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 <stable@xxxxxxxxxxxxxxx> know about it.
>From a053fb7e512c77f0742bceb578b10025256e1911 Mon Sep 17 00:00:00 2001
From: Grazvydas Ignotas <notasas@xxxxxxxxx>
Date: Sun, 23 Oct 2016 21:31:44 +0300
Subject: drm/amdgpu: fix sched fence slab teardown
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From: Grazvydas Ignotas <notasas@xxxxxxxxx>
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().
Fixes: 189e0fb76304 ("drm/amdgpu: RCU protected amd_sched_fence_release")
Acked-by: Chunming Zhou <david1.zhou@xxxxxxx>
Reviewed-by: Christian König <christian.koenig@xxxxxxx>
Signed-off-by: Grazvydas Ignotas <notasas@xxxxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/amd/scheduler/gpu_scheduler.c | 1 +
1 file changed, 1 insertion(+)
--- 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_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 notasas@xxxxxxxxx are
queue-4.8/drm-amdgpu-fix-sched-fence-slab-teardown.patch
queue-4.8/drm-amd-fix-scheduler-fence-teardown-order-v2.patch
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