On 2018/08/23 21:07, Michal Hocko wrote:
> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index 57390c7666e5..e7d8bb1bee2a 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -519,21 +519,20 @@ static int mn_invl_range_start(struct mmu_notifier *mn,
> struct gntdev_grant_map *map;
> int ret = 0;
>
> - /* TODO do we really need a mutex here? */
> if (blockable)
> mutex_lock(&priv->lock);
> else if (!mutex_trylock(&priv->lock))
> return -EAGAIN;
>
> list_for_each_entry(map, &priv->maps, next) {
> - if (in_range(map, start, end)) {
> + if (!blockable && in_range(map, start, end)) {
This still looks strange. Prior to 93065ac753e4, in_range() test was
inside unmap_if_in_range(). But this patch removes in_range() test
if blockable == true. That is, unmap_if_in_range() will unconditionally
unmap if blockable == true, which seems to be an unexpected change.
> ret = -EAGAIN;
> goto out_unlock;
> }
> unmap_if_in_range(map, start, end);
> }
