To free fences, call_rcu() is used, which calls amdgpu_fence_free() after a grace period. During teardown, there is no guarantee all callbacks have finished, so amdgpu_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: b44135351a3a ("drm/amdgpu: RCU protected amdgpu_fence_release") Signed-off-by: Grazvydas Ignotas notasas@gmail.com --- drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c index 3a2e42f..77b34ec 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c @@ -68,6 +68,7 @@ int amdgpu_fence_slab_init(void)
void amdgpu_fence_slab_fini(void) { + rcu_barrier(); kmem_cache_destroy(amdgpu_fence_slab); } /*