In preparation for implementing lockless slab shrink,
we need to dynamically allocate the virtio-balloon shrinker,
so that it can be freed asynchronously using kfree_rcu().
Then it doesn't need to wait for RCU read-side critical
section when releasing the struct virtio_balloon.
Signed-off-by: Qi Z
From: Qi Zheng
In preparation for implementing lockless slab shrink,
we need to dynamically allocate the virtio-balloon shrinker,
so that it can be freed asynchronously using kfree_rcu().
Then it doesn't need to wait for RCU read-side critical
section when releasing the struct virtio_balloon.
Si
