[PATCH v1 07/10] mm/truncate: use folio_split() in truncate_inode_partial_folio()

Zi Yan
2026-03-27T01:43:19Z

After READ_ONLY_THP_FOR_FS is removed, FS either supports large folio or
not. folio_split() can be used on a FS with large folio support without
worrying about getting a THP on a FS without large folio support.

Signed-off-by: Zi Yan <ziy@nvidia.com>
---
include/linux/huge_mm.h | 25 ++-----------------------
mm/truncate.c | 8 ++++----
2 files changed, 6 insertions(+), 27 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 1258fa37e85b..171de8138e98 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -389,27 +389,6 @@ static inline int split_huge_page_to_order(struct page *page, unsigned int new_o
return split_huge_page_to_list_to_order(page, NULL, new_order);
}

-/**
- * try_folio_split_to_order() - try to split a @folio at @page to @new_order
- * using non uniform split.
- * @folio: folio to be split
- * @page: split to @new_order at the given page
- * @new_order: the target split order
- *
- * Try to split a @folio at @page using non uniform split to @new_order, if
- * non uniform split is not supported, fall back to uniform split. After-split
- * folios are put back to LRU list. Use min_order_for_split() to get the lower
- * bound of @new_order.
- *
- * Return: 0 - split is successful, otherwise split failed.
- */
-static inline int try_folio_split_to_order(struct folio *folio,
- struct page *page, unsigned int new_order)
-{
- if (folio_check_splittable(folio, new_order, SPLIT_TYPE_NON_UNIFORM))
- return split_huge_page_to_order(&folio->page, new_order);
- return folio_split(folio, new_order, page, NULL);
-}
static inline int split_huge_page(struct page *page)
{
return split_huge_page_to_list_to_order(page, NULL, 0);
@@ -641,8 +620,8 @@ static inline int split_folio_to_list(struct folio *folio, struct list_head *lis
return -EINVAL;
}

-static inline int try_folio_split_to_order(struct folio *folio,
- struct page *page, unsigned int new_order)
+static inline int folio_split(struct folio *folio, unsigned int new_order,
+ struct page *page, struct list_head *list);
{
VM_WARN_ON_ONCE_FOLIO(1, folio);
return -EINVAL;
diff --git a/mm/truncate.c b/mm/truncate.c
index 2931d66c16d0..6973b05ec4b8 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -177,7 +177,7 @@ int truncate_inode_folio(struct address_space *mapping, struct folio *folio)
return 0;
}

-static int try_folio_split_or_unmap(struct folio *folio, struct page *split_at,
+static int folio_split_or_unmap(struct folio *folio, struct page *split_at,
unsigned long min_order)
{
enum ttu_flags ttu_flags =
@@ -186,7 +186,7 @@ static int try_folio_split_or_unmap(struct folio *folio, struct page *split_at,
TTU_IGNORE_MLOCK;
int ret;

- ret = try_folio_split_to_order(folio, split_at, min_order);
+ ret = folio_split(folio, min_order, split_at, NULL);

/*
* If the split fails, unmap the folio, so it will be refaulted
@@ -252,7 +252,7 @@ bool truncate_inode_partial_folio(struct folio *folio, loff_t start, loff_t end)

min_order = mapping_min_folio_order(folio->mapping);
split_at = folio_page(folio, PAGE_ALIGN_DOWN(offset) / PAGE_SIZE);
- if (!try_folio_split_or_unmap(folio, split_at, min_order)) {
+ if (!folio_split_or_unmap(folio, split_at, min_order)) {
/*
* try to split at offset + length to make sure folios within
* the range can be dropped, especially to avoid memory waste
@@ -279,7 +279,7 @@ bool truncate_inode_partial_folio(struct folio *folio, loff_t start, loff_t end)
/* make sure folio2 is large and does not change its mapping */
if (folio_test_large(folio2) &&
folio2->mapping == folio->mapping)
- try_folio_split_or_unmap(folio2, split_at2, min_order);
+ folio_split_or_unmap(folio2, split_at2, min_order);

folio_unlock(folio2);
out:
--
2.43.0