From: Grazvydas Ignotas Date: Sun, 23 Oct 2016 18:31:44 +0000 (+0300) Subject: drm/amdgpu: fix sched fence slab teardown X-Git-Tag: v4.9-rc4~15^2~4^2^2~9 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=a053fb7e512c77f0742bceb578b10025256e1911;p=karo-tx-linux.git drm/amdgpu: fix sched fence slab teardown 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") Acked-by: Chunming Zhou Reviewed-by: Christian König Signed-off-by: Grazvydas Ignotas Signed-off-by: Alex Deucher --- diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c index 963a24d46a93..910b8d5b21c5 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); }