[PATCH 4.1 003/127] xen/gntdev: Grant maps should not be subject to NUMA balancing

[Greg Kroah-Hartman]

4.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>

commit 9c17d96500f78d7ecdb71ca6942830158bc75a2b upstream.

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 those maps could partcipate in NUMA
balancing, it wouldn't provide any benefit since we are unable
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.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/xen/gntdev.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -804,7 +804,7 @@ static int gntdev_mmap(struct file *flip
 
 	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;