Re: [PATCH 2/4] mm: ksm: refer to special VMAs via VM_SPECIAL in ksm_compatible()

[Chengming Zhou]

On 2025/5/19 16:51, Lorenzo Stoakes wrote:
> There's no need to spell out all the special cases, also doing it this way
> makes it absolutely clear that we preclude unmergeable VMAs in general, and
> puts the other excluded flags in stark and clear contrast.
>
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>

Nice.

Reviewed-by: Chengming Zhou <chengming.zhou@xxxxxxxxx>

Thanks!

> ---
>   mm/ksm.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 08d486f188ff..d0c763abd499 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -679,9 +679,8 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr, bool lock_v
>   
>   static bool ksm_compatible(const struct file *file, vm_flags_t vm_flags)
>   {
> -	if (vm_flags & (VM_SHARED   | VM_MAYSHARE   | VM_PFNMAP  |
> -			VM_IO       | VM_DONTEXPAND | VM_HUGETLB |
> -			VM_MIXEDMAP | VM_DROPPABLE))
> +	if (vm_flags & (VM_SHARED  | VM_MAYSHARE | VM_SPECIAL |
> +			VM_HUGETLB | VM_DROPPABLE))
>   		return false;		/* just ignore the advice */
>   
>   	if (file_is_dax(file))