_reclaim = 0; for (i = 0; i <= classzone_idx; i++) { zone = pgdat->node_zones + i; if (!managed_zone(zone)) continue; nr_boost_reclaim += zone->watermark_boost; zone_boosts[i] = zone->watermark_boost; } boosted = nr_boost_reclaim; restart: sc.priority = DEF_PRIORITY; do { unsigned long nr_reclaimed = sc.nr_reclaimed; bool raise_priority = true; bool balanced; bool ret; sc.reclaim_idx = classzone_idx; /* * If the number of buffer_heads exceeds the maximum allowed * then consider reclaiming from all zones. This has a dual * purpose -- on 64-bit systems it is expected that * buffer_heads are stripped during active rotation. On 32-bit * systems, highmem pages can pin lowmem memory and shrinking * buffers can relieve lowmem pressure. Reclaim may still not * go ahead if all eligible zones for the original allocation * request are balanced to avoid excessive reclaim from kswapd. */ if (buffer_heads_over_limit) { for (i = MAX_NR_ZONES - 1; i >= 0; i--) { zone = pgdat->node_zones + i; if (!managed_zone(zone)) continue; sc.reclaim_idx = i; break; } } /* * If the pgdat is imbalanced then ignore boosting and preserve * the watermarks for a later time and restart. Note that the * zone watermarks will be still reset at the end of balancing * on the grounds that the normal reclaim should be enough to * re-evaluate if boosting is required when kswapd next wakes. */ balanced = pgdat_balanced(pgdat, sc.order, classzone_idx); if (!balanced && nr_boost_reclaim) { nr_boost_reclaim = 0; goto restart; } /* * If boosting is not active then only reclaim if there are no * eligible zones. Note that sc.reclaim_idx is not used as * buffer_heads_over_limit may have adjusted it. */ if (!nr_boost_reclaim && balanced) goto out; /* Limit the priority of boosting to avoid reclaim writeback */ if (nr_boost_reclaim && sc.priority == DEF_PRIORITY - 2) raise_priority = false; /* * Do not writeback or swap pages for boosted reclaim. The * intent is to relieve pressure not issue sub-optimal IO * from reclaim context. If no pages are reclaimed, the * reclaim will be aborted. */ sc.may_writepage = !laptop_mode && !nr_boost_reclaim; #ifndef OPLUS_FEATURE_PERFORMANCE sc.may_swap = !nr_boost_reclaim; #endif /* * Do some background aging of the anon list, to give * pages a chance to be referenced before reclaiming. All * pages are rotated regardless of classzone as this is * about consistent aging. */ age_active_anon(pgdat, &sc); /* * If we're getting trouble reclaiming, start doing writepage * even in laptop mode. */ if (sc.priority < DEF_PRIORITY - 2) sc.may_writepage = 1; /* Call soft limit reclaim before calling shrink_node. */ sc.nr_scanned = 0; nr_soft_scanned = 0; nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(pgdat, sc.order, sc.gfp_mask, &nr_soft_scanned); sc.nr_reclaimed += nr_soft_reclaimed; /* * There should be no need to raise the scanning priority if * enough pages are already being scanned that that high * watermark would be met at 100% efficiency. */ if (kswapd_shrink_node(pgdat, &sc)) raise_priority = false; /* * If the low watermark is met there is no need for processes * to be throttled on pfmemalloc_wait as they should not be * able to safely make forward progress. Wake them */ if (waitqueue_active(&pgdat->pfmemalloc_wait) && allow_direct_reclaim(pgdat)) wake_up_all(&pgdat->pfmemalloc_wait); /* Check if kswapd should be suspending */ __fs_reclaim_release(); ret = try_to_freeze(); __fs_reclaim_acquire(); if (ret || kthread_should_stop()) break; /* * Raise priority if scanning rate is too low or there was no * progress in reclaiming pages */ nr_reclaimed = sc.nr_reclaimed - nr_reclaimed; nr_boost_reclaim -= min(nr_boost_reclaim, nr_reclaimed); /* * If reclaim made no progress for a boost, stop reclaim as * IO cannot be queued and it could be an infinite loop in * extreme circumstances. */ if (nr_boost_reclaim && !nr_reclaimed) break; if (raise_priority || !nr_reclaimed) sc.priority--; } while (sc.priority >= 1); if (!sc.nr_reclaimed) pgdat->kswapd_failures++; out: /* If reclaim was boosted, account for the reclaim done in this pass */ if (boosted) { unsigned long flags; for (i = 0; i <= classzone_idx; i++) { if (!zone_boosts[i]) continue; /* Increments are under the zone lock */ zone = pgdat->node_zones + i; spin_lock_irqsave(&zone->lock, flags); zone->watermark_boost -= min(zone->watermark_boost, zone_boosts[i]); spin_unlock_irqrestore(&zone->lock, flags); } /* * As there is now likely space, wakeup kcompact to defragment * pageblocks. */ wakeup_kcompactd(pgdat, pageblock_order, classzone_idx); } snapshot_refaults(NULL, pgdat); __fs_reclaim_release(); psi_memstall_leave(&pflags); /* * Return the order kswapd stopped reclaiming at as * prepare_kswapd_sleep() takes it into account. If another caller * entered the allocator slow path while kswapd was awake, order will * remain at the higher level. */ return sc.order; } /* * The pgdat->kswapd_classzone_idx is used to pass the highest zone index to be * reclaimed by kswapd from the waker. If the value is MAX_NR_ZONES which is not * a valid index then either kswapd runs for first time or kswapd couldn't sleep * after previous reclaim attempt (node is still unbalanced). In that case * return the zone index of the previous kswapd reclaim cycle. */ static enum zone_type kswapd_classzone_idx(pg_data_t *pgdat, enum zone_type prev_classzone_idx) { enum zone_type curr_idx = READ_ONCE(pgdat->kswapd_classzone_idx); return curr_idx == MAX_NR_ZONES ? prev_classzone_idx : curr_idx; } static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_order, unsigned int classzone_idx) { long remaining = 0; DEFINE_WAIT(wait); if (freezing(current) || kthread_should_stop()) return; prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); /* * Try to sleep for a short interval. Note that kcompactd will only be * woken if it is possible to sleep for a short interval. This is * deliberate on the assumption that if reclaim cannot keep an * eligible zone balanced that it's also unlikely that compaction will * succeed. */ if (prepare_kswapd_sleep(pgdat, reclaim_order, classzone_idx)) { /* * Compaction records what page blocks it recently failed to * isolate pages from and skips them in the future scanning. * When kswapd is going to sleep, it is reasonable to assume * that pages and compaction may succeed so reset the cache. */ reset_isolation_suitable(pgdat); /* * We have freed the memory, now we should compact it to make * allocation of the requested order possible. */ wakeup_kcompactd(pgdat, alloc_order, classzone_idx); remaining = schedule_timeout(HZ/10); /* * If woken prematurely then reset kswapd_classzone_idx and * order. The values will either be from a wakeup request or * the previous request that slept prematurely. */ if (remaining) { WRITE_ONCE(pgdat->kswapd_classzone_idx, kswapd_classzone_idx(pgdat, classzone_idx)); if (READ_ONCE(pgdat->kswapd_order) < reclaim_order) WRITE_ONCE(pgdat->kswapd_order, reclaim_order); } finish_wait(&pgdat->kswapd_wait, &wait); prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); } /* * After a short sleep, check if it was a premature sleep. If not, then * go fully to sleep until explicitly woken up. */ if (!remaining && prepare_kswapd_sleep(pgdat, reclaim_order, classzone_idx)) { trace_mm_vmscan_kswapd_sleep(pgdat->node_id); /* * vmstat counters are not perfectly accurate and the estimated * value for counters such as NR_FREE_PAGES can deviate from the * true value by nr_online_cpus * threshold. To avoid the zone * watermarks being breached while under pressure, we reduce the * per-cpu vmstat threshold while kswapd is awake and restore * them before going back to sleep. */ set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold); if (!kthread_should_stop()) schedule(); set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold); } else { if (remaining) count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); else count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); } finish_wait(&pgdat->kswapd_wait, &wait); } /* * The background pageout daemon, started as a kernel thread * from the init process. * * This basically trickles out pages so that we have _some_ * free memory available even if there is no other activity * that frees anything up. This is needed for things like routing * etc, where we otherwise might have all activity going on in * asynchronous contexts that cannot page things out. * * If there are applications that are active memory-allocators * (most normal use), this basically shouldn't matter. */ #if defined(OPLUS_FEATURE_MULTI_KSWAPD) && defined(CONFIG_OPLUS_MULTI_KSWAPD) int kswapd(void *p) #else static int kswapd(void *p) #endif { unsigned int alloc_order, reclaim_order; unsigned int classzone_idx = MAX_NR_ZONES - 1; pg_data_t *pgdat = (pg_data_t*)p; struct task_struct *tsk = current; struct reclaim_state reclaim_state = { .reclaimed_slab = 0, }; #if defined(OPLUS_FEATURE_MULTI_KSWAPD) && defined(CONFIG_KSWAPD_UNBIND_MAX_CPU) struct cpumask mask; struct cpumask *cpumask = &mask; cpumask_copy(cpumask, cpumask_of_node(pgdat->node_id)); if (kswapd_unbind_cpu != -1 && cpumask_test_cpu(kswapd_unbind_cpu, cpumask)) cpumask_clear_cpu(kswapd_unbind_cpu, cpumask); #else const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); #endif if (!cpumask_empty(cpumask)) set_cpus_allowed_ptr(tsk, cpumask); current->reclaim_state = &reclaim_state; /* * Tell the memory management that we're a "memory allocator", * and that if we need more memory we should get access to it * regardless (see "__alloc_pages()"). "kswapd" should * never get caught in the normal page freeing logic. * * (Kswapd normally doesn't need memory anyway, but sometimes * you need a small amount of memory in order to be able to * page out something else, and this flag essentially protects * us from recursively trying to free more memory as we're * trying to free the first piece of memory in the first place). */ tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; set_freezable(); WRITE_ONCE(pgdat->kswapd_order, 0); WRITE_ONCE(pgdat->kswapd_classzone_idx, MAX_NR_ZONES); for ( ; ; ) { bool ret; alloc_order = reclaim_order = READ_ONCE(pgdat->kswapd_order); classzone_idx = kswapd_classzone_idx(pgdat, classzone_idx); kswapd_try_sleep: kswapd_try_to_sleep(pgdat, alloc_order, reclaim_order, classzone_idx); /* Read the new order and classzone_idx */ alloc_order = reclaim_order = READ_ONCE(pgdat->kswapd_order); classzone_idx = kswapd_classzone_idx(pgdat, classzone_idx); WRITE_ONCE(pgdat->kswapd_order, 0); WRITE_ONCE(pgdat->kswapd_classzone_idx, MAX_NR_ZONES); ret = try_to_freeze(); if (kthread_should_stop()) break; /* * We can speed up thawing tasks if we don't call balance_pgdat * after returning from the refrigerator */ if (ret) continue; /* * Reclaim begins at the requested order but if a high-order * reclaim fails then kswapd falls back to reclaiming for * order-0. If that happens, kswapd will consider sleeping * for the order it finished reclaiming at (reclaim_order) * but kcompactd is woken to compact for the original * request (alloc_order). */ trace_mm_vmscan_kswapd_wake(pgdat->node_id, classzone_idx, alloc_order); reclaim_order = balance_pgdat(pgdat, alloc_order, classzone_idx); if (reclaim_order < alloc_order) goto kswapd_try_sleep; } tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD); current->reclaim_state = NULL; return 0; } /* * A zone is low on free memory or too fragmented for high-order memory. If * kswapd should reclaim (direct reclaim is deferred), wake it up for the zone's * pgdat. It will wake up kcompactd after reclaiming memory. If kswapd reclaim * has failed or is not needed, still wake up kcompactd if only compaction is * needed. */ void wakeup_kswapd(struct zone *zone, gfp_t gfp_flags, int order, enum zone_type classzone_idx) { pg_data_t *pgdat; enum zone_type curr_idx; if (!managed_zone(zone)) return; if (!cpuset_zone_allowed(zone, gfp_flags)) return; pgdat = zone->zone_pgdat; curr_idx = READ_ONCE(pgdat->kswapd_classzone_idx); if (curr_idx == MAX_NR_ZONES || curr_idx < classzone_idx) WRITE_ONCE(pgdat->kswapd_classzone_idx, classzone_idx); if (READ_ONCE(pgdat->kswapd_order) < order) WRITE_ONCE(pgdat->kswapd_order, order); if (!waitqueue_active(&pgdat->kswapd_wait)) return; /* Hopeless node, leave it to direct reclaim if possible */ if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES || (pgdat_balanced(pgdat, order, classzone_idx) && !pgdat_watermark_boosted(pgdat, classzone_idx))) { /* * There may be plenty of free memory available, but it's too * fragmented for high-order allocations. Wake up kcompactd * and rely on compaction_suitable() to determine if it's * needed. If it fails, it will defer subsequent attempts to * ratelimit its work. */ if (!(gfp_flags & __GFP_DIRECT_RECLAIM)) wakeup_kcompactd(pgdat, order, classzone_idx); return; } trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, classzone_idx, order, gfp_flags); wake_up_interruptible(&pgdat->kswapd_wait); } #ifdef CONFIG_HIBERNATION /* * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of * freed pages. * * Rather than trying to age LRUs the aim is to preserve the overall * LRU order by reclaiming preferentially * inactive > active > active referenced > active mapped */ unsigned long shrink_all_memory(unsigned long nr_to_reclaim) { struct reclaim_state reclaim_state = {}; struct scan_control sc = { .nr_to_reclaim = nr_to_reclaim, .gfp_mask = GFP_HIGHUSER_MOVABLE, .reclaim_idx = MAX_NR_ZONES - 1, .priority = DEF_PRIORITY, .may_writepage = 1, .may_unmap = 1, .may_swap = 1, .hibernation_mode = 1, }; struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); struct task_struct *p = current; unsigned long nr_reclaimed; unsigned int noreclaim_flag; fs_reclaim_acquire(sc.gfp_mask); noreclaim_flag = memalloc_noreclaim_save(); reclaim_state.reclaimed_slab = 0; p->reclaim_state = &reclaim_state; nr_reclaimed = do_try_to_free_pages(zonelist, &sc); p->reclaim_state = NULL; memalloc_noreclaim_restore(noreclaim_flag); fs_reclaim_release(sc.gfp_mask); return nr_reclaimed; } #endif /* CONFIG_HIBERNATION */ /* It's optimal to keep kswapds on the same CPUs as their memory, but not required for correctness. So if the last cpu in a node goes away, we get changed to run anywhere: as the first one comes back, restore their cpu bindings. */ static int kswapd_cpu_online(unsigned int cpu) { #if defined(OPLUS_FEATURE_MULTI_KSWAPD) && defined(CONFIG_OPLUS_MULTI_KSWAPD) return kswapd_cpu_online_ext(cpu); #else int nid, hid; int nr_threads = kswapd_threads_current; for_each_node_state(nid, N_MEMORY) { pg_data_t *pgdat = NODE_DATA(nid); const struct cpumask *mask; mask = cpumask_of_node(pgdat->node_id); if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) { for (hid = 0; hid < nr_threads; hid++) { /* One of our CPUs online: restore mask */ set_cpus_allowed_ptr(pgdat->kswapd[hid], mask); } } } return 0; #endif } /* * This kswapd start function will be called by init and node-hot-add. * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. */ int kswapd_run(int nid) { #if defined(OPLUS_FEATURE_MULTI_KSWAPD) && defined(CONFIG_OPLUS_MULTI_KSWAPD) return kswapd_run_ext(nid); #else pg_data_t *pgdat = NODE_DATA(nid); int ret = 0; int hid, nr_threads; if (pgdat->kswapd[0]) return 0; nr_threads = kswapd_threads; for (hid = 0; hid < nr_threads; hid++) { pgdat->kswapd[hid] = kthread_run(kswapd, pgdat, "kswapd%d:%d", nid, hid); if (IS_ERR(pgdat->kswapd[hid])) { /* failure at boot is fatal */ BUG_ON(system_state < SYSTEM_RUNNING); pr_err("Failed to start kswapd%d on node %d\n", hid, nid); ret = PTR_ERR(pgdat->kswapd[hid]); pgdat->kswapd[hid] = NULL; } } kswapd_threads_current = nr_threads; return ret; #endif } /* * Called by memory hotplug when all memory in a node is offlined. Caller must * hold mem_hotplug_begin/end(). */ void kswapd_stop(int nid) { #if defined(OPLUS_FEATURE_MULTI_KSWAPD) && defined(CONFIG_OPLUS_MULTI_KSWAPD) return kswapd_stop_ext(nid); #else struct task_struct *kswapd; int hid; int nr_threads = kswapd_threads_current; for (hid = 0; hid < nr_threads; hid++) { kswapd = NODE_DATA(nid)->kswapd[hid]; if (kswapd) { kthread_stop(kswapd); NODE_DATA(nid)->kswapd[hid] = NULL; } } #endif } static int __init kswapd_init(void) { int nid, ret; swap_setup(); for_each_node_state(nid, N_MEMORY) kswapd_run(nid); ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "mm/vmscan:online", kswapd_cpu_online, NULL); WARN_ON(ret < 0); return 0; } module_init(kswapd_init) #ifdef CONFIG_NUMA /* * Node reclaim mode * * If non-zero call node_reclaim when the number of free pages falls below * the watermarks. */ int node_reclaim_mode __read_mostly; #define RECLAIM_OFF 0 #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ #define RECLAIM_UNMAP (1<<2) /* Unmap pages during reclaim */ /* * Priority for NODE_RECLAIM. This determines the fraction of pages * of a node considered for each zone_reclaim. 4 scans 1/16th of * a zone. */ #define NODE_RECLAIM_PRIORITY 4 /* * Percentage of pages in a zone that must be unmapped for node_reclaim to * occur. */ int sysctl_min_unmapped_ratio = 1; /* * If the number of slab pages in a zone grows beyond this percentage then * slab reclaim needs to occur. */ int sysctl_min_slab_ratio = 5; static inline unsigned long node_unmapped_file_pages(struct pglist_data *pgdat) { unsigned long file_mapped = node_page_state(pgdat, NR_FILE_MAPPED); unsigned long file_lru = node_page_state(pgdat, NR_INACTIVE_FILE) + node_page_state(pgdat, NR_ACTIVE_FILE); /* * It's possible for there to be more file mapped pages than * accounted for by the pages on the file LRU lists because * tmpfs pages accounted for as ANON can also be FILE_MAPPED */ return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; } /* Work out how many page cache pages we can reclaim in this reclaim_mode */ static unsigned long node_pagecache_reclaimable(struct pglist_data *pgdat) { unsigned long nr_pagecache_reclaimable; unsigned long delta = 0; /* * If RECLAIM_UNMAP is set, then all file pages are considered * potentially reclaimable. Otherwise, we have to worry about * pages like swapcache and node_unmapped_file_pages() provides * a better estimate */ if (node_reclaim_mode & RECLAIM_UNMAP) nr_pagecache_reclaimable = node_page_state(pgdat, NR_FILE_PAGES); else nr_pagecache_reclaimable = node_unmapped_file_pages(pgdat); /* If we can't clean pages, remove dirty pages from consideration */ if (!(node_reclaim_mode & RECLAIM_WRITE)) delta += node_page_state(pgdat, NR_FILE_DIRTY); /* Watch for any possible underflows due to delta */ if (unlikely(delta > nr_pagecache_reclaimable)) delta = nr_pagecache_reclaimable; return nr_pagecache_reclaimable - delta; } /* * Try to free up some pages from this node through reclaim. */ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) { /* Minimum pages needed in order to stay on node */ const unsigned long nr_pages = 1 << order; struct task_struct *p = current; struct reclaim_state reclaim_state = {}; unsigned int noreclaim_flag; struct scan_control sc = { .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), .gfp_mask = current_gfp_context(gfp_mask), .order = order, .priority = NODE_RECLAIM_PRIORITY, .may_writepage = !!(node_reclaim_mode & RECLAIM_WRITE), .may_unmap = !!(node_reclaim_mode & RECLAIM_UNMAP), .may_swap = 1, .reclaim_idx = gfp_zone(gfp_mask), }; cond_resched(); fs_reclaim_acquire(sc.gfp_mask); /* * We need to be able to allocate from the reserves for RECLAIM_UNMAP * and we also need to be able to write out pages for RECLAIM_WRITE * and RECLAIM_UNMAP. */ noreclaim_flag = memalloc_noreclaim_save(); p->flags |= PF_SWAPWRITE; reclaim_state.reclaimed_slab = 0; p->reclaim_state = &reclaim_state; if (node_pagecache_reclaimable(pgdat) > pgdat->min_unmapped_pages) { /* * Free memory by calling shrink node with increasing * priorities until we have enough memory freed. */ do { shrink_node(pgdat, &sc); } while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0); } p->reclaim_state = NULL; current->flags &= ~PF_SWAPWRITE; memalloc_noreclaim_restore(noreclaim_flag); fs_reclaim_release(sc.gfp_mask); return sc.nr_reclaimed >= nr_pages; } int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) { int ret; /* * Node reclaim reclaims unmapped file backed pages and * slab pages if we are over the defined limits. * * A small portion of unmapped file backed pages is needed for * file I/O otherwise pages read by file I/O will be immediately * thrown out if the node is overallocated. So we do not reclaim * if less than a specified percentage of the node is used by * unmapped file backed pages. */ if (node_pagecache_reclaimable(pgdat) <= pgdat->min_unmapped_pages && node_page_state(pgdat, NR_SLAB_RECLAIMABLE) <= pgdat->min_slab_pages) return NODE_RECLAIM_FULL; /* * Do not scan if the allocation should not be delayed. */ if (!gfpflags_allow_blocking(gfp_mask) || (current->flags & PF_MEMALLOC)) return NODE_RECLAIM_NOSCAN; /* * Only run node reclaim on the local node or on nodes that do not * have associated processors. This will favor the local processor * over remote processors and spread off node memory allocations * as wide as possible. */ if (node_state(pgdat->node_id, N_CPU) && pgdat->node_id != numa_node_id()) return NODE_RECLAIM_NOSCAN; if (test_and_set_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags)) return NODE_RECLAIM_NOSCAN; ret = __node_reclaim(pgdat, gfp_mask, order); clear_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags); if (!ret) count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); return ret; } #endif /* * page_evictable - test whether a page is evictable * @page: the page to test * * Test whether page is evictable--i.e., should be placed on active/inactive * lists vs unevictable list. * * Reasons page might not be evictable: * (1) page's mapping marked unevictable * (2) page is part of an mlocked VMA * */ int page_evictable(struct page *page) { int ret; /* Prevent address_space of inode and swap cache from being freed */ rcu_read_lock(); ret = !mapping_unevictable(page_mapping(page)) && !PageMlocked(page); rcu_read_unlock(); return ret; } #ifdef CONFIG_SHMEM /** * check_move_unevictable_pages - check pages for evictability and move to appropriate zone lru list * @pages: array of pages to check * @nr_pages: number of pages to check * * Checks pages for evictability and moves them to the appropriate lru list. * * This function is only used for SysV IPC SHM_UNLOCK. */ void check_move_unevictable_pages(struct page **pages, int nr_pages) { struct lruvec *lruvec; struct pglist_data *pgdat = NULL; int pgscanned = 0; int pgrescued = 0; int i; for (i = 0; i < nr_pages; i++) { struct page *page = pages[i]; struct pglist_data *pagepgdat = page_pgdat(page); pgscanned++; if (pagepgdat != pgdat) { if (pgdat) spin_unlock_irq(&pgdat->lru_lock); pgdat = pagepgdat; spin_lock_irq(&pgdat->lru_lock); } lruvec = mem_cgroup_page_lruvec(page, pgdat); if (!PageLRU(page) || !PageUnevictable(page)) continue; if (page_evictable(page)) { del_page_from_lru_list(page, lruvec); ClearPageUnevictable(page); add_page_to_lru_list(page, lruvec); pgrescued++; } } if (pgdat) { __count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued); __count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned); spin_unlock_irq(&pgdat->lru_lock); } } #endif /* CONFIG_SHMEM */ #ifdef CONFIG_HYBRIDSWAP_SWAPD #define PARA_BUF_LEN 128 static inline bool debug_get_val(char *buf, char *token, unsigned long *val) { int ret = -EINVAL; char *str = strstr(buf, token); if (!str) return ret; ret = kstrtoul(str + strlen(token), 0, val); if (ret) return -EINVAL; if (*val > 200) { pr_err("%lu is invalid\n", *val); return -EINVAL; } return 0; } static ssize_t swappiness_para_write(struct file *file, const char __user *buff, size_t len, loff_t *ppos) { char kbuf[PARA_BUF_LEN] = {'0'}; char *str; long val; if (len > PARA_BUF_LEN - 1) { pr_err("len %d is too long\n", len); return -EINVAL; } if (copy_from_user(&kbuf, buff, len)) return -EFAULT; kbuf[len] = '\0'; str = strstrip(kbuf); if (!str) { pr_err("buff %s is invalid\n", kbuf); return -EINVAL; } if (!debug_get_val(str, "vm_swappiness=", &val)) { vm_swappiness = val; return len; } if (!debug_get_val(str, "direct_swappiness=", &val)) { direct_vm_swappiness = val; return len; } if (!debug_get_val(str, "swapd_swappiness=", &val)) { hybridswapd_swappiness = val; return len; } return -EINVAL; } static ssize_t swappiness_para_read(struct file *file, char __user *buffer, size_t count, loff_t *off) { char kbuf[PARA_BUF_LEN] = {'0'}; int len; len = snprintf(kbuf, PARA_BUF_LEN, "vm_swappiness: %d\n", vm_swappiness); len += snprintf(kbuf + len, PARA_BUF_LEN - len, "direct_swappiness: %d\n", direct_vm_swappiness); len += snprintf(kbuf + len, PARA_BUF_LEN - len, "swapd_swappiness: %d\n", hybridswapd_swappiness); if (len == PARA_BUF_LEN) kbuf[len - 1] = '\0'; if (len > *off) len -= *off; else len = 0; if (copy_to_user(buffer, kbuf + *off, (len < count ? len : count))) return -EFAULT; *off += (len < count ? len : count); return (len < count ? len : count); } static const struct file_operations proc_swappiness_para_ops = { .write = swappiness_para_write, .read = swappiness_para_read, }; int create_swappiness_para_proc(void) { struct proc_dir_entry * para_entry = proc_create("oplus_healthinfo/swappiness_para", S_IRUSR|S_IWUSR, NULL, &proc_swappiness_para_ops); if (para_entry) { printk("Register swappiness_para interface passed.\n"); return 0; } pr_err("Register swappiness_para interface failed.\n"); return -ENOMEM; } EXPORT_SYMBOL(create_swappiness_para_proc); #endif