Re: [PATCH v4 1/3] mm: add new api to enable ksm per process

[Johannes Weiner <hannes@cmpxchg.org>]

On Fri, Mar 10, 2023 at 10:28:49AM -0800, Stefan Roesch wrote:
> @@ -534,16 +534,58 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr,
>  	return (ret & VM_FAULT_OOM) ? -ENOMEM : 0;
>  }
>  
> +static bool vma_ksm_compatible(struct vm_area_struct *vma)
> +{
> +	/*
> +	 * Be somewhat over-protective for now!
> +	 */
> +	if (vma->vm_flags & (VM_MERGEABLE | VM_SHARED  | VM_MAYSHARE   |
> +			     VM_PFNMAP    | VM_IO      | VM_DONTEXPAND |
> +			     VM_HUGETLB | VM_MIXEDMAP))
> +		return false;		/* just ignore the advice */
> +
> +	if (vma_is_dax(vma))
> +		return false;
> +
> +#ifdef VM_SAO
> +	if (*vm_flags & VM_SAO)
> +		return false;
> +#endif
> +#ifdef VM_SPARC_ADI
> +	if (*vm_flags & VM_SPARC_ADI)
> +		return false;
> +#endif

These two also need to check vma->vm_flags, or it won't build on those
configs.

Otherwise, the patch looks good to me.