Re: [PATCH] drm/amdgpu: move lockdep assert to the right place.

["Bhardwaj, Rajneesh" <rajneesh.bhardwaj@amd.com>]

On 2/4/2022 1:32 PM, Christian König wrote:
> Am 04.02.22 um 19:12 schrieb Bhardwaj, Rajneesh:
>> [Sorry for top posting]
>>
>> Hi Christian
>>
>> I think you forgot the below hunk, without which the issue is not 
>> fixed completely on a multi GPU system.
>
> No, that is perfectly intentional. While removing a bo_va structure it 
> can happen that there are still mappings attached to it (for example 
> because the application crashed).


OK. but for me, at boot time, I see flood of warning messages coming 
from  amdgpu_vm_bo_del so the previous patch doesn't help.


>
> Because of this locking the VM before the remove is mandatory. Only 
> while adding a bo_va structure we can avoid that.
>
> Regards,
> Christian.
>
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> index dcc80d6e099e..6f68fc9da56a 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> @@ -2670,8 +2670,6 @@ void amdgpu_vm_bo_del(struct amdgpu_device *adev,
>>         struct amdgpu_vm *vm = bo_va->base.vm;
>>         struct amdgpu_vm_bo_base **base;
>>
>> -       dma_resv_assert_held(vm->root.bo->tbo.base.resv);
>> -
>>         if (bo) {
>>                 dma_resv_assert_held(bo->tbo.base.resv);
>>                 if (bo->tbo.base.resv == vm->root.bo->tbo.base.resv)
>>
>>
>> If you chose to include the above hunk, please feel free to add
>>
>> Reviewed-and-tested-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@amd.com>
>>
>> On 2/4/2022 11:27 AM, Felix Kuehling wrote:
>>>
>>> Am 2022-02-04 um 03:52 schrieb Christian König:
>>>> Since newly added BOs don't have any mappings it's ok to add them
>>>> without holding the VM lock. Only when we add per VM BOs the lock is
>>>> mandatory.
>>>>
>>>> Signed-off-by: Christian König <christian.koenig@amd.com>
>>>> Reported-by: Bhardwaj, Rajneesh <Rajneesh.Bhardwaj@amd.com>
>>>
>>> Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
>>>
>>>
>>>> ---
>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 4 ++--
>>>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c 
>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>>> index fdc6a1fd74af..dcc80d6e099e 100644
>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>>> @@ -375,6 +375,8 @@ static void amdgpu_vm_bo_base_init(struct 
>>>> amdgpu_vm_bo_base *base,
>>>>       if (bo->tbo.base.resv != vm->root.bo->tbo.base.resv)
>>>>           return;
>>>>   + dma_resv_assert_held(vm->root.bo->tbo.base.resv);
>>>> +
>>>>       vm->bulk_moveable = false;
>>>>       if (bo->tbo.type == ttm_bo_type_kernel && bo->parent)
>>>>           amdgpu_vm_bo_relocated(base);
>>>> @@ -2260,8 +2262,6 @@ struct amdgpu_bo_va *amdgpu_vm_bo_add(struct 
>>>> amdgpu_device *adev,
>>>>   {
>>>>       struct amdgpu_bo_va *bo_va;
>>>>   - dma_resv_assert_held(vm->root.bo->tbo.base.resv);
>>>> -
>>>>       bo_va = kzalloc(sizeof(struct amdgpu_bo_va), GFP_KERNEL);
>>>>       if (bo_va == NULL) {
>>>>           return NULL;
>