1 files changed, 205 insertions, 130 deletions

diff --git a/mm/workingset.c b/mm/workingset.c
index 1a86645b7b3c..e9f05634747a 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -16,6 +16,7 @@
 #include <linux/dax.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
+#include "internal.h"
 
 /*
  *		Double CLOCK lists
@@ -111,9 +112,20 @@
  *
  *   NR_inactive + (R - E) <= NR_inactive + NR_active
  *
- * which can be further simplified to
+ * If we have swap we should consider about NR_inactive_anon and
+ * NR_active_anon, so for page cache and anonymous respectively:
  *
- *   (R - E) <= NR_active
+ *   NR_inactive_file + (R - E) <= NR_inactive_file + NR_active_file
+ *   + NR_inactive_anon + NR_active_anon
+ *
+ *   NR_inactive_anon + (R - E) <= NR_inactive_anon + NR_active_anon
+ *   + NR_inactive_file + NR_active_file
+ *
+ * Which can be further simplified to:
+ *
+ *   (R - E) <= NR_active_file + NR_inactive_anon + NR_active_anon
+ *
+ *   (R - E) <= NR_active_anon + NR_inactive_file + NR_active_file
  *
  * Put into words, the refault distance (out-of-cache) can be seen as
  * a deficit in inactive list space (in-cache).  If the inactive list
@@ -130,14 +142,14 @@
  * are no longer in active use.
  *
  * So when a refault distance of (R - E) is observed and there are at
- * least (R - E) active pages, the refaulting page is activated
- * optimistically in the hope that (R - E) active pages are actually
+ * least (R - E) pages in the userspace workingset, the refaulting page
+ * is activated optimistically in the hope that (R - E) pages are actually
  * used less frequently than the refaulting page - or even not used at
  * all anymore.
  *
  * That means if inactive cache is refaulting with a suitable refault
  * distance, we assume the cache workingset is transitioning and put
- * pressure on the current active list.
+ * pressure on the current workingset.
  *
  * If this is wrong and demotion kicks in, the pages which are truly
  * used more frequently will be reactivated while the less frequently
@@ -223,11 +235,12 @@ static void *lru_gen_eviction(struct folio *folio)
 	unsigned long token;
 	unsigned long min_seq;
 	struct lruvec *lruvec;
-	struct lru_gen_struct *lrugen;
+	struct lru_gen_folio *lrugen;
 	int type = folio_is_file_lru(folio);
 	int delta = folio_nr_pages(folio);
 	int refs = folio_lru_refs(folio);
-	int tier = lru_tier_from_refs(refs);
+	bool workingset = folio_test_workingset(folio);
+	int tier = lru_tier_from_refs(refs, workingset);
 	struct mem_cgroup *memcg = folio_memcg(folio);
 	struct pglist_data *pgdat = folio_pgdat(folio);
 
@@ -241,60 +254,71 @@ static void *lru_gen_eviction(struct folio *folio)
 	hist = lru_hist_from_seq(min_seq);
 	atomic_long_add(delta, &lrugen->evicted[hist][type][tier]);
 
-	return pack_shadow(mem_cgroup_id(memcg), pgdat, token, refs);
+	return pack_shadow(mem_cgroup_id(memcg), pgdat, token, workingset);
+}
+
+/*
+ * Tests if the shadow entry is for a folio that was recently evicted.
+ * Fills in @lruvec, @token, @workingset with the values unpacked from shadow.
+ */
+static bool lru_gen_test_recent(void *shadow, struct lruvec **lruvec,
+				unsigned long *token, bool *workingset)
+{
+	int memcg_id;
+	unsigned long max_seq;
+	struct mem_cgroup *memcg;
+	struct pglist_data *pgdat;
+
+	unpack_shadow(shadow, &memcg_id, &pgdat, token, workingset);
+
+	memcg = mem_cgroup_from_id(memcg_id);
+	*lruvec = mem_cgroup_lruvec(memcg, pgdat);
+
+	max_seq = READ_ONCE((*lruvec)->lrugen.max_seq);
+	max_seq &= EVICTION_MASK >> LRU_REFS_WIDTH;
+
+	return abs_diff(max_seq, *token >> LRU_REFS_WIDTH) < MAX_NR_GENS;
 }
 
 static void lru_gen_refault(struct folio *folio, void *shadow)
 {
+	bool recent;
 	int hist, tier, refs;
-	int memcg_id;
 	bool workingset;
 	unsigned long token;
-	unsigned long min_seq;
 	struct lruvec *lruvec;
-	struct lru_gen_struct *lrugen;
-	struct mem_cgroup *memcg;
-	struct pglist_data *pgdat;
+	struct lru_gen_folio *lrugen;
 	int type = folio_is_file_lru(folio);
 	int delta = folio_nr_pages(folio);
 
-	unpack_shadow(shadow, &memcg_id, &pgdat, &token, &workingset);
-
-	if (pgdat != folio_pgdat(folio))
-		return;
-
 	rcu_read_lock();
 
-	memcg = folio_memcg_rcu(folio);
-	if (memcg_id != mem_cgroup_id(memcg))
+	recent = lru_gen_test_recent(shadow, &lruvec, &token, &workingset);
+	if (lruvec != folio_lruvec(folio))
 		goto unlock;
 
-	lruvec = mem_cgroup_lruvec(memcg, pgdat);
-	lrugen = &lruvec->lrugen;
+	mod_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + type, delta);
 
-	min_seq = READ_ONCE(lrugen->min_seq[type]);
-	if ((token >> LRU_REFS_WIDTH) != (min_seq & (EVICTION_MASK >> LRU_REFS_WIDTH)))
+	if (!recent)
 		goto unlock;
 
-	hist = lru_hist_from_seq(min_seq);
-	/* see the comment in folio_lru_refs() */
-	refs = (token & (BIT(LRU_REFS_WIDTH) - 1)) + workingset;
-	tier = lru_tier_from_refs(refs);
+	lrugen = &lruvec->lrugen;
+
+	hist = lru_hist_from_seq(READ_ONCE(lrugen->min_seq[type]));
+	refs = (token & (BIT(LRU_REFS_WIDTH) - 1)) + 1;
+	tier = lru_tier_from_refs(refs, workingset);
 
 	atomic_long_add(delta, &lrugen->refaulted[hist][type][tier]);
-	mod_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + type, delta);
 
-	/*
-	 * Count the following two cases as stalls:
-	 * 1. For pages accessed through page tables, hotter pages pushed out
-	 *    hot pages which refaulted immediately.
-	 * 2. For pages accessed multiple times through file descriptors,
-	 *    numbers of accesses might have been out of the range.
-	 */
-	if (lru_gen_in_fault() || refs == BIT(LRU_REFS_WIDTH)) {
+	/* see folio_add_lru() where folio_set_active() will be called */
+	if (lru_gen_in_fault())
+		mod_lruvec_state(lruvec, WORKINGSET_ACTIVATE_BASE + type, delta);
+
+	if (workingset) {
 		folio_set_workingset(folio);
 		mod_lruvec_state(lruvec, WORKINGSET_RESTORE_BASE + type, delta);
-	}
+	} else
+		set_mask_bits(&folio->flags.f, LRU_REFS_MASK, (refs - 1UL) << LRU_REFS_PGOFF);
 unlock:
 	rcu_read_unlock();
 }
@@ -306,6 +330,12 @@ static void *lru_gen_eviction(struct folio *folio)
 	return NULL;
 }
 
+static bool lru_gen_test_recent(void *shadow, struct lruvec **lruvec,
+				unsigned long *token, bool *workingset)
+{
+	return false;
+}
+
 static void lru_gen_refault(struct folio *folio, void *shadow)
 {
 }
@@ -374,39 +404,42 @@ void *workingset_eviction(struct folio *folio, struct mem_cgroup *target_memcg)
 }
 
 /**
- * workingset_refault - Evaluate the refault of a previously evicted folio.
- * @folio: The freshly allocated replacement folio.
- * @shadow: Shadow entry of the evicted folio.
- *
- * Calculates and evaluates the refault distance of the previously
- * evicted folio in the context of the node and the memcg whose memory
- * pressure caused the eviction.
+ * workingset_test_recent - tests if the shadow entry is for a folio that was
+ * recently evicted. Also fills in @workingset with the value unpacked from
+ * shadow.
+ * @shadow: the shadow entry to be tested.
+ * @file: whether the corresponding folio is from the file lru.
+ * @workingset: where the workingset value unpacked from shadow should
+ * be stored.
+ * @flush: whether to flush cgroup rstat.
+ *
+ * Return: true if the shadow is for a recently evicted folio; false otherwise.
  */
-void workingset_refault(struct folio *folio, void *shadow)
+bool workingset_test_recent(void *shadow, bool file, bool *workingset,
+				bool flush)
 {
-	bool file = folio_is_file_lru(folio);
 	struct mem_cgroup *eviction_memcg;
 	struct lruvec *eviction_lruvec;
 	unsigned long refault_distance;
 	unsigned long workingset_size;
-	struct pglist_data *pgdat;
-	struct mem_cgroup *memcg;
-	unsigned long eviction;
-	struct lruvec *lruvec;
 	unsigned long refault;
-	bool workingset;
 	int memcgid;
-	long nr;
+	struct pglist_data *pgdat;
+	unsigned long eviction;
 
 	if (lru_gen_enabled()) {
-		lru_gen_refault(folio, shadow);
-		return;
+		bool recent;
+
+		rcu_read_lock();
+		recent = lru_gen_test_recent(shadow, &eviction_lruvec, &eviction, workingset);
+		rcu_read_unlock();
+		return recent;
 	}
 
-	unpack_shadow(shadow, &memcgid, &pgdat, &eviction, &workingset);
+	rcu_read_lock();
+	unpack_shadow(shadow, &memcgid, &pgdat, &eviction, workingset);
 	eviction <<= bucket_order;
 
-	rcu_read_lock();
 	/*
 	 * Look up the memcg associated with the stored ID. It might
 	 * have been deleted since the folio's eviction.
@@ -424,8 +457,25 @@ void workingset_refault(struct folio *folio, void *shadow)
 	 * configurations instead.
 	 */
 	eviction_memcg = mem_cgroup_from_id(memcgid);
+	if (!mem_cgroup_tryget(eviction_memcg))
+		eviction_memcg = NULL;
+	rcu_read_unlock();
+
 	if (!mem_cgroup_disabled() && !eviction_memcg)
-		goto out;
+		return false;
+	/*
+	 * Flush stats (and potentially sleep) outside the RCU read section.
+	 *
+	 * Note that workingset_test_recent() itself might be called in RCU read
+	 * section (for e.g, in cachestat) - these callers need to skip flushing
+	 * stats (via the flush argument).
+	 *
+	 * XXX: With per-memcg flushing and thresholding, is ratelimiting
+	 * still needed here?
+	 */
+	if (flush)
+		mem_cgroup_flush_stats_ratelimited(eviction_memcg);
+
 	eviction_lruvec = mem_cgroup_lruvec(eviction_memcg, pgdat);
 	refault = atomic_long_read(&eviction_lruvec->nonresident_age);
 
@@ -448,33 +498,18 @@ void workingset_refault(struct folio *folio, void *shadow)
 	refault_distance = (refault - eviction) & EVICTION_MASK;
 
 	/*
-	 * The activation decision for this folio is made at the level
-	 * where the eviction occurred, as that is where the LRU order
-	 * during folio reclaim is being determined.
-	 *
-	 * However, the cgroup that will own the folio is the one that
-	 * is actually experiencing the refault event.
-	 */
-	nr = folio_nr_pages(folio);
-	memcg = folio_memcg(folio);
-	lruvec = mem_cgroup_lruvec(memcg, pgdat);
-
-	mod_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + file, nr);
-
-	mem_cgroup_flush_stats_delayed();
-	/*
 	 * Compare the distance to the existing workingset size. We
 	 * don't activate pages that couldn't stay resident even if
 	 * all the memory was available to the workingset. Whether
 	 * workingset competition needs to consider anon or not depends
-	 * on having swap.
+	 * on having free swap space.
 	 */
 	workingset_size = lruvec_page_state(eviction_lruvec, NR_ACTIVE_FILE);
 	if (!file) {
 		workingset_size += lruvec_page_state(eviction_lruvec,
 						     NR_INACTIVE_FILE);
 	}
-	if (mem_cgroup_get_nr_swap_pages(memcg) > 0) {
+	if (mem_cgroup_get_nr_swap_pages(eviction_memcg) > 0) {
 		workingset_size += lruvec_page_state(eviction_lruvec,
 						     NR_ACTIVE_ANON);
 		if (file) {
@@ -482,8 +517,54 @@ void workingset_refault(struct folio *folio, void *shadow)
 						     NR_INACTIVE_ANON);
 		}
 	}
-	if (refault_distance > workingset_size)
-		goto out;
+
+	mem_cgroup_put(eviction_memcg);
+	return refault_distance <= workingset_size;
+}
+
+/**
+ * workingset_refault - Evaluate the refault of a previously evicted folio.
+ * @folio: The freshly allocated replacement folio.
+ * @shadow: Shadow entry of the evicted folio.
+ *
+ * Calculates and evaluates the refault distance of the previously
+ * evicted folio in the context of the node and the memcg whose memory
+ * pressure caused the eviction.
+ */
+void workingset_refault(struct folio *folio, void *shadow)
+{
+	bool file = folio_is_file_lru(folio);
+	struct pglist_data *pgdat;
+	struct mem_cgroup *memcg;
+	struct lruvec *lruvec;
+	bool workingset;
+	long nr;
+
+	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
+
+	if (lru_gen_enabled()) {
+		lru_gen_refault(folio, shadow);
+		return;
+	}
+
+	/*
+	 * The activation decision for this folio is made at the level
+	 * where the eviction occurred, as that is where the LRU order
+	 * during folio reclaim is being determined.
+	 *
+	 * However, the cgroup that will own the folio is the one that
+	 * is actually experiencing the refault event. Make sure the folio is
+	 * locked to guarantee folio_memcg() stability throughout.
+	 */
+	nr = folio_nr_pages(folio);
+	memcg = folio_memcg(folio);
+	pgdat = folio_pgdat(folio);
+	lruvec = mem_cgroup_lruvec(memcg, pgdat);
+
+	mod_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + file, nr);
+
+	if (!workingset_test_recent(shadow, file, &workingset, true))
+		return;
 
 	folio_set_active(folio);
 	workingset_age_nonresident(lruvec, nr);
@@ -499,8 +580,6 @@ void workingset_refault(struct folio *folio, void *shadow)
 		lru_note_cost_refault(folio);
 		mod_lruvec_state(lruvec, WORKINGSET_RESTORE_BASE + file, nr);
 	}
-out:
-	rcu_read_unlock();
 }
 
 /**
@@ -509,22 +588,12 @@ out:
  */
 void workingset_activation(struct folio *folio)
 {
-	struct mem_cgroup *memcg;
-
-	rcu_read_lock();
 	/*
 	 * Filter non-memcg pages here, e.g. unmap can call
 	 * mark_page_accessed() on VDSO pages.
-	 *
-	 * XXX: See workingset_refault() - this should return
-	 * root_mem_cgroup even for !CONFIG_MEMCG.
 	 */
-	memcg = folio_memcg_rcu(folio);
-	if (!mem_cgroup_disabled() && !memcg)
-		goto out;
-	workingset_age_nonresident(folio_lruvec(folio), folio_nr_pages(folio));
-out:
-	rcu_read_unlock();
+	if (mem_cgroup_disabled() || folio_memcg_charged(folio))
+		workingset_age_nonresident(folio_lruvec(folio), folio_nr_pages(folio));
 }
 
 /*
@@ -543,7 +612,7 @@ struct list_lru shadow_nodes;
 
 void workingset_update_node(struct xa_node *node)
 {
-	struct address_space *mapping;
+	struct page *page = virt_to_page(node);
 
 	/*
 	 * Track non-empty nodes that contain only shadow entries;
@@ -553,18 +622,17 @@ void workingset_update_node(struct xa_node *node)
 	 * already where they should be. The list_empty() test is safe
 	 * as node->private_list is protected by the i_pages lock.
 	 */
-	mapping = container_of(node->array, struct address_space, i_pages);
-	lockdep_assert_held(&mapping->i_pages.xa_lock);
+	lockdep_assert_held(&node->array->xa_lock);
 
 	if (node->count && node->count == node->nr_values) {
 		if (list_empty(&node->private_list)) {
-			list_lru_add(&shadow_nodes, &node->private_list);
-			__inc_lruvec_kmem_state(node, WORKINGSET_NODES);
+			list_lru_add_obj(&shadow_nodes, &node->private_list);
+			__inc_node_page_state(page, WORKINGSET_NODES);
 		}
 	} else {
 		if (!list_empty(&node->private_list)) {
-			list_lru_del(&shadow_nodes, &node->private_list);
-			__dec_lruvec_kmem_state(node, WORKINGSET_NODES);
+			list_lru_del_obj(&shadow_nodes, &node->private_list);
+			__dec_node_page_state(page, WORKINGSET_NODES);
 		}
 	}
 }
@@ -607,6 +675,7 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 		struct lruvec *lruvec;
 		int i;
 
+		mem_cgroup_flush_stats_ratelimited(sc->memcg);
 		lruvec = mem_cgroup_lruvec(sc->memcg, NODE_DATA(sc->nid));
 		for (pages = 0, i = 0; i < NR_LRU_LISTS; i++)
 			pages += lruvec_page_state_local(lruvec,
@@ -628,8 +697,7 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 
 static enum lru_status shadow_lru_isolate(struct list_head *item,
 					  struct list_lru_one *lru,
-					  spinlock_t *lru_lock,
-					  void *arg) __must_hold(lru_lock)
+					  void *arg) __must_hold(lru->lock)
 {
 	struct xa_node *node = container_of(item, struct xa_node, private_list);
 	struct address_space *mapping;
@@ -638,35 +706,38 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
 	/*
 	 * Page cache insertions and deletions synchronously maintain
 	 * the shadow node LRU under the i_pages lock and the
-	 * lru_lock.  Because the page cache tree is emptied before
-	 * the inode can be destroyed, holding the lru_lock pins any
+	 * &lru->lock. Because the page cache tree is emptied before
+	 * the inode can be destroyed, holding the &lru->lock pins any
 	 * address_space that has nodes on the LRU.
 	 *
 	 * We can then safely transition to the i_pages lock to
 	 * pin only the address_space of the particular node we want
-	 * to reclaim, take the node off-LRU, and drop the lru_lock.
+	 * to reclaim, take the node off-LRU, and drop the &lru->lock.
 	 */
 
 	mapping = container_of(node->array, struct address_space, i_pages);
 
 	/* Coming from the list, invert the lock order */
 	if (!xa_trylock(&mapping->i_pages)) {
-		spin_unlock_irq(lru_lock);
+		spin_unlock_irq(&lru->lock);
 		ret = LRU_RETRY;
 		goto out;
 	}
 
-	if (!spin_trylock(&mapping->host->i_lock)) {
-		xa_unlock(&mapping->i_pages);
-		spin_unlock_irq(lru_lock);
-		ret = LRU_RETRY;
-		goto out;
+	/* For page cache we need to hold i_lock */
+	if (mapping->host != NULL) {
+		if (!spin_trylock(&mapping->host->i_lock)) {
+			xa_unlock(&mapping->i_pages);
+			spin_unlock_irq(&lru->lock);
+			ret = LRU_RETRY;
+			goto out;
+		}
 	}
 
 	list_lru_isolate(lru, item);
-	__dec_lruvec_kmem_state(node, WORKINGSET_NODES);
+	__dec_node_page_state(virt_to_page(node), WORKINGSET_NODES);
 
-	spin_unlock(lru_lock);
+	spin_unlock(&lru->lock);
 
 	/*
 	 * The nodes should only contain one or more shadow entries,
@@ -678,17 +749,18 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
 	if (WARN_ON_ONCE(node->count != node->nr_values))
 		goto out_invalid;
 	xa_delete_node(node, workingset_update_node);
-	__inc_lruvec_kmem_state(node, WORKINGSET_NODERECLAIM);
+	mod_lruvec_kmem_state(node, WORKINGSET_NODERECLAIM, 1);
 
 out_invalid:
 	xa_unlock_irq(&mapping->i_pages);
-	if (mapping_shrinkable(mapping))
-		inode_add_lru(mapping->host);
-	spin_unlock(&mapping->host->i_lock);
+	if (mapping->host != NULL) {
+		if (mapping_shrinkable(mapping))
+			inode_lru_list_add(mapping->host);
+		spin_unlock(&mapping->host->i_lock);
+	}
 	ret = LRU_REMOVED_RETRY;
 out:
 	cond_resched();
-	spin_lock_irq(lru_lock);
 	return ret;
 }
 
@@ -700,13 +772,6 @@ static unsigned long scan_shadow_nodes(struct shrinker *shrinker,
 					NULL);
 }
 
-static struct shrinker workingset_shadow_shrinker = {
-	.count_objects = count_shadow_nodes,
-	.scan_objects = scan_shadow_nodes,
-	.seeks = 0, /* ->count reports only fully expendable nodes */
-	.flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE,
-};
-
 /*
  * Our list_lru->lock is IRQ-safe as it nests inside the IRQ-safe
  * i_pages lock.
@@ -715,9 +780,10 @@ static struct lock_class_key shadow_nodes_key;
 
 static int __init workingset_init(void)
 {
+	struct shrinker *workingset_shadow_shrinker;
 	unsigned int timestamp_bits;
 	unsigned int max_order;
-	int ret;
+	int ret = -ENOMEM;
 
 	BUILD_BUG_ON(BITS_PER_LONG < EVICTION_SHIFT);
 	/*
@@ -734,17 +800,26 @@ static int __init workingset_init(void)
 	pr_info("workingset: timestamp_bits=%d max_order=%d bucket_order=%u\n",
 	       timestamp_bits, max_order, bucket_order);
 
-	ret = prealloc_shrinker(&workingset_shadow_shrinker, "mm-shadow");
-	if (ret)
+	workingset_shadow_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE |
+						    SHRINKER_MEMCG_AWARE,
+						    "mm-shadow");
+	if (!workingset_shadow_shrinker)
 		goto err;
-	ret = __list_lru_init(&shadow_nodes, true, &shadow_nodes_key,
-			      &workingset_shadow_shrinker);
+
+	ret = list_lru_init_memcg_key(&shadow_nodes, workingset_shadow_shrinker,
+				      &shadow_nodes_key);
 	if (ret)
 		goto err_list_lru;
-	register_shrinker_prepared(&workingset_shadow_shrinker);
+
+	workingset_shadow_shrinker->count_objects = count_shadow_nodes;
+	workingset_shadow_shrinker->scan_objects = scan_shadow_nodes;
+	/* ->count reports only fully expendable nodes */
+	workingset_shadow_shrinker->seeks = 0;
+
+	shrinker_register(workingset_shadow_shrinker);
 	return 0;
 err_list_lru:
-	free_prealloced_shrinker(&workingset_shadow_shrinker);
+	shrinker_free(workingset_shadow_shrinker);
 err:
 	return ret;
 }