Re: [PATCH V2 1/3] mm/hugetlb: fix mremap move length truncation

["David Hildenbrand (Arm)" <david@kernel.org>]

On 10/19/26 13:30, Li Zhe wrote:
> move_hugetlb_page_tables() returns the number of bytes moved, but
> its return type is int while the generic move_page_tables() path uses
> unsigned long lengths.
> 
> A hugetlb mremap() move length above INT_MAX can therefore be
> misreported to copy_vma_and_data(). The out-of-range conversion to int
> is implementation-defined; on common 64-bit builds, for example, a
> 4 GiB move can be reported as zero, making the caller treat the move as
> a failure and use the wrong length for rollback.

Sounds like we want to CC stable here, right?

> 
> Return unsigned long from move_hugetlb_page_tables(), matching
> move_page_tables() and preserving the full byte count.
> 
> Fixes: 550a7d60bd5e ("mm, hugepages: add mremap() support for hugepage backed vma")
> Signed-off-by: Li Zhe <lizhe.67@bytedance.com>
> ---
>  include/linux/hugetlb.h | 18 +++++++++---------
>  mm/hugetlb.c            |  8 ++++----
>  2 files changed, 13 insertions(+), 13 deletions(-)
> 
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 16c4c4caa126..cc12040e4032 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -121,10 +121,10 @@ void hugepage_put_subpool(struct hugepage_subpool *spool);
>  
>  void hugetlb_dup_vma_private(struct vm_area_struct *vma);
>  void clear_vma_resv_huge_pages(struct vm_area_struct *vma);
> -int move_hugetlb_page_tables(struct vm_area_struct *vma,
> -			     struct vm_area_struct *new_vma,
> -			     unsigned long old_addr, unsigned long new_addr,
> -			     unsigned long len);
> +unsigned long move_hugetlb_page_tables(struct vm_area_struct *vma,
> +				       struct vm_area_struct *new_vma,
> +				       unsigned long old_addr, unsigned long new_addr,
> +				       unsigned long len);

While at it, can you convert all these to use double tab indent instead?

Acked-by: David Hildenbrand (Arm) <david@kernel.org>

-- 
Cheers,

David