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

From: Boris Ostrovsky
Date: Tue Nov 10 2015 - 14:21:50 EST

Doing so will cause the grant to be unmapped and then, during
fault handling, the fault to be mistakenly treated as NUMA hint

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

Marking grant maps' VMAs as VM_IO will exclude them from being
part of NUMA balancing.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
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;

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