Re: [PATCH 7.2 v4 03/12] mm/huge_memory: remove READ_ONLY_THP_FOR_FS from file_thp_enabled()

Zi Yan
2026-04-24T14:58:54Z

On 23 Apr 2026, at 22:49, Zi Yan wrote:

> Replace it with a check on the max folio order of the file's address space
> mapping, making sure PMD THP is supported. Also remove the read-only fd
> check, since collapse_file() now makes sure all to-be-collapsed folios are
> clean and the created PMD file THP can be handled by FSes properly.
>
> Signed-off-by: Zi Yan <ziy@nvidia.com>
> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> ---
> mm/huge_memory.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 1f0d0b780943..f0db1390a18f 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -86,9 +86,6 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma)
> {
> struct inode *inode;
>
> - if (!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS))
> - return false;
> -
> if (!vma->vm_file)
> return false;
>
> @@ -97,7 +94,10 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma)
> if (IS_ANON_FILE(inode))
> return false;
>
> - return !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode);
> + if (!mapping_pmd_thp_support(inode->i_mapping))
> + return false;

sashiko told me that I need to check vma->vm_file->f_mapping, since
folio->mapping needs to match vma->vm_file->f_mapping and inode->i_mapping
and vma->vm_file->f_mapping can diverge.

I will fix this one.

> +
> + return S_ISREG(inode->i_mode);
> }
>
> /* If returns true, we are unable to access the VMA's folios. */
> --
> 2.43.0

Best Regards,
Yan, Zi