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

[Nico Pache]

On 4/29/26 9:29 AM, Zi Yan wrote:

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().

Thank you for cleaning that up!

Reviewed-by: Nico Pache <npa...@redhat.com>

Signed-off-by: Zi Yan <z...@nvidia.com>
Reviewed-by: Baolin Wang <baolin.w...@linux.alibaba.com>
Acked-by: David Hildenbrand (Arm) <da...@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;
  }