[PATCH] drm/kfd: fix ttm_bo_release warning

[Felix Kuehling]

On 2021-09-23 8:09 a.m., Yu, Lang wrote:
> [AMD Official Use Only]
>
>
>
>> -----Original Message-----
>> From: Koenig, Christian <Christian.Koenig at amd.com>
>> Sent: Thursday, September 23, 2021 7:40 PM
>> To: Yu, Lang <Lang.Yu at amd.com>; amd-gfx at lists.freedesktop.org
>> Cc: Kuehling, Felix <Felix.Kuehling at amd.com>; Christian K nig
>> <C3B6christian.koenig at amd.com>; Huang, Ray <Ray.Huang at amd.com>
>> Subject: Re: [PATCH] drm/kfd: fix ttm_bo_release warning
>>
>>
>>
>> Am 23.09.21 um 11:44 schrieb Lang Yu:
>>> If a BO is pinned, unpin it before freeing it.
>>>
>>> Call Trace:
>>> 	ttm_bo_put+0x30/0x50 [ttm]
>>> 	amdgpu_bo_unref+0x1e/0x30 [amdgpu]
>>> 	amdgpu_gem_object_free+0x34/0x50 [amdgpu]
>>> 	drm_gem_object_free+0x1d/0x30 [drm]
>>> 	amdgpu_amdkfd_gpuvm_free_memory_of_gpu+0x31f/0x3a0 [amdgpu]
>>> 	kfd_process_device_free_bos+0xa3/0xf0 [amdgpu]
>>> 	kfd_process_wq_release+0x224/0x2e0 [amdgpu]
>>> 	process_one_work+0x220/0x3c0
>>> 	worker_thread+0x4d/0x3f0
>>> 	kthread+0x114/0x150
>>> 	process_one_work+0x3c0/0x3c0
>>> 	kthread_park+0x90/0x90
>>> 	ret_from_fork+0x22/0x30
>>>
>>> Signed-off-by: Lang Yu <lang.yu at amd.com>
>>> ---
>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 3 +++
>>>    1 file changed, 3 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>>> index 2d6b2d77b738..7e693b064072 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>>> @@ -1567,6 +1567,9 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
>>>    	pr_debug("Release VA 0x%llx - 0x%llx\n", mem->va,
>>>    		mem->va + bo_size * (1 + mem->aql_queue));
>>>
>>> +	if (mem->bo->tbo.pin_count)
>>> +		amdgpu_bo_unpin(mem->bo);
>>> +
>> NAK, using mem->bo->tbo.pin_count like this is illegal.
> I didn't  get your point. I referred to function-"void amdgpu_bo_unpin(struct amdgpu_bo *bo)",
> which uses it like this.
>
>> Where was the BO pinned in the first place?
> I found two places:
>
> 	ret = kfd_process_alloc_gpuvm(pdd, qpd->ib_base, PAGE_SIZE, flags,
> 				      &kaddr);
>
> 	ret = kfd_process_alloc_gpuvm(pdd, qpd->cwsr_base,
> 				      KFD_CWSR_TBA_TMA_SIZE, flags, &kaddr);

These two allocations are created by the kernel mode driver. There is 
another case where a user-allocated BO can get pinned because we need to 
kmap it (in kfd_ioctl_create_event).

Regards,
   Felix


> Regards,
> Lang
>
>> Christian.
>>
>>>    	ret = unreserve_bo_and_vms(&ctx, false, false);
>>>
>>>    	/* Remove from VM internal data structures */