Merge 8be976a0937a ("mm: multi-gen LRU: design doc") into android-mainline
Steps on the way to 6.1-rc1
Resolves conflicts in:
fs/exec.c
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Change-Id: Ia649390f891780ed03530adcf0fac9560635e58f
diff --git a/Documentation/admin-guide/mm/index.rst b/Documentation/admin-guide/mm/index.rst
index 1bd1111..d1064e0 100644
--- a/Documentation/admin-guide/mm/index.rst
+++ b/Documentation/admin-guide/mm/index.rst
@@ -32,6 +32,7 @@
idle_page_tracking
ksm
memory-hotplug
+ multigen_lru
nommu-mmap
numa_memory_policy
numaperf
diff --git a/Documentation/admin-guide/mm/multigen_lru.rst b/Documentation/admin-guide/mm/multigen_lru.rst
new file mode 100644
index 0000000..33e0688
--- /dev/null
+++ b/Documentation/admin-guide/mm/multigen_lru.rst
@@ -0,0 +1,162 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+Multi-Gen LRU
+=============
+The multi-gen LRU is an alternative LRU implementation that optimizes
+page reclaim and improves performance under memory pressure. Page
+reclaim decides the kernel's caching policy and ability to overcommit
+memory. It directly impacts the kswapd CPU usage and RAM efficiency.
+
+Quick start
+===========
+Build the kernel with the following configurations.
+
+* ``CONFIG_LRU_GEN=y``
+* ``CONFIG_LRU_GEN_ENABLED=y``
+
+All set!
+
+Runtime options
+===============
+``/sys/kernel/mm/lru_gen/`` contains stable ABIs described in the
+following subsections.
+
+Kill switch
+-----------
+``enabled`` accepts different values to enable or disable the
+following components. Its default value depends on
+``CONFIG_LRU_GEN_ENABLED``. All the components should be enabled
+unless some of them have unforeseen side effects. Writing to
+``enabled`` has no effect when a component is not supported by the
+hardware, and valid values will be accepted even when the main switch
+is off.
+
+====== ===============================================================
+Values Components
+====== ===============================================================
+0x0001 The main switch for the multi-gen LRU.
+0x0002 Clearing the accessed bit in leaf page table entries in large
+ batches, when MMU sets it (e.g., on x86). This behavior can
+ theoretically worsen lock contention (mmap_lock). If it is
+ disabled, the multi-gen LRU will suffer a minor performance
+ degradation for workloads that contiguously map hot pages,
+ whose accessed bits can be otherwise cleared by fewer larger
+ batches.
+0x0004 Clearing the accessed bit in non-leaf page table entries as
+ well, when MMU sets it (e.g., on x86). This behavior was not
+ verified on x86 varieties other than Intel and AMD. If it is
+ disabled, the multi-gen LRU will suffer a negligible
+ performance degradation.
+[yYnN] Apply to all the components above.
+====== ===============================================================
+
+E.g.,
+::
+
+ echo y >/sys/kernel/mm/lru_gen/enabled
+ cat /sys/kernel/mm/lru_gen/enabled
+ 0x0007
+ echo 5 >/sys/kernel/mm/lru_gen/enabled
+ cat /sys/kernel/mm/lru_gen/enabled
+ 0x0005
+
+Thrashing prevention
+--------------------
+Personal computers are more sensitive to thrashing because it can
+cause janks (lags when rendering UI) and negatively impact user
+experience. The multi-gen LRU offers thrashing prevention to the
+majority of laptop and desktop users who do not have ``oomd``.
+
+Users can write ``N`` to ``min_ttl_ms`` to prevent the working set of
+``N`` milliseconds from getting evicted. The OOM killer is triggered
+if this working set cannot be kept in memory. In other words, this
+option works as an adjustable pressure relief valve, and when open, it
+terminates applications that are hopefully not being used.
+
+Based on the average human detectable lag (~100ms), ``N=1000`` usually
+eliminates intolerable janks due to thrashing. Larger values like
+``N=3000`` make janks less noticeable at the risk of premature OOM
+kills.
+
+The default value ``0`` means disabled.
+
+Experimental features
+=====================
+``/sys/kernel/debug/lru_gen`` accepts commands described in the
+following subsections. Multiple command lines are supported, so does
+concatenation with delimiters ``,`` and ``;``.
+
+``/sys/kernel/debug/lru_gen_full`` provides additional stats for
+debugging. ``CONFIG_LRU_GEN_STATS=y`` keeps historical stats from
+evicted generations in this file.
+
+Working set estimation
+----------------------
+Working set estimation measures how much memory an application needs
+in a given time interval, and it is usually done with little impact on
+the performance of the application. E.g., data centers want to
+optimize job scheduling (bin packing) to improve memory utilizations.
+When a new job comes in, the job scheduler needs to find out whether
+each server it manages can allocate a certain amount of memory for
+this new job before it can pick a candidate. To do so, the job
+scheduler needs to estimate the working sets of the existing jobs.
+
+When it is read, ``lru_gen`` returns a histogram of numbers of pages
+accessed over different time intervals for each memcg and node.
+``MAX_NR_GENS`` decides the number of bins for each histogram. The
+histograms are noncumulative.
+::
+
+ memcg memcg_id memcg_path
+ node node_id
+ min_gen_nr age_in_ms nr_anon_pages nr_file_pages
+ ...
+ max_gen_nr age_in_ms nr_anon_pages nr_file_pages
+
+Each bin contains an estimated number of pages that have been accessed
+within ``age_in_ms``. E.g., ``min_gen_nr`` contains the coldest pages
+and ``max_gen_nr`` contains the hottest pages, since ``age_in_ms`` of
+the former is the largest and that of the latter is the smallest.
+
+Users can write the following command to ``lru_gen`` to create a new
+generation ``max_gen_nr+1``:
+
+ ``+ memcg_id node_id max_gen_nr [can_swap [force_scan]]``
+
+``can_swap`` defaults to the swap setting and, if it is set to ``1``,
+it forces the scan of anon pages when swap is off, and vice versa.
+``force_scan`` defaults to ``1`` and, if it is set to ``0``, it
+employs heuristics to reduce the overhead, which is likely to reduce
+the coverage as well.
+
+A typical use case is that a job scheduler runs this command at a
+certain time interval to create new generations, and it ranks the
+servers it manages based on the sizes of their cold pages defined by
+this time interval.
+
+Proactive reclaim
+-----------------
+Proactive reclaim induces page reclaim when there is no memory
+pressure. It usually targets cold pages only. E.g., when a new job
+comes in, the job scheduler wants to proactively reclaim cold pages on
+the server it selected, to improve the chance of successfully landing
+this new job.
+
+Users can write the following command to ``lru_gen`` to evict
+generations less than or equal to ``min_gen_nr``.
+
+ ``- memcg_id node_id min_gen_nr [swappiness [nr_to_reclaim]]``
+
+``min_gen_nr`` should be less than ``max_gen_nr-1``, since
+``max_gen_nr`` and ``max_gen_nr-1`` are not fully aged (equivalent to
+the active list) and therefore cannot be evicted. ``swappiness``
+overrides the default value in ``/proc/sys/vm/swappiness``.
+``nr_to_reclaim`` limits the number of pages to evict.
+
+A typical use case is that a job scheduler runs this command before it
+tries to land a new job on a server. If it fails to materialize enough
+cold pages because of the overestimation, it retries on the next
+server according to the ranking result obtained from the working set
+estimation step. This less forceful approach limits the impacts on the
+existing jobs.
diff --git a/Documentation/mm/index.rst b/Documentation/mm/index.rst
index 575ccd4..4aa12b8 100644
--- a/Documentation/mm/index.rst
+++ b/Documentation/mm/index.rst
@@ -51,6 +51,7 @@
ksm
memory-model
mmu_notifier
+ multigen_lru
numa
overcommit-accounting
page_migration
diff --git a/Documentation/mm/multigen_lru.rst b/Documentation/mm/multigen_lru.rst
new file mode 100644
index 0000000..d7062c6
--- /dev/null
+++ b/Documentation/mm/multigen_lru.rst
@@ -0,0 +1,159 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+Multi-Gen LRU
+=============
+The multi-gen LRU is an alternative LRU implementation that optimizes
+page reclaim and improves performance under memory pressure. Page
+reclaim decides the kernel's caching policy and ability to overcommit
+memory. It directly impacts the kswapd CPU usage and RAM efficiency.
+
+Design overview
+===============
+Objectives
+----------
+The design objectives are:
+
+* Good representation of access recency
+* Try to profit from spatial locality
+* Fast paths to make obvious choices
+* Simple self-correcting heuristics
+
+The representation of access recency is at the core of all LRU
+implementations. In the multi-gen LRU, each generation represents a
+group of pages with similar access recency. Generations establish a
+(time-based) common frame of reference and therefore help make better
+choices, e.g., between different memcgs on a computer or different
+computers in a data center (for job scheduling).
+
+Exploiting spatial locality improves efficiency when gathering the
+accessed bit. A rmap walk targets a single page and does not try to
+profit from discovering a young PTE. A page table walk can sweep all
+the young PTEs in an address space, but the address space can be too
+sparse to make a profit. The key is to optimize both methods and use
+them in combination.
+
+Fast paths reduce code complexity and runtime overhead. Unmapped pages
+do not require TLB flushes; clean pages do not require writeback.
+These facts are only helpful when other conditions, e.g., access
+recency, are similar. With generations as a common frame of reference,
+additional factors stand out. But obvious choices might not be good
+choices; thus self-correction is necessary.
+
+The benefits of simple self-correcting heuristics are self-evident.
+Again, with generations as a common frame of reference, this becomes
+attainable. Specifically, pages in the same generation can be
+categorized based on additional factors, and a feedback loop can
+statistically compare the refault percentages across those categories
+and infer which of them are better choices.
+
+Assumptions
+-----------
+The protection of hot pages and the selection of cold pages are based
+on page access channels and patterns. There are two access channels:
+
+* Accesses through page tables
+* Accesses through file descriptors
+
+The protection of the former channel is by design stronger because:
+
+1. The uncertainty in determining the access patterns of the former
+ channel is higher due to the approximation of the accessed bit.
+2. The cost of evicting the former channel is higher due to the TLB
+ flushes required and the likelihood of encountering the dirty bit.
+3. The penalty of underprotecting the former channel is higher because
+ applications usually do not prepare themselves for major page
+ faults like they do for blocked I/O. E.g., GUI applications
+ commonly use dedicated I/O threads to avoid blocking rendering
+ threads.
+
+There are also two access patterns:
+
+* Accesses exhibiting temporal locality
+* Accesses not exhibiting temporal locality
+
+For the reasons listed above, the former channel is assumed to follow
+the former pattern unless ``VM_SEQ_READ`` or ``VM_RAND_READ`` is
+present, and the latter channel is assumed to follow the latter
+pattern unless outlying refaults have been observed.
+
+Workflow overview
+=================
+Evictable pages are divided into multiple generations for each
+``lruvec``. The youngest generation number is stored in
+``lrugen->max_seq`` for both anon and file types as they are aged on
+an equal footing. The oldest generation numbers are stored in
+``lrugen->min_seq[]`` separately for anon and file types as clean file
+pages can be evicted regardless of swap constraints. These three
+variables are monotonically increasing.
+
+Generation numbers are truncated into ``order_base_2(MAX_NR_GENS+1)``
+bits in order to fit into the gen counter in ``folio->flags``. Each
+truncated generation number is an index to ``lrugen->lists[]``. The
+sliding window technique is used to track at least ``MIN_NR_GENS`` and
+at most ``MAX_NR_GENS`` generations. The gen counter stores a value
+within ``[1, MAX_NR_GENS]`` while a page is on one of
+``lrugen->lists[]``; otherwise it stores zero.
+
+Each generation is divided into multiple tiers. A page accessed ``N``
+times through file descriptors is in tier ``order_base_2(N)``. Unlike
+generations, tiers do not have dedicated ``lrugen->lists[]``. In
+contrast to moving across generations, which requires the LRU lock,
+moving across tiers only involves atomic operations on
+``folio->flags`` and therefore has a negligible cost. A feedback loop
+modeled after the PID controller monitors refaults over all the tiers
+from anon and file types and decides which tiers from which types to
+evict or protect.
+
+There are two conceptually independent procedures: the aging and the
+eviction. They form a closed-loop system, i.e., the page reclaim.
+
+Aging
+-----
+The aging produces young generations. Given an ``lruvec``, it
+increments ``max_seq`` when ``max_seq-min_seq+1`` approaches
+``MIN_NR_GENS``. The aging promotes hot pages to the youngest
+generation when it finds them accessed through page tables; the
+demotion of cold pages happens consequently when it increments
+``max_seq``. The aging uses page table walks and rmap walks to find
+young PTEs. For the former, it iterates ``lruvec_memcg()->mm_list``
+and calls ``walk_page_range()`` with each ``mm_struct`` on this list
+to scan PTEs, and after each iteration, it increments ``max_seq``. For
+the latter, when the eviction walks the rmap and finds a young PTE,
+the aging scans the adjacent PTEs. For both, on finding a young PTE,
+the aging clears the accessed bit and updates the gen counter of the
+page mapped by this PTE to ``(max_seq%MAX_NR_GENS)+1``.
+
+Eviction
+--------
+The eviction consumes old generations. Given an ``lruvec``, it
+increments ``min_seq`` when ``lrugen->lists[]`` indexed by
+``min_seq%MAX_NR_GENS`` becomes empty. To select a type and a tier to
+evict from, it first compares ``min_seq[]`` to select the older type.
+If both types are equally old, it selects the one whose first tier has
+a lower refault percentage. The first tier contains single-use
+unmapped clean pages, which are the best bet. The eviction sorts a
+page according to its gen counter if the aging has found this page
+accessed through page tables and updated its gen counter. It also
+moves a page to the next generation, i.e., ``min_seq+1``, if this page
+was accessed multiple times through file descriptors and the feedback
+loop has detected outlying refaults from the tier this page is in. To
+this end, the feedback loop uses the first tier as the baseline, for
+the reason stated earlier.
+
+Summary
+-------
+The multi-gen LRU can be disassembled into the following parts:
+
+* Generations
+* Rmap walks
+* Page table walks
+* Bloom filters
+* PID controller
+
+The aging and the eviction form a producer-consumer model;
+specifically, the latter drives the former by the sliding window over
+generations. Within the aging, rmap walks drive page table walks by
+inserting hot densely populated page tables to the Bloom filters.
+Within the eviction, the PID controller uses refaults as the feedback
+to select types to evict and tiers to protect.
diff --git a/fs/exec.c b/fs/exec.c
index de084e4..436f5a5 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1010,6 +1010,7 @@ static int exec_mmap(struct mm_struct *mm)
active_mm = tsk->active_mm;
tsk->active_mm = mm;
tsk->mm = mm;
+ lru_gen_add_mm(mm);
/*
* This prevents preemption while active_mm is being loaded and
* it and mm are being updated, which could cause problems for
@@ -1025,6 +1026,7 @@ static int exec_mmap(struct mm_struct *mm)
tsk->mm->vmacache_seqnum = 0;
vmacache_flush(tsk);
task_unlock(tsk);
+ lru_gen_use_mm(mm);
if (old_mm) {
mmap_read_unlock(old_mm);
BUG_ON(active_mm != old_mm);
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index e8b173a..aac9860 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -780,7 +780,8 @@ static int fuse_check_page(struct page *page)
1 << PG_active |
1 << PG_workingset |
1 << PG_reclaim |
- 1 << PG_waiters))) {
+ 1 << PG_waiters |
+ LRU_GEN_MASK | LRU_REFS_MASK))) {
dump_page(page, "fuse: trying to steal weird page");
return 1;
}
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 398f0bc..23b102b 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -433,6 +433,18 @@ static inline void cgroup_put(struct cgroup *cgrp)
css_put(&cgrp->self);
}
+extern struct mutex cgroup_mutex;
+
+static inline void cgroup_lock(void)
+{
+ mutex_lock(&cgroup_mutex);
+}
+
+static inline void cgroup_unlock(void)
+{
+ mutex_unlock(&cgroup_mutex);
+}
+
/**
* task_css_set_check - obtain a task's css_set with extra access conditions
* @task: the task to obtain css_set for
@@ -447,7 +459,6 @@ static inline void cgroup_put(struct cgroup *cgrp)
* as locks used during the cgroup_subsys::attach() methods.
*/
#ifdef CONFIG_PROVE_RCU
-extern struct mutex cgroup_mutex;
extern spinlock_t css_set_lock;
#define task_css_set_check(task, __c) \
rcu_dereference_check((task)->cgroups, \
@@ -707,6 +718,8 @@ struct cgroup;
static inline u64 cgroup_id(const struct cgroup *cgrp) { return 1; }
static inline void css_get(struct cgroup_subsys_state *css) {}
static inline void css_put(struct cgroup_subsys_state *css) {}
+static inline void cgroup_lock(void) {}
+static inline void cgroup_unlock(void) {}
static inline int cgroup_attach_task_all(struct task_struct *from,
struct task_struct *t) { return 0; }
static inline int cgroupstats_build(struct cgroupstats *stats,
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index cf11588..b92ac2a 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -350,6 +350,11 @@ struct mem_cgroup {
struct deferred_split deferred_split_queue;
#endif
+#ifdef CONFIG_LRU_GEN
+ /* per-memcg mm_struct list */
+ struct lru_gen_mm_list mm_list;
+#endif
+
struct mem_cgroup_per_node *nodeinfo[];
};
@@ -445,6 +450,7 @@ static inline struct obj_cgroup *__folio_objcg(struct folio *folio)
* - LRU isolation
* - lock_page_memcg()
* - exclusive reference
+ * - mem_cgroup_trylock_pages()
*
* For a kmem folio a caller should hold an rcu read lock to protect memcg
* associated with a kmem folio from being released.
@@ -506,6 +512,7 @@ static inline struct mem_cgroup *folio_memcg_rcu(struct folio *folio)
* - LRU isolation
* - lock_page_memcg()
* - exclusive reference
+ * - mem_cgroup_trylock_pages()
*
* For a kmem page a caller should hold an rcu read lock to protect memcg
* associated with a kmem page from being released.
@@ -960,6 +967,23 @@ void unlock_page_memcg(struct page *page);
void __mod_memcg_state(struct mem_cgroup *memcg, int idx, int val);
+/* try to stablize folio_memcg() for all the pages in a memcg */
+static inline bool mem_cgroup_trylock_pages(struct mem_cgroup *memcg)
+{
+ rcu_read_lock();
+
+ if (mem_cgroup_disabled() || !atomic_read(&memcg->moving_account))
+ return true;
+
+ rcu_read_unlock();
+ return false;
+}
+
+static inline void mem_cgroup_unlock_pages(void)
+{
+ rcu_read_unlock();
+}
+
/* idx can be of type enum memcg_stat_item or node_stat_item */
static inline void mod_memcg_state(struct mem_cgroup *memcg,
int idx, int val)
@@ -1434,6 +1458,18 @@ static inline void folio_memcg_unlock(struct folio *folio)
{
}
+static inline bool mem_cgroup_trylock_pages(struct mem_cgroup *memcg)
+{
+ /* to match folio_memcg_rcu() */
+ rcu_read_lock();
+ return true;
+}
+
+static inline void mem_cgroup_unlock_pages(void)
+{
+ rcu_read_unlock();
+}
+
static inline void mem_cgroup_handle_over_high(void)
{
}
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 8a5ad9d..7cc9ffc 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1490,6 +1490,11 @@ static inline unsigned long folio_pfn(struct folio *folio)
return page_to_pfn(&folio->page);
}
+static inline struct folio *pfn_folio(unsigned long pfn)
+{
+ return page_folio(pfn_to_page(pfn));
+}
+
static inline atomic_t *folio_pincount_ptr(struct folio *folio)
{
return &folio_page(folio, 1)->compound_pincount;
diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index fb8aadb..4949eda 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -40,6 +40,9 @@ static __always_inline void __update_lru_size(struct lruvec *lruvec,
{
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
+ lockdep_assert_held(&lruvec->lru_lock);
+ WARN_ON_ONCE(nr_pages != (int)nr_pages);
+
__mod_lruvec_state(lruvec, NR_LRU_BASE + lru, nr_pages);
__mod_zone_page_state(&pgdat->node_zones[zid],
NR_ZONE_LRU_BASE + lru, nr_pages);
@@ -101,11 +104,224 @@ static __always_inline enum lru_list folio_lru_list(struct folio *folio)
return lru;
}
+#ifdef CONFIG_LRU_GEN
+
+#ifdef CONFIG_LRU_GEN_ENABLED
+static inline bool lru_gen_enabled(void)
+{
+ DECLARE_STATIC_KEY_TRUE(lru_gen_caps[NR_LRU_GEN_CAPS]);
+
+ return static_branch_likely(&lru_gen_caps[LRU_GEN_CORE]);
+}
+#else
+static inline bool lru_gen_enabled(void)
+{
+ DECLARE_STATIC_KEY_FALSE(lru_gen_caps[NR_LRU_GEN_CAPS]);
+
+ return static_branch_unlikely(&lru_gen_caps[LRU_GEN_CORE]);
+}
+#endif
+
+static inline bool lru_gen_in_fault(void)
+{
+ return current->in_lru_fault;
+}
+
+static inline int lru_gen_from_seq(unsigned long seq)
+{
+ return seq % MAX_NR_GENS;
+}
+
+static inline int lru_hist_from_seq(unsigned long seq)
+{
+ return seq % NR_HIST_GENS;
+}
+
+static inline int lru_tier_from_refs(int refs)
+{
+ VM_WARN_ON_ONCE(refs > BIT(LRU_REFS_WIDTH));
+
+ /* see the comment in folio_lru_refs() */
+ return order_base_2(refs + 1);
+}
+
+static inline int folio_lru_refs(struct folio *folio)
+{
+ unsigned long flags = READ_ONCE(folio->flags);
+ bool workingset = flags & BIT(PG_workingset);
+
+ /*
+ * Return the number of accesses beyond PG_referenced, i.e., N-1 if the
+ * total number of accesses is N>1, since N=0,1 both map to the first
+ * tier. lru_tier_from_refs() will account for this off-by-one. Also see
+ * the comment on MAX_NR_TIERS.
+ */
+ return ((flags & LRU_REFS_MASK) >> LRU_REFS_PGOFF) + workingset;
+}
+
+static inline int folio_lru_gen(struct folio *folio)
+{
+ unsigned long flags = READ_ONCE(folio->flags);
+
+ return ((flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1;
+}
+
+static inline bool lru_gen_is_active(struct lruvec *lruvec, int gen)
+{
+ unsigned long max_seq = lruvec->lrugen.max_seq;
+
+ VM_WARN_ON_ONCE(gen >= MAX_NR_GENS);
+
+ /* see the comment on MIN_NR_GENS */
+ return gen == lru_gen_from_seq(max_seq) || gen == lru_gen_from_seq(max_seq - 1);
+}
+
+static inline void lru_gen_update_size(struct lruvec *lruvec, struct folio *folio,
+ int old_gen, int new_gen)
+{
+ int type = folio_is_file_lru(folio);
+ int zone = folio_zonenum(folio);
+ int delta = folio_nr_pages(folio);
+ enum lru_list lru = type * LRU_INACTIVE_FILE;
+ struct lru_gen_struct *lrugen = &lruvec->lrugen;
+
+ VM_WARN_ON_ONCE(old_gen != -1 && old_gen >= MAX_NR_GENS);
+ VM_WARN_ON_ONCE(new_gen != -1 && new_gen >= MAX_NR_GENS);
+ VM_WARN_ON_ONCE(old_gen == -1 && new_gen == -1);
+
+ if (old_gen >= 0)
+ WRITE_ONCE(lrugen->nr_pages[old_gen][type][zone],
+ lrugen->nr_pages[old_gen][type][zone] - delta);
+ if (new_gen >= 0)
+ WRITE_ONCE(lrugen->nr_pages[new_gen][type][zone],
+ lrugen->nr_pages[new_gen][type][zone] + delta);
+
+ /* addition */
+ if (old_gen < 0) {
+ if (lru_gen_is_active(lruvec, new_gen))
+ lru += LRU_ACTIVE;
+ __update_lru_size(lruvec, lru, zone, delta);
+ return;
+ }
+
+ /* deletion */
+ if (new_gen < 0) {
+ if (lru_gen_is_active(lruvec, old_gen))
+ lru += LRU_ACTIVE;
+ __update_lru_size(lruvec, lru, zone, -delta);
+ return;
+ }
+
+ /* promotion */
+ if (!lru_gen_is_active(lruvec, old_gen) && lru_gen_is_active(lruvec, new_gen)) {
+ __update_lru_size(lruvec, lru, zone, -delta);
+ __update_lru_size(lruvec, lru + LRU_ACTIVE, zone, delta);
+ }
+
+ /* demotion requires isolation, e.g., lru_deactivate_fn() */
+ VM_WARN_ON_ONCE(lru_gen_is_active(lruvec, old_gen) && !lru_gen_is_active(lruvec, new_gen));
+}
+
+static inline bool lru_gen_add_folio(struct lruvec *lruvec, struct folio *folio, bool reclaiming)
+{
+ unsigned long seq;
+ unsigned long flags;
+ int gen = folio_lru_gen(folio);
+ int type = folio_is_file_lru(folio);
+ int zone = folio_zonenum(folio);
+ struct lru_gen_struct *lrugen = &lruvec->lrugen;
+
+ VM_WARN_ON_ONCE_FOLIO(gen != -1, folio);
+
+ if (folio_test_unevictable(folio) || !lrugen->enabled)
+ return false;
+ /*
+ * There are three common cases for this page:
+ * 1. If it's hot, e.g., freshly faulted in or previously hot and
+ * migrated, add it to the youngest generation.
+ * 2. If it's cold but can't be evicted immediately, i.e., an anon page
+ * not in swapcache or a dirty page pending writeback, add it to the
+ * second oldest generation.
+ * 3. Everything else (clean, cold) is added to the oldest generation.
+ */
+ if (folio_test_active(folio))
+ seq = lrugen->max_seq;
+ else if ((type == LRU_GEN_ANON && !folio_test_swapcache(folio)) ||
+ (folio_test_reclaim(folio) &&
+ (folio_test_dirty(folio) || folio_test_writeback(folio))))
+ seq = lrugen->min_seq[type] + 1;
+ else
+ seq = lrugen->min_seq[type];
+
+ gen = lru_gen_from_seq(seq);
+ flags = (gen + 1UL) << LRU_GEN_PGOFF;
+ /* see the comment on MIN_NR_GENS about PG_active */
+ set_mask_bits(&folio->flags, LRU_GEN_MASK | BIT(PG_active), flags);
+
+ lru_gen_update_size(lruvec, folio, -1, gen);
+ /* for folio_rotate_reclaimable() */
+ if (reclaiming)
+ list_add_tail(&folio->lru, &lrugen->lists[gen][type][zone]);
+ else
+ list_add(&folio->lru, &lrugen->lists[gen][type][zone]);
+
+ return true;
+}
+
+static inline bool lru_gen_del_folio(struct lruvec *lruvec, struct folio *folio, bool reclaiming)
+{
+ unsigned long flags;
+ int gen = folio_lru_gen(folio);
+
+ if (gen < 0)
+ return false;
+
+ VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio), folio);
+ VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio);
+
+ /* for folio_migrate_flags() */
+ flags = !reclaiming && lru_gen_is_active(lruvec, gen) ? BIT(PG_active) : 0;
+ flags = set_mask_bits(&folio->flags, LRU_GEN_MASK, flags);
+ gen = ((flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1;
+
+ lru_gen_update_size(lruvec, folio, gen, -1);
+ list_del(&folio->lru);
+
+ return true;
+}
+
+#else /* !CONFIG_LRU_GEN */
+
+static inline bool lru_gen_enabled(void)
+{
+ return false;
+}
+
+static inline bool lru_gen_in_fault(void)
+{
+ return false;
+}
+
+static inline bool lru_gen_add_folio(struct lruvec *lruvec, struct folio *folio, bool reclaiming)
+{
+ return false;
+}
+
+static inline bool lru_gen_del_folio(struct lruvec *lruvec, struct folio *folio, bool reclaiming)
+{
+ return false;
+}
+
+#endif /* CONFIG_LRU_GEN */
+
static __always_inline
void lruvec_add_folio(struct lruvec *lruvec, struct folio *folio)
{
enum lru_list lru = folio_lru_list(folio);
+ if (lru_gen_add_folio(lruvec, folio, false))
+ return;
+
update_lru_size(lruvec, lru, folio_zonenum(folio),
folio_nr_pages(folio));
if (lru != LRU_UNEVICTABLE)
@@ -123,6 +339,9 @@ void lruvec_add_folio_tail(struct lruvec *lruvec, struct folio *folio)
{
enum lru_list lru = folio_lru_list(folio);
+ if (lru_gen_add_folio(lruvec, folio, true))
+ return;
+
update_lru_size(lruvec, lru, folio_zonenum(folio),
folio_nr_pages(folio));
/* This is not expected to be used on LRU_UNEVICTABLE */
@@ -140,6 +359,9 @@ void lruvec_del_folio(struct lruvec *lruvec, struct folio *folio)
{
enum lru_list lru = folio_lru_list(folio);
+ if (lru_gen_del_folio(lruvec, folio, false))
+ return;
+
if (lru != LRU_UNEVICTABLE)
list_del(&folio->lru);
update_lru_size(lruvec, lru, folio_zonenum(folio),
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index cf97f38..e179781 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -672,6 +672,22 @@ struct mm_struct {
*/
unsigned long ksm_merging_pages;
#endif
+#ifdef CONFIG_LRU_GEN
+ struct {
+ /* this mm_struct is on lru_gen_mm_list */
+ struct list_head list;
+ /*
+ * Set when switching to this mm_struct, as a hint of
+ * whether it has been used since the last time per-node
+ * page table walkers cleared the corresponding bits.
+ */
+ unsigned long bitmap;
+#ifdef CONFIG_MEMCG
+ /* points to the memcg of "owner" above */
+ struct mem_cgroup *memcg;
+#endif
+ } lru_gen;
+#endif /* CONFIG_LRU_GEN */
} __randomize_layout;
/*
@@ -698,6 +714,66 @@ static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
return (struct cpumask *)&mm->cpu_bitmap;
}
+#ifdef CONFIG_LRU_GEN
+
+struct lru_gen_mm_list {
+ /* mm_struct list for page table walkers */
+ struct list_head fifo;
+ /* protects the list above */
+ spinlock_t lock;
+};
+
+void lru_gen_add_mm(struct mm_struct *mm);
+void lru_gen_del_mm(struct mm_struct *mm);
+#ifdef CONFIG_MEMCG
+void lru_gen_migrate_mm(struct mm_struct *mm);
+#endif
+
+static inline void lru_gen_init_mm(struct mm_struct *mm)
+{
+ INIT_LIST_HEAD(&mm->lru_gen.list);
+ mm->lru_gen.bitmap = 0;
+#ifdef CONFIG_MEMCG
+ mm->lru_gen.memcg = NULL;
+#endif
+}
+
+static inline void lru_gen_use_mm(struct mm_struct *mm)
+{
+ /*
+ * When the bitmap is set, page reclaim knows this mm_struct has been
+ * used since the last time it cleared the bitmap. So it might be worth
+ * walking the page tables of this mm_struct to clear the accessed bit.
+ */
+ WRITE_ONCE(mm->lru_gen.bitmap, -1);
+}
+
+#else /* !CONFIG_LRU_GEN */
+
+static inline void lru_gen_add_mm(struct mm_struct *mm)
+{
+}
+
+static inline void lru_gen_del_mm(struct mm_struct *mm)
+{
+}
+
+#ifdef CONFIG_MEMCG
+static inline void lru_gen_migrate_mm(struct mm_struct *mm)
+{
+}
+#endif
+
+static inline void lru_gen_init_mm(struct mm_struct *mm)
+{
+}
+
+static inline void lru_gen_use_mm(struct mm_struct *mm)
+{
+}
+
+#endif /* CONFIG_LRU_GEN */
+
struct mmu_gather;
extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm);
extern void tlb_gather_mmu_fullmm(struct mmu_gather *tlb, struct mm_struct *mm);
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index fe6c5e0..ee5bbd6 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -316,6 +316,207 @@ enum lruvec_flags {
*/
};
+#endif /* !__GENERATING_BOUNDS_H */
+
+/*
+ * Evictable pages are divided into multiple generations. The youngest and the
+ * oldest generation numbers, max_seq and min_seq, are monotonically increasing.
+ * They form a sliding window of a variable size [MIN_NR_GENS, MAX_NR_GENS]. An
+ * offset within MAX_NR_GENS, i.e., gen, indexes the LRU list of the
+ * corresponding generation. The gen counter in folio->flags stores gen+1 while
+ * a page is on one of lrugen->lists[]. Otherwise it stores 0.
+ *
+ * A page is added to the youngest generation on faulting. The aging needs to
+ * check the accessed bit at least twice before handing this page over to the
+ * eviction. The first check takes care of the accessed bit set on the initial
+ * fault; the second check makes sure this page hasn't been used since then.
+ * This process, AKA second chance, requires a minimum of two generations,
+ * hence MIN_NR_GENS. And to maintain ABI compatibility with the active/inactive
+ * LRU, e.g., /proc/vmstat, these two generations are considered active; the
+ * rest of generations, if they exist, are considered inactive. See
+ * lru_gen_is_active().
+ *
+ * PG_active is always cleared while a page is on one of lrugen->lists[] so that
+ * the aging needs not to worry about it. And it's set again when a page
+ * considered active is isolated for non-reclaiming purposes, e.g., migration.
+ * See lru_gen_add_folio() and lru_gen_del_folio().
+ *
+ * MAX_NR_GENS is set to 4 so that the multi-gen LRU can support twice the
+ * number of categories of the active/inactive LRU when keeping track of
+ * accesses through page tables. This requires order_base_2(MAX_NR_GENS+1) bits
+ * in folio->flags.
+ */
+#define MIN_NR_GENS 2U
+#define MAX_NR_GENS 4U
+
+/*
+ * Each generation is divided into multiple tiers. A page accessed N times
+ * through file descriptors is in tier order_base_2(N). A page in the first tier
+ * (N=0,1) is marked by PG_referenced unless it was faulted in through page
+ * tables or read ahead. A page in any other tier (N>1) is marked by
+ * PG_referenced and PG_workingset. This implies a minimum of two tiers is
+ * supported without using additional bits in folio->flags.
+ *
+ * In contrast to moving across generations which requires the LRU lock, moving
+ * across tiers only involves atomic operations on folio->flags and therefore
+ * has a negligible cost in the buffered access path. In the eviction path,
+ * comparisons of refaulted/(evicted+protected) from the first tier and the
+ * rest infer whether pages accessed multiple times through file descriptors
+ * are statistically hot and thus worth protecting.
+ *
+ * MAX_NR_TIERS is set to 4 so that the multi-gen LRU can support twice the
+ * number of categories of the active/inactive LRU when keeping track of
+ * accesses through file descriptors. This uses MAX_NR_TIERS-2 spare bits in
+ * folio->flags.
+ */
+#define MAX_NR_TIERS 4U
+
+#ifndef __GENERATING_BOUNDS_H
+
+struct lruvec;
+struct page_vma_mapped_walk;
+
+#define LRU_GEN_MASK ((BIT(LRU_GEN_WIDTH) - 1) << LRU_GEN_PGOFF)
+#define LRU_REFS_MASK ((BIT(LRU_REFS_WIDTH) - 1) << LRU_REFS_PGOFF)
+
+#ifdef CONFIG_LRU_GEN
+
+enum {
+ LRU_GEN_ANON,
+ LRU_GEN_FILE,
+};
+
+enum {
+ LRU_GEN_CORE,
+ LRU_GEN_MM_WALK,
+ LRU_GEN_NONLEAF_YOUNG,
+ NR_LRU_GEN_CAPS
+};
+
+#define MIN_LRU_BATCH BITS_PER_LONG
+#define MAX_LRU_BATCH (MIN_LRU_BATCH * 64)
+
+/* whether to keep historical stats from evicted generations */
+#ifdef CONFIG_LRU_GEN_STATS
+#define NR_HIST_GENS MAX_NR_GENS
+#else
+#define NR_HIST_GENS 1U
+#endif
+
+/*
+ * The youngest generation number is stored in max_seq for both anon and file
+ * types as they are aged on an equal footing. The oldest generation numbers are
+ * stored in min_seq[] separately for anon and file types as clean file pages
+ * can be evicted regardless of swap constraints.
+ *
+ * Normally anon and file min_seq are in sync. But if swapping is constrained,
+ * e.g., out of swap space, file min_seq is allowed to advance and leave anon
+ * min_seq behind.
+ *
+ * The number of pages in each generation is eventually consistent and therefore
+ * can be transiently negative when reset_batch_size() is pending.
+ */
+struct lru_gen_struct {
+ /* the aging increments the youngest generation number */
+ unsigned long max_seq;
+ /* the eviction increments the oldest generation numbers */
+ unsigned long min_seq[ANON_AND_FILE];
+ /* the birth time of each generation in jiffies */
+ unsigned long timestamps[MAX_NR_GENS];
+ /* the multi-gen LRU lists, lazily sorted on eviction */
+ struct list_head lists[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES];
+ /* the multi-gen LRU sizes, eventually consistent */
+ long nr_pages[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES];
+ /* the exponential moving average of refaulted */
+ unsigned long avg_refaulted[ANON_AND_FILE][MAX_NR_TIERS];
+ /* the exponential moving average of evicted+protected */
+ unsigned long avg_total[ANON_AND_FILE][MAX_NR_TIERS];
+ /* the first tier doesn't need protection, hence the minus one */
+ unsigned long protected[NR_HIST_GENS][ANON_AND_FILE][MAX_NR_TIERS - 1];
+ /* can be modified without holding the LRU lock */
+ atomic_long_t evicted[NR_HIST_GENS][ANON_AND_FILE][MAX_NR_TIERS];
+ atomic_long_t refaulted[NR_HIST_GENS][ANON_AND_FILE][MAX_NR_TIERS];
+ /* whether the multi-gen LRU is enabled */
+ bool enabled;
+};
+
+enum {
+ MM_LEAF_TOTAL, /* total leaf entries */
+ MM_LEAF_OLD, /* old leaf entries */
+ MM_LEAF_YOUNG, /* young leaf entries */
+ MM_NONLEAF_TOTAL, /* total non-leaf entries */
+ MM_NONLEAF_FOUND, /* non-leaf entries found in Bloom filters */
+ MM_NONLEAF_ADDED, /* non-leaf entries added to Bloom filters */
+ NR_MM_STATS
+};
+
+/* double-buffering Bloom filters */
+#define NR_BLOOM_FILTERS 2
+
+struct lru_gen_mm_state {
+ /* set to max_seq after each iteration */
+ unsigned long seq;
+ /* where the current iteration continues (inclusive) */
+ struct list_head *head;
+ /* where the last iteration ended (exclusive) */
+ struct list_head *tail;
+ /* to wait for the last page table walker to finish */
+ struct wait_queue_head wait;
+ /* Bloom filters flip after each iteration */
+ unsigned long *filters[NR_BLOOM_FILTERS];
+ /* the mm stats for debugging */
+ unsigned long stats[NR_HIST_GENS][NR_MM_STATS];
+ /* the number of concurrent page table walkers */
+ int nr_walkers;
+};
+
+struct lru_gen_mm_walk {
+ /* the lruvec under reclaim */
+ struct lruvec *lruvec;
+ /* unstable max_seq from lru_gen_struct */
+ unsigned long max_seq;
+ /* the next address within an mm to scan */
+ unsigned long next_addr;
+ /* to batch promoted pages */
+ int nr_pages[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES];
+ /* to batch the mm stats */
+ int mm_stats[NR_MM_STATS];
+ /* total batched items */
+ int batched;
+ bool can_swap;
+ bool force_scan;
+};
+
+void lru_gen_init_lruvec(struct lruvec *lruvec);
+void lru_gen_look_around(struct page_vma_mapped_walk *pvmw);
+
+#ifdef CONFIG_MEMCG
+void lru_gen_init_memcg(struct mem_cgroup *memcg);
+void lru_gen_exit_memcg(struct mem_cgroup *memcg);
+#endif
+
+#else /* !CONFIG_LRU_GEN */
+
+static inline void lru_gen_init_lruvec(struct lruvec *lruvec)
+{
+}
+
+static inline void lru_gen_look_around(struct page_vma_mapped_walk *pvmw)
+{
+}
+
+#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
+
+#endif /* CONFIG_LRU_GEN */
+
struct lruvec {
struct list_head lists[NR_LRU_LISTS];
/* per lruvec lru_lock for memcg */
@@ -333,6 +534,12 @@ struct lruvec {
unsigned long refaults[ANON_AND_FILE];
/* Various lruvec state flags (enum lruvec_flags) */
unsigned long flags;
+#ifdef CONFIG_LRU_GEN
+ /* evictable pages divided into generations */
+ struct lru_gen_struct lrugen;
+ /* to concurrently iterate lru_gen_mm_list */
+ struct lru_gen_mm_state mm_state;
+#endif
#ifdef CONFIG_MEMCG
struct pglist_data *pgdat;
#endif
@@ -748,6 +955,8 @@ static inline bool zone_is_empty(struct zone *zone)
#define ZONES_PGOFF (NODES_PGOFF - ZONES_WIDTH)
#define LAST_CPUPID_PGOFF (ZONES_PGOFF - LAST_CPUPID_WIDTH)
#define KASAN_TAG_PGOFF (LAST_CPUPID_PGOFF - KASAN_TAG_WIDTH)
+#define LRU_GEN_PGOFF (KASAN_TAG_PGOFF - LRU_GEN_WIDTH)
+#define LRU_REFS_PGOFF (LRU_GEN_PGOFF - LRU_REFS_WIDTH)
/*
* Define the bit shifts to access each section. For non-existent
@@ -1026,6 +1235,11 @@ typedef struct pglist_data {
unsigned long flags;
+#ifdef CONFIG_LRU_GEN
+ /* kswap mm walk data */
+ struct lru_gen_mm_walk mm_walk;
+#endif
+
ZONE_PADDING(_pad2_)
/* Per-node vmstats */
diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h
index 0c45fb0..ef7c6fc 100644
--- a/include/linux/nodemask.h
+++ b/include/linux/nodemask.h
@@ -493,6 +493,7 @@ static inline int num_node_state(enum node_states state)
#define first_online_node 0
#define first_memory_node 0
#define next_online_node(nid) (MAX_NUMNODES)
+#define next_memory_node(nid) (MAX_NUMNODES)
#define nr_node_ids 1U
#define nr_online_nodes 1U
diff --git a/include/linux/page-flags-layout.h b/include/linux/page-flags-layout.h
index ef1e3e73..7d79818 100644
--- a/include/linux/page-flags-layout.h
+++ b/include/linux/page-flags-layout.h
@@ -55,7 +55,8 @@
#define SECTIONS_WIDTH 0
#endif
-#if ZONES_WIDTH + SECTIONS_WIDTH + NODES_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS
+#if ZONES_WIDTH + LRU_GEN_WIDTH + SECTIONS_WIDTH + NODES_SHIFT \
+ <= BITS_PER_LONG - NR_PAGEFLAGS
#define NODES_WIDTH NODES_SHIFT
#elif defined(CONFIG_SPARSEMEM_VMEMMAP)
#error "Vmemmap: No space for nodes field in page flags"
@@ -89,8 +90,8 @@
#define LAST_CPUPID_SHIFT 0
#endif
-#if ZONES_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + KASAN_TAG_WIDTH + LAST_CPUPID_SHIFT \
- <= BITS_PER_LONG - NR_PAGEFLAGS
+#if ZONES_WIDTH + LRU_GEN_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + \
+ KASAN_TAG_WIDTH + LAST_CPUPID_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS
#define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT
#else
#define LAST_CPUPID_WIDTH 0
@@ -100,10 +101,15 @@
#define LAST_CPUPID_NOT_IN_PAGE_FLAGS
#endif
-#if ZONES_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + KASAN_TAG_WIDTH + LAST_CPUPID_WIDTH \
- > BITS_PER_LONG - NR_PAGEFLAGS
+#if ZONES_WIDTH + LRU_GEN_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + \
+ KASAN_TAG_WIDTH + LAST_CPUPID_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS
#error "Not enough bits in page flags"
#endif
+/* see the comment on MAX_NR_TIERS */
+#define LRU_REFS_WIDTH min(__LRU_REFS_WIDTH, BITS_PER_LONG - NR_PAGEFLAGS - \
+ ZONES_WIDTH - LRU_GEN_WIDTH - SECTIONS_WIDTH - \
+ NODES_WIDTH - KASAN_TAG_WIDTH - LAST_CPUPID_WIDTH)
+
#endif
#endif /* _LINUX_PAGE_FLAGS_LAYOUT */
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 465ff35..0b0ae50 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -1058,7 +1058,7 @@ static __always_inline void __ClearPageAnonExclusive(struct page *page)
1UL << PG_private | 1UL << PG_private_2 | \
1UL << PG_writeback | 1UL << PG_reserved | \
1UL << PG_slab | 1UL << PG_active | \
- 1UL << PG_unevictable | __PG_MLOCKED)
+ 1UL << PG_unevictable | __PG_MLOCKED | LRU_GEN_MASK)
/*
* Flags checked when a page is prepped for return by the page allocator.
@@ -1069,7 +1069,7 @@ static __always_inline void __ClearPageAnonExclusive(struct page *page)
* alloc-free cycle to prevent from reusing the page.
*/
#define PAGE_FLAGS_CHECK_AT_PREP \
- (PAGEFLAGS_MASK & ~__PG_HWPOISON)
+ ((PAGEFLAGS_MASK & ~__PG_HWPOISON) | LRU_GEN_MASK | LRU_REFS_MASK)
#define PAGE_FLAGS_PRIVATE \
(1UL << PG_private | 1UL << PG_private_2)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 894bce1..02ff3b0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -926,6 +926,10 @@ struct task_struct {
#ifdef CONFIG_MEMCG
unsigned in_user_fault:1;
#endif
+#ifdef CONFIG_LRU_GEN
+ /* whether the LRU algorithm may apply to this access */
+ unsigned in_lru_fault:1;
+#endif
#ifdef CONFIG_COMPAT_BRK
unsigned brk_randomized:1;
#endif
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 43150b9..6308150b 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -162,6 +162,10 @@ union swap_header {
*/
struct reclaim_state {
unsigned long reclaimed_slab;
+#ifdef CONFIG_LRU_GEN
+ /* per-thread mm walk data */
+ struct lru_gen_mm_walk *mm_walk;
+#endif
};
#ifdef __KERNEL__
diff --git a/kernel/bounds.c b/kernel/bounds.c
index 9795d75..b529182 100644
--- a/kernel/bounds.c
+++ b/kernel/bounds.c
@@ -22,6 +22,13 @@ int main(void)
DEFINE(NR_CPUS_BITS, ilog2(CONFIG_NR_CPUS));
#endif
DEFINE(SPINLOCK_SIZE, sizeof(spinlock_t));
+#ifdef CONFIG_LRU_GEN
+ DEFINE(LRU_GEN_WIDTH, order_base_2(MAX_NR_GENS + 1));
+ DEFINE(__LRU_REFS_WIDTH, MAX_NR_TIERS - 2);
+#else
+ DEFINE(LRU_GEN_WIDTH, 0);
+ DEFINE(__LRU_REFS_WIDTH, 0);
+#endif
/* End of constants */
return 0;
diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index 2c7ecca..fd40208 100644
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -164,7 +164,6 @@ struct cgroup_mgctx {
#define DEFINE_CGROUP_MGCTX(name) \
struct cgroup_mgctx name = CGROUP_MGCTX_INIT(name)
-extern struct mutex cgroup_mutex;
extern spinlock_t css_set_lock;
extern struct cgroup_subsys *cgroup_subsys[];
extern struct list_head cgroup_roots;
diff --git a/kernel/exit.c b/kernel/exit.c
index 4b8e7c9..0addd8b 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -466,6 +466,7 @@ void mm_update_next_owner(struct mm_struct *mm)
goto retry;
}
WRITE_ONCE(mm->owner, c);
+ lru_gen_migrate_mm(mm);
task_unlock(c);
put_task_struct(c);
}
diff --git a/kernel/fork.c b/kernel/fork.c
index e654237..326f56f 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1163,6 +1163,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
goto fail_nocontext;
mm->user_ns = get_user_ns(user_ns);
+ lru_gen_init_mm(mm);
return mm;
fail_nocontext:
@@ -1205,6 +1206,7 @@ static inline void __mmput(struct mm_struct *mm)
}
if (mm->binfmt)
module_put(mm->binfmt->module);
+ lru_gen_del_mm(mm);
mmdrop(mm);
}
@@ -2708,6 +2710,13 @@ pid_t kernel_clone(struct kernel_clone_args *args)
get_task_struct(p);
}
+ if (IS_ENABLED(CONFIG_LRU_GEN) && !(clone_flags & CLONE_VM)) {
+ /* lock the task to synchronize with memcg migration */
+ task_lock(p);
+ lru_gen_add_mm(p->mm);
+ task_unlock(p);
+ }
+
wake_up_new_task(p);
/* forking complete and child started to run, tell ptracer */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1aa04a7..16de2fd 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5257,6 +5257,7 @@ context_switch(struct rq *rq, struct task_struct *prev,
* finish_task_switch()'s mmdrop().
*/
switch_mm_irqs_off(prev->active_mm, next->mm, next);
+ lru_gen_use_mm(next->mm);
if (!prev->mm) { // from kernel
/* will mmdrop() in finish_task_switch(). */
diff --git a/mm/Kconfig b/mm/Kconfig
index 39a9195..57e1d8c 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1124,6 +1124,32 @@
purposes. It is required to enable userfaultfd write protection on
file-backed memory types like shmem and hugetlbfs.
+# multi-gen LRU {
+config LRU_GEN
+ bool "Multi-Gen LRU"
+ depends on MMU
+ # make sure folio->flags has enough spare bits
+ depends on 64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP
+ help
+ A high performance LRU implementation to overcommit memory. See
+ Documentation/admin-guide/mm/multigen_lru.rst for details.
+
+config LRU_GEN_ENABLED
+ bool "Enable by default"
+ depends on LRU_GEN
+ help
+ This option enables the multi-gen LRU by default.
+
+config LRU_GEN_STATS
+ bool "Full stats for debugging"
+ depends on LRU_GEN
+ help
+ Do not enable this option unless you plan to look at historical stats
+ from evicted generations for debugging purpose.
+
+ This option has a per-memcg and per-node memory overhead.
+# }
+
source "mm/damon/Kconfig"
endmenu
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index f4a656b..949d7c3 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2444,7 +2444,8 @@ static void __split_huge_page_tail(struct page *head, int tail,
#ifdef CONFIG_64BIT
(1L << PG_arch_2) |
#endif
- (1L << PG_dirty)));
+ (1L << PG_dirty) |
+ LRU_GEN_MASK | LRU_REFS_MASK));
/* ->mapping in first tail page is compound_mapcount */
VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
diff --git a/mm/internal.h b/mm/internal.h
index 55ce10e..cf134d58 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -83,6 +83,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf);
void folio_rotate_reclaimable(struct folio *folio);
bool __folio_end_writeback(struct folio *folio);
void deactivate_file_folio(struct folio *folio);
+void folio_activate(struct folio *folio);
void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
unsigned long floor, unsigned long ceiling);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 29aeaf3..8dd24e5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2783,6 +2783,7 @@ static void commit_charge(struct folio *folio, struct mem_cgroup *memcg)
* - LRU isolation
* - lock_page_memcg()
* - exclusive reference
+ * - mem_cgroup_trylock_pages()
*/
folio->memcg_data = (unsigned long)memcg;
}
@@ -5169,6 +5170,7 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg)
static void mem_cgroup_free(struct mem_cgroup *memcg)
{
+ lru_gen_exit_memcg(memcg);
memcg_wb_domain_exit(memcg);
__mem_cgroup_free(memcg);
}
@@ -5227,6 +5229,7 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
memcg->deferred_split_queue.split_queue_len = 0;
#endif
idr_replace(&mem_cgroup_idr, memcg, memcg->id.id);
+ lru_gen_init_memcg(memcg);
return memcg;
fail:
mem_cgroup_id_remove(memcg);
@@ -6195,6 +6198,30 @@ static void mem_cgroup_move_task(void)
}
#endif
+#ifdef CONFIG_LRU_GEN
+static void mem_cgroup_attach(struct cgroup_taskset *tset)
+{
+ struct task_struct *task;
+ struct cgroup_subsys_state *css;
+
+ /* find the first leader if there is any */
+ cgroup_taskset_for_each_leader(task, css, tset)
+ break;
+
+ if (!task)
+ return;
+
+ task_lock(task);
+ if (task->mm && READ_ONCE(task->mm->owner) == task)
+ lru_gen_migrate_mm(task->mm);
+ task_unlock(task);
+}
+#else
+static void mem_cgroup_attach(struct cgroup_taskset *tset)
+{
+}
+#endif /* CONFIG_LRU_GEN */
+
static int seq_puts_memcg_tunable(struct seq_file *m, unsigned long value)
{
if (value == PAGE_COUNTER_MAX)
@@ -6600,6 +6627,7 @@ struct cgroup_subsys memory_cgrp_subsys = {
.css_reset = mem_cgroup_css_reset,
.css_rstat_flush = mem_cgroup_css_rstat_flush,
.can_attach = mem_cgroup_can_attach,
+ .attach = mem_cgroup_attach,
.cancel_attach = mem_cgroup_cancel_attach,
.post_attach = mem_cgroup_move_task,
.dfl_cftypes = memory_files,
diff --git a/mm/memory.c b/mm/memory.c
index 6755855c..2be6855 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5118,6 +5118,27 @@ static inline void mm_account_fault(struct pt_regs *regs,
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
}
+#ifdef CONFIG_LRU_GEN
+static void lru_gen_enter_fault(struct vm_area_struct *vma)
+{
+ /* the LRU algorithm doesn't apply to sequential or random reads */
+ current->in_lru_fault = !(vma->vm_flags & (VM_SEQ_READ | VM_RAND_READ));
+}
+
+static void lru_gen_exit_fault(void)
+{
+ current->in_lru_fault = false;
+}
+#else
+static void lru_gen_enter_fault(struct vm_area_struct *vma)
+{
+}
+
+static void lru_gen_exit_fault(void)
+{
+}
+#endif /* CONFIG_LRU_GEN */
+
/*
* By the time we get here, we already hold the mm semaphore
*
@@ -5149,11 +5170,15 @@ vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
if (flags & FAULT_FLAG_USER)
mem_cgroup_enter_user_fault();
+ lru_gen_enter_fault(vma);
+
if (unlikely(is_vm_hugetlb_page(vma)))
ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
else
ret = __handle_mm_fault(vma, address, flags);
+ lru_gen_exit_fault();
+
if (flags & FAULT_FLAG_USER) {
mem_cgroup_exit_user_fault();
/*
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 9ddaf0e1..0d7b2bd 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -65,14 +65,16 @@ void __init mminit_verify_pageflags_layout(void)
shift = 8 * sizeof(unsigned long);
width = shift - SECTIONS_WIDTH - NODES_WIDTH - ZONES_WIDTH
- - LAST_CPUPID_SHIFT - KASAN_TAG_WIDTH;
+ - LAST_CPUPID_SHIFT - KASAN_TAG_WIDTH - LRU_GEN_WIDTH - LRU_REFS_WIDTH;
mminit_dprintk(MMINIT_TRACE, "pageflags_layout_widths",
- "Section %d Node %d Zone %d Lastcpupid %d Kasantag %d Flags %d\n",
+ "Section %d Node %d Zone %d Lastcpupid %d Kasantag %d Gen %d Tier %d Flags %d\n",
SECTIONS_WIDTH,
NODES_WIDTH,
ZONES_WIDTH,
LAST_CPUPID_WIDTH,
KASAN_TAG_WIDTH,
+ LRU_GEN_WIDTH,
+ LRU_REFS_WIDTH,
NR_PAGEFLAGS);
mminit_dprintk(MMINIT_TRACE, "pageflags_layout_shifts",
"Section %d Node %d Zone %d Lastcpupid %d Kasantag %d\n",
diff --git a/mm/mmzone.c b/mm/mmzone.c
index 0ae7571..68e1511b 100644
--- a/mm/mmzone.c
+++ b/mm/mmzone.c
@@ -88,6 +88,8 @@ void lruvec_init(struct lruvec *lruvec)
* Poison its list head, so that any operations on it would crash.
*/
list_del(&lruvec->lists[LRU_UNEVICTABLE]);
+
+ lru_gen_init_lruvec(lruvec);
}
#if defined(CONFIG_NUMA_BALANCING) && !defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS)
diff --git a/mm/rmap.c b/mm/rmap.c
index 98ecdb9..baff14b1 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -828,6 +828,12 @@ static bool folio_referenced_one(struct folio *folio,
}
if (pvmw.pte) {
+ if (lru_gen_enabled() && pte_young(*pvmw.pte) &&
+ !(vma->vm_flags & (VM_SEQ_READ | VM_RAND_READ))) {
+ lru_gen_look_around(&pvmw);
+ referenced++;
+ }
+
if (ptep_clear_flush_young_notify(vma, address,
pvmw.pte)) {
/*
diff --git a/mm/swap.c b/mm/swap.c
index 9cee7f6..0a3871a 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -366,7 +366,7 @@ static void folio_activate_drain(int cpu)
folio_batch_move_lru(fbatch, folio_activate_fn);
}
-static void folio_activate(struct folio *folio)
+void folio_activate(struct folio *folio)
{
if (folio_test_lru(folio) && !folio_test_active(folio) &&
!folio_test_unevictable(folio)) {
@@ -385,7 +385,7 @@ static inline void folio_activate_drain(int cpu)
{
}
-static void folio_activate(struct folio *folio)
+void folio_activate(struct folio *folio)
{
struct lruvec *lruvec;
@@ -428,6 +428,40 @@ static void __lru_cache_activate_folio(struct folio *folio)
local_unlock(&cpu_fbatches.lock);
}
+#ifdef CONFIG_LRU_GEN
+static void folio_inc_refs(struct folio *folio)
+{
+ unsigned long new_flags, old_flags = READ_ONCE(folio->flags);
+
+ if (folio_test_unevictable(folio))
+ return;
+
+ if (!folio_test_referenced(folio)) {
+ folio_set_referenced(folio);
+ return;
+ }
+
+ if (!folio_test_workingset(folio)) {
+ folio_set_workingset(folio);
+ return;
+ }
+
+ /* see the comment on MAX_NR_TIERS */
+ do {
+ new_flags = old_flags & LRU_REFS_MASK;
+ if (new_flags == LRU_REFS_MASK)
+ break;
+
+ new_flags += BIT(LRU_REFS_PGOFF);
+ new_flags |= old_flags & ~LRU_REFS_MASK;
+ } while (!try_cmpxchg(&folio->flags, &old_flags, new_flags));
+}
+#else
+static void folio_inc_refs(struct folio *folio)
+{
+}
+#endif /* CONFIG_LRU_GEN */
+
/*
* Mark a page as having seen activity.
*
@@ -440,6 +474,11 @@ static void __lru_cache_activate_folio(struct folio *folio)
*/
void folio_mark_accessed(struct folio *folio)
{
+ if (lru_gen_enabled()) {
+ folio_inc_refs(folio);
+ return;
+ }
+
if (!folio_test_referenced(folio)) {
folio_set_referenced(folio);
} else if (folio_test_unevictable(folio)) {
@@ -484,6 +523,11 @@ void folio_add_lru(struct folio *folio)
folio_test_unevictable(folio), folio);
VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
+ /* see the comment in lru_gen_add_folio() */
+ if (lru_gen_enabled() && !folio_test_unevictable(folio) &&
+ lru_gen_in_fault() && !(current->flags & PF_MEMALLOC))
+ folio_set_active(folio);
+
folio_get(folio);
local_lock(&cpu_fbatches.lock);
fbatch = this_cpu_ptr(&cpu_fbatches.lru_add);
@@ -575,7 +619,7 @@ static void lru_deactivate_file_fn(struct lruvec *lruvec, struct folio *folio)
static void lru_deactivate_fn(struct lruvec *lruvec, struct folio *folio)
{
- if (folio_test_active(folio) && !folio_test_unevictable(folio)) {
+ if (!folio_test_unevictable(folio) && (folio_test_active(folio) || lru_gen_enabled())) {
long nr_pages = folio_nr_pages(folio);
lruvec_del_folio(lruvec, folio);
@@ -688,8 +732,8 @@ void deactivate_page(struct page *page)
{
struct folio *folio = page_folio(page);
- if (folio_test_lru(folio) && folio_test_active(folio) &&
- !folio_test_unevictable(folio)) {
+ if (folio_test_lru(folio) && !folio_test_unevictable(folio) &&
+ (folio_test_active(folio) || lru_gen_enabled())) {
struct folio_batch *fbatch;
folio_get(folio);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index ca1c208..4ce1ed6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -49,6 +49,10 @@
#include <linux/printk.h>
#include <linux/dax.h>
#include <linux/psi.h>
+#include <linux/pagewalk.h>
+#include <linux/shmem_fs.h>
+#include <linux/ctype.h>
+#include <linux/debugfs.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
@@ -132,6 +136,12 @@ struct scan_control {
/* 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 int memcgs_need_aging:1;
+ unsigned long last_reclaimed;
+#endif
+
/* Allocation order */
s8 order;
@@ -1337,9 +1347,11 @@ static int __remove_mapping(struct address_space *mapping, struct folio *folio,
if (folio_test_swapcache(folio)) {
swp_entry_t swap = folio_swap_entry(folio);
- mem_cgroup_swapout(folio, swap);
+
+ /* get a shadow entry before mem_cgroup_swapout() clears folio_memcg() */
if (reclaimed && !mapping_exiting(mapping))
shadow = workingset_eviction(folio, target_memcg);
+ mem_cgroup_swapout(folio, swap);
__delete_from_swap_cache(folio, swap, shadow);
xa_unlock_irq(&mapping->i_pages);
put_swap_page(&folio->page, swap);
@@ -1636,6 +1648,11 @@ static unsigned int shrink_page_list(struct list_head *page_list,
if (!sc->may_unmap && folio_mapped(folio))
goto keep_locked;
+ /* folio_update_gen() tried to promote this page? */
+ if (lru_gen_enabled() && !ignore_references &&
+ folio_mapped(folio) && folio_test_referenced(folio))
+ goto keep_locked;
+
/*
* The number of dirty pages determines if a node is marked
* reclaim_congested. kswapd will stall and start writing
@@ -2736,6 +2753,9 @@ static void prepare_scan_count(pg_data_t *pgdat, struct scan_control *sc)
unsigned long file;
struct lruvec *target_lruvec;
+ if (lru_gen_enabled())
+ return;
+
target_lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup, pgdat);
/*
@@ -3058,6 +3078,2756 @@ static bool can_age_anon_pages(struct pglist_data *pgdat,
return can_demote(pgdat->node_id, sc);
}
+#ifdef CONFIG_LRU_GEN
+
+#ifdef CONFIG_LRU_GEN_ENABLED
+DEFINE_STATIC_KEY_ARRAY_TRUE(lru_gen_caps, NR_LRU_GEN_CAPS);
+#define get_cap(cap) static_branch_likely(&lru_gen_caps[cap])
+#else
+DEFINE_STATIC_KEY_ARRAY_FALSE(lru_gen_caps, NR_LRU_GEN_CAPS);
+#define get_cap(cap) static_branch_unlikely(&lru_gen_caps[cap])
+#endif
+
+/******************************************************************************
+ * shorthand helpers
+ ******************************************************************************/
+
+#define LRU_REFS_FLAGS (BIT(PG_referenced) | BIT(PG_workingset))
+
+#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 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_WARN_ON_ONCE(!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);
+ struct pglist_data *pgdat = lruvec_pgdat(lruvec);
+
+ if (!can_demote(pgdat->node_id, sc) &&
+ 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_WARN_ON_ONCE(!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_WARN_ON_ONCE(!list_empty(&mm->lru_gen.list));
+#ifdef CONFIG_MEMCG
+ VM_WARN_ON_ONCE(mm->lru_gen.memcg);
+ 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;
+
+ /* the first addition since the last iteration */
+ 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;
+
+ /* where the last iteration ended (exclusive) */
+ if (lruvec->mm_state.tail == &mm->lru_gen.list)
+ lruvec->mm_state.tail = lruvec->mm_state.tail->next;
+
+ /* where the current iteration continues (inclusive) */
+ if (lruvec->mm_state.head != &mm->lru_gen.list)
+ continue;
+
+ lruvec->mm_state.head = lruvec->mm_state.head->next;
+ /* the deletion ends the current iteration */
+ 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;
+ struct task_struct *task = rcu_dereference_protected(mm->owner, true);
+
+ VM_WARN_ON_ONCE(task->mm != mm);
+ lockdep_assert_held(&task->alloc_lock);
+
+ /* for mm_update_next_owner() */
+ if (mem_cgroup_disabled())
+ return;
+
+ rcu_read_lock();
+ memcg = mem_cgroup_from_task(task);
+ rcu_read_unlock();
+ if (memcg == mm->lru_gen.memcg)
+ return;
+
+ VM_WARN_ON_ONCE(!mm->lru_gen.memcg);
+ VM_WARN_ON_ONCE(list_empty(&mm->lru_gen.list));
+
+ 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);
+
+ 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_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN);
+ 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);
+ int key = pgdat->node_id % BITS_PER_TYPE(mm->lru_gen.bitmap);
+
+ if (!walk->force_scan && !test_bit(key, &mm->lru_gen.bitmap))
+ return true;
+
+ clear_bit(key, &mm->lru_gen.bitmap);
+
+ 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;
+
+ 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 left to do.
+ * 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.
+ */
+ spin_lock(&mm_list->lock);
+
+ VM_WARN_ON_ONCE(mm_state->seq + 1 < walk->max_seq);
+ VM_WARN_ON_ONCE(*iter && mm_state->seq > walk->max_seq);
+ VM_WARN_ON_ONCE(*iter && !mm_state->nr_walkers);
+
+ if (walk->max_seq <= mm_state->seq) {
+ if (!*iter)
+ last = false;
+ goto done;
+ }
+
+ if (!mm_state->nr_walkers) {
+ VM_WARN_ON_ONCE(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;
+
+ /* force 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->force_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 (*iter || last)
+ reset_mm_stats(lruvec, walk, last);
+
+ spin_unlock(&mm_list->lock);
+
+ if (mm && first)
+ reset_bloom_filter(lruvec, walk->max_seq + 1);
+
+ if (*iter)
+ mmput_async(*iter);
+
+ *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;
+
+ spin_lock(&mm_list->lock);
+
+ VM_WARN_ON_ONCE(mm_state->seq + 1 < max_seq);
+
+ if (max_seq > mm_state->seq && !mm_state->nr_walkers) {
+ VM_WARN_ON_ONCE(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 to
+ * turn off protection when SP>PV or turn on protection when SP<PV.
+ *
+ * For future optimizations:
+ * 1. The D term may discount the other two terms over time so that long-lived
+ * generations can resist stale information.
+ */
+struct ctrl_pos {
+ unsigned long refaulted;
+ unsigned long total;
+ int gain;
+};
+
+static void read_ctrl_pos(struct lruvec *lruvec, int type, int tier, int gain,
+ struct ctrl_pos *pos)
+{
+ struct lru_gen_struct *lrugen = &lruvec->lrugen;
+ 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->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
+ ******************************************************************************/
+
+/* promote pages accessed through page tables */
+static int folio_update_gen(struct folio *folio, int gen)
+{
+ unsigned long new_flags, old_flags = READ_ONCE(folio->flags);
+
+ VM_WARN_ON_ONCE(gen >= MAX_NR_GENS);
+ VM_WARN_ON_ONCE(!rcu_read_lock_held());
+
+ do {
+ /* lru_gen_del_folio() has isolated this page? */
+ if (!(old_flags & LRU_GEN_MASK)) {
+ /* for shrink_page_list() */
+ new_flags = old_flags | BIT(PG_referenced);
+ continue;
+ }
+
+ new_flags = old_flags & ~(LRU_GEN_MASK | LRU_REFS_MASK | LRU_REFS_FLAGS);
+ new_flags |= (gen + 1UL) << LRU_GEN_PGOFF;
+ } while (!try_cmpxchg(&folio->flags, &old_flags, new_flags));
+
+ return ((old_flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1;
+}
+
+/* protect pages accessed multiple times through file descriptors */
+static int folio_inc_gen(struct lruvec *lruvec, struct folio *folio, bool reclaiming)
+{
+ int type = folio_is_file_lru(folio);
+ struct lru_gen_struct *lrugen = &lruvec->lrugen;
+ int new_gen, old_gen = lru_gen_from_seq(lrugen->min_seq[type]);
+ unsigned long new_flags, old_flags = READ_ONCE(folio->flags);
+
+ VM_WARN_ON_ONCE_FOLIO(!(old_flags & LRU_GEN_MASK), folio);
+
+ do {
+ new_gen = ((old_flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1;
+ /* folio_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 = old_flags & ~(LRU_GEN_MASK | LRU_REFS_MASK | LRU_REFS_FLAGS);
+ new_flags |= (new_gen + 1UL) << LRU_GEN_PGOFF;
+ /* for folio_end_writeback() */
+ if (reclaiming)
+ new_flags |= BIT(PG_reclaim);
+ } while (!try_cmpxchg(&folio->flags, &old_flags, new_flags));
+
+ lru_gen_update_size(lruvec, folio, old_gen, new_gen);
+
+ return new_gen;
+}
+
+static void update_batch_size(struct lru_gen_mm_walk *walk, struct folio *folio,
+ int old_gen, int new_gen)
+{
+ int type = folio_is_file_lru(folio);
+ int zone = folio_zonenum(folio);
+ int delta = folio_nr_pages(folio);
+
+ VM_WARN_ON_ONCE(old_gen >= MAX_NR_GENS);
+ VM_WARN_ON_ONCE(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 *args)
+{
+ struct address_space *mapping;
+ struct vm_area_struct *vma = args->vma;
+ struct lru_gen_mm_walk *walk = args->private;
+
+ if (!vma_is_accessible(vma))
+ return true;
+
+ if (is_vm_hugetlb_page(vma))
+ return true;
+
+ if (vma->vm_flags & (VM_LOCKED | VM_SPECIAL | VM_SEQ_READ | VM_RAND_READ))
+ return true;
+
+ if (vma == get_gate_vma(vma->vm_mm))
+ return true;
+
+ if (vma_is_anonymous(vma))
+ return !walk->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;
+
+ if (shmem_mapping(mapping))
+ return !walk->can_swap;
+
+ /* to exclude special mappings like dax, etc. */
+ return !mapping->a_ops->read_folio;
+}
+
+/*
+ * 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(unsigned long mask, unsigned long size, struct mm_walk *args,
+ unsigned long *vm_start, unsigned long *vm_end)
+{
+ unsigned long start = round_up(*vm_end, size);
+ unsigned long end = (start | ~mask) + 1;
+
+ VM_WARN_ON_ONCE(mask & size);
+ VM_WARN_ON_ONCE((start & mask) != (*vm_start & mask));
+
+ while (args->vma) {
+ if (start >= args->vma->vm_end) {
+ args->vma = args->vma->vm_next;
+ continue;
+ }
+
+ if (end && end <= args->vma->vm_start)
+ return false;
+
+ if (should_skip_vma(args->vma->vm_start, args->vma->vm_end, args)) {
+ args->vma = args->vma->vm_next;
+ continue;
+ }
+
+ *vm_start = max(start, args->vma->vm_start);
+ *vm_end = min(end - 1, args->vma->vm_end - 1) + 1;
+
+ return true;
+ }
+
+ return false;
+}
+
+static unsigned long get_pte_pfn(pte_t pte, struct vm_area_struct *vma, unsigned long addr)
+{
+ unsigned long pfn = pte_pfn(pte);
+
+ VM_WARN_ON_ONCE(addr < vma->vm_start || addr >= vma->vm_end);
+
+ if (!pte_present(pte) || is_zero_pfn(pfn))
+ return -1;
+
+ if (WARN_ON_ONCE(pte_devmap(pte) || pte_special(pte)))
+ return -1;
+
+ if (WARN_ON_ONCE(!pfn_valid(pfn)))
+ return -1;
+
+ return pfn;
+}
+
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG)
+static unsigned long get_pmd_pfn(pmd_t pmd, struct vm_area_struct *vma, unsigned long addr)
+{
+ unsigned long pfn = pmd_pfn(pmd);
+
+ VM_WARN_ON_ONCE(addr < vma->vm_start || addr >= vma->vm_end);
+
+ if (!pmd_present(pmd) || is_huge_zero_pmd(pmd))
+ return -1;
+
+ if (WARN_ON_ONCE(pmd_devmap(pmd)))
+ return -1;
+
+ if (WARN_ON_ONCE(!pfn_valid(pfn)))
+ return -1;
+
+ return pfn;
+}
+#endif
+
+static struct folio *get_pfn_folio(unsigned long pfn, struct mem_cgroup *memcg,
+ struct pglist_data *pgdat, bool can_swap)
+{
+ struct folio *folio;
+
+ /* try to avoid unnecessary memory loads */
+ if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat))
+ return NULL;
+
+ folio = pfn_folio(pfn);
+ if (folio_nid(folio) != pgdat->node_id)
+ return NULL;
+
+ if (folio_memcg_rcu(folio) != memcg)
+ return NULL;
+
+ /* file VMAs can contain anon pages from COW */
+ if (!folio_is_file_lru(folio) && !can_swap)
+ return NULL;
+
+ return folio;
+}
+
+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 *args)
+{
+ int i;
+ pte_t *pte;
+ spinlock_t *ptl;
+ unsigned long addr;
+ int total = 0;
+ int young = 0;
+ struct lru_gen_mm_walk *walk = args->private;
+ struct mem_cgroup *memcg = lruvec_memcg(walk->lruvec);
+ struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec);
+ int old_gen, new_gen = lru_gen_from_seq(walk->max_seq);
+
+ VM_WARN_ON_ONCE(pmd_leaf(*pmd));
+
+ ptl = pte_lockptr(args->mm, pmd);
+ if (!spin_trylock(ptl))
+ return false;
+
+ arch_enter_lazy_mmu_mode();
+
+ pte = pte_offset_map(pmd, start & PMD_MASK);
+restart:
+ for (i = pte_index(start), addr = start; addr != end; i++, addr += PAGE_SIZE) {
+ unsigned long pfn;
+ struct folio *folio;
+
+ total++;
+ walk->mm_stats[MM_LEAF_TOTAL]++;
+
+ pfn = get_pte_pfn(pte[i], args->vma, addr);
+ if (pfn == -1)
+ continue;
+
+ if (!pte_young(pte[i])) {
+ walk->mm_stats[MM_LEAF_OLD]++;
+ continue;
+ }
+
+ folio = get_pfn_folio(pfn, memcg, pgdat, walk->can_swap);
+ if (!folio)
+ continue;
+
+ if (!ptep_test_and_clear_young(args->vma, addr, pte + i))
+ VM_WARN_ON_ONCE(true);
+
+ young++;
+ walk->mm_stats[MM_LEAF_YOUNG]++;
+
+ if (pte_dirty(pte[i]) && !folio_test_dirty(folio) &&
+ !(folio_test_anon(folio) && folio_test_swapbacked(folio) &&
+ !folio_test_swapcache(folio)))
+ folio_mark_dirty(folio);
+
+ old_gen = folio_update_gen(folio, new_gen);
+ if (old_gen >= 0 && old_gen != new_gen)
+ update_batch_size(walk, folio, old_gen, new_gen);
+ }
+
+ if (i < PTRS_PER_PTE && get_next_vma(PMD_MASK, PAGE_SIZE, args, &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 *args, unsigned long *bitmap, unsigned long *start)
+{
+ int i;
+ pmd_t *pmd;
+ spinlock_t *ptl;
+ struct lru_gen_mm_walk *walk = args->private;
+ struct mem_cgroup *memcg = lruvec_memcg(walk->lruvec);
+ struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec);
+ int old_gen, new_gen = lru_gen_from_seq(walk->max_seq);
+
+ VM_WARN_ON_ONCE(pud_leaf(*pud));
+
+ /* try to batch at most 1+MIN_LRU_BATCH+1 entries */
+ if (*start == -1) {
+ *start = next;
+ return;
+ }
+
+ i = next == -1 ? 0 : pmd_index(next) - pmd_index(*start);
+ if (i && i <= MIN_LRU_BATCH) {
+ __set_bit(i - 1, bitmap);
+ return;
+ }
+
+ pmd = pmd_offset(pud, *start);
+
+ ptl = pmd_lockptr(args->mm, pmd);
+ if (!spin_trylock(ptl))
+ goto done;
+
+ arch_enter_lazy_mmu_mode();
+
+ do {
+ unsigned long pfn;
+ struct folio *folio;
+ unsigned long addr = i ? (*start & PMD_MASK) + i * PMD_SIZE : *start;
+
+ pfn = get_pmd_pfn(pmd[i], vma, addr);
+ if (pfn == -1)
+ 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;
+ }
+
+ folio = get_pfn_folio(pfn, memcg, pgdat, walk->can_swap);
+ if (!folio)
+ goto next;
+
+ if (!pmdp_test_and_clear_young(vma, addr, pmd + i))
+ goto next;
+
+ walk->mm_stats[MM_LEAF_YOUNG]++;
+
+ if (pmd_dirty(pmd[i]) && !folio_test_dirty(folio) &&
+ !(folio_test_anon(folio) && folio_test_swapbacked(folio) &&
+ !folio_test_swapcache(folio)))
+ folio_mark_dirty(folio);
+
+ old_gen = folio_update_gen(folio, new_gen);
+ if (old_gen >= 0 && old_gen != new_gen)
+ update_batch_size(walk, folio, old_gen, new_gen);
+next:
+ i = i > MIN_LRU_BATCH ? 0 : find_next_bit(bitmap, MIN_LRU_BATCH, i) + 1;
+ } while (i <= MIN_LRU_BATCH);
+
+ arch_leave_lazy_mmu_mode();
+ spin_unlock(ptl);
+done:
+ *start = -1;
+ bitmap_zero(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 *args, unsigned long *bitmap, unsigned long *start)
+{
+}
+#endif
+
+static void walk_pmd_range(pud_t *pud, unsigned long start, unsigned long end,
+ struct mm_walk *args)
+{
+ 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 *walk = args->private;
+ unsigned long bitmap[BITS_TO_LONGS(MIN_LRU_BATCH)] = {};
+
+ VM_WARN_ON_ONCE(pud_leaf(*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 = args->vma;
+ for (i = pmd_index(start), 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) || is_huge_zero_pmd(val)) {
+ walk->mm_stats[MM_LEAF_TOTAL]++;
+ continue;
+ }
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ if (pmd_trans_huge(val)) {
+ unsigned long pfn = pmd_pfn(val);
+ struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec);
+
+ walk->mm_stats[MM_LEAF_TOTAL]++;
+
+ if (!pmd_young(val)) {
+ walk->mm_stats[MM_LEAF_OLD]++;
+ continue;
+ }
+
+ /* try to avoid unnecessary memory loads */
+ if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat))
+ continue;
+
+ walk_pmd_range_locked(pud, addr, vma, args, bitmap, &pos);
+ continue;
+ }
+#endif
+ walk->mm_stats[MM_NONLEAF_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, args, bitmap, &pos);
+ }
+#endif
+ if (!walk->force_scan && !test_bloom_filter(walk->lruvec, walk->max_seq, pmd + i))
+ continue;
+
+ walk->mm_stats[MM_NONLEAF_FOUND]++;
+
+ if (!walk_pte_range(&val, addr, next, args))
+ continue;
+
+ walk->mm_stats[MM_NONLEAF_ADDED]++;
+
+ /* carry over to the next generation */
+ update_bloom_filter(walk->lruvec, walk->max_seq + 1, pmd + i);
+ }
+
+ walk_pmd_range_locked(pud, -1, vma, args, bitmap, &pos);
+
+ if (i < PTRS_PER_PMD && get_next_vma(PUD_MASK, PMD_SIZE, args, &start, &end))
+ goto restart;
+}
+
+static int walk_pud_range(p4d_t *p4d, unsigned long start, unsigned long end,
+ struct mm_walk *args)
+{
+ int i;
+ pud_t *pud;
+ unsigned long addr;
+ unsigned long next;
+ struct lru_gen_mm_walk *walk = args->private;
+
+ VM_WARN_ON_ONCE(p4d_leaf(*p4d));
+
+ pud = pud_offset(p4d, start & P4D_MASK);
+restart:
+ for (i = pud_index(start), 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_leaf(val)))
+ continue;
+
+ walk_pmd_range(&val, addr, next, args);
+
+ /* a racy check to curtail the waiting time */
+ if (wq_has_sleeper(&walk->lruvec->mm_state.wait))
+ return 1;
+
+ if (need_resched() || walk->batched >= MAX_LRU_BATCH) {
+ end = (addr | ~PUD_MASK) + 1;
+ goto done;
+ }
+ }
+
+ if (i < PTRS_PER_PUD && get_next_vma(P4D_MASK, PUD_SIZE, args, &start, &end))
+ goto restart;
+
+ end = round_up(end, P4D_SIZE);
+done:
+ if (!end || !args->vma)
+ return 1;
+
+ walk->next_addr = max(end, args->vma->vm_start);
+
+ return -EAGAIN;
+}
+
+static void walk_mm(struct lruvec *lruvec, struct mm_struct *mm, struct lru_gen_mm_walk *walk)
+{
+ static const struct mm_walk_ops mm_walk_ops = {
+ .test_walk = should_skip_vma,
+ .p4d_entry = walk_pud_range,
+ };
+
+ int err;
+ struct mem_cgroup *memcg = lruvec_memcg(lruvec);
+
+ walk->next_addr = FIRST_USER_ADDRESS;
+
+ do {
+ err = -EBUSY;
+
+ /* folio_update_gen() requires stable folio_memcg() */
+ if (!mem_cgroup_trylock_pages(memcg))
+ break;
+
+ /* the caller might be holding the lock for write */
+ if (mmap_read_trylock(mm)) {
+ err = walk_page_range(mm, walk->next_addr, ULONG_MAX, &mm_walk_ops, walk);
+
+ mmap_read_unlock(mm);
+ }
+
+ mem_cgroup_unlock_pages();
+
+ if (walk->batched) {
+ spin_lock_irq(&lruvec->lru_lock);
+ reset_batch_size(lruvec, walk);
+ spin_unlock_irq(&lruvec->lru_lock);
+ }
+
+ cond_resched();
+ } while (err == -EAGAIN);
+}
+
+static struct lru_gen_mm_walk *set_mm_walk(struct pglist_data *pgdat)
+{
+ struct lru_gen_mm_walk *walk = current->reclaim_state->mm_walk;
+
+ if (pgdat && current_is_kswapd()) {
+ VM_WARN_ON_ONCE(walk);
+
+ walk = &pgdat->mm_walk;
+ } else if (!pgdat && !walk) {
+ VM_WARN_ON_ONCE(current_is_kswapd());
+
+ walk = kzalloc(sizeof(*walk), __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN);
+ }
+
+ current->reclaim_state->mm_walk = walk;
+
+ return walk;
+}
+
+static void clear_mm_walk(void)
+{
+ struct lru_gen_mm_walk *walk = current->reclaim_state->mm_walk;
+
+ VM_WARN_ON_ONCE(walk && memchr_inv(walk->nr_pages, 0, sizeof(walk->nr_pages)));
+ VM_WARN_ON_ONCE(walk && memchr_inv(walk->mm_stats, 0, sizeof(walk->mm_stats)));
+
+ current->reclaim_state->mm_walk = NULL;
+
+ if (!current_is_kswapd())
+ kfree(walk);
+}
+
+static bool inc_min_seq(struct lruvec *lruvec, int type, bool can_swap)
+{
+ int zone;
+ int remaining = MAX_LRU_BATCH;
+ struct lru_gen_struct *lrugen = &lruvec->lrugen;
+ int new_gen, old_gen = lru_gen_from_seq(lrugen->min_seq[type]);
+
+ if (type == LRU_GEN_ANON && !can_swap)
+ goto done;
+
+ /* prevent cold/hot inversion if force_scan is true */
+ for (zone = 0; zone < MAX_NR_ZONES; zone++) {
+ struct list_head *head = &lrugen->lists[old_gen][type][zone];
+
+ while (!list_empty(head)) {
+ struct folio *folio = lru_to_folio(head);
+
+ VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio);
+ VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio), folio);
+ VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio);
+ VM_WARN_ON_ONCE_FOLIO(folio_zonenum(folio) != zone, folio);
+
+ new_gen = folio_inc_gen(lruvec, folio, false);
+ list_move_tail(&folio->lru, &lrugen->lists[new_gen][type][zone]);
+
+ if (!--remaining)
+ return false;
+ }
+ }
+done:
+ reset_ctrl_pos(lruvec, type, true);
+ WRITE_ONCE(lrugen->min_seq[type], lrugen->min_seq[type] + 1);
+
+ return true;
+}
+
+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_WARN_ON_ONCE(!seq_is_valid(lruvec));
+
+ /* find the oldest populated generation */
+ 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, bool can_swap, bool force_scan)
+{
+ int prev, next;
+ int type, zone;
+ struct lru_gen_struct *lrugen = &lruvec->lrugen;
+
+ spin_lock_irq(&lruvec->lru_lock);
+
+ VM_WARN_ON_ONCE(!seq_is_valid(lruvec));
+
+ for (type = ANON_AND_FILE - 1; type >= 0; type--) {
+ if (get_nr_gens(lruvec, type) != MAX_NR_GENS)
+ continue;
+
+ VM_WARN_ON_ONCE(!force_scan && (type == LRU_GEN_FILE || can_swap));
+
+ while (!inc_min_seq(lruvec, type, can_swap)) {
+ spin_unlock_irq(&lruvec->lru_lock);
+ cond_resched();
+ spin_lock_irq(&lruvec->lru_lock);
+ }
+ }
+
+ /*
+ * 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.
+ */
+ 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;
+
+ __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(&lruvec->lru_lock);
+}
+
+static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long max_seq,
+ struct scan_control *sc, bool can_swap, bool force_scan)
+{
+ bool success;
+ struct lru_gen_mm_walk *walk;
+ struct mm_struct *mm = NULL;
+ struct lru_gen_struct *lrugen = &lruvec->lrugen;
+
+ VM_WARN_ON_ONCE(max_seq > READ_ONCE(lrugen->max_seq));
+
+ /* see the comment in iterate_mm_list() */
+ if (max_seq <= READ_ONCE(lruvec->mm_state.seq)) {
+ success = false;
+ goto done;
+ }
+
+ /*
+ * 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 (!force_scan && !(arch_has_hw_pte_young() && get_cap(LRU_GEN_MM_WALK))) {
+ success = iterate_mm_list_nowalk(lruvec, max_seq);
+ goto done;
+ }
+
+ walk = set_mm_walk(NULL);
+ 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->force_scan = force_scan;
+
+ do {
+ success = iterate_mm_list(lruvec, walk, &mm);
+ if (mm)
+ walk_mm(lruvec, mm, walk);
+
+ cond_resched();
+ } while (mm);
+done:
+ if (!success) {
+ 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);
+ }
+
+ VM_WARN_ON_ONCE(max_seq != READ_ONCE(lrugen->max_seq));
+
+ inc_max_seq(lruvec, can_swap, force_scan);
+ /* 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 bool should_run_aging(struct lruvec *lruvec, unsigned long max_seq, unsigned long *min_seq,
+ struct scan_control *sc, bool can_swap, unsigned long *nr_to_scan)
+{
+ int gen, type, zone;
+ unsigned long old = 0;
+ unsigned long young = 0;
+ unsigned long total = 0;
+ struct lru_gen_struct *lrugen = &lruvec->lrugen;
+ struct mem_cgroup *memcg = lruvec_memcg(lruvec);
+
+ for (type = !can_swap; type < ANON_AND_FILE; type++) {
+ unsigned long seq;
+
+ for (seq = min_seq[type]; seq <= max_seq; seq++) {
+ unsigned long size = 0;
+
+ gen = lru_gen_from_seq(seq);
+
+ for (zone = 0; zone < MAX_NR_ZONES; zone++)
+ size += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L);
+
+ total += size;
+ if (seq == max_seq)
+ young += size;
+ else if (seq + MIN_NR_GENS == max_seq)
+ old += size;
+ }
+ }
+
+ /* try to scrape all its memory if this memcg was deleted */
+ *nr_to_scan = mem_cgroup_online(memcg) ? (total >> sc->priority) : total;
+
+ /*
+ * The aging tries to be lazy to reduce the overhead, while the eviction
+ * stalls when the number of generations reaches MIN_NR_GENS. Hence, the
+ * ideal number of generations is MIN_NR_GENS+1.
+ */
+ if (min_seq[!can_swap] + MIN_NR_GENS > max_seq)
+ return true;
+ if (min_seq[!can_swap] + MIN_NR_GENS < max_seq)
+ return false;
+
+ /*
+ * It's also ideal to spread pages out evenly, i.e., 1/(MIN_NR_GENS+1)
+ * of the total number of pages for each generation. A reasonable range
+ * for this average portion is [1/MIN_NR_GENS, 1/(MIN_NR_GENS+2)]. The
+ * aging cares about the upper bound of hot pages, while the eviction
+ * cares about the lower bound of cold pages.
+ */
+ if (young * MIN_NR_GENS > total)
+ return true;
+ if (old * (MIN_NR_GENS + 2) < total)
+ return true;
+
+ return false;
+}
+
+static bool age_lruvec(struct lruvec *lruvec, struct scan_control *sc, unsigned long min_ttl)
+{
+ bool need_aging;
+ unsigned long nr_to_scan;
+ int swappiness = get_swappiness(lruvec, sc);
+ struct mem_cgroup *memcg = lruvec_memcg(lruvec);
+ DEFINE_MAX_SEQ(lruvec);
+ DEFINE_MIN_SEQ(lruvec);
+
+ VM_WARN_ON_ONCE(sc->memcg_low_reclaim);
+
+ mem_cgroup_calculate_protection(NULL, memcg);
+
+ if (mem_cgroup_below_min(memcg))
+ return false;
+
+ need_aging = should_run_aging(lruvec, max_seq, min_seq, sc, swappiness, &nr_to_scan);
+
+ 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;
+
+ /* the size is likely too small to be helpful */
+ if (!nr_to_scan && sc->priority != DEF_PRIORITY)
+ return false;
+ }
+
+ if (need_aging)
+ 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_WARN_ON_ONCE(!current_is_kswapd());
+
+ sc->last_reclaimed = sc->nr_reclaimed;
+
+ /*
+ * To reduce the chance of going into the aging path, which can be
+ * costly, optimistically skip it if the flag below was 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;
+ return;
+ }
+
+ set_mm_walk(pgdat);
+
+ memcg = mem_cgroup_iter(NULL, NULL, NULL);
+ do {
+ struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
+
+ if (age_lruvec(lruvec, sc, min_ttl))
+ success = true;
+
+ cond_resched();
+ } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)));
+
+ clear_mm_walk();
+
+ /* check the order to exclude compaction-induced reclaim */
+ if (success || !min_ttl || sc->order)
+ return;
+
+ /*
+ * The main goal is to OOM kill if every generation from all memcgs is
+ * younger than min_ttl. However, another possibility is all memcgs are
+ * either below min or empty.
+ */
+ if (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 forms a feedback loop between the
+ * eviction and 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 lru_gen_mm_walk *walk;
+ int young = 0;
+ unsigned long bitmap[BITS_TO_LONGS(MIN_LRU_BATCH)] = {};
+ struct folio *folio = pfn_folio(pvmw->pfn);
+ struct mem_cgroup *memcg = folio_memcg(folio);
+ struct pglist_data *pgdat = folio_pgdat(folio);
+ struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
+ DEFINE_MAX_SEQ(lruvec);
+ int old_gen, new_gen = lru_gen_from_seq(max_seq);
+
+ lockdep_assert_held(pvmw->ptl);
+ VM_WARN_ON_ONCE_FOLIO(folio_test_lru(folio), folio);
+
+ if (spin_is_contended(pvmw->ptl))
+ return;
+
+ /* avoid taking the LRU lock under the PTL when possible */
+ walk = current->reclaim_state ? current->reclaim_state->mm_walk : NULL;
+
+ 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;
+
+ pfn = get_pte_pfn(pte[i], pvmw->vma, addr);
+ if (pfn == -1)
+ continue;
+
+ if (!pte_young(pte[i]))
+ continue;
+
+ folio = get_pfn_folio(pfn, memcg, pgdat, !walk || walk->can_swap);
+ if (!folio)
+ continue;
+
+ if (!ptep_test_and_clear_young(pvmw->vma, addr, pte + i))
+ VM_WARN_ON_ONCE(true);
+
+ young++;
+
+ if (pte_dirty(pte[i]) && !folio_test_dirty(folio) &&
+ !(folio_test_anon(folio) && folio_test_swapbacked(folio) &&
+ !folio_test_swapcache(folio)))
+ folio_mark_dirty(folio);
+
+ old_gen = folio_lru_gen(folio);
+ if (old_gen < 0)
+ folio_set_referenced(folio);
+ 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);
+
+ if (!walk && bitmap_weight(bitmap, MIN_LRU_BATCH) < PAGEVEC_SIZE) {
+ for_each_set_bit(i, bitmap, MIN_LRU_BATCH) {
+ folio = pfn_folio(pte_pfn(pte[i]));
+ folio_activate(folio);
+ }
+ return;
+ }
+
+ /* folio_update_gen() requires stable folio_memcg() */
+ if (!mem_cgroup_trylock_pages(memcg))
+ return;
+
+ if (!walk) {
+ spin_lock_irq(&lruvec->lru_lock);
+ new_gen = lru_gen_from_seq(lruvec->lrugen.max_seq);
+ }
+
+ for_each_set_bit(i, bitmap, MIN_LRU_BATCH) {
+ folio = pfn_folio(pte_pfn(pte[i]));
+ if (folio_memcg_rcu(folio) != memcg)
+ continue;
+
+ old_gen = folio_update_gen(folio, new_gen);
+ if (old_gen < 0 || old_gen == new_gen)
+ continue;
+
+ if (walk)
+ update_batch_size(walk, folio, old_gen, new_gen);
+ else
+ lru_gen_update_size(lruvec, folio, old_gen, new_gen);
+ }
+
+ if (!walk)
+ spin_unlock_irq(&lruvec->lru_lock);
+
+ mem_cgroup_unlock_pages();
+}
+
+/******************************************************************************
+ * the eviction
+ ******************************************************************************/
+
+static bool sort_folio(struct lruvec *lruvec, struct folio *folio, int tier_idx)
+{
+ bool success;
+ int gen = folio_lru_gen(folio);
+ int type = folio_is_file_lru(folio);
+ int zone = folio_zonenum(folio);
+ int delta = folio_nr_pages(folio);
+ int refs = folio_lru_refs(folio);
+ int tier = lru_tier_from_refs(refs);
+ struct lru_gen_struct *lrugen = &lruvec->lrugen;
+
+ VM_WARN_ON_ONCE_FOLIO(gen >= MAX_NR_GENS, folio);
+
+ /* unevictable */
+ if (!folio_evictable(folio)) {
+ success = lru_gen_del_folio(lruvec, folio, true);
+ VM_WARN_ON_ONCE_FOLIO(!success, folio);
+ folio_set_unevictable(folio);
+ lruvec_add_folio(lruvec, folio);
+ __count_vm_events(UNEVICTABLE_PGCULLED, delta);
+ return true;
+ }
+
+ /* dirty lazyfree */
+ if (type == LRU_GEN_FILE && folio_test_anon(folio) && folio_test_dirty(folio)) {
+ success = lru_gen_del_folio(lruvec, folio, true);
+ VM_WARN_ON_ONCE_FOLIO(!success, folio);
+ folio_set_swapbacked(folio);
+ lruvec_add_folio_tail(lruvec, folio);
+ return true;
+ }
+
+ /* promoted */
+ if (gen != lru_gen_from_seq(lrugen->min_seq[type])) {
+ list_move(&folio->lru, &lrugen->lists[gen][type][zone]);
+ return true;
+ }
+
+ /* protected */
+ if (tier > tier_idx) {
+ int hist = lru_hist_from_seq(lrugen->min_seq[type]);
+
+ gen = folio_inc_gen(lruvec, folio, false);
+ list_move_tail(&folio->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_BASE + type, delta);
+ return true;
+ }
+
+ /* waiting for writeback */
+ if (folio_test_locked(folio) || folio_test_writeback(folio) ||
+ (type == LRU_GEN_FILE && folio_test_dirty(folio))) {
+ gen = folio_inc_gen(lruvec, folio, true);
+ list_move(&folio->lru, &lrugen->lists[gen][type][zone]);
+ return true;
+ }
+
+ return false;
+}
+
+static bool isolate_folio(struct lruvec *lruvec, struct folio *folio, struct scan_control *sc)
+{
+ bool success;
+
+ /* unmapping inhibited */
+ if (!sc->may_unmap && folio_mapped(folio))
+ return false;
+
+ /* swapping inhibited */
+ if (!(sc->may_writepage && (sc->gfp_mask & __GFP_IO)) &&
+ (folio_test_dirty(folio) ||
+ (folio_test_anon(folio) && !folio_test_swapcache(folio))))
+ return false;
+
+ /* raced with release_pages() */
+ if (!folio_try_get(folio))
+ return false;
+
+ /* raced with another isolation */
+ if (!folio_test_clear_lru(folio)) {
+ folio_put(folio);
+ return false;
+ }
+
+ /* see the comment on MAX_NR_TIERS */
+ if (!folio_test_referenced(folio))
+ set_mask_bits(&folio->flags, LRU_REFS_MASK | LRU_REFS_FLAGS, 0);
+
+ /* for shrink_page_list() */
+ folio_clear_reclaim(folio);
+ folio_clear_referenced(folio);
+
+ success = lru_gen_del_folio(lruvec, folio, true);
+ VM_WARN_ON_ONCE_FOLIO(!success, folio);
+
+ return true;
+}
+
+static int scan_folios(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_WARN_ON_ONCE(!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 folio *folio = lru_to_folio(head);
+ int delta = folio_nr_pages(folio);
+
+ VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio);
+ VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio), folio);
+ VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio);
+ VM_WARN_ON_ONCE_FOLIO(folio_zonenum(folio) != zone, folio);
+
+ scanned += delta;
+
+ if (sort_folio(lruvec, folio, tier))
+ sorted += delta;
+ else if (isolate_folio(lruvec, folio, sc)) {
+ list_add(&folio->lru, list);
+ isolated += delta;
+ } else {
+ list_move(&folio->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 (!cgroup_reclaim(sc)) {
+ __count_vm_events(item, isolated);
+ __count_vm_events(PGREFILL, sorted);
+ }
+ __count_memcg_events(memcg, item, isolated);
+ __count_memcg_events(memcg, PGREFILL, sorted);
+ __count_vm_events(PGSCAN_ANON + type, isolated);
+
+ /*
+ * There might not be eligible pages due to reclaim_idx, may_unmap and
+ * may_writepage. Check the remaining to prevent livelock if it's not
+ * making progress.
+ */
+ 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_folios(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);
+
+ /*
+ * 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_folios(lruvec, sc, type, tier, list);
+ if (scanned)
+ break;
+
+ type = !type;
+ tier = -1;
+ }
+
+ *type_scanned = type;
+
+ return scanned;
+}
+
+static int evict_folios(struct lruvec *lruvec, struct scan_control *sc, int swappiness,
+ bool *need_swapping)
+{
+ int type;
+ int scanned;
+ int reclaimed;
+ LIST_HEAD(list);
+ struct folio *folio;
+ enum vm_event_item item;
+ struct reclaim_stat stat;
+ struct lru_gen_mm_walk *walk;
+ struct mem_cgroup *memcg = lruvec_memcg(lruvec);
+ struct pglist_data *pgdat = lruvec_pgdat(lruvec);
+
+ spin_lock_irq(&lruvec->lru_lock);
+
+ scanned = isolate_folios(lruvec, sc, swappiness, &type, &list);
+
+ scanned += try_to_inc_min_seq(lruvec, swappiness);
+
+ if (get_nr_gens(lruvec, !swappiness) == MIN_NR_GENS)
+ scanned = 0;
+
+ spin_unlock_irq(&lruvec->lru_lock);
+
+ if (list_empty(&list))
+ return scanned;
+
+ reclaimed = shrink_page_list(&list, pgdat, sc, &stat, false);
+
+ list_for_each_entry(folio, &list, lru) {
+ /* restore LRU_REFS_FLAGS cleared by isolate_folio() */
+ if (folio_test_workingset(folio))
+ folio_set_referenced(folio);
+
+ /* don't add rejected pages to the oldest generation */
+ if (folio_test_reclaim(folio) &&
+ (folio_test_dirty(folio) || folio_test_writeback(folio)))
+ folio_clear_active(folio);
+ else
+ folio_set_active(folio);
+ }
+
+ spin_lock_irq(&lruvec->lru_lock);
+
+ move_pages_to_lru(lruvec, &list);
+
+ walk = current->reclaim_state->mm_walk;
+ if (walk && walk->batched)
+ reset_batch_size(lruvec, walk);
+
+ item = current_is_kswapd() ? PGSTEAL_KSWAPD : PGSTEAL_DIRECT;
+ if (!cgroup_reclaim(sc))
+ __count_vm_events(item, reclaimed);
+ __count_memcg_events(memcg, item, reclaimed);
+ __count_vm_events(PGSTEAL_ANON + type, reclaimed);
+
+ spin_unlock_irq(&lruvec->lru_lock);
+
+ mem_cgroup_uncharge_list(&list);
+ free_unref_page_list(&list);
+
+ sc->nr_reclaimed += reclaimed;
+
+ if (need_swapping && type == LRU_GEN_ANON)
+ *need_swapping = true;
+
+ return scanned;
+}
+
+/*
+ * For future optimizations:
+ * 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, bool *need_aging)
+{
+ unsigned long nr_to_scan;
+ struct mem_cgroup *memcg = lruvec_memcg(lruvec);
+ DEFINE_MAX_SEQ(lruvec);
+ DEFINE_MIN_SEQ(lruvec);
+
+ if (mem_cgroup_below_min(memcg) ||
+ (mem_cgroup_below_low(memcg) && !sc->memcg_low_reclaim))
+ return 0;
+
+ *need_aging = should_run_aging(lruvec, max_seq, min_seq, sc, can_swap, &nr_to_scan);
+ if (!*need_aging)
+ return nr_to_scan;
+
+ /* skip the aging path at the default priority */
+ if (sc->priority == DEF_PRIORITY)
+ goto done;
+
+ /* 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;
+done:
+ return min_seq[!can_swap] + MIN_NR_GENS <= max_seq ? nr_to_scan : 0;
+}
+
+static bool should_abort_scan(struct lruvec *lruvec, unsigned long seq,
+ struct scan_control *sc, bool need_swapping)
+{
+ int i;
+ DEFINE_MAX_SEQ(lruvec);
+
+ if (!current_is_kswapd()) {
+ /* age each memcg once to ensure fairness */
+ if (max_seq - seq > 1)
+ return true;
+
+ /* over-swapping can increase allocation latency */
+ if (sc->nr_reclaimed >= sc->nr_to_reclaim && need_swapping)
+ return true;
+
+ /* give this thread a chance to exit and free its memory */
+ if (fatal_signal_pending(current)) {
+ sc->nr_reclaimed += MIN_LRU_BATCH;
+ return true;
+ }
+
+ if (cgroup_reclaim(sc))
+ return false;
+ } else if (sc->nr_reclaimed - sc->last_reclaimed < sc->nr_to_reclaim)
+ return false;
+
+ /* keep scanning at low priorities to ensure fairness */
+ if (sc->priority > DEF_PRIORITY - 2)
+ return false;
+
+ /*
+ * A minimum amount of work was done under global memory pressure. For
+ * kswapd, it may be overshooting. For direct reclaim, the target isn't
+ * met, and yet the allocation may still succeed, since kswapd may have
+ * caught up. In either case, it's better to stop now, and restart if
+ * necessary.
+ */
+ for (i = 0; i <= sc->reclaim_idx; i++) {
+ unsigned long wmark;
+ struct zone *zone = lruvec_pgdat(lruvec)->node_zones + i;
+
+ if (!managed_zone(zone))
+ continue;
+
+ wmark = current_is_kswapd() ? high_wmark_pages(zone) : low_wmark_pages(zone);
+ if (wmark > zone_page_state(zone, NR_FREE_PAGES))
+ return false;
+ }
+
+ sc->nr_reclaimed += MIN_LRU_BATCH;
+
+ return true;
+}
+
+static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
+{
+ struct blk_plug plug;
+ bool need_aging = false;
+ bool need_swapping = false;
+ unsigned long scanned = 0;
+ unsigned long reclaimed = sc->nr_reclaimed;
+ DEFINE_MAX_SEQ(lruvec);
+
+ 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);
+ else if (!cgroup_reclaim(sc) && get_swappiness(lruvec, sc))
+ swappiness = 1;
+ else
+ swappiness = 0;
+
+ nr_to_scan = get_nr_to_scan(lruvec, sc, swappiness, &need_aging);
+ if (!nr_to_scan)
+ goto done;
+
+ delta = evict_folios(lruvec, sc, swappiness, &need_swapping);
+ if (!delta)
+ goto done;
+
+ scanned += delta;
+ if (scanned >= nr_to_scan)
+ break;
+
+ if (should_abort_scan(lruvec, max_seq, sc, need_swapping))
+ break;
+
+ cond_resched();
+ }
+
+ /* see the comment in lru_gen_age_node() */
+ if (sc->nr_reclaimed - reclaimed >= MIN_LRU_BATCH && !need_aging)
+ sc->memcgs_need_aging = false;
+done:
+ clear_mm_walk();
+
+ 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;
+ }
+ }
+
+ 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 folio *folio = lru_to_folio(head);
+
+ VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio);
+ VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio) != active, folio);
+ VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio);
+ VM_WARN_ON_ONCE_FOLIO(folio_lru_gen(folio) != -1, folio);
+
+ lruvec_del_folio(lruvec, folio);
+ success = lru_gen_add_folio(lruvec, folio, false);
+ VM_WARN_ON_ONCE(!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 folio *folio = lru_to_folio(head);
+
+ VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio);
+ VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio), folio);
+ VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio);
+ VM_WARN_ON_ONCE_FOLIO(folio_zonenum(folio) != zone, folio);
+
+ success = lru_gen_del_folio(lruvec, folio, false);
+ VM_WARN_ON_ONCE(!success);
+ lruvec_add_folio(lruvec, folio);
+
+ if (!--remaining)
+ return false;
+ }
+ }
+
+ return true;
+}
+
+static void lru_gen_change_state(bool enabled)
+{
+ static DEFINE_MUTEX(state_mutex);
+
+ struct mem_cgroup *memcg;
+
+ cgroup_lock();
+ cpus_read_lock();
+ get_online_mems();
+ mutex_lock(&state_mutex);
+
+ if (enabled == lru_gen_enabled())
+ goto unlock;
+
+ if (enabled)
+ 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 lruvec *lruvec = get_lruvec(memcg, nid);
+
+ if (!lruvec)
+ continue;
+
+ spin_lock_irq(&lruvec->lru_lock);
+
+ VM_WARN_ON_ONCE(!seq_is_valid(lruvec));
+ VM_WARN_ON_ONCE(!state_is_valid(lruvec));
+
+ lruvec->lrugen.enabled = enabled;
+
+ while (!(enabled ? fill_evictable(lruvec) : drain_evictable(lruvec))) {
+ spin_unlock_irq(&lruvec->lru_lock);
+ cond_resched();
+ spin_lock_irq(&lruvec->lru_lock);
+ }
+
+ spin_unlock_irq(&lruvec->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)));
+}
+
+/* see Documentation/admin-guide/mm/multigen_lru.rst for details */
+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_enabled(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);
+}
+
+/* see Documentation/admin-guide/mm/multigen_lru.rst for details */
+static ssize_t store_enabled(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 enabled = caps & BIT(i);
+
+ if (i == LRU_GEN_CORE)
+ lru_gen_change_state(enabled);
+ else if (enabled)
+ static_branch_enable(&lru_gen_caps[i]);
+ else
+ static_branch_disable(&lru_gen_caps[i]);
+ }
+
+ return len;
+}
+
+static struct kobj_attribute lru_gen_enabled_attr = __ATTR(
+ enabled, 0644, show_enabled, store_enabled
+);
+
+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++) {
+ const char *s = " ";
+ unsigned long n[3] = {};
+
+ if (seq == max_seq) {
+ s = "RT ";
+ n[0] = READ_ONCE(lrugen->avg_refaulted[type][tier]);
+ n[1] = READ_ONCE(lrugen->avg_total[type][tier]);
+ } else if (seq == min_seq[type] || NR_HIST_GENS > 1) {
+ s = "rep";
+ 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]);
+ }
+
+ for (i = 0; i < 3; i++)
+ seq_printf(m, " %10lu%c", n[i], s[i]);
+ }
+ seq_putc(m, '\n');
+ }
+
+ seq_puts(m, " ");
+ for (i = 0; i < NR_MM_STATS; i++) {
+ const char *s = " ";
+ unsigned long n = 0;
+
+ if (seq == max_seq && NR_HIST_GENS == 1) {
+ s = "LOYNFA";
+ n = READ_ONCE(lruvec->mm_state.stats[hist][i]);
+ } else if (seq != max_seq && NR_HIST_GENS > 1) {
+ s = "loynfa";
+ n = READ_ONCE(lruvec->mm_state.stats[hist][i]);
+ }
+
+ seq_printf(m, " %10lu%c", n, s[i]);
+ }
+ seq_putc(m, '\n');
+}
+
+/* see Documentation/admin-guide/mm/multigen_lru.rst for details */
+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++) {
+ unsigned long size = 0;
+ char mark = full && seq < min_seq[type] ? 'x' : ' ';
+
+ for (zone = 0; zone < MAX_NR_ZONES; zone++)
+ size += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L);
+
+ seq_printf(m, " %10lu%c", size, 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 force_scan)
+{
+ DEFINE_MAX_SEQ(lruvec);
+ DEFINE_MIN_SEQ(lruvec);
+
+ if (seq < max_seq)
+ return 0;
+
+ if (seq > max_seq)
+ return -EINVAL;
+
+ if (!force_scan && min_seq[!can_swap] + MAX_NR_GENS - 1 <= max_seq)
+ return -ERANGE;
+
+ try_to_inc_max_seq(lruvec, max_seq, sc, can_swap, force_scan);
+
+ return 0;
+}
+
+static int run_eviction(struct lruvec *lruvec, unsigned long seq, struct scan_control *sc,
+ int swappiness, unsigned long nr_to_reclaim)
+{
+ DEFINE_MAX_SEQ(lruvec);
+
+ if (seq + MIN_NR_GENS > max_seq)
+ return -EINVAL;
+
+ sc->nr_reclaimed = 0;
+
+ while (!signal_pending(current)) {
+ DEFINE_MIN_SEQ(lruvec);
+
+ if (seq < min_seq[!swappiness])
+ return 0;
+
+ if (sc->nr_reclaimed >= nr_to_reclaim)
+ return 0;
+
+ if (!evict_folios(lruvec, sc, swappiness, NULL))
+ return 0;
+
+ cond_resched();
+ }
+
+ return -EINTR;
+}
+
+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 (nid < 0 || nid >= MAX_NUMNODES || !node_state(nid, N_MEMORY))
+ return -EINVAL;
+
+ 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)
+ return -EINVAL;
+ }
+
+ if (memcg_id != mem_cgroup_id(memcg))
+ 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;
+}
+
+/* see Documentation/admin-guide/mm/multigen_lru.rst for details */
+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;
+ struct blk_plug plug;
+ int err = -EINVAL;
+ 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;
+ }
+
+ set_task_reclaim_state(current, &sc.reclaim_state);
+ flags = memalloc_noreclaim_save();
+ blk_start_plug(&plug);
+ if (!set_mm_walk(NULL)) {
+ err = -ENOMEM;
+ goto done;
+ }
+
+ next = buf;
+ next[len] = '\0';
+
+ 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;
+ }
+done:
+ clear_mm_walk();
+ blk_finish_plug(&plug);
+ memalloc_noreclaim_restore(flags);
+ set_task_reclaim_state(current, NULL);
+
+ 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_WARN_ON_ONCE(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);
+
+ 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 /* !CONFIG_LRU_GEN */
+
+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 */
+
static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
{
unsigned long nr[NR_LRU_LISTS];
@@ -3069,6 +5839,11 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
struct blk_plug plug;
bool scan_adjusted;
+ if (lru_gen_enabled()) {
+ lru_gen_shrink_lruvec(lruvec, sc);
+ return;
+ }
+
get_scan_count(lruvec, sc, nr);
/* Record the original scan target for proportional adjustments later */
@@ -3575,6 +6350,9 @@ static void snapshot_refaults(struct mem_cgroup *target_memcg, pg_data_t *pgdat)
struct lruvec *target_lruvec;
unsigned long refaults;
+ if (lru_gen_enabled())
+ return;
+
target_lruvec = mem_cgroup_lruvec(target_memcg, pgdat);
refaults = lruvec_page_state(target_lruvec, WORKINGSET_ACTIVATE_ANON);
target_lruvec->refaults[WORKINGSET_ANON] = refaults;
@@ -3941,12 +6719,16 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
}
#endif
-static void age_active_anon(struct pglist_data *pgdat,
- struct scan_control *sc)
+static void kswapd_age_node(struct pglist_data *pgdat, struct scan_control *sc)
{
struct mem_cgroup *memcg;
struct lruvec *lruvec;
+ if (lru_gen_enabled()) {
+ lru_gen_age_node(pgdat, sc);
+ return;
+ }
+
if (!can_age_anon_pages(pgdat, sc))
return;
@@ -4266,12 +7048,11 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int highest_zoneidx)
sc.may_swap = !nr_boost_reclaim;
/*
- * 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.
+ * Do some background aging, 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);
+ kswapd_age_node(pgdat, &sc);
/*
* If we're getting trouble reclaiming, start doing writepage
diff --git a/mm/workingset.c b/mm/workingset.c
index a5e8486..ae7e984 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -187,7 +187,6 @@ static unsigned int bucket_order __read_mostly;
static void *pack_shadow(int memcgid, pg_data_t *pgdat, unsigned long eviction,
bool workingset)
{
- eviction >>= bucket_order;
eviction &= EVICTION_MASK;
eviction = (eviction << MEM_CGROUP_ID_SHIFT) | memcgid;
eviction = (eviction << NODES_SHIFT) | pgdat->node_id;
@@ -212,10 +211,107 @@ static void unpack_shadow(void *shadow, int *memcgidp, pg_data_t **pgdat,
*memcgidp = memcgid;
*pgdat = NODE_DATA(nid);
- *evictionp = entry << bucket_order;
+ *evictionp = entry;
*workingsetp = workingset;
}
+#ifdef CONFIG_LRU_GEN
+
+static void *lru_gen_eviction(struct folio *folio)
+{
+ int hist;
+ unsigned long token;
+ unsigned long min_seq;
+ struct lruvec *lruvec;
+ struct lru_gen_struct *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);
+ struct mem_cgroup *memcg = folio_memcg(folio);
+ struct pglist_data *pgdat = folio_pgdat(folio);
+
+ BUILD_BUG_ON(LRU_GEN_WIDTH + LRU_REFS_WIDTH > BITS_PER_LONG - EVICTION_SHIFT);
+
+ lruvec = mem_cgroup_lruvec(memcg, pgdat);
+ lrugen = &lruvec->lrugen;
+ min_seq = READ_ONCE(lrugen->min_seq[type]);
+ token = (min_seq << LRU_REFS_WIDTH) | max(refs - 1, 0);
+
+ 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);
+}
+
+static void lru_gen_refault(struct folio *folio, void *shadow)
+{
+ 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;
+ 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))
+ goto unlock;
+
+ lruvec = mem_cgroup_lruvec(memcg, pgdat);
+ lrugen = &lruvec->lrugen;
+
+ min_seq = READ_ONCE(lrugen->min_seq[type]);
+ if ((token >> LRU_REFS_WIDTH) != (min_seq & (EVICTION_MASK >> LRU_REFS_WIDTH)))
+ 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);
+
+ 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)) {
+ folio_set_workingset(folio);
+ mod_lruvec_state(lruvec, WORKINGSET_RESTORE_BASE + type, delta);
+ }
+unlock:
+ rcu_read_unlock();
+}
+
+#else /* !CONFIG_LRU_GEN */
+
+static void *lru_gen_eviction(struct folio *folio)
+{
+ return NULL;
+}
+
+static void lru_gen_refault(struct folio *folio, void *shadow)
+{
+}
+
+#endif /* CONFIG_LRU_GEN */
+
/**
* workingset_age_nonresident - age non-resident entries as LRU ages
* @lruvec: the lruvec that was aged
@@ -264,10 +360,14 @@ void *workingset_eviction(struct folio *folio, struct mem_cgroup *target_memcg)
VM_BUG_ON_FOLIO(folio_ref_count(folio), folio);
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
+ if (lru_gen_enabled())
+ return lru_gen_eviction(folio);
+
lruvec = mem_cgroup_lruvec(target_memcg, pgdat);
/* XXX: target_memcg can be NULL, go through lruvec */
memcgid = mem_cgroup_id(lruvec_memcg(lruvec));
eviction = atomic_long_read(&lruvec->nonresident_age);
+ eviction >>= bucket_order;
workingset_age_nonresident(lruvec, folio_nr_pages(folio));
return pack_shadow(memcgid, pgdat, eviction,
folio_test_workingset(folio));
@@ -298,7 +398,13 @@ void workingset_refault(struct folio *folio, void *shadow)
int memcgid;
long nr;
+ if (lru_gen_enabled()) {
+ lru_gen_refault(folio, shadow);
+ return;
+ }
+
unpack_shadow(shadow, &memcgid, &pgdat, &eviction, &workingset);
+ eviction <<= bucket_order;
rcu_read_lock();
/*
