Re: [PATCH] xen/gntdev: Grant maps should not be subject to NUMA balancing

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Tue, Nov 10, 2015 at 02:22:44PM -0500, Boris Ostrovsky wrote:
> Doing so will cause the grant to be unmapped and then, during
> fault handling, the fault to be mistakenly treated as NUMA hint
> fault.
> 
> In addition, even if we those maps could partcipate in NUMA
> balancing it wouldn't provide any benefit since we wouldn't be
> able to determine physical page's node (even if/when VNUMA is
> implemented).
> 
> Marking grant maps' VMAs as VM_IO will exclude them from being
> part of NUMA balancing.
> 

Should this be 'cc:stable@vger.kernel.org' ?


> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> ---
>  drivers/xen/gntdev.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index 67b9163..bf312df 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -802,7 +802,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
>  
>  	vma->vm_ops = &gntdev_vmops;
>  
> -	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
> +	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_IO;
>  
>  	if (use_ptemod)
>  		vma->vm_flags |= VM_DONTCOPY;
> -- 
> 1.7.1
>