[ Adding Greg has he seems to have this patch queued for 3.10 and 3.14 ]
On Mon, Aug 24, 2015 at 11:09:09AM +0200, Jiri Slaby wrote:
> From: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
>
> 3.12-stable review patch. If anyone has any objections, please let me know.
>
> ===============
>
> commit 30b03d05e07467b8c6ec683ea96b5bffcbcd3931 upstream.
>
> While gntdev_release() is called the MMU notifier is still registered
> and can traverse priv->maps list even if no pages are mapped (which is
> the case -- gntdev_release() is called after all). But
> gntdev_release() will clear that list, so make sure that only one of
> those things happens at the same time.
>
> Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
> ---
> drivers/xen/gntdev.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index e41c79c986ea..f2ca8d0af55f 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -529,12 +529,14 @@ static int gntdev_release(struct inode *inode, struct file *flip)
>
> pr_debug("priv %p\n", priv);
>
> + mutex_lock(&priv->lock);
Since 3.12 doesn't seem to include 1401c00e59ea ("xen/gntdev: convert
priv->lock to a mutex"), this shouldn't be applied as priv->lock is
actually a spinlock. So, you'll need to pick 1401c00e59ea or backport
this patch using the appropriate locking directives. Not sure what's
the best solution. Maybe Marek or David can help...?
Cheers,
--
Luís
> while (!list_empty(&priv->maps)) {
> map = list_entry(priv->maps.next, struct grant_map, next);
> list_del(&map->next);
> gntdev_put_map(NULL /* already removed */, map);
> }
> WARN_ON(!list_empty(&priv->freeable_maps));
> + mutex_unlock(&priv->lock);
>
> if (use_ptemod)
> mmu_notifier_unregister(&priv->mn, priv->mm);
> --
> 2.5.0
>
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