From ead7512d0518851a228b6141ba9ccf143982d843 Mon Sep 17 00:00:00 2001
From: Kalesh Singh <kaleshsingh@google.com>
Date: Tue, 8 Nov 2022 09:13:07 -0800
Subject: [PATCH] Revert "FROMLIST: mm: multi-gen LRU: groundwork"

This reverts commit fe302bd1f9332f24eca774d2f958c95f807cf342.

To be replaced with upstream version.

Bug: 249601646
Change-Id: I5a206480f838c304fb1c960fec2615894c2421bb
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---
 fs/fuse/dev.c                     |   3 +-
 include/linux/mm.h                |   2 -
 include/linux/mm_inline.h         | 174 ------------------------------
 include/linux/mmzone.h            |  94 ----------------
 include/linux/page-flags-layout.h |  11 +-
 include/linux/page-flags.h        |   4 +-
 include/linux/sched.h             |   4 -
 kernel/bounds.c                   |   7 --
 mm/Kconfig                        |   8 --
 mm/huge_memory.c                  |   3 +-
 mm/memcontrol.c                   |   2 -
 mm/memory.c                       |  25 -----
 mm/mm_init.c                      |   6 +-
 mm/mmzone.c                       |   2 -
 mm/swap.c                         |   9 +-
 mm/vmscan.c                       |  75 -------------
 16 files changed, 13 insertions(+), 416 deletions(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index c13be2fa891f..c3cd2b2c3276 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -795,8 +795,7 @@ static int fuse_check_page(struct page *page)
 	       1 << PG_active |
 	       1 << PG_workingset |
 	       1 << PG_reclaim |
-	       1 << PG_waiters |
-	       LRU_GEN_MASK | LRU_REFS_MASK))) {
+	       1 << PG_waiters))) {
 		dump_page(page, "fuse: trying to steal weird page");
 		return 1;
 	}
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 37e346e14819..587d335000a0 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1107,8 +1107,6 @@ vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf);
 #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
diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index 9c71c4757cf3..3fcd1461f57c 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -31,8 +31,6 @@ static __always_inline void __update_lru_size(struct lruvec *lruvec,
 {
 	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
 
-	lockdep_assert_held(&pgdat->lru_lock);
-
 	__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);
@@ -89,177 +87,11 @@ static __always_inline enum lru_list page_lru(struct page *page)
 	return lru;
 }
 
-#ifdef CONFIG_LRU_GEN
-
-static inline bool lru_gen_enabled(void)
-{
-	return true;
-}
-
-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 bool lru_gen_is_active(struct lruvec *lruvec, int gen)
-{
-	unsigned long max_seq = lruvec->lrugen.max_seq;
-
-	VM_BUG_ON(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 page *page,
-				       int old_gen, int new_gen)
-{
-	int type = page_is_file_lru(page);
-	int zone = page_zonenum(page);
-	int delta = thp_nr_pages(page);
-	enum lru_list lru = type * LRU_INACTIVE_FILE;
-	struct lru_gen_struct *lrugen = &lruvec->lrugen;
-
-	VM_BUG_ON(old_gen != -1 && old_gen >= MAX_NR_GENS);
-	VM_BUG_ON(new_gen != -1 && new_gen >= MAX_NR_GENS);
-	VM_BUG_ON(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;
-	}
-}
-
-static inline bool lru_gen_add_page(struct lruvec *lruvec, struct page *page, bool reclaiming)
-{
-	int gen;
-	unsigned long old_flags, new_flags;
-	int type = page_is_file_lru(page);
-	int zone = page_zonenum(page);
-	struct lru_gen_struct *lrugen = &lruvec->lrugen;
-
-	if (PageUnevictable(page))
-		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 (PageActive(page))
-		gen = lru_gen_from_seq(lrugen->max_seq);
-	else if ((type == LRU_GEN_ANON && !PageSwapCache(page)) ||
-		 (PageReclaim(page) && (PageDirty(page) || PageWriteback(page))))
-		gen = lru_gen_from_seq(lrugen->min_seq[type] + 1);
-	else
-		gen = lru_gen_from_seq(lrugen->min_seq[type]);
-
-	do {
-		new_flags = old_flags = READ_ONCE(page->flags);
-		VM_BUG_ON_PAGE(new_flags & LRU_GEN_MASK, page);
-
-		/* see the comment on MIN_NR_GENS */
-		new_flags &= ~(LRU_GEN_MASK | BIT(PG_active));
-		new_flags |= (gen + 1UL) << LRU_GEN_PGOFF;
-	} while (cmpxchg(&page->flags, old_flags, new_flags) != old_flags);
-
-	lru_gen_update_size(lruvec, page, -1, gen);
-	/* for rotate_reclaimable_page() */
-	if (reclaiming)
-		list_add_tail(&page->lru, &lrugen->lists[gen][type][zone]);
-	else
-		list_add(&page->lru, &lrugen->lists[gen][type][zone]);
-
-	return true;
-}
-
-static inline bool lru_gen_del_page(struct lruvec *lruvec, struct page *page, bool reclaiming)
-{
-	int gen;
-	unsigned long old_flags, new_flags;
-
-	do {
-		new_flags = old_flags = READ_ONCE(page->flags);
-		if (!(new_flags & LRU_GEN_MASK))
-			return false;
-
-		VM_BUG_ON_PAGE(PageActive(page), page);
-		VM_BUG_ON_PAGE(PageUnevictable(page), page);
-
-		gen = ((new_flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1;
-
-		new_flags &= ~LRU_GEN_MASK;
-		/* for shrink_page_list() */
-		if (reclaiming)
-			new_flags &= ~(BIT(PG_referenced) | BIT(PG_reclaim));
-		else if (lru_gen_is_active(lruvec, gen))
-			new_flags |= BIT(PG_active);
-	} while (cmpxchg(&page->flags, old_flags, new_flags) != old_flags);
-
-	lru_gen_update_size(lruvec, page, gen, -1);
-	list_del(&page->lru);
-
-	return true;
-}
-
-#else
-
-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_page(struct lruvec *lruvec, struct page *page, bool reclaiming)
-{
-	return false;
-}
-
-static inline bool lru_gen_del_page(struct lruvec *lruvec, struct page *page, bool reclaiming)
-{
-	return false;
-}
-
-#endif /* CONFIG_LRU_GEN */
-
 static __always_inline void add_page_to_lru_list(struct page *page,
 				struct lruvec *lruvec)
 {
 	enum lru_list lru = page_lru(page);
 
-	if (lru_gen_add_page(lruvec, page, false))
-		return;
-
 	update_lru_size(lruvec, lru, page_zonenum(page), thp_nr_pages(page));
 	list_add(&page->lru, &lruvec->lists[lru]);
 }
@@ -269,9 +101,6 @@ static __always_inline void add_page_to_lru_list_tail(struct page *page,
 {
 	enum lru_list lru = page_lru(page);
 
-	if (lru_gen_add_page(lruvec, page, true))
-		return;
-
 	update_lru_size(lruvec, lru, page_zonenum(page), thp_nr_pages(page));
 	list_add_tail(&page->lru, &lruvec->lists[lru]);
 }
@@ -279,9 +108,6 @@ static __always_inline void add_page_to_lru_list_tail(struct page *page,
 static __always_inline void del_page_from_lru_list(struct page *page,
 				struct lruvec *lruvec)
 {
-	if (lru_gen_del_page(lruvec, page, false))
-		return;
-
 	list_del(&page->lru);
 	update_lru_size(lruvec, page_lru(page), page_zonenum(page),
 			-thp_nr_pages(page));
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 6dc35f96d566..1c273045fd28 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -281,96 +281,6 @@ 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, gen, indexes the LRU list of the corresponding
- * generation. The gen counter in page->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, 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_page() and lru_gen_del_page().
- *
- * MAX_NR_GENS is set to 4 so that the multi-gen LRU can support twice of the
- * categories of the active/inactive LRU when keeping track of accesses through
- * page tables. It requires order_base_2(MAX_NR_GENS+1) bits in page->flags.
- */
-#define MIN_NR_GENS		2U
-#define MAX_NR_GENS		4U
-
-#ifndef __GENERATING_BOUNDS_H
-
-struct lruvec;
-
-#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,
-};
-
-/*
- * 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.
- */
-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 multi-gen LRU lists */
-	struct list_head lists[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES];
-	/* the sizes of the above lists */
-	unsigned long nr_pages[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES];
-};
-
-void lru_gen_init_lruvec(struct lruvec *lruvec);
-
-#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)
-{
-}
-
-#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];
 	/*
@@ -386,10 +296,6 @@ 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;
-#endif
 #ifdef CONFIG_MEMCG
 	struct pglist_data *pgdat;
 #endif
diff --git a/include/linux/page-flags-layout.h b/include/linux/page-flags-layout.h
index c1946cdb845f..ef1e3e736e14 100644
--- a/include/linux/page-flags-layout.h
+++ b/include/linux/page-flags-layout.h
@@ -55,8 +55,7 @@
 #define SECTIONS_WIDTH		0
 #endif
 
-#if ZONES_WIDTH + LRU_GEN_WIDTH + LRU_REFS_WIDTH + SECTIONS_WIDTH + NODES_SHIFT \
-	<= BITS_PER_LONG - NR_PAGEFLAGS
+#if ZONES_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"
@@ -90,8 +89,8 @@
 #define LAST_CPUPID_SHIFT 0
 #endif
 
-#if ZONES_WIDTH + LRU_GEN_WIDTH + LRU_REFS_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + \
-	KASAN_TAG_WIDTH + LAST_CPUPID_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS
+#if ZONES_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
@@ -101,8 +100,8 @@
 #define LAST_CPUPID_NOT_IN_PAGE_FLAGS
 #endif
 
-#if ZONES_WIDTH + LRU_GEN_WIDTH + LRU_REFS_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + \
-	KASAN_TAG_WIDTH + LAST_CPUPID_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS
+#if ZONES_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + KASAN_TAG_WIDTH + LAST_CPUPID_WIDTH \
+	> BITS_PER_LONG - NR_PAGEFLAGS
 #error "Not enough bits in page flags"
 #endif
 
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 1d2a9a3103da..bb164257c18b 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -803,7 +803,7 @@ static inline void ClearPageSlabPfmemalloc(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 | LRU_GEN_MASK)
+	 1UL << PG_unevictable	| __PG_MLOCKED)
 
 /*
  * Flags checked when a page is prepped for return by the page allocator.
@@ -814,7 +814,7 @@ static inline void ClearPageSlabPfmemalloc(struct page *page)
  * alloc-free cycle to prevent from reusing the page.
  */
 #define PAGE_FLAGS_CHECK_AT_PREP	\
-	((((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON) | LRU_GEN_MASK | LRU_REFS_MASK)
+	(((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
 
 #define PAGE_FLAGS_PRIVATE				\
 	(1UL << PG_private | 1UL << PG_private_2)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index df2259962ba1..637d25c31374 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -835,10 +835,6 @@ 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/kernel/bounds.c b/kernel/bounds.c
index e08fb89f87f4..9795d75b09b2 100644
--- a/kernel/bounds.c
+++ b/kernel/bounds.c
@@ -22,13 +22,6 @@ 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, 0);
-#else
-	DEFINE(LRU_GEN_WIDTH, 0);
-	DEFINE(LRU_REFS_WIDTH, 0);
-#endif
 	/* End of constants */
 
 	return 0;
diff --git a/mm/Kconfig b/mm/Kconfig
index 5261cd2fffe3..f125f504ed97 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -915,14 +915,6 @@ config ANON_VMA_NAME
 	  area from being merged with adjacent virtual memory areas due to the
 	  difference in their name.
 
-config LRU_GEN
-	bool "Multi-Gen LRU"
-	depends on MMU
-	# the following options can use up the spare bits in page flags
-	depends on !MAXSMP && (64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP)
-	help
-	  A high performance LRU implementation to overcommit memory.
-
 source "mm/damon/Kconfig"
 
 endmenu
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b42288c06b96..d76041c186ed 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2402,8 +2402,7 @@ static void __split_huge_page_tail(struct page *head, int tail,
 #ifdef CONFIG_64BIT
 			 (1L << PG_arch_2) |
 #endif
-			 (1L << PG_dirty) |
-			 LRU_GEN_MASK | LRU_REFS_MASK));
+			 (1L << PG_dirty)));
 
 	/* ->mapping in first tail page is compound_mapcount */
 	VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ebe2fd121c45..ece377d5f681 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5254,7 +5254,6 @@ 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);
 	/*
 	 * Flush percpu vmstats and vmevents to guarantee the value correctness
@@ -5330,7 +5329,6 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
 #endif
 	idr_replace(&mem_cgroup_idr, memcg, memcg->id.id);
 	trace_android_vh_mem_cgroup_alloc(memcg);
-	lru_gen_init_memcg(memcg);
 	return memcg;
 fail:
 	mem_cgroup_id_remove(memcg);
diff --git a/mm/memory.c b/mm/memory.c
index 60967daa0a63..e9bb4af8e09d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5182,27 +5182,6 @@ bool can_reuse_spf_vma(struct vm_area_struct *vma, unsigned long address)
 }
 #endif /* CONFIG_SPECULATIVE_PAGE_FAULT */
 
-#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
  *
@@ -5234,15 +5213,11 @@ 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 9351e8a25a80..954f0f93bb8a 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -65,16 +65,14 @@ 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 - LRU_GEN_WIDTH - LRU_REFS_WIDTH;
+		- LAST_CPUPID_SHIFT - KASAN_TAG_WIDTH;
 	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_widths",
-		"Section %d Node %d Zone %d Lastcpupid %d Kasantag %d Gen %d Tier %d Flags %d\n",
+		"Section %d Node %d Zone %d Lastcpupid %d Kasantag %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 595400d7dcec..f04cbef1eb88 100644
--- a/mm/mmzone.c
+++ b/mm/mmzone.c
@@ -95,8 +95,6 @@ void lruvec_init(struct lruvec *lruvec)
 
 	for_each_lru(lru)
 		INIT_LIST_HEAD(&lruvec->lists[lru]);
-
-	lru_gen_init_lruvec(lruvec);
 }
 
 #if defined(CONFIG_NUMA_BALANCING) && !defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS)
diff --git a/mm/swap.c b/mm/swap.c
index 989aa8211884..d683795541b1 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -481,11 +481,6 @@ void lru_cache_add(struct page *page)
 	VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
 	VM_BUG_ON_PAGE(PageLRU(page), page);
 
-	/* see the comment in lru_gen_add_page() */
-	if (lru_gen_enabled() && !PageUnevictable(page) &&
-	    lru_gen_in_fault() && !(current->flags & PF_MEMALLOC))
-		SetPageActive(page);
-
 	get_page(page);
 	local_lock(&lru_pvecs.lock);
 	pvec = this_cpu_ptr(&lru_pvecs.lru_add);
@@ -592,7 +587,7 @@ static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec,
 static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
 			    void *arg)
 {
-	if (PageLRU(page) && !PageUnevictable(page) && (PageActive(page) || lru_gen_enabled())) {
+	if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
 		int nr_pages = thp_nr_pages(page);
 
 		del_page_from_lru_list(page, lruvec);
@@ -729,7 +724,7 @@ void deactivate_file_page(struct page *page)
  */
 void deactivate_page(struct page *page)
 {
-	if (PageLRU(page) && !PageUnevictable(page) && (PageActive(page) || lru_gen_enabled())) {
+	if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
 		struct pagevec *pvec;
 
 		local_lock(&lru_pvecs.lock);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index f16619a98909..4cb00dce37a2 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2616,81 +2616,6 @@ out:
 	}
 }
 
-#ifdef CONFIG_LRU_GEN
-
-/******************************************************************************
- *                          shorthand helpers
- ******************************************************************************/
-
-#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_BUG_ON(!mem_cgroup_disabled());
-
-	return pgdat ? &pgdat->__lruvec : NULL;
-}
-
-/******************************************************************************
- *                          initialization
- ******************************************************************************/
-
-void lru_gen_init_lruvec(struct lruvec *lruvec)
-{
-	int gen, type, zone;
-	struct lru_gen_struct *lrugen = &lruvec->lrugen;
-
-	lrugen->max_seq = MIN_NR_GENS + 1;
-
-	for_each_gen_type_zone(gen, type, zone)
-		INIT_LIST_HEAD(&lrugen->lists[gen][type][zone]);
-}
-
-#ifdef CONFIG_MEMCG
-void lru_gen_init_memcg(struct mem_cgroup *memcg)
-{
-}
-
-void lru_gen_exit_memcg(struct mem_cgroup *memcg)
-{
-	int nid;
-
-	for_each_node(nid) {
-		struct lruvec *lruvec = get_lruvec(memcg, nid);
-
-		VM_BUG_ON(memchr_inv(lruvec->lrugen.nr_pages, 0,
-				     sizeof(lruvec->lrugen.nr_pages)));
-	}
-}
-#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);
-
-	return 0;
-};
-late_initcall(init_lru_gen);
-
-#endif /* CONFIG_LRU_GEN */
-
 static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
 {
 	unsigned long nr[NR_LRU_LISTS];