Acked-by: Chunming Zhou <david1.zhou at amd.com> On 2016å¹´10æ??24æ?¥ 02:31, Grazvydas Ignotas wrote: > To free fences, call_rcu() is used, which calls amd_sched_fence_free() > after a grace period. During teardown, there is no guarantee all > callbacks have finished, so sched_fence_slab may be destroyed before > all fences have been freed. If we are lucky, this results in some slab > warnings, if not, we get a crash in one of rcu threads because callback > is called after amdgpu has already been unloaded. > > Fix it with a rcu_barrier(). > > Fixes: 189e0fb76304 ("drm/amdgpu: RCU protected amd_sched_fence_release") > Signed-off-by: Grazvydas Ignotas <notasas at gmail.com> > --- > drivers/gpu/drm/amd/scheduler/gpu_scheduler.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c > index 963a24d..910b8d5 100644 > --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c > +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c > @@ -645,6 +645,7 @@ void amd_sched_fini(struct amd_gpu_scheduler *sched) > { > if (sched->thread) > kthread_stop(sched->thread); > + rcu_barrier(); > if (atomic_dec_and_test(&sched_fence_slab_ref)) > kmem_cache_destroy(sched_fence_slab); > }