Patch "drm/amdgpu: fix sched fence slab teardown" has been added to the 4.8-stable tree

This is a note to let you know that I've just added the patch titled

drm/amdgpu: fix sched fence slab teardown

to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-amdgpu-fix-sched-fence-slab-teardown.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Grazvydas Ignotas <[email protected]>
Date: Sun, 23 Oct 2016 21:31:44 +0300
Subject: drm/amdgpu: fix sched fence slab teardown
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From: Grazvydas Ignotas <[email protected]>

commit a053fb7e512c77f0742bceb578b10025256e1911 upstream.

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().

---
 drivers/gpu/drm/amd/scheduler/gpu_scheduler.c |    1 +
 1 file changed, 1 insertion(+)

@@ -645,6 +645,7 @@ void amd_sched_fini(struct amd_gpu_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);
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/drm-amdgpu-fix-sched-fence-slab-teardown.patch queue-4.8/drm-amd-fix-scheduler-fence-teardown-order-v2.patch