On Tue, Jun 26, 2012 at 12:59:58PM +0200, Christian Borntraeger wrote:
> From: Jens Freimann <jfrei@xxxxxxxxxxxxxxxxxx>
>
> On some architectures address spaces are set up in a way that this is
> not necessary to work properly but on some others (like s390) it is.
> Make sure we operate on the user address space to allow copy_xxx_user()
> from the vhost_worker() thread by setting it explicitly before calling
> use_mm() and revert it after unuse_mm().
>
> Signed-off-by: Jens Freimann <jfrei@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Dave, can you queue this up for 3.5 please?
Thanks.
> ---
> drivers/vhost/vhost.c | 3 +++
> 1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 94dbd25..112156f 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -191,7 +191,9 @@ static int vhost_worker(void *data)
> struct vhost_dev *dev = data;
> struct vhost_work *work = NULL;
> unsigned uninitialized_var(seq);
> + mm_segment_t oldfs = get_fs();
>
> + set_fs(USER_DS);
> use_mm(dev->mm);
>
> for (;;) {
> @@ -229,6 +231,7 @@ static int vhost_worker(void *data)
>
> }
> unuse_mm(dev->mm);
> + set_fs(oldfs);
> return 0;
> }
>
> --
> 1.7.0.4
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