Re: SG does not ignore dxferp (direct io + mmap)

["Ewan D. Milne" <emilne@redhat.com>]

On Mon, 2016-11-21 at 12:34 -0500, Douglas Gilbert wrote:
> There was also this change which seems closer to the problem area:
> 
> commit 461c7fa126794157484dca48e88effa4963e3af3
> Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Date:   Tue Feb 2 16:57:35 2016 -0800
> 
>      drivers/scsi/sg.c: mark VMA as VM_IO to prevent migration
> ...
> 
> diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
> index 503ab8b..5e82067 100644
> --- a/drivers/scsi/sg.c
> +++ b/drivers/scsi/sg.c
> @@ -1261,7 +1261,7 @@ sg_mmap(struct file *filp, struct vm_area_struct *vma)
>          }
> 
>          sfp->mmap_called = 1;
> -       vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
> +       vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
>          vma->vm_private_data = sfp;
>          vma->vm_ops = &sg_mmap_vm_ops;
>          return 0;
> 
> Doug Gilbert
> 

Neither this change nor "sg: fix dxferp in from_to case" appears to
fix the issue when applied on top of 4.4.  Still looking...

-Ewan