On Tue, Oct 11, 2011 at 03:16:06PM -0400, Daniel De Graaf wrote:
> On 10/11/2011 01:32 PM, Konrad Rzeszutek Wilk wrote:
> > On Tue, Oct 11, 2011 at 07:13:38PM +0200, Dario Faggioli wrote:
> >> Hello everyone,
Dario, does the patch fix the problem for you?
.. snip..
> it'll also trigger this message; that's also fixed here. Compile tested only.
>
> -------------------------------------------------------->8
>
> gntdev_put_map tries to acquire a mutex when freeing pages back to the
> xenballoon pool, so it cannot be called with a spinlock held. In
> gntdev_release, the spinlock is not needed as we are freeing the
> structure later; in the ioctl, only the list manipulation needs to be
> under the lock.
>
> Reported-By: Dario Faggioli <raistlin@xxxxxxxx>
> Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
> ---
> drivers/xen/gntdev.c | 5 ++---
> 1 files changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index f914b26..23b1c83 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -462,13 +462,11 @@ static int gntdev_release(struct inode *inode, struct
> file *flip)
>
> pr_debug("priv %p\n", priv);
>
> - spin_lock(&priv->lock);
> while (!list_empty(&priv->maps)) {
> map = list_entry(priv->maps.next, struct grant_map, next);
> list_del(&map->next);
> gntdev_put_map(map);
> }
> - spin_unlock(&priv->lock);
>
> if (use_ptemod)
> mmu_notifier_unregister(&priv->mn, priv->mm);
> @@ -532,10 +530,11 @@ static long gntdev_ioctl_unmap_grant_ref(struct
> gntdev_priv *priv,
> map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
> if (map) {
> list_del(&map->next);
> - gntdev_put_map(map);
> err = 0;
> }
> spin_unlock(&priv->lock);
> + if (map)
> + gntdev_put_map(map);
> return err;
> }
>
> --
> 1.7.6.4
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