>-----Original Message-----
>From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> On Behalf Of Deng,
>Emily
>Sent: Monday, September 10, 2018 6:33 PM
>To: Koenig, Christian <Christian.Koenig at amd.com>; amd-
>gfx at lists.freedesktop.org
>Subject: RE: [PATCH v2] drm/amdgpu: Fix the dead lock issue.
>
>>-----Original Message-----
>>From: Koenig, Christian
>>Sent: Monday, September 10, 2018 6:02 PM
>>To: Deng, Emily <Emily.Deng at amd.com>; amd-gfx at lists.freedesktop.org
>>Subject: Re: [PATCH v2] drm/amdgpu: Fix the dead lock issue.
>>
>>Am 10.09.2018 um 11:55 schrieb Deng, Emily:
>>>> -----Original Message-----
>>>> From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> On Behalf Of
>>>> Christian König
>>>> Sent: Monday, September 10, 2018 5:49 PM
>>>> To: Deng, Emily <Emily.Deng at amd.com>; amd-gfx at lists.freedesktop.org
>>>> Subject: Re: [PATCH v2] drm/amdgpu: Fix the dead lock issue.
>>>>
>>>> Am 10.09.2018 um 11:47 schrieb Deng, Emily:
>>>>>> -----Original Message-----
>>>>>> From: Christian König <ckoenig.leichtzumerken at gmail.com>
>>>>>> Sent: Monday, September 10, 2018 5:41 PM
>>>>>> To: Deng, Emily <Emily.Deng at amd.com>;
>>>>>> amd-gfx at lists.freedesktop.org
>>>>>> Subject: Re: [PATCH v2] drm/amdgpu: Fix the dead lock issue.
>>>>>>
>>>>>> Am 10.09.2018 um 11:34 schrieb Emily Deng:
>>>>>>> It will ramdomly have the dead lock issue when test TDR:
>>>>>>> 1. amdgpu_device_handle_vram_lost gets the lock shadow_list_lock 2.
>>>>>>> amdgpu_bo_create locked the bo's resv lock 3.
>>>>>>> amdgpu_bo_create_shadow is waiting for the shadow_list_lock 4.
>>>>>>> amdgpu_device_recover_vram_from_shadow is waiting for the bo's
>>>>>>> resv lock.
>>>>>>>
>>>>>>> v2:
>>>>>>> Make a local copy of the list
>>>>>>>
>>>>>>> Signed-off-by: Emily Deng <Emily.Deng at amd.com>
>>>>>>> ---
>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 12
>+++++++++++-
>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_object.h | 1 +
>>>>>>> 2 files changed, 12 insertions(+), 1 deletion(-)
>>>>>>>
>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>>>>> index acfc63e..2b9f597 100644
>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>>>>> @@ -3006,6 +3006,9 @@ static int
>>>>>> amdgpu_device_handle_vram_lost(struct amdgpu_device *adev)
>>>>>>> long r = 1;
>>>>>>> int i = 0;
>>>>>>> long tmo;
>>>>>>> + struct list_head local_shadow_list;
>>>>>>> +
>>>>>>> + INIT_LIST_HEAD(&local_shadow_list);
>>>>>>>
>>>>>>> if (amdgpu_sriov_runtime(adev))
>>>>>>> tmo = msecs_to_jiffies(8000); @@ -3013,8 +3016,15
>>@@ static
>>>>>>> int
>>>>>> amdgpu_device_handle_vram_lost(struct amdgpu_device *adev)
>>>>>>> tmo = msecs_to_jiffies(100);
>>>>>>>
>>>>>>> DRM_INFO("recover vram bo from shadow start\n");
>>>>>>> +
>>>>>>> mutex_lock(&adev->shadow_list_lock);
>>>>>>> list_for_each_entry_safe(bo, tmp, &adev->shadow_list,
>>>>>>> shadow_list) {
>>>>>>> + amdgpu_bo_ref(bo);
>>>>>>> + list_add_tail(&bo->copy_shadow_list,
>&local_shadow_list);
>>>>>>> + }
>>>>>> Please don't add an extra copy_shadow_list field to amdgpu_bo.
>>>>> If don't use an extra variable, the local shadow list will change
>>>>> according the adev->shadow_list, both for adding or deleting, it is
>>>>> not we
>>>> want.
>>>>
>>>> That is not correct, see amdgpu_bo_destroy:
>>>>> Â Â Â Â Â Â Â if (!list_empty(&bo->shadow_list)) {
>>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â mutex_lock(&adev->shadow_list_lock);
>>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â list_del_init(&bo->shadow_list);
>>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â mutex_unlock(&adev->shadow_list_lock);
>>>>> Â Â Â Â Â Â Â }
>>>> The BO is only removed from the list when it is destroyed, since we
>>>> grabbed a local reference it can't be destroyed. So we are safe here.
The amdgpu_bo_ref could only avoid deleting the bo, but
when it is already in amdgpu_bo_destroy, the shadow_list seems still will be delete.
>>> Sorry I am not meaning the delete, what about the adding.
>>
>>That will still go to adev->shadow_list and not affect our local list in any way.
>
>>We are not interested in any newly allocated shadow BOs, so that should
>>be unproblematic.
>Understand, will send a patch later.
>
>Best wishes
>Emily Deng
>>Regards,
>>Christian.
>>
>>>> Regards,
>>>> Christian.
>>>>
>>>>>> Instead just use bo->shadow list for this. When you hold a
>>>>>> reference to the BO it should not be removed from the shadow list.
>>>>>>
>>>>>> Additional to that you can just use list_splice_init() to move the
>>>>>> whole shadow list to your local list.
>>>>>>
>>>>>> Christian.
>>>>>>
>>>>>>> + mutex_unlock(&adev->shadow_list_lock);
>>>>>>> +
>>>>>>> + list_for_each_entry_safe(bo, tmp, &local_shadow_list,
>>>>>>> +copy_shadow_list) {
>>>>>>> next = NULL;
>>>>>>> amdgpu_device_recover_vram_from_shadow(adev,
>>ring, bo,
>>>>>> &next);
>>>>>>> if (fence) {
>>>>>>> @@ -3033,8 +3043,8 @@ static int
>>>>>> amdgpu_device_handle_vram_lost(struct
>>>>>>> amdgpu_device *adev)
>>>>>>>
>>>>>>> dma_fence_put(fence);
>>>>>>> fence = next;
>>>>>>> + amdgpu_bo_unref(&bo);
>>>>>>> }
>>>>>>> - mutex_unlock(&adev->shadow_list_lock);
>>>>>>>
>>>>>>> if (fence) {
>>>>>>> r = dma_fence_wait_timeout(fence, false, tmo); diff --
>>git
>>>>>>> a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
>>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
>>>>>>> index 907fdf4..cfee16c 100644
>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
>>>>>>> @@ -103,6 +103,7 @@ struct amdgpu_bo {
>>>>>>> struct list_head mn_list;
>>>>>>> struct list_head shadow_list;
>>>>>>> };
>>>>>>> + struct list_head copy_shadow_list;
>>>>>>>
>>>>>>> struct kgd_mem *kfd_bo;
>>>>>>> };
>>>> _______________________________________________
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>>>> amd-gfx at lists.freedesktop.org
>>>> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
>
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