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-rw-r--r--virt/kvm/kvm_main.c22
1 files changed, 21 insertions, 1 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 83c57bcc6eb6..cdf1fa3c60ae 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5810,6 +5810,7 @@ static int kvm_vm_worker_thread(void *context)
* we have to locally copy anything that is needed beyond initialization
*/
struct kvm_vm_worker_thread_context *init_context = context;
+ struct task_struct *parent;
struct kvm *kvm = init_context->kvm;
kvm_vm_thread_fn_t thread_fn = init_context->thread_fn;
uintptr_t data = init_context->data;
@@ -5836,7 +5837,7 @@ init_complete:
init_context = NULL;
if (err)
- return err;
+ goto out;
/* Wait to be woken up by the spawner before proceeding. */
kthread_parkme();
@@ -5844,6 +5845,25 @@ init_complete:
if (!kthread_should_stop())
err = thread_fn(kvm, data);
+out:
+ /*
+ * Move kthread back to its original cgroup to prevent it lingering in
+ * the cgroup of the VM process, after the latter finishes its
+ * execution.
+ *
+ * kthread_stop() waits on the 'exited' completion condition which is
+ * set in exit_mm(), via mm_release(), in do_exit(). However, the
+ * kthread is removed from the cgroup in the cgroup_exit() which is
+ * called after the exit_mm(). This causes the kthread_stop() to return
+ * before the kthread actually quits the cgroup.
+ */
+ rcu_read_lock();
+ parent = rcu_dereference(current->real_parent);
+ get_task_struct(parent);
+ rcu_read_unlock();
+ cgroup_attach_task_all(parent, current);
+ put_task_struct(parent);
+
return err;
}