[PATCH v5 04/14] mm/khugepaged: remove READ_ONLY_THP_FOR_FS check in hugepage_enabled()

Zi Yan
2026-04-29T15:30:35Z

Remove the READ_ONLY_THP_FOR_FS gate and khugepaged for file-backed
pmd-sized hugepages are enabled by the global transparent hugepage control.
khugepaged can still be enabled by per-size control for anon and shmem when
the global control is off.

Add shmem_hpage_pmd_enabled() stub for !CONFIG_SHMEM to remove
IS_ENABLED(SHMEM) in hugepage_enabled().

Clean up hugepage_enabled() by moving anon code to anon_hpage_enabled().

Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
---
include/linux/shmem_fs.h | 2 +-
mm/khugepaged.c | 26 ++++++++++++++++----------
2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index 93a0ba872ebe0..acb8dd961b45c 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -127,7 +127,7 @@ int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
void shmem_truncate_range(struct inode *inode, loff_t start, uoff_t end);
int shmem_unuse(unsigned int type);

-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && defined(CONFIG_SHMEM)
unsigned long shmem_allowable_huge_orders(struct inode *inode,
struct vm_area_struct *vma, pgoff_t index,
loff_t write_end, bool shmem_huge_force);
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 71209a72195ab..d6971ada8f199 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -524,26 +524,32 @@ static inline int collapse_test_exit_or_disable(struct mm_struct *mm)
mm_flags_test(MMF_DISABLE_THP_COMPLETELY, mm);
}

+static inline bool anon_hpage_enabled(void)
+{
+ if (READ_ONCE(huge_anon_orders_always))
+ return true;
+ if (READ_ONCE(huge_anon_orders_madvise))
+ return true;
+ if (READ_ONCE(huge_anon_orders_inherit) &&
+ hugepage_global_enabled())
+ return true;
+ return false;
+}
+
static bool hugepage_enabled(void)
{
/*
* We cover the anon, shmem and the file-backed case here; file-backed
- * hugepages, when configured in, are determined by the global control.
+ * hugepages are determined by the global control.
* Anon hugepages are determined by its per-size mTHP control.
* Shmem pmd-sized hugepages are also determined by its pmd-size control,
* except when the global shmem_huge is set to SHMEM_HUGE_DENY.
*/
- if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) &&
- hugepage_global_enabled())
- return true;
- if (READ_ONCE(huge_anon_orders_always))
+ if (hugepage_global_enabled())
return true;
- if (READ_ONCE(huge_anon_orders_madvise))
- return true;
- if (READ_ONCE(huge_anon_orders_inherit) &&
- hugepage_global_enabled())
+ if (anon_hpage_enabled())
return true;
- if (IS_ENABLED(CONFIG_SHMEM) && shmem_hpage_pmd_enabled())
+ if (shmem_hpage_pmd_enabled())
return true;
return false;
}
--
2.53.0