Received-SPF: pass (google.com: domain of linux-kernel+bounces-183346-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1;
From: Byungchul Park <byungchul@sk.com>
To: linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Cc: kernel_team@skhynix.com,
	akpm@linux-foundation.org,
	ying.huang@intel.com,
	vernhao@tencent.com,
	mgorman@techsingularity.net,
	hughd@google.com,
	willy@infradead.org,
	david@redhat.com,
	peterz@infradead.org,
	luto@kernel.org,
	tglx@linutronix.de,
	mingo@redhat.com,
	bp@alien8.de,
	dave.hansen@linux.intel.com,
	rjgolo@gmail.com
Subject: [RESEND PATCH v10 06/12] mm: add folio_put_ugen() to deliver unmap generation number to pcp or buddy
Date: Mon, 20 May 2024 11:17:28 +0900
Message-Id: <20240520021734.21527-7-byungchul@sk.com>
In-Reply-To: <20240520021734.21527-1-byungchul@sk.com>
References: <20240520021734.21527-1-byungchul@sk.com>
Precedence: bulk

Introduced a new API, folio_put_ugen(), to deliver unmap generation
number to pcp or buddy that will be used by luf mechanism to track need
of tlb flush for each page residing in pcp or buddy.

For now, the delivery should work for the following call path that is of
releasing source folios during migration:

	folio_put_ugen()
	   __folio_put_ugen()
	      free_unref_page()
	         free_unref_page_commit()
	         free_one_page()
	            __free_one_page()

The generation number should be handed over properly when pages travel
between pcp and buddy, and must do necessary handling on exit from pcp
or buddy.  This patch doesn't include actual body for tlb flush on the
exit, which will be filled by the main patch of luf mechanism.

Signed-off-by: Byungchul Park <byungchul@sk.com>
---
 include/linux/mm.h    |  22 +++++++
 include/linux/sched.h |   1 +
 mm/compaction.c       |  10 +++
 mm/internal.h         |  70 +++++++++++++++++++-
 mm/page_alloc.c       | 144 ++++++++++++++++++++++++++++++++++--------
 mm/page_isolation.c   |   6 ++
 mm/page_reporting.c   |  10 +++
 mm/swap.c             |  12 +++-
 8 files changed, 247 insertions(+), 28 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index dc33f8269fb5..2369ebedb8bd 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1312,6 +1312,7 @@ static inline struct folio *virt_to_folio(const void *x)
 }
 
 void __folio_put(struct folio *folio);
+void __folio_put_ugen(struct folio *folio, unsigned short int ugen);
 
 void put_pages_list(struct list_head *pages);
 
@@ -1509,6 +1510,27 @@ static inline void folio_put(struct folio *folio)
 		__folio_put(folio);
 }
 
+/**
+ * folio_put_ugen - Decrement the last reference count on a folio.
+ * @folio: The folio.
+ * @ugen: The unmap generation # of TLB flush that the folio requires.
+ *
+ * The folio's reference count should be one since the only user, folio
+ * migration code, calls folio_put_ugen() only when the folio has no
+ * reference else.  The memory will be released back to the page
+ * allocator and may be used by another allocation immediately.  Do not
+ * access the memory or the struct folio after calling folio_put_ugen().
+ *
+ * Context: May be called in process or interrupt context, but not in NMI
+ * context.  May be called while holding a spinlock.
+ */
+static inline void folio_put_ugen(struct folio *folio, unsigned short int ugen)
+{
+	if (WARN_ON(!folio_put_testzero(folio)))
+		return;
+	__folio_put_ugen(folio, ugen);
+}
+
 /**
  * folio_put_refs - Reduce the reference count on a folio.
  * @folio: The folio.
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4118b3f959c3..2aa48adad226 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1339,6 +1339,7 @@ struct task_struct {
 #endif
 
 	struct tlbflush_unmap_batch	tlb_ubc;
+	unsigned short int		ugen;
 
 	/* Cache last used pipe for splice(): */
 	struct pipe_inode_info		*splice_pipe;
diff --git a/mm/compaction.c b/mm/compaction.c
index e731d45befc7..13799fbb2a9a 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -701,6 +701,11 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
 	if (locked)
 		spin_unlock_irqrestore(&cc->zone->lock, flags);
 
+	/*
+	 * Check and flush before using the isolated pages.
+	 */
+	check_flush_task_ugen();
+
 	/*
 	 * Be careful to not go outside of the pageblock.
 	 */
@@ -1673,6 +1678,11 @@ static void fast_isolate_freepages(struct compact_control *cc)
 
 		spin_unlock_irqrestore(&cc->zone->lock, flags);
 
+		/*
+		 * Check and flush before using the isolated pages.
+		 */
+		check_flush_task_ugen();
+
 		/* Skip fast search if enough freepages isolated */
 		if (cc->nr_freepages >= cc->nr_migratepages)
 			break;
diff --git a/mm/internal.h b/mm/internal.h
index eb9c7d8650fc..332662047c17 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -638,7 +638,7 @@ extern bool free_pages_prepare(struct page *page, unsigned int order);
 
 extern int user_min_free_kbytes;
 
-void free_unref_page(struct page *page, unsigned int order);
+void free_unref_page(struct page *page, unsigned int order, unsigned short int ugen);
 void free_unref_folios(struct folio_batch *fbatch);
 
 extern void zone_pcp_reset(struct zone *zone);
@@ -1512,4 +1512,72 @@ static inline void shrinker_debugfs_remove(struct dentry *debugfs_entry,
 void workingset_update_node(struct xa_node *node);
 extern struct list_lru shadow_nodes;
 
+#if defined(CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH)
+static inline unsigned short int ugen_latest(unsigned short int a, unsigned short int b)
+{
+	if (!a || !b)
+		return a + b;
+
+	/*
+	 * The ugen is wrapped around so let's use this trick.
+	 */
+	if ((short int)(a - b) < 0)
+		return b;
+	else
+		return a;
+}
+
+static inline void update_task_ugen(unsigned short int ugen)
+{
+	current->ugen = ugen_latest(current->ugen, ugen);
+}
+
+static inline unsigned short int hand_over_task_ugen(void)
+{
+	unsigned short int ret = current->ugen;
+
+	current->ugen = 0;
+	return ret;
+}
+
+static inline void check_flush_task_ugen(void)
+{
+	/*
+	 * XXX: luf mechanism will handle this. For now, do nothing but
+	 * reset current's ugen to finalize this turn.
+	 */
+	current->ugen = 0;
+}
+
+/*
+ * Check the constratints of what luf currently supports.
+ */
+static inline bool can_luf_folio(struct folio *f)
+{
+	bool can_luf = true;
+
+	/*
+	 * XXX: Remove the constraint once luf handles zone device folio.
+	 */
+	can_luf = can_luf && likely(!folio_is_zone_device(f));
+
+	/*
+	 * XXX: Remove the constraint once luf handles hugetlb folio.
+	 */
+	can_luf = can_luf && likely(!folio_test_hugetlb(f));
+
+	/*
+	 * XXX: Remove the constraint once luf handles large folio.
+	 */
+	can_luf = can_luf && likely(!folio_test_large(f));
+
+	return can_luf;
+}
+#else /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */
+static inline unsigned short int ugen_latest(unsigned short int a, unsigned short int b) { return 0; }
+static inline void update_task_ugen(unsigned short int ugen) {}
+static inline unsigned short int hand_over_task_ugen(void) { return 0; }
+static inline void check_flush_task_ugen(void) {}
+static inline bool can_luf_folio(struct folio *f) { return false; }
+#endif
 #endif	/* __MM_INTERNAL_H */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 917b22b429d1..2cd278c207d1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -696,6 +696,7 @@ static inline void __del_page_from_free_list(struct page *page, struct zone *zon
 	if (page_reported(page))
 		__ClearPageReported(page);
 
+	update_task_ugen(page_buddy_ugen(page));
 	list_del(&page->buddy_list);
 	__ClearPageBuddy(page);
 	set_page_private(page, 0);
@@ -768,7 +769,7 @@ buddy_merge_likely(unsigned long pfn, unsigned long buddy_pfn,
 static inline void __free_one_page(struct page *page,
 		unsigned long pfn,
 		struct zone *zone, unsigned int order,
-		int migratetype, fpi_t fpi_flags)
+		int migratetype, fpi_t fpi_flags, unsigned short int ugen)
 {
 	struct capture_control *capc = task_capc(zone);
 	unsigned long buddy_pfn = 0;
@@ -783,12 +784,22 @@ static inline void __free_one_page(struct page *page,
 	VM_BUG_ON_PAGE(pfn & ((1 << order) - 1), page);
 	VM_BUG_ON_PAGE(bad_range(zone, page), page);
 
+	/*
+	 * Ensure private is zero before using it inside buddy.
+	 */
+	set_page_private(page, 0);
+
 	account_freepages(zone, 1 << order, migratetype);
 
 	while (order < MAX_PAGE_ORDER) {
 		int buddy_mt = migratetype;
 
 		if (compaction_capture(capc, page, order, migratetype)) {
+			/*
+			 * Capturer will check_flush_task_ugen() through
+			 * prep_new_page().
+			 */
+			update_task_ugen(ugen);
 			account_freepages(zone, -(1 << order), migratetype);
 			return;
 		}
@@ -819,6 +830,11 @@ static inline void __free_one_page(struct page *page,
 		if (page_is_guard(buddy))
 			clear_page_guard(zone, buddy, order);
 		else
+			/*
+			 * __del_page_from_free_list() updates current's
+			 * ugen that pairs with hand_over_task_ugen() below
+			 * in this funtion.
+			 */
 			__del_page_from_free_list(buddy, zone, order, buddy_mt);
 
 		if (unlikely(buddy_mt != migratetype)) {
@@ -837,7 +853,8 @@ static inline void __free_one_page(struct page *page,
 	}
 
 done_merging:
-	set_buddy_order_ugen(page, order, 0);
+	ugen = ugen_latest(ugen, hand_over_task_ugen());
+	set_buddy_order_ugen(page, order, ugen);
 
 	if (fpi_flags & FPI_TO_TAIL)
 		to_tail = true;
@@ -1048,6 +1065,11 @@ __always_inline bool free_pages_prepare(struct page *page,
 
 	VM_BUG_ON_PAGE(PageTail(page), page);
 
+	/*
+	 * Ensure private is zero before using it inside pcp.
+	 */
+	set_page_private(page, 0);
+
 	trace_mm_page_free(page, order);
 	kmsan_free_page(page, order);
 
@@ -1179,17 +1201,23 @@ static void free_pcppages_bulk(struct zone *zone, int count,
 		do {
 			unsigned long pfn;
 			int mt;
+			unsigned short int ugen;
 
 			page = list_last_entry(list, struct page, pcp_list);
 			pfn = page_to_pfn(page);
 			mt = get_pfnblock_migratetype(page, pfn);
 
+			/*
+			 * pcp uses private to store ugen.
+			 */
+			ugen = page_private(page);
+
 			/* must delete to avoid corrupting pcp list */
 			list_del(&page->pcp_list);
 			count -= nr_pages;
 			pcp->count -= nr_pages;
 
-			__free_one_page(page, pfn, zone, order, mt, FPI_NONE);
+			__free_one_page(page, pfn, zone, order, mt, FPI_NONE, ugen);
 			trace_mm_page_pcpu_drain(page, order, mt);
 		} while (count > 0 && !list_empty(list));
 	}
@@ -1199,14 +1227,14 @@ static void free_pcppages_bulk(struct zone *zone, int count,
 
 static void free_one_page(struct zone *zone, struct page *page,
 			  unsigned long pfn, unsigned int order,
-			  fpi_t fpi_flags)
+			  fpi_t fpi_flags, unsigned short int ugen)
 {
 	unsigned long flags;
 	int migratetype;
 
 	spin_lock_irqsave(&zone->lock, flags);
 	migratetype = get_pfnblock_migratetype(page, pfn);
-	__free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
+	__free_one_page(page, pfn, zone, order, migratetype, fpi_flags, ugen);
 	spin_unlock_irqrestore(&zone->lock, flags);
 }
 
@@ -1219,7 +1247,7 @@ static void __free_pages_ok(struct page *page, unsigned int order,
 	if (!free_pages_prepare(page, order))
 		return;
 
-	free_one_page(zone, page, pfn, order, fpi_flags);
+	free_one_page(zone, page, pfn, order, fpi_flags, 0);
 
 	__count_vm_events(PGFREE, 1 << order);
 }
@@ -1484,6 +1512,10 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
 static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
 							unsigned int alloc_flags)
 {
+	/*
+	 * Check and flush before using the pages.
+	 */
+	check_flush_task_ugen();
 	post_alloc_hook(page, order, gfp_flags);
 
 	if (order && (gfp_flags & __GFP_COMP))
@@ -1519,6 +1551,10 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
 		page = get_page_from_free_area(area, migratetype);
 		if (!page)
 			continue;
+		/*
+		 * del_page_from_free_list() updates current's ugen that
+		 * pairs with check_flush_task_ugen() in prep_new_page().
+		 */
 		del_page_from_free_list(page, zone, current_order, migratetype);
 		expand(zone, page, order, current_order, migratetype);
 		trace_mm_page_alloc_zone_locked(page, order, migratetype,
@@ -1681,7 +1717,8 @@ static unsigned long find_large_buddy(unsigned long start_pfn)
 
 /* Split a multi-block free page into its individual pageblocks */
 static void split_large_buddy(struct zone *zone, struct page *page,
-			      unsigned long pfn, int order)
+			      unsigned long pfn, int order,
+			      unsigned short int ugen)
 {
 	unsigned long end_pfn = pfn + (1 << order);
 
@@ -1694,7 +1731,7 @@ static void split_large_buddy(struct zone *zone, struct page *page,
 	while (pfn != end_pfn) {
 		int mt = get_pfnblock_migratetype(page, pfn);
 
-		__free_one_page(page, pfn, zone, pageblock_order, mt, FPI_NONE);
+		__free_one_page(page, pfn, zone, pageblock_order, mt, FPI_NONE, ugen);
 		pfn += pageblock_nr_pages;
 		page = pfn_to_page(pfn);
 	}
@@ -1736,22 +1773,34 @@ bool move_freepages_block_isolate(struct zone *zone, struct page *page,
 	if (pfn != start_pfn) {
 		struct page *buddy = pfn_to_page(pfn);
 		int order = buddy_order(buddy);
+		unsigned short int ugen;
 
+		/*
+		 * del_page_from_free_list() updates current's ugen that
+		 * pairs with the following hand_over_task_ugen().
+		 */
 		del_page_from_free_list(buddy, zone, order,
 					get_pfnblock_migratetype(buddy, pfn));
+		ugen = hand_over_task_ugen();
 		set_pageblock_migratetype(page, migratetype);
-		split_large_buddy(zone, buddy, pfn, order);
+		split_large_buddy(zone, buddy, pfn, order, ugen);
 		return true;
 	}
 
 	/* We're the starting block of a larger buddy */
 	if (PageBuddy(page) && buddy_order(page) > pageblock_order) {
 		int order = buddy_order(page);
+		unsigned short int ugen;
 
+		/*
+		 * del_page_from_free_list() updates current's ugen that
+		 * pairs with the following hand_over_task_ugen().
+		 */
 		del_page_from_free_list(page, zone, order,
 					get_pfnblock_migratetype(page, pfn));
+		ugen = hand_over_task_ugen();
 		set_pageblock_migratetype(page, migratetype);
-		split_large_buddy(zone, page, pfn, order);
+		split_large_buddy(zone, page, pfn, order, ugen);
 		return true;
 	}
 move:
@@ -1871,6 +1920,10 @@ steal_suitable_fallback(struct zone *zone, struct page *page,
 
 	/* Take ownership for orders >= pageblock_order */
 	if (current_order >= pageblock_order) {
+		/*
+		 * del_page_from_free_list() updates current's ugen that
+		 * pairs with check_flush_task_ugen() in prep_new_page().
+		 */
 		del_page_from_free_list(page, zone, current_order, block_type);
 		change_pageblock_range(page, current_order, start_type);
 		expand(zone, page, order, current_order, start_type);
@@ -1926,6 +1979,10 @@ steal_suitable_fallback(struct zone *zone, struct page *page,
 	}
 
 single_page:
+	/*
+	 * del_page_from_free_list() updates current's ugen that pairs
+	 * with check_flush_task_ugen() in prep_new_page().
+	 */
 	del_page_from_free_list(page, zone, current_order, block_type);
 	expand(zone, page, order, current_order, block_type);
 	return page;
@@ -2547,7 +2604,7 @@ static int nr_pcp_high(struct per_cpu_pages *pcp, struct zone *zone,
 
 static void free_unref_page_commit(struct zone *zone, struct per_cpu_pages *pcp,
 				   struct page *page, int migratetype,
-				   unsigned int order)
+				   unsigned int order, unsigned short int ugen)
 {
 	int high, batch;
 	int pindex;
@@ -2561,6 +2618,11 @@ static void free_unref_page_commit(struct zone *zone, struct per_cpu_pages *pcp,
 	pcp->alloc_factor >>= 1;
 	__count_vm_events(PGFREE, 1 << order);
 	pindex = order_to_pindex(migratetype, order);
+
+	/*
+	 * pcp uses private to store ugen.
+	 */
+	set_page_private(page, ugen);
 	list_add(&page->pcp_list, &pcp->lists[pindex]);
 	pcp->count += 1 << order;
 
@@ -2596,7 +2658,8 @@ static void free_unref_page_commit(struct zone *zone, struct per_cpu_pages *pcp,
 /*
  * Free a pcp page
  */
-void free_unref_page(struct page *page, unsigned int order)
+void free_unref_page(struct page *page, unsigned int order,
+		     unsigned short int ugen)
 {
 	unsigned long __maybe_unused UP_flags;
 	struct per_cpu_pages *pcp;
@@ -2622,7 +2685,7 @@ void free_unref_page(struct page *page, unsigned int order)
 	migratetype = get_pfnblock_migratetype(page, pfn);
 	if (unlikely(migratetype >= MIGRATE_PCPTYPES)) {
 		if (unlikely(is_migrate_isolate(migratetype))) {
-			free_one_page(page_zone(page), page, pfn, order, FPI_NONE);
+			free_one_page(page_zone(page), page, pfn, order, FPI_NONE, ugen);
 			return;
 		}
 		migratetype = MIGRATE_MOVABLE;
@@ -2632,10 +2695,10 @@ void free_unref_page(struct page *page, unsigned int order)
 	pcp_trylock_prepare(UP_flags);
 	pcp = pcp_spin_trylock(zone->per_cpu_pageset);
 	if (pcp) {
-		free_unref_page_commit(zone, pcp, page, migratetype, order);
+		free_unref_page_commit(zone, pcp, page, migratetype, order, ugen);
 		pcp_spin_unlock(pcp);
 	} else {
-		free_one_page(zone, page, pfn, order, FPI_NONE);
+		free_one_page(zone, page, pfn, order, FPI_NONE, ugen);
 	}
 	pcp_trylock_finish(UP_flags);
 }
@@ -2666,7 +2729,7 @@ void free_unref_folios(struct folio_batch *folios)
 		 */
 		if (!pcp_allowed_order(order)) {
 			free_one_page(folio_zone(folio), &folio->page,
-				      pfn, order, FPI_NONE);
+				      pfn, order, FPI_NONE, 0);
 			continue;
 		}
 		folio->private = (void *)(unsigned long)order;
@@ -2702,7 +2765,7 @@ void free_unref_folios(struct folio_batch *folios)
 			 */
 			if (is_migrate_isolate(migratetype)) {
 				free_one_page(zone, &folio->page, pfn,
-					      order, FPI_NONE);
+					      order, FPI_NONE, 0);
 				continue;
 			}
 
@@ -2715,7 +2778,7 @@ void free_unref_folios(struct folio_batch *folios)
 			if (unlikely(!pcp)) {
 				pcp_trylock_finish(UP_flags);
 				free_one_page(zone, &folio->page, pfn,
-					      order, FPI_NONE);
+					      order, FPI_NONE, 0);
 				continue;
 			}
 			locked_zone = zone;
@@ -2730,7 +2793,7 @@ void free_unref_folios(struct folio_batch *folios)
 
 		trace_mm_page_free_batched(&folio->page);
 		free_unref_page_commit(zone, pcp, &folio->page, migratetype,
-				order);
+				order, 0);
 	}
 
 	if (pcp) {
@@ -2781,6 +2844,11 @@ int __isolate_free_page(struct page *page, unsigned int order)
 			return 0;
 	}
 
+	/*
+	 * del_page_from_free_list() updates current's ugen. The user of
+	 * the isolated page should check_flush_task_ugen() before using
+	 * it.
+	 */
 	del_page_from_free_list(page, zone, order, mt);
 
 	/*
@@ -2822,7 +2890,7 @@ void __putback_isolated_page(struct page *page, unsigned int order, int mt)
 
 	/* Return isolated page to tail of freelist. */
 	__free_one_page(page, page_to_pfn(page), zone, order, mt,
-			FPI_SKIP_REPORT_NOTIFY | FPI_TO_TAIL);
+			FPI_SKIP_REPORT_NOTIFY | FPI_TO_TAIL, 0);
 }
 
 /*
@@ -2965,6 +3033,11 @@ struct page *__rmqueue_pcplist(struct zone *zone, unsigned int order,
 		}
 
 		page = list_first_entry(list, struct page, pcp_list);
+
+		/*
+		 * Pairs with check_flush_task_ugen() in prep_new_page().
+		 */
+		update_task_ugen(page_private(page));
 		list_del(&page->pcp_list);
 		pcp->count -= 1 << order;
 	} while (check_new_pages(page, order));
@@ -4791,11 +4864,11 @@ void __free_pages(struct page *page, unsigned int order)
 	struct alloc_tag *tag = pgalloc_tag_get(page);
 
 	if (put_page_testzero(page))
-		free_unref_page(page, order);
+		free_unref_page(page, order, 0);
 	else if (!head) {
 		pgalloc_tag_sub_pages(tag, (1 << order) - 1);
 		while (order-- > 0)
-			free_unref_page(page + (1 << order), order);
+			free_unref_page(page + (1 << order), order, 0);
 	}
 }
 EXPORT_SYMBOL(__free_pages);
@@ -4857,7 +4930,7 @@ void __page_frag_cache_drain(struct page *page, unsigned int count)
 	VM_BUG_ON_PAGE(page_ref_count(page) == 0, page);
 
 	if (page_ref_sub_and_test(page, count))
-		free_unref_page(page, compound_order(page));
+		free_unref_page(page, compound_order(page), 0);
 }
 EXPORT_SYMBOL(__page_frag_cache_drain);
 
@@ -4898,7 +4971,7 @@ void *__page_frag_alloc_align(struct page_frag_cache *nc,
 			goto refill;
 
 		if (unlikely(nc->pfmemalloc)) {
-			free_unref_page(page, compound_order(page));
+			free_unref_page(page, compound_order(page), 0);
 			goto refill;
 		}
 
@@ -4942,7 +5015,7 @@ void page_frag_free(void *addr)
 	struct page *page = virt_to_head_page(addr);
 
 	if (unlikely(put_page_testzero(page)))
-		free_unref_page(page, compound_order(page));
+		free_unref_page(page, compound_order(page), 0);
 }
 EXPORT_SYMBOL(page_frag_free);
 
@@ -6751,10 +6824,19 @@ void __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
 		BUG_ON(!PageBuddy(page));
 		VM_WARN_ON(get_pageblock_migratetype(page) != MIGRATE_ISOLATE);
 		order = buddy_order(page);
+		/*
+		 * del_page_from_free_list() updates current's ugen that
+		 * pairs with check_flush_task_ugen() below in this function.
+		 */
 		del_page_from_free_list(page, zone, order, MIGRATE_ISOLATE);
 		pfn += (1 << order);
 	}
 	spin_unlock_irqrestore(&zone->lock, flags);
+
+	/*
+	 * Check and flush before using it.
+	 */
+	check_flush_task_ugen();
 }
 #endif
 
@@ -6830,6 +6912,11 @@ bool take_page_off_buddy(struct page *page)
 			int migratetype = get_pfnblock_migratetype(page_head,
 								   pfn_head);
 
+			/*
+			 * del_page_from_free_list() updates current's
+			 * ugen that pairs with check_flush_task_ugen() below
+			 * in this function.
+			 */
 			del_page_from_free_list(page_head, zone, page_order,
 						migratetype);
 			break_down_buddy_pages(zone, page_head, page, 0,
@@ -6842,6 +6929,11 @@ bool take_page_off_buddy(struct page *page)
 			break;
 	}
 	spin_unlock_irqrestore(&zone->lock, flags);
+
+	/*
+	 * Check and flush before using it.
+	 */
+	check_flush_task_ugen();
 	return ret;
 }
 
@@ -6860,7 +6952,7 @@ bool put_page_back_buddy(struct page *page)
 		int migratetype = get_pfnblock_migratetype(page, pfn);
 
 		ClearPageHWPoisonTakenOff(page);
-		__free_one_page(page, pfn, zone, 0, migratetype, FPI_NONE);
+		__free_one_page(page, pfn, zone, 0, migratetype, FPI_NONE, 0);
 		if (TestClearPageHWPoison(page)) {
 			ret = true;
 		}
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 042937d5abe4..5823da60a621 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -260,6 +260,12 @@ static void unset_migratetype_isolate(struct page *page, int migratetype)
 	zone->nr_isolate_pageblock--;
 out:
 	spin_unlock_irqrestore(&zone->lock, flags);
+
+	/*
+	 * Check and flush for the pages that have been isolated.
+	 */
+	if (isolated_page)
+		check_flush_task_ugen();
 }
 
 static inline struct page *
diff --git a/mm/page_reporting.c b/mm/page_reporting.c
index e4c428e61d8c..4f94a3ea1b22 100644
--- a/mm/page_reporting.c
+++ b/mm/page_reporting.c
@@ -221,6 +221,11 @@ page_reporting_cycle(struct page_reporting_dev_info *prdev, struct zone *zone,
 		/* release lock before waiting on report processing */
 		spin_unlock_irq(&zone->lock);
 
+		/*
+		 * Check and flush before using the isolated pages.
+		 */
+		check_flush_task_ugen();
+
 		/* begin processing pages in local list */
 		err = prdev->report(prdev, sgl, PAGE_REPORTING_CAPACITY);
 
@@ -253,6 +258,11 @@ page_reporting_cycle(struct page_reporting_dev_info *prdev, struct zone *zone,
 
 	spin_unlock_irq(&zone->lock);
 
+	/*
+	 * Check and flush before using the isolated pages.
+	 */
+	check_flush_task_ugen();
+
 	return err;
 }
 
diff --git a/mm/swap.c b/mm/swap.c
index f0d478eee292..0fc5a5e8457f 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -126,10 +126,20 @@ void __folio_put(struct folio *folio)
 	if (folio_test_large(folio) && folio_test_large_rmappable(folio))
 		folio_undo_large_rmappable(folio);
 	mem_cgroup_uncharge(folio);
-	free_unref_page(&folio->page, folio_order(folio));
+	free_unref_page(&folio->page, folio_order(folio), 0);
 }
 EXPORT_SYMBOL(__folio_put);
 
+void __folio_put_ugen(struct folio *folio, unsigned short int ugen)
+{
+	if (WARN_ON(!can_luf_folio(folio)))
+		return;
+
+	page_cache_release(folio);
+	mem_cgroup_uncharge(folio);
+	free_unref_page(&folio->page, 0, ugen);
+}
+
 /**
  * put_pages_list() - release a list of pages
  * @pages: list of pages threaded on page->lru
-- 
2.17.1