xen/gntdev: Grant maps should not be subject to NUMA balancing

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@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 91cc44611062cd5ca76611ad7a749057cf4e2a65..7ffbb93906285a0c520f8ca8ef9fe0803b1fe074 100644 (file)
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -765,7 +765,7 @@ 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;