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Subject[PATCH] xen/gntdev: do not set VM_PFNMAP
Since when we are using the m2p_override it is not true anymore that the
mmap'ed area doesn't have corresponsing struct pages.

Removing the VM_PFNMAP flag makes get_user_pages work on the mmap'ed user vma.
An example test case would be using a Xen userspace block backend
(QDISK) on a file on NFS using O_DIRECT.

The patch should be backported back to 2.6.38.

Signed-off-by: Stefano Stabellini <>
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 99d8151..1ffd03b 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -722,7 +722,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)

if (use_ptemod)
- vma->vm_flags |= VM_DONTCOPY|VM_PFNMAP;
+ vma->vm_flags |= VM_DONTCOPY;

vma->vm_private_data = map;


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