#include <linux/spinlock.h>
#include <linux/list.h>
+#include <linux/list_nulls.h>
#include <linux/wait.h>
#include <linux/bitops.h>
#include <linux/cache.h>
#define LRU_GEN_MASK ((BIT(LRU_GEN_WIDTH) - 1) << LRU_GEN_PGOFF)
#define LRU_REFS_MASK ((BIT(LRU_REFS_WIDTH) - 1) << LRU_REFS_PGOFF)
+/* see the comment on MEMCG_NR_GENS */
+enum {
+ MEMCG_LRU_NOP,
+ MEMCG_LRU_HEAD,
+ MEMCG_LRU_TAIL,
+ MEMCG_LRU_OLD,
+ MEMCG_LRU_YOUNG,
+};
+
#ifdef CONFIG_LRU_GEN
enum {
atomic_long_t refaulted[NR_HIST_GENS][ANON_AND_FILE][MAX_NR_TIERS];
/* whether the multi-gen LRU is enabled */
bool enabled;
+#ifdef CONFIG_MEMCG
+ /* the memcg generation this lru_gen_folio belongs to */
+ u8 gen;
+ /* the list segment this lru_gen_folio belongs to */
+ u8 seg;
+ /* per-node lru_gen_folio list for global reclaim */
+ struct hlist_nulls_node list;
+#endif
};
enum {
void lru_gen_look_around(struct page_vma_mapped_walk *pvmw);
#ifdef CONFIG_MEMCG
+
+/*
+ * For each node, memcgs are divided into two generations: the old and the
+ * young. For each generation, memcgs are randomly sharded into multiple bins
+ * to improve scalability. For each bin, the hlist_nulls is virtually divided
+ * into three segments: the head, the tail and the default.
+ *
+ * An onlining memcg is added to the tail of a random bin in the old generation.
+ * The eviction starts at the head of a random bin in the old generation. The
+ * per-node memcg generation counter, whose reminder (mod MEMCG_NR_GENS) indexes
+ * the old generation, is incremented when all its bins become empty.
+ *
+ * There are four operations:
+ * 1. MEMCG_LRU_HEAD, which moves an memcg to the head of a random bin in its
+ * current generation (old or young) and updates its "seg" to "head";
+ * 2. MEMCG_LRU_TAIL, which moves an memcg to the tail of a random bin in its
+ * current generation (old or young) and updates its "seg" to "tail";
+ * 3. MEMCG_LRU_OLD, which moves an memcg to the head of a random bin in the old
+ * generation, updates its "gen" to "old" and resets its "seg" to "default";
+ * 4. MEMCG_LRU_YOUNG, which moves an memcg to the tail of a random bin in the
+ * young generation, updates its "gen" to "young" and resets its "seg" to
+ * "default".
+ *
+ * The events that trigger the above operations are:
+ * 1. Exceeding the soft limit, which triggers MEMCG_LRU_HEAD;
+ * 2. The first attempt to reclaim an memcg below low, which triggers
+ * MEMCG_LRU_TAIL;
+ * 3. The first attempt to reclaim an memcg below reclaimable size threshold,
+ * which triggers MEMCG_LRU_TAIL;
+ * 4. The second attempt to reclaim an memcg below reclaimable size threshold,
+ * which triggers MEMCG_LRU_YOUNG;
+ * 5. Attempting to reclaim an memcg below min, which triggers MEMCG_LRU_YOUNG;
+ * 6. Finishing the aging on the eviction path, which triggers MEMCG_LRU_YOUNG;
+ * 7. Offlining an memcg, which triggers MEMCG_LRU_OLD.
+ *
+ * Note that memcg LRU only applies to global reclaim, and the round-robin
+ * incrementing of their max_seq counters ensures the eventual fairness to all
+ * eligible memcgs. For memcg reclaim, it still relies on mem_cgroup_iter().
+ */
+#define MEMCG_NR_GENS 2
+#define MEMCG_NR_BINS 8
+
+struct lru_gen_memcg {
+ /* the per-node memcg generation counter */
+ unsigned long seq;
+ /* each memcg has one lru_gen_folio per node */
+ unsigned long nr_memcgs[MEMCG_NR_GENS];
+ /* per-node lru_gen_folio list for global reclaim */
+ struct hlist_nulls_head fifo[MEMCG_NR_GENS][MEMCG_NR_BINS];
+ /* protects the above */
+ spinlock_t lock;
+};
+
+void lru_gen_init_pgdat(struct pglist_data *pgdat);
+
void lru_gen_init_memcg(struct mem_cgroup *memcg);
void lru_gen_exit_memcg(struct mem_cgroup *memcg);
-#endif
+void lru_gen_online_memcg(struct mem_cgroup *memcg);
+void lru_gen_offline_memcg(struct mem_cgroup *memcg);
+void lru_gen_release_memcg(struct mem_cgroup *memcg);
+void lru_gen_rotate_memcg(struct lruvec *lruvec, int op);
+
+#else /* !CONFIG_MEMCG */
+
+#define MEMCG_NR_GENS 1
+
+struct lru_gen_memcg {
+};
+
+static inline void lru_gen_init_pgdat(struct pglist_data *pgdat)
+{
+}
+
+#endif /* CONFIG_MEMCG */
#else /* !CONFIG_LRU_GEN */
+static inline void lru_gen_init_pgdat(struct pglist_data *pgdat)
+{
+}
+
static inline void lru_gen_init_lruvec(struct lruvec *lruvec)
{
}
}
#ifdef CONFIG_MEMCG
+
static inline void lru_gen_init_memcg(struct mem_cgroup *memcg)
{
}
static inline void lru_gen_exit_memcg(struct mem_cgroup *memcg)
{
}
-#endif
+
+static inline void lru_gen_online_memcg(struct mem_cgroup *memcg)
+{
+}
+
+static inline void lru_gen_offline_memcg(struct mem_cgroup *memcg)
+{
+}
+
+static inline void lru_gen_release_memcg(struct mem_cgroup *memcg)
+{
+}
+
+static inline void lru_gen_rotate_memcg(struct lruvec *lruvec, int op)
+{
+}
+
+#endif /* CONFIG_MEMCG */
#endif /* CONFIG_LRU_GEN */
#ifdef CONFIG_LRU_GEN
/* kswap mm walk data */
struct lru_gen_mm_walk mm_walk;
+ /* lru_gen_folio list */
+ struct lru_gen_memcg memcg_lru;
#endif
CACHELINE_PADDING(_pad2_);
#include <linux/ctype.h>
#include <linux/debugfs.h>
#include <linux/khugepaged.h>
+#include <linux/rculist_nulls.h>
+#include <linux/random.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
/* Always discard instead of demoting to lower tier memory */
unsigned int no_demotion:1;
-#ifdef CONFIG_LRU_GEN
- /* help kswapd make better choices among multiple memcgs */
- unsigned long last_reclaimed;
-#endif
-
/* Allocation order */
s8 order;
for ((type) = 0; (type) < ANON_AND_FILE; (type)++) \
for ((zone) = 0; (zone) < MAX_NR_ZONES; (zone)++)
+#define get_memcg_gen(seq) ((seq) % MEMCG_NR_GENS)
+#define get_memcg_bin(bin) ((bin) % MEMCG_NR_BINS)
+
static struct lruvec *get_lruvec(struct mem_cgroup *memcg, int nid)
{
struct pglist_data *pgdat = NODE_DATA(nid);
if (sc->priority <= DEF_PRIORITY - 2)
wait_event_killable(lruvec->mm_state.wait,
max_seq < READ_ONCE(lrugen->max_seq));
-
- return max_seq < READ_ONCE(lrugen->max_seq);
+ return false;
}
VM_WARN_ON_ONCE(max_seq != READ_ONCE(lrugen->max_seq));
VM_WARN_ON_ONCE(!current_is_kswapd());
- sc->last_reclaimed = sc->nr_reclaimed;
-
/* check the order to exclude compaction-induced reclaim */
if (!min_ttl || sc->order || sc->priority == DEF_PRIORITY)
return;
* 1. Defer try_to_inc_max_seq() to workqueues to reduce latency for memcg
* reclaim.
*/
-static unsigned long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc,
- bool can_swap)
+static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc, bool can_swap)
{
unsigned long nr_to_scan;
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
if (sc->priority == DEF_PRIORITY)
return nr_to_scan;
- try_to_inc_max_seq(lruvec, max_seq, sc, can_swap, false);
-
/* skip this lruvec as it's low on cold folios */
- return 0;
+ return try_to_inc_max_seq(lruvec, max_seq, sc, can_swap, false) ? -1 : 0;
}
static unsigned long get_nr_to_reclaim(struct scan_control *sc)
if (!global_reclaim(sc))
return -1;
- /* discount the previous progress for kswapd */
- if (current_is_kswapd())
- return sc->nr_to_reclaim + sc->last_reclaimed;
-
return max(sc->nr_to_reclaim, compact_gap(sc->order));
}
-static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
+static bool try_to_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
{
- struct blk_plug plug;
+ long nr_to_scan;
unsigned long scanned = 0;
unsigned long nr_to_reclaim = get_nr_to_reclaim(sc);
- lru_add_drain();
-
- blk_start_plug(&plug);
-
- set_mm_walk(lruvec_pgdat(lruvec));
-
while (true) {
int delta;
int swappiness;
- unsigned long nr_to_scan;
if (sc->may_swap)
swappiness = get_swappiness(lruvec, sc);
swappiness = 0;
nr_to_scan = get_nr_to_scan(lruvec, sc, swappiness);
- if (!nr_to_scan)
+ if (nr_to_scan <= 0)
break;
delta = evict_folios(lruvec, sc, swappiness);
cond_resched();
}
+ /* whether try_to_inc_max_seq() was successful */
+ return nr_to_scan < 0;
+}
+
+static int shrink_one(struct lruvec *lruvec, struct scan_control *sc)
+{
+ bool success;
+ unsigned long scanned = sc->nr_scanned;
+ unsigned long reclaimed = sc->nr_reclaimed;
+ int seg = lru_gen_memcg_seg(lruvec);
+ struct mem_cgroup *memcg = lruvec_memcg(lruvec);
+ struct pglist_data *pgdat = lruvec_pgdat(lruvec);
+
+ /* see the comment on MEMCG_NR_GENS */
+ if (!lruvec_is_sizable(lruvec, sc))
+ return seg != MEMCG_LRU_TAIL ? MEMCG_LRU_TAIL : MEMCG_LRU_YOUNG;
+
+ mem_cgroup_calculate_protection(NULL, memcg);
+
+ if (mem_cgroup_below_min(NULL, memcg))
+ return MEMCG_LRU_YOUNG;
+
+ if (mem_cgroup_below_low(NULL, memcg)) {
+ /* see the comment on MEMCG_NR_GENS */
+ if (seg != MEMCG_LRU_TAIL)
+ return MEMCG_LRU_TAIL;
+
+ memcg_memory_event(memcg, MEMCG_LOW);
+ }
+
+ success = try_to_shrink_lruvec(lruvec, sc);
+
+ shrink_slab(sc->gfp_mask, pgdat->node_id, memcg, sc->priority);
+
+ if (!sc->proactive)
+ vmpressure(sc->gfp_mask, memcg, false, sc->nr_scanned - scanned,
+ sc->nr_reclaimed - reclaimed);
+
+ sc->nr_reclaimed += current->reclaim_state->reclaimed_slab;
+ current->reclaim_state->reclaimed_slab = 0;
+
+ return success ? MEMCG_LRU_YOUNG : 0;
+}
+
+#ifdef CONFIG_MEMCG
+
+static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc)
+{
+ int gen;
+ int bin;
+ int first_bin;
+ struct lruvec *lruvec;
+ struct lru_gen_folio *lrugen;
+ const struct hlist_nulls_node *pos;
+ int op = 0;
+ struct mem_cgroup *memcg = NULL;
+ unsigned long nr_to_reclaim = get_nr_to_reclaim(sc);
+
+ bin = first_bin = get_random_u32_below(MEMCG_NR_BINS);
+restart:
+ gen = get_memcg_gen(READ_ONCE(pgdat->memcg_lru.seq));
+
+ rcu_read_lock();
+
+ hlist_nulls_for_each_entry_rcu(lrugen, pos, &pgdat->memcg_lru.fifo[gen][bin], list) {
+ if (op)
+ lru_gen_rotate_memcg(lruvec, op);
+
+ mem_cgroup_put(memcg);
+
+ lruvec = container_of(lrugen, struct lruvec, lrugen);
+ memcg = lruvec_memcg(lruvec);
+
+ if (!mem_cgroup_tryget(memcg)) {
+ op = 0;
+ memcg = NULL;
+ continue;
+ }
+
+ rcu_read_unlock();
+
+ op = shrink_one(lruvec, sc);
+
+ if (sc->nr_reclaimed >= nr_to_reclaim)
+ goto success;
+
+ rcu_read_lock();
+ }
+
+ rcu_read_unlock();
+
+ /* restart if raced with lru_gen_rotate_memcg() */
+ if (gen != get_nulls_value(pos))
+ goto restart;
+
+ /* try the rest of the bins of the current generation */
+ bin = get_memcg_bin(bin + 1);
+ if (bin != first_bin)
+ goto restart;
+success:
+ if (op)
+ lru_gen_rotate_memcg(lruvec, op);
+
+ mem_cgroup_put(memcg);
+}
+
+static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
+{
+ struct blk_plug plug;
+
+ VM_WARN_ON_ONCE(global_reclaim(sc));
+
+ lru_add_drain();
+
+ blk_start_plug(&plug);
+
+ set_mm_walk(lruvec_pgdat(lruvec));
+
+ if (try_to_shrink_lruvec(lruvec, sc))
+ lru_gen_rotate_memcg(lruvec, MEMCG_LRU_YOUNG);
+
clear_mm_walk();
blk_finish_plug(&plug);
}
+#else /* !CONFIG_MEMCG */
+
+static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc)
+{
+ BUILD_BUG();
+}
+
+static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
+{
+ BUILD_BUG();
+}
+
+#endif
+
+static void set_initial_priority(struct pglist_data *pgdat, struct scan_control *sc)
+{
+ int priority;
+ unsigned long reclaimable;
+ struct lruvec *lruvec = mem_cgroup_lruvec(NULL, pgdat);
+
+ if (sc->priority != DEF_PRIORITY || sc->nr_to_reclaim < MIN_LRU_BATCH)
+ return;
+ /*
+ * Determine the initial priority based on ((total / MEMCG_NR_GENS) >>
+ * priority) * reclaimed_to_scanned_ratio = nr_to_reclaim, where the
+ * estimated reclaimed_to_scanned_ratio = inactive / total.
+ */
+ reclaimable = node_page_state(pgdat, NR_INACTIVE_FILE);
+ if (get_swappiness(lruvec, sc))
+ reclaimable += node_page_state(pgdat, NR_INACTIVE_ANON);
+
+ reclaimable /= MEMCG_NR_GENS;
+
+ /* round down reclaimable and round up sc->nr_to_reclaim */
+ priority = fls_long(reclaimable) - 1 - fls_long(sc->nr_to_reclaim - 1);
+
+ sc->priority = clamp(priority, 0, DEF_PRIORITY);
+}
+
+static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *sc)
+{
+ struct blk_plug plug;
+ unsigned long reclaimed = sc->nr_reclaimed;
+
+ VM_WARN_ON_ONCE(!global_reclaim(sc));
+
+ lru_add_drain();
+
+ blk_start_plug(&plug);
+
+ set_mm_walk(pgdat);
+
+ set_initial_priority(pgdat, sc);
+
+ if (current_is_kswapd())
+ sc->nr_reclaimed = 0;
+
+ if (mem_cgroup_disabled())
+ shrink_one(&pgdat->__lruvec, sc);
+ else
+ shrink_many(pgdat, sc);
+
+ if (current_is_kswapd())
+ sc->nr_reclaimed += reclaimed;
+
+ clear_mm_walk();
+
+ blk_finish_plug(&plug);
+
+ /* kswapd should never fail */
+ pgdat->kswapd_failures = 0;
+}
+
+#ifdef CONFIG_MEMCG
+void lru_gen_rotate_memcg(struct lruvec *lruvec, int op)
+{
+ int seg;
+ int old, new;
+ int bin = get_random_u32_below(MEMCG_NR_BINS);
+ struct pglist_data *pgdat = lruvec_pgdat(lruvec);
+
+ spin_lock(&pgdat->memcg_lru.lock);
+
+ VM_WARN_ON_ONCE(hlist_nulls_unhashed(&lruvec->lrugen.list));
+
+ seg = 0;
+ new = old = lruvec->lrugen.gen;
+
+ /* see the comment on MEMCG_NR_GENS */
+ if (op == MEMCG_LRU_HEAD)
+ seg = MEMCG_LRU_HEAD;
+ else if (op == MEMCG_LRU_TAIL)
+ seg = MEMCG_LRU_TAIL;
+ else if (op == MEMCG_LRU_OLD)
+ new = get_memcg_gen(pgdat->memcg_lru.seq);
+ else if (op == MEMCG_LRU_YOUNG)
+ new = get_memcg_gen(pgdat->memcg_lru.seq + 1);
+ else
+ VM_WARN_ON_ONCE(true);
+
+ hlist_nulls_del_rcu(&lruvec->lrugen.list);
+
+ if (op == MEMCG_LRU_HEAD || op == MEMCG_LRU_OLD)
+ hlist_nulls_add_head_rcu(&lruvec->lrugen.list, &pgdat->memcg_lru.fifo[new][bin]);
+ else
+ hlist_nulls_add_tail_rcu(&lruvec->lrugen.list, &pgdat->memcg_lru.fifo[new][bin]);
+
+ pgdat->memcg_lru.nr_memcgs[old]--;
+ pgdat->memcg_lru.nr_memcgs[new]++;
+
+ lruvec->lrugen.gen = new;
+ WRITE_ONCE(lruvec->lrugen.seg, seg);
+
+ if (!pgdat->memcg_lru.nr_memcgs[old] && old == get_memcg_gen(pgdat->memcg_lru.seq))
+ WRITE_ONCE(pgdat->memcg_lru.seq, pgdat->memcg_lru.seq + 1);
+
+ spin_unlock(&pgdat->memcg_lru.lock);
+}
+#endif
+
/******************************************************************************
* state change
******************************************************************************/
if (!mem_cgroup_disabled()) {
rcu_read_lock();
+
memcg = mem_cgroup_from_id(memcg_id);
-#ifdef CONFIG_MEMCG
- if (memcg && !css_tryget(&memcg->css))
+ if (!mem_cgroup_tryget(memcg))
memcg = NULL;
-#endif
+
rcu_read_unlock();
if (!memcg)
}
#ifdef CONFIG_MEMCG
+
+void lru_gen_init_pgdat(struct pglist_data *pgdat)
+{
+ int i, j;
+
+ spin_lock_init(&pgdat->memcg_lru.lock);
+
+ for (i = 0; i < MEMCG_NR_GENS; i++) {
+ for (j = 0; j < MEMCG_NR_BINS; j++)
+ INIT_HLIST_NULLS_HEAD(&pgdat->memcg_lru.fifo[i][j], i);
+ }
+}
+
void lru_gen_init_memcg(struct mem_cgroup *memcg)
{
INIT_LIST_HEAD(&memcg->mm_list.fifo);
}
}
}
-#endif
+
+void lru_gen_online_memcg(struct mem_cgroup *memcg)
+{
+ int gen;
+ int nid;
+ int bin = get_random_u32_below(MEMCG_NR_BINS);
+
+ for_each_node(nid) {
+ struct pglist_data *pgdat = NODE_DATA(nid);
+ struct lruvec *lruvec = get_lruvec(memcg, nid);
+
+ spin_lock(&pgdat->memcg_lru.lock);
+
+ VM_WARN_ON_ONCE(!hlist_nulls_unhashed(&lruvec->lrugen.list));
+
+ gen = get_memcg_gen(pgdat->memcg_lru.seq);
+
+ hlist_nulls_add_tail_rcu(&lruvec->lrugen.list, &pgdat->memcg_lru.fifo[gen][bin]);
+ pgdat->memcg_lru.nr_memcgs[gen]++;
+
+ lruvec->lrugen.gen = gen;
+
+ spin_unlock(&pgdat->memcg_lru.lock);
+ }
+}
+
+void lru_gen_offline_memcg(struct mem_cgroup *memcg)
+{
+ int nid;
+
+ for_each_node(nid) {
+ struct lruvec *lruvec = get_lruvec(memcg, nid);
+
+ lru_gen_rotate_memcg(lruvec, MEMCG_LRU_OLD);
+ }
+}
+
+void lru_gen_release_memcg(struct mem_cgroup *memcg)
+{
+ int gen;
+ int nid;
+
+ for_each_node(nid) {
+ struct pglist_data *pgdat = NODE_DATA(nid);
+ struct lruvec *lruvec = get_lruvec(memcg, nid);
+
+ spin_lock(&pgdat->memcg_lru.lock);
+
+ VM_WARN_ON_ONCE(hlist_nulls_unhashed(&lruvec->lrugen.list));
+
+ gen = lruvec->lrugen.gen;
+
+ hlist_nulls_del_rcu(&lruvec->lrugen.list);
+ pgdat->memcg_lru.nr_memcgs[gen]--;
+
+ if (!pgdat->memcg_lru.nr_memcgs[gen] && gen == get_memcg_gen(pgdat->memcg_lru.seq))
+ WRITE_ONCE(pgdat->memcg_lru.seq, pgdat->memcg_lru.seq + 1);
+
+ spin_unlock(&pgdat->memcg_lru.lock);
+ }
+}
+
+#endif /* CONFIG_MEMCG */
static int __init init_lru_gen(void)
{
{
}
+static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *sc)
+{
+}
+
#endif /* CONFIG_LRU_GEN */
static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
bool proportional_reclaim;
struct blk_plug plug;
- if (lru_gen_enabled()) {
+ if (lru_gen_enabled() && !global_reclaim(sc)) {
lru_gen_shrink_lruvec(lruvec, sc);
return;
}
struct lruvec *target_lruvec;
bool reclaimable = false;
+ if (lru_gen_enabled() && global_reclaim(sc)) {
+ lru_gen_shrink_node(pgdat, sc);
+ return;
+ }
+
target_lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup, pgdat);
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