[PATCH 0/4] mm/vmstat: simplify folio stat APIs

[PATCH 0/4] mm/vmstat: simplify folio stat APIs

[Ye Liu]

From: Ye Liu <liuye@kylinos.cn>

This series simplifies folio statistics accounting by:
1. Replacing node_stat_mod_folio/zone_stat_mod_folio with more semantic
   add_folio/sub_folio functions
2. Removing unused __node_stat_* and __zone_stat_* wrapper functions

Ye Liu (4):
  mm/vmstat: use node_stat_add_folio/sub_folio for folio_nr_pages
    operations
  mm/vmstat: use zone_stat_add_folio/sub_folio for folio_nr_pages
    operations
  mm/vmstat: remove unused __node_stat_* wrappers
  mm/vmstat: remove unused __zone_stat_* wrappers

 fs/nfs/internal.h      |  2 +-
 fs/nfs/write.c         |  2 +-
 include/linux/vmstat.h | 36 ------------------------------------
 mm/compaction.c        |  5 ++---
 mm/gup.c               |  5 ++---
 mm/khugepaged.c        | 10 ++++------
 mm/mempolicy.c         |  5 ++---
 mm/migrate.c           | 12 +++++-------
 mm/mlock.c             |  6 +++---
 mm/page-writeback.c    | 16 ++++++++--------
 mm/page_alloc.c        |  2 +-
 mm/swap_state.c        |  4 ++--
 12 files changed, 31 insertions(+), 74 deletions(-)

-- 
2.43.0

[PATCH 1/4] mm/vmstat: use node_stat_add_folio/sub_folio for folio_nr_pages operations

[Ye Liu]

From: Ye Liu <liuye@kylinos.cn>

Replace node_stat_mod_folio() calls that pass folio_nr_pages(folio) or
-folio_nr_pages(folio) as the third argument with the more concise
node_stat_add_folio() and node_stat_sub_folio() functions respectively.

This makes the code more readable and reduces the number of arguments
passed to these functions.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
---
 fs/nfs/internal.h   |  2 +-
 fs/nfs/write.c      |  2 +-
 mm/compaction.c     |  5 ++---
 mm/gup.c            |  5 ++---
 mm/khugepaged.c     | 10 ++++------
 mm/mempolicy.c      |  5 ++---
 mm/migrate.c        | 12 +++++-------
 mm/page-writeback.c |  4 ++--
 mm/swap_state.c     |  4 ++--
 9 files changed, 21 insertions(+), 28 deletions(-)

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index fc5456377160..f5c52a2d2a1f 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -858,7 +858,7 @@ static inline void nfs_folio_mark_unstable(struct folio *folio,
 		/* This page is really still in write-back - just that the
 		 * writeback is happening on the server now.
 		 */
-		node_stat_mod_folio(folio, NR_WRITEBACK, nr);
+		node_stat_add_folio(folio, NR_WRITEBACK);
 		bdi_wb_stat_mod(inode, WB_WRITEBACK, nr);
 		__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 	}
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index cc02b57de3c7..a8700824a61b 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -871,7 +871,7 @@ static void nfs_folio_clear_commit(struct folio *folio)
 	if (folio) {
 		long nr = folio_nr_pages(folio);
 
-		node_stat_mod_folio(folio, NR_WRITEBACK, -nr);
+		node_stat_sub_folio(folio, NR_WRITEBACK);
 		bdi_wb_stat_mod(folio->mapping->host, WB_WRITEBACK, -nr);
 	}
 }
diff --git a/mm/compaction.c b/mm/compaction.c
index 3648ce22c807..d7ce622aeed1 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1215,9 +1215,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 
 		/* Successfully isolated */
 		lruvec_del_folio(lruvec, folio);
-		node_stat_mod_folio(folio,
-				NR_ISOLATED_ANON + folio_is_file_lru(folio),
-				folio_nr_pages(folio));
+		node_stat_add_folio(folio,
+				NR_ISOLATED_ANON + folio_is_file_lru(folio));
 
 isolate_success:
 		list_add(&folio->lru, &cc->migratepages);
diff --git a/mm/gup.c b/mm/gup.c
index ad9ded39609c..2cb2efa20bff 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2304,9 +2304,8 @@ static unsigned long collect_longterm_unpinnable_folios(
 			continue;
 
 		list_add_tail(&folio->lru, movable_folio_list);
-		node_stat_mod_folio(folio,
-				    NR_ISOLATED_ANON + folio_is_file_lru(folio),
-				    folio_nr_pages(folio));
+		node_stat_add_folio(folio,
+				    NR_ISOLATED_ANON + folio_is_file_lru(folio));
 	}
 
 	return collected;
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index b8452dbdb043..f662de753305 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -502,9 +502,8 @@ void __khugepaged_exit(struct mm_struct *mm)
 
 static void release_pte_folio(struct folio *folio)
 {
-	node_stat_mod_folio(folio,
-			NR_ISOLATED_ANON + folio_is_file_lru(folio),
-			-folio_nr_pages(folio));
+	node_stat_sub_folio(folio,
+			NR_ISOLATED_ANON + folio_is_file_lru(folio));
 	folio_unlock(folio);
 	folio_putback_lru(folio);
 }
@@ -650,9 +649,8 @@ static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma,
 			result = SCAN_DEL_PAGE_LRU;
 			goto out;
 		}
-		node_stat_mod_folio(folio,
-				NR_ISOLATED_ANON + folio_is_file_lru(folio),
-				folio_nr_pages(folio));
+		node_stat_add_folio(folio,
+				NR_ISOLATED_ANON + folio_is_file_lru(folio));
 		VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
 		VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
 
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 4e4421b22b59..1c413f66b35f 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1259,9 +1259,8 @@ static bool migrate_folio_add(struct folio *folio, struct list_head *foliolist,
 	if ((flags & MPOL_MF_MOVE_ALL) || !folio_maybe_mapped_shared(folio)) {
 		if (folio_isolate_lru(folio)) {
 			list_add_tail(&folio->lru, foliolist);
-			node_stat_mod_folio(folio,
-				NR_ISOLATED_ANON + folio_is_file_lru(folio),
-				folio_nr_pages(folio));
+			node_stat_add_folio(folio,
+				NR_ISOLATED_ANON + folio_is_file_lru(folio));
 		} else {
 			/*
 			 * Non-movable folio may reach here.  And, there may be
diff --git a/mm/migrate.c b/mm/migrate.c
index 8a64291ab5b4..dc8cfee37a70 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -268,8 +268,8 @@ void putback_movable_pages(struct list_head *l)
 		if (unlikely(page_has_movable_ops(&folio->page))) {
 			putback_movable_ops_page(&folio->page);
 		} else {
-			node_stat_mod_folio(folio, NR_ISOLATED_ANON +
-					folio_is_file_lru(folio), -folio_nr_pages(folio));
+			node_stat_sub_folio(folio, NR_ISOLATED_ANON +
+					folio_is_file_lru(folio));
 			folio_putback_lru(folio);
 		}
 	}
@@ -2272,9 +2272,8 @@ static int __add_folio_for_migration(struct folio *folio, int node,
 			return 1;
 	} else if (folio_isolate_lru(folio)) {
 		list_add_tail(&folio->lru, pagelist);
-		node_stat_mod_folio(folio,
-			NR_ISOLATED_ANON + folio_is_file_lru(folio),
-			folio_nr_pages(folio));
+		node_stat_add_folio(folio,
+			NR_ISOLATED_ANON + folio_is_file_lru(folio));
 		return 1;
 	}
 	return -EBUSY;
@@ -2726,8 +2725,7 @@ int migrate_misplaced_folio_prepare(struct folio *folio,
 	if (!folio_isolate_lru(folio))
 		return -EAGAIN;
 
-	node_stat_mod_folio(folio, NR_ISOLATED_ANON + folio_is_file_lru(folio),
-			    nr_pages);
+	node_stat_add_folio(folio, NR_ISOLATED_ANON + folio_is_file_lru(folio));
 	return 0;
 }
 
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 833f743f309f..87e9ea41313a 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2750,7 +2750,7 @@ bool folio_redirty_for_writepage(struct writeback_control *wbc,
 
 		wb = unlocked_inode_to_wb_begin(inode, &cookie);
 		current->nr_dirtied -= nr;
-		node_stat_mod_folio(folio, NR_DIRTIED, -nr);
+		node_stat_sub_folio(folio, NR_DIRTIED);
 		wb_stat_mod(wb, WB_DIRTIED, -nr);
 		unlocked_inode_to_wb_end(inode, &cookie);
 	}
@@ -2981,7 +2981,7 @@ bool __folio_end_writeback(struct folio *folio)
 
 	lruvec_stat_mod_folio(folio, NR_WRITEBACK, -nr);
 	zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, -nr);
-	node_stat_mod_folio(folio, NR_WRITTEN, nr);
+	node_stat_add_folio(folio, NR_WRITTEN);
 
 	return ret;
 }
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 1415a5c54a43..d08e923c9979 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -160,7 +160,7 @@ void __swap_cache_add_folio(struct swap_cluster_info *ci,
 	folio_set_swapcache(folio);
 	folio->swap = entry;
 
-	node_stat_mod_folio(folio, NR_FILE_PAGES, nr_pages);
+	node_stat_add_folio(folio, NR_FILE_PAGES);
 	lruvec_stat_mod_folio(folio, NR_SWAPCACHE, nr_pages);
 }
 
@@ -265,7 +265,7 @@ void __swap_cache_del_folio(struct swap_cluster_info *ci, struct folio *folio,
 
 	folio->swap.val = 0;
 	folio_clear_swapcache(folio);
-	node_stat_mod_folio(folio, NR_FILE_PAGES, -nr_pages);
+	node_stat_sub_folio(folio, NR_FILE_PAGES);
 	lruvec_stat_mod_folio(folio, NR_SWAPCACHE, -nr_pages);
 
 	if (!folio_swapped) {
-- 
2.43.0

[PATCH 2/4] mm/vmstat: use zone_stat_add_folio/sub_folio for folio_nr_pages operations

[Ye Liu]

From: Ye Liu <liuye@kylinos.cn>

Replace zone_stat_mod_folio() calls that pass folio_nr_pages(folio) or
-folio_nr_pages(folio) as the third argument with the more concise
zone_stat_add_folio() and zone_stat_sub_folio() functions respectively.

This makes the code more readable and reduces the number of arguments
passed to these functions.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
---
 mm/mlock.c          | 4 ++--
 mm/page-writeback.c | 8 ++++----
 mm/page_alloc.c     | 2 +-
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/mm/mlock.c b/mm/mlock.c
index 8c227fefa2df..0cafcb2f4e8d 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -249,7 +249,7 @@ void mlock_folio(struct folio *folio)
 	if (!folio_test_set_mlocked(folio)) {
 		int nr_pages = folio_nr_pages(folio);
 
-		zone_stat_mod_folio(folio, NR_MLOCK, nr_pages);
+		zone_stat_add_folio(folio, NR_MLOCK);
 		__count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);
 	}
 
@@ -273,7 +273,7 @@ void mlock_new_folio(struct folio *folio)
 	fbatch = this_cpu_ptr(&mlock_fbatch.fbatch);
 	folio_set_mlocked(folio);
 
-	zone_stat_mod_folio(folio, NR_MLOCK, nr_pages);
+	zone_stat_add_folio(folio, NR_MLOCK);
 	__count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);
 
 	folio_get(folio);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 87e9ea41313a..6f9b7b081ab7 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2647,7 +2647,7 @@ void folio_account_cleaned(struct folio *folio, struct bdi_writeback *wb)
 	long nr = folio_nr_pages(folio);
 
 	lruvec_stat_mod_folio(folio, NR_FILE_DIRTY, -nr);
-	zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, -nr);
+	zone_stat_sub_folio(folio, NR_ZONE_WRITE_PENDING);
 	wb_stat_mod(wb, WB_RECLAIMABLE, -nr);
 	task_io_account_cancelled_write(nr * PAGE_SIZE);
 }
@@ -2916,7 +2916,7 @@ bool folio_clear_dirty_for_io(struct folio *folio)
 		if (folio_test_clear_dirty(folio)) {
 			long nr = folio_nr_pages(folio);
 			lruvec_stat_mod_folio(folio, NR_FILE_DIRTY, -nr);
-			zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, -nr);
+			zone_stat_sub_folio(folio, NR_ZONE_WRITE_PENDING);
 			wb_stat_mod(wb, WB_RECLAIMABLE, -nr);
 			ret = true;
 		}
@@ -2980,7 +2980,7 @@ bool __folio_end_writeback(struct folio *folio)
 	}
 
 	lruvec_stat_mod_folio(folio, NR_WRITEBACK, -nr);
-	zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, -nr);
+	zone_stat_sub_folio(folio, NR_ZONE_WRITE_PENDING);
 	node_stat_add_folio(folio, NR_WRITTEN);
 
 	return ret;
@@ -3032,7 +3032,7 @@ void __folio_start_writeback(struct folio *folio, bool keep_write)
 	}
 
 	lruvec_stat_mod_folio(folio, NR_WRITEBACK, nr);
-	zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, nr);
+	zone_stat_add_folio(folio, NR_ZONE_WRITE_PENDING);
 
 	access_ret = arch_make_folio_accessible(folio);
 	/*
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 65e205111553..a81ceb4181ea 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1327,7 +1327,7 @@ __always_inline bool __free_pages_prepare(struct page *page,
 		long nr_pages = folio_nr_pages(folio);
 
 		__folio_clear_mlocked(folio);
-		zone_stat_mod_folio(folio, NR_MLOCK, -nr_pages);
+		zone_stat_sub_folio(folio, NR_MLOCK);
 		count_vm_events(UNEVICTABLE_PGCLEARED, nr_pages);
 	}
 
-- 
2.43.0

[PATCH 3/4] mm/vmstat: remove unused __node_stat_* wrappers

[Ye Liu]

From: Ye Liu <liuye@kylinos.cn>

Replace the single call to __node_stat_mod_folio()
with node_stat_mod_folio(), and remove the dead inline __node_stat_*
wrapper definitions from include/linux/vmstat.h.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
---
 include/linux/vmstat.h | 18 ------------------
 mm/page-writeback.c    |  2 +-
 2 files changed, 1 insertion(+), 19 deletions(-)

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 3c9c266cf782..54da7d820f78 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -440,24 +440,6 @@ static inline void zone_stat_sub_folio(struct folio *folio,
 	mod_zone_page_state(folio_zone(folio), item, -folio_nr_pages(folio));
 }
 
-static inline void __node_stat_mod_folio(struct folio *folio,
-		enum node_stat_item item, long nr)
-{
-	__mod_node_page_state(folio_pgdat(folio), item, nr);
-}
-
-static inline void __node_stat_add_folio(struct folio *folio,
-		enum node_stat_item item)
-{
-	__mod_node_page_state(folio_pgdat(folio), item, folio_nr_pages(folio));
-}
-
-static inline void __node_stat_sub_folio(struct folio *folio,
-		enum node_stat_item item)
-{
-	__mod_node_page_state(folio_pgdat(folio), item, -folio_nr_pages(folio));
-}
-
 static inline void node_stat_mod_folio(struct folio *folio,
 		enum node_stat_item item, long nr)
 {
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 6f9b7b081ab7..ed3301753e89 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2627,7 +2627,7 @@ static void folio_account_dirtied(struct folio *folio,
 
 		lruvec_stat_mod_folio(folio, NR_FILE_DIRTY, nr);
 		__zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, nr);
-		__node_stat_mod_folio(folio, NR_DIRTIED, nr);
+		node_stat_mod_folio(folio, NR_DIRTIED, nr);
 		wb_stat_mod(wb, WB_RECLAIMABLE, nr);
 		wb_stat_mod(wb, WB_DIRTIED, nr);
 		task_io_account_write(nr * PAGE_SIZE);
-- 
2.43.0

[PATCH 4/4] mm/vmstat: remove unused __zone_stat_* wrappers

[Ye Liu]

From: Ye Liu <liuye@kylinos.cn>

Replace the remaining __zone_stat_mod_folio() call with
zone_stat_mod_folio(), and remove the dead inline
__zone_stat_* wrappers definitions from include/linux/vmstat.h.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
---
 include/linux/vmstat.h | 18 ------------------
 mm/mlock.c             |  2 +-
 mm/page-writeback.c    |  2 +-
 3 files changed, 2 insertions(+), 20 deletions(-)

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 54da7d820f78..009b80e3c048 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -404,24 +404,6 @@ static inline void drain_zonestat(struct zone *zone,
 			struct per_cpu_zonestat *pzstats) { }
 #endif		/* CONFIG_SMP */
 
-static inline void __zone_stat_mod_folio(struct folio *folio,
-		enum zone_stat_item item, long nr)
-{
-	__mod_zone_page_state(folio_zone(folio), item, nr);
-}
-
-static inline void __zone_stat_add_folio(struct folio *folio,
-		enum zone_stat_item item)
-{
-	__mod_zone_page_state(folio_zone(folio), item, folio_nr_pages(folio));
-}
-
-static inline void __zone_stat_sub_folio(struct folio *folio,
-		enum zone_stat_item item)
-{
-	__mod_zone_page_state(folio_zone(folio), item, -folio_nr_pages(folio));
-}
-
 static inline void zone_stat_mod_folio(struct folio *folio,
 		enum zone_stat_item item, long nr)
 {
diff --git a/mm/mlock.c b/mm/mlock.c
index 0cafcb2f4e8d..654487063fbb 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -141,7 +141,7 @@ static struct lruvec *__munlock_folio(struct folio *folio, struct lruvec *lruvec
 
 munlock:
 	if (folio_test_clear_mlocked(folio)) {
-		__zone_stat_mod_folio(folio, NR_MLOCK, -nr_pages);
+		zone_stat_mod_folio(folio, NR_MLOCK, -nr_pages);
 		if (isolated || !folio_test_unevictable(folio))
 			__count_vm_events(UNEVICTABLE_PGMUNLOCKED, nr_pages);
 		else
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index ed3301753e89..dc15d775761e 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2626,7 +2626,7 @@ static void folio_account_dirtied(struct folio *folio,
 		wb = inode_to_wb(inode);
 
 		lruvec_stat_mod_folio(folio, NR_FILE_DIRTY, nr);
-		__zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, nr);
+		zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, nr);
 		node_stat_mod_folio(folio, NR_DIRTIED, nr);
 		wb_stat_mod(wb, WB_RECLAIMABLE, nr);
 		wb_stat_mod(wb, WB_DIRTIED, nr);
-- 
2.43.0

Re: [PATCH 0/4] mm/vmstat: simplify folio stat APIs

[Matthew Wilcox]

On Tue, Apr 14, 2026 at 05:15:17PM +0800, Ye Liu wrote:
> From: Ye Liu <liuye@kylinos.cn>
> 
> This series simplifies folio statistics accounting by:
> 1. Replacing node_stat_mod_folio/zone_stat_mod_folio with more semantic
>    add_folio/sub_folio functions
> 2. Removing unused __node_stat_* and __zone_stat_* wrapper functions

I'm not convinced this is the right approach.  We've often computed
folio_nr_pages() for use by several different functions, and you're
making us recompute it.

Re: [PATCH 3/4] mm/vmstat: remove unused __node_stat_* wrappers

[Joshua Hahn]

On Tue, 14 Apr 2026 17:15:20 +0800 Ye Liu <ye.liu@linux.dev> wrote:

> From: Ye Liu <liuye@kylinos.cn>
> 
> Replace the single call to __node_stat_mod_folio()
> with node_stat_mod_folio(), and remove the dead inline __node_stat_*
> wrapper definitions from include/linux/vmstat.h.
> 
> Signed-off-by: Ye Liu <liuye@kylinos.cn>
> ---
>  include/linux/vmstat.h | 18 ------------------
>  mm/page-writeback.c    |  2 +-
>  2 files changed, 1 insertion(+), 19 deletions(-)
> 
> diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
> index 3c9c266cf782..54da7d820f78 100644
> --- a/include/linux/vmstat.h
> +++ b/include/linux/vmstat.h
> @@ -440,24 +440,6 @@ static inline void zone_stat_sub_folio(struct folio *folio,
>  	mod_zone_page_state(folio_zone(folio), item, -folio_nr_pages(folio));
>  }
>  
> -static inline void __node_stat_mod_folio(struct folio *folio,
> -		enum node_stat_item item, long nr)
> -{
> -	__mod_node_page_state(folio_pgdat(folio), item, nr);
> -}
> -
> -static inline void __node_stat_add_folio(struct folio *folio,
> -		enum node_stat_item item)
> -{
> -	__mod_node_page_state(folio_pgdat(folio), item, folio_nr_pages(folio));
> -}
> -
> -static inline void __node_stat_sub_folio(struct folio *folio,
> -		enum node_stat_item item)
> -{
> -	__mod_node_page_state(folio_pgdat(folio), item, -folio_nr_pages(folio));
> -}
> -
>  static inline void node_stat_mod_folio(struct folio *folio,
>  		enum node_stat_item item, long nr)
>  {
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 6f9b7b081ab7..ed3301753e89 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -2627,7 +2627,7 @@ static void folio_account_dirtied(struct folio *folio,
>  
>  		lruvec_stat_mod_folio(folio, NR_FILE_DIRTY, nr);
>  		__zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, nr);
> -		__node_stat_mod_folio(folio, NR_DIRTIED, nr);
> +		node_stat_mod_folio(folio, NR_DIRTIED, nr);

Hi Ye, thank you for the patch,

In addition to what Matthew has pointed out, I also wanted to note that this
substitution isn't trivial; there are differences between the __ prefixed
version of node_stat_mod_folio and the one without. Even though the correctness
of the two versions might be the same, I think that a change like this should
be supplemented by a description of what side effects this change has
(i.e. introducing additional overhead from the cmpxchg loop).

Thank you, I hope you have a great day!
Joshua

Re: [PATCH 1/4] mm/vmstat: use node_stat_add_folio/sub_folio for folio_nr_pages operations

[David Hildenbrand (Arm)]

On 4/14/26 11:15, Ye Liu wrote:
> From: Ye Liu <liuye@kylinos.cn>
> 
> Replace node_stat_mod_folio() calls that pass folio_nr_pages(folio) or
> -folio_nr_pages(folio) as the third argument with the more concise
> node_stat_add_folio() and node_stat_sub_folio() functions respectively.
> 
> This makes the code more readable and reduces the number of arguments
> passed to these functions.

Also, that makes it clearer that we always account the full folio, never
parts of it.

-- 
Cheers,

David

Re: [PATCH 0/4] mm/vmstat: simplify folio stat APIs

[Ye Liu]

在 2026/4/14 21:18, Matthew Wilcox 写道:
> On Tue, Apr 14, 2026 at 05:15:17PM +0800, Ye Liu wrote:
>> From: Ye Liu <liuye@kylinos.cn>
>>
>> This series simplifies folio statistics accounting by:
>> 1. Replacing node_stat_mod_folio/zone_stat_mod_folio with more semantic
>>    add_folio/sub_folio functions
>> 2. Removing unused __node_stat_* and __zone_stat_* wrapper functions
> 
> I'm not convinced this is the right approach.  We've often computed
> folio_nr_pages() for use by several different functions, and you're
> making us recompute it.


Thank you for your feedback, Matthew. I acknowledge that this change may
introduce additional calls to folio_nr_pages() in some cases where the
value was previously computed once and reused. However, the new
add_folio/sub_folio functions provide clearer semantics, explicitly
indicating that we're accounting for the entire folio rather than
potentially partial pages. The overhead of recomputing folio_nr_pages()
is minimal in most scenarios, and the improved readability and reduced
argument passing outweigh this concern.

-- 
Thanks,
Ye Liu

Re: [PATCH 1/4] mm/vmstat: use node_stat_add_folio/sub_folio for folio_nr_pages operations

[Ye Liu]

在 2026/4/15 01:52, David Hildenbrand (Arm) 写道:
> On 4/14/26 11:15, Ye Liu wrote:
>> From: Ye Liu <liuye@kylinos.cn>
>>
>> Replace node_stat_mod_folio() calls that pass folio_nr_pages(folio) or
>> -folio_nr_pages(folio) as the third argument with the more concise
>> node_stat_add_folio() and node_stat_sub_folio() functions respectively.
>>
>> This makes the code more readable and reduces the number of arguments
>> passed to these functions.
> 
> Also, that makes it clearer that we always account the full folio, never
> parts of it.
> 

Thank you, David, for your support. I agree that the new functions make
the intent more explicit.

-- 
Thanks,
Ye Liu

Re: [PATCH 3/4] mm/vmstat: remove unused __node_stat_* wrappers

[Ye Liu]

在 2026/4/14 22:59, Joshua Hahn 写道:
> On Tue, 14 Apr 2026 17:15:20 +0800 Ye Liu <ye.liu@linux.dev> wrote:
> 
>> From: Ye Liu <liuye@kylinos.cn>
>>
>> Replace the single call to __node_stat_mod_folio()
>> with node_stat_mod_folio(), and remove the dead inline __node_stat_*
>> wrapper definitions from include/linux/vmstat.h.
>>
>> Signed-off-by: Ye Liu <liuye@kylinos.cn>
>> ---
>>  include/linux/vmstat.h | 18 ------------------
>>  mm/page-writeback.c    |  2 +-
>>  2 files changed, 1 insertion(+), 19 deletions(-)
>>
>> diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
>> index 3c9c266cf782..54da7d820f78 100644
>> --- a/include/linux/vmstat.h
>> +++ b/include/linux/vmstat.h
>> @@ -440,24 +440,6 @@ static inline void zone_stat_sub_folio(struct folio *folio,
>>  	mod_zone_page_state(folio_zone(folio), item, -folio_nr_pages(folio));
>>  }
>>  
>> -static inline void __node_stat_mod_folio(struct folio *folio,
>> -		enum node_stat_item item, long nr)
>> -{
>> -	__mod_node_page_state(folio_pgdat(folio), item, nr);
>> -}
>> -
>> -static inline void __node_stat_add_folio(struct folio *folio,
>> -		enum node_stat_item item)
>> -{
>> -	__mod_node_page_state(folio_pgdat(folio), item, folio_nr_pages(folio));
>> -}
>> -
>> -static inline void __node_stat_sub_folio(struct folio *folio,
>> -		enum node_stat_item item)
>> -{
>> -	__mod_node_page_state(folio_pgdat(folio), item, -folio_nr_pages(folio));
>> -}
>> -
>>  static inline void node_stat_mod_folio(struct folio *folio,
>>  		enum node_stat_item item, long nr)
>>  {
>> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
>> index 6f9b7b081ab7..ed3301753e89 100644
>> --- a/mm/page-writeback.c
>> +++ b/mm/page-writeback.c
>> @@ -2627,7 +2627,7 @@ static void folio_account_dirtied(struct folio *folio,
>>  
>>  		lruvec_stat_mod_folio(folio, NR_FILE_DIRTY, nr);
>>  		__zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, nr);
>> -		__node_stat_mod_folio(folio, NR_DIRTIED, nr);
>> +		node_stat_mod_folio(folio, NR_DIRTIED, nr);
> 
> Hi Ye, thank you for the patch,
> 
> In addition to what Matthew has pointed out, I also wanted to note that this
> substitution isn't trivial; there are differences between the __ prefixed
> version of node_stat_mod_folio and the one without. Even though the correctness
> of the two versions might be the same, I think that a change like this should
> be supplemented by a description of what side effects this change has
> (i.e. introducing additional overhead from the cmpxchg loop).
> 
> Thank you, I hope you have a great day!
> Joshua

Thank you for your review, Joshua. Regarding the difference between
__node_stat_mod_folio and node_stat_mod_folio: in the current implementation,
both functions ultimately use __mod_node_page_state, as mod_node_page_state
is defined as __mod_node_page_state. There is no functional difference
between them in terms of atomicity or overhead. The __ prefixed versions
were wrappers that are now unused, which is why we're removing them.

-- 
Thanks,
Ye Liu

Re: [PATCH 3/4] mm/vmstat: remove unused __node_stat_* wrappers

[Joshua Hahn]

On Wed, 15 Apr 2026 08:50:54 +0800 Ye Liu <ye.liu@linux.dev> wrote:

> 
> 
> 在 2026/4/14 22:59, Joshua Hahn 写道:
> > On Tue, 14 Apr 2026 17:15:20 +0800 Ye Liu <ye.liu@linux.dev> wrote:
> > 
> >> From: Ye Liu <liuye@kylinos.cn>
> >>
> >> Replace the single call to __node_stat_mod_folio()
> >> with node_stat_mod_folio(), and remove the dead inline __node_stat_*
> >> wrapper definitions from include/linux/vmstat.h.
> >>
> >> Signed-off-by: Ye Liu <liuye@kylinos.cn>
> >> ---
> >>  include/linux/vmstat.h | 18 ------------------
> >>  mm/page-writeback.c    |  2 +-
> >>  2 files changed, 1 insertion(+), 19 deletions(-)
> >>
> >> diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
> >> index 3c9c266cf782..54da7d820f78 100644
> >> --- a/include/linux/vmstat.h
> >> +++ b/include/linux/vmstat.h
> >> @@ -440,24 +440,6 @@ static inline void zone_stat_sub_folio(struct folio *folio,
> >>  	mod_zone_page_state(folio_zone(folio), item, -folio_nr_pages(folio));
> >>  }
> >>  
> >> -static inline void __node_stat_mod_folio(struct folio *folio,
> >> -		enum node_stat_item item, long nr)
> >> -{
> >> -	__mod_node_page_state(folio_pgdat(folio), item, nr);
> >> -}
> >> -
> >> -static inline void __node_stat_add_folio(struct folio *folio,
> >> -		enum node_stat_item item)
> >> -{
> >> -	__mod_node_page_state(folio_pgdat(folio), item, folio_nr_pages(folio));
> >> -}
> >> -
> >> -static inline void __node_stat_sub_folio(struct folio *folio,
> >> -		enum node_stat_item item)
> >> -{
> >> -	__mod_node_page_state(folio_pgdat(folio), item, -folio_nr_pages(folio));
> >> -}
> >> -
> >>  static inline void node_stat_mod_folio(struct folio *folio,
> >>  		enum node_stat_item item, long nr)
> >>  {
> >> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> >> index 6f9b7b081ab7..ed3301753e89 100644
> >> --- a/mm/page-writeback.c
> >> +++ b/mm/page-writeback.c
> >> @@ -2627,7 +2627,7 @@ static void folio_account_dirtied(struct folio *folio,
> >>  
> >>  		lruvec_stat_mod_folio(folio, NR_FILE_DIRTY, nr);
> >>  		__zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, nr);
> >> -		__node_stat_mod_folio(folio, NR_DIRTIED, nr);
> >> +		node_stat_mod_folio(folio, NR_DIRTIED, nr);
> > 
> > Hi Ye, thank you for the patch,
> > 
> > In addition to what Matthew has pointed out, I also wanted to note that this
> > substitution isn't trivial; there are differences between the __ prefixed
> > version of node_stat_mod_folio and the one without. Even though the correctness
> > of the two versions might be the same, I think that a change like this should
> > be supplemented by a description of what side effects this change has
> > (i.e. introducing additional overhead from the cmpxchg loop).
> > 
> > Thank you, I hope you have a great day!
> > Joshua
> 
> Thank you for your review, Joshua. Regarding the difference between
> __node_stat_mod_folio and node_stat_mod_folio: in the current implementation,
> both functions ultimately use __mod_node_page_state, as mod_node_page_state
> is defined as __mod_node_page_state. There is no functional difference
> between them in terms of atomicity or overhead. The __ prefixed versions
> were wrappers that are now unused, which is why we're removing them.

Hello Ye,

Thanks for the quick response. However, I'm not sure that's true.
For #ifdef CONFIG_HAVE_CMPXCHG_LOCAL in mm/vmstat.c, I can see that
mod_node_page_state calls mod_node_state, which includes the cmpxchg loop.
I think many users enalbe this config, including x86. IMHO, we should document
this effect of the changes.

Thank you, I hope you have a great day!
Joshua

Re: [PATCH 0/4] mm/vmstat: simplify folio stat APIs

[Matthew Wilcox]

On Wed, Apr 15, 2026 at 08:47:24AM +0800, Ye Liu wrote:
> Thank you for your feedback, Matthew. I acknowledge that this change may
> introduce additional calls to folio_nr_pages() in some cases where the
> value was previously computed once and reused. However, the new
> add_folio/sub_folio functions provide clearer semantics, explicitly
> indicating that we're accounting for the entire folio rather than
> potentially partial pages. The overhead of recomputing folio_nr_pages()
> is minimal in most scenarios, and the improved readability and reduced
> argument passing outweigh this concern.

I disagree.

Re: [PATCH 3/4] mm/vmstat: remove unused __node_stat_* wrappers

[Ye Liu]

在 2026/4/15 10:29, Joshua Hahn 写道:
> On Wed, 15 Apr 2026 08:50:54 +0800 Ye Liu <ye.liu@linux.dev> wrote:
> 
>>
>>
>> 在 2026/4/14 22:59, Joshua Hahn 写道:
>>> On Tue, 14 Apr 2026 17:15:20 +0800 Ye Liu <ye.liu@linux.dev> wrote:
>>>
>>>> From: Ye Liu <liuye@kylinos.cn>
>>>>
>>>> Replace the single call to __node_stat_mod_folio()
>>>> with node_stat_mod_folio(), and remove the dead inline __node_stat_*
>>>> wrapper definitions from include/linux/vmstat.h.
>>>>
>>>> Signed-off-by: Ye Liu <liuye@kylinos.cn>
>>>> ---
>>>>  include/linux/vmstat.h | 18 ------------------
>>>>  mm/page-writeback.c    |  2 +-
>>>>  2 files changed, 1 insertion(+), 19 deletions(-)
>>>>
>>>> diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
>>>> index 3c9c266cf782..54da7d820f78 100644
>>>> --- a/include/linux/vmstat.h
>>>> +++ b/include/linux/vmstat.h
>>>> @@ -440,24 +440,6 @@ static inline void zone_stat_sub_folio(struct folio *folio,
>>>>  	mod_zone_page_state(folio_zone(folio), item, -folio_nr_pages(folio));
>>>>  }
>>>>  
>>>> -static inline void __node_stat_mod_folio(struct folio *folio,
>>>> -		enum node_stat_item item, long nr)
>>>> -{
>>>> -	__mod_node_page_state(folio_pgdat(folio), item, nr);
>>>> -}
>>>> -
>>>> -static inline void __node_stat_add_folio(struct folio *folio,
>>>> -		enum node_stat_item item)
>>>> -{
>>>> -	__mod_node_page_state(folio_pgdat(folio), item, folio_nr_pages(folio));
>>>> -}
>>>> -
>>>> -static inline void __node_stat_sub_folio(struct folio *folio,
>>>> -		enum node_stat_item item)
>>>> -{
>>>> -	__mod_node_page_state(folio_pgdat(folio), item, -folio_nr_pages(folio));
>>>> -}
>>>> -
>>>>  static inline void node_stat_mod_folio(struct folio *folio,
>>>>  		enum node_stat_item item, long nr)
>>>>  {
>>>> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
>>>> index 6f9b7b081ab7..ed3301753e89 100644
>>>> --- a/mm/page-writeback.c
>>>> +++ b/mm/page-writeback.c
>>>> @@ -2627,7 +2627,7 @@ static void folio_account_dirtied(struct folio *folio,
>>>>  
>>>>  		lruvec_stat_mod_folio(folio, NR_FILE_DIRTY, nr);
>>>>  		__zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, nr);
>>>> -		__node_stat_mod_folio(folio, NR_DIRTIED, nr);
>>>> +		node_stat_mod_folio(folio, NR_DIRTIED, nr);
>>>
>>> Hi Ye, thank you for the patch,
>>>
>>> In addition to what Matthew has pointed out, I also wanted to note that this
>>> substitution isn't trivial; there are differences between the __ prefixed
>>> version of node_stat_mod_folio and the one without. Even though the correctness
>>> of the two versions might be the same, I think that a change like this should
>>> be supplemented by a description of what side effects this change has
>>> (i.e. introducing additional overhead from the cmpxchg loop).
>>>
>>> Thank you, I hope you have a great day!
>>> Joshua
>>
>> Thank you for your review, Joshua. Regarding the difference between
>> __node_stat_mod_folio and node_stat_mod_folio: in the current implementation,
>> both functions ultimately use __mod_node_page_state, as mod_node_page_state
>> is defined as __mod_node_page_state. There is no functional difference
>> between them in terms of atomicity or overhead. The __ prefixed versions
>> were wrappers that are now unused, which is why we're removing them.
> 
> Hello Ye,
> 
> Thanks for the quick response. However, I'm not sure that's true.
> For #ifdef CONFIG_HAVE_CMPXCHG_LOCAL in mm/vmstat.c, I can see that
> mod_node_page_state calls mod_node_state, which includes the cmpxchg loop.
> I think many users enalbe this config, including x86. IMHO, we should document
> this effect of the changes.
> 
> Thank you, I hope you have a great day!
> Joshua

Thank you for your review, Joshua. You are correct that there is a difference.
The __node_stat_mod_folio call goes directly to __mod_node_page_state, which
assumes the caller already has the necessary serialization. By contrast,
node_stat_mod_folio goes through mod_node_page_state, which on systems with
CONFIG_HAVE_CMPXCHG_LOCAL uses a this_cpu_try_cmpxchg() loop and on other
systems serializes via local_irq_save/restore.

That means the wrapper removal is not purely cosmetic: it changes the
update path from a direct per-cpu diff update to a serializing update
path, and therefore incurs extra overhead.

-- 
Thanks,
Ye Liu

Re: [PATCH 0/4] mm/vmstat: simplify folio stat APIs

[Ye Liu]

在 2026/4/15 11:59, Matthew Wilcox 写道:
> On Wed, Apr 15, 2026 at 08:47:24AM +0800, Ye Liu wrote:
>> Thank you for your feedback, Matthew. I acknowledge that this change may
>> introduce additional calls to folio_nr_pages() in some cases where the
>> value was previously computed once and reused. However, the new
>> add_folio/sub_folio functions provide clearer semantics, explicitly
>> indicating that we're accounting for the entire folio rather than
>> potentially partial pages. The overhead of recomputing folio_nr_pages()
>> is minimal in most scenarios, and the improved readability and reduced
>> argument passing outweigh this concern.
> 
> I disagree.

Thanks for the direct feedback.

-- 
Thanks,
Ye Liu