Re: [PATCH v3 3/6] drm/amdgpu: delay the use of amdgpu_vm_set_task_info

["Christian König" <christian.koenig@amd.com>]

Am 23.09.24 um 12:25 schrieb Tvrtko Ursulin:
>
> On 20/09/2024 10:06, Pierre-Eric Pelloux-Prayer wrote:
>> At this point the vm is locked so we safely modify it without risk of
>> concurrent access.
>
> To which particular lock this is referring to and does this imply 
> previous placement was unsafe?

We use the root PDs dma_resv object as VM lock to protect most field 
inside the VM structure, only a few are protected by an additional spinlock.

And yes, previously it was possible that you got a mangled process/task 
name because no lock was protecting the task_info structure.

Regards,
Christian.

>
> Regards,
>
> Tvrtko
>
>> Signed-off-by: Pierre-Eric Pelloux-Prayer 
>> <pierre-eric.pelloux-prayer@amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> index 1e475eb01417..891128ecee6d 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> @@ -309,9 +309,6 @@ static int amdgpu_cs_pass1(struct 
>> amdgpu_cs_parser *p,
>>           p->gang_leader->uf_addr = uf_offset;
>>       kvfree(chunk_array);
>>   -    /* Use this opportunity to fill in task info for the vm */
>> -    amdgpu_vm_set_task_info(vm);
>> -
>>       return 0;
>>     free_all_kdata:
>> @@ -1180,6 +1177,9 @@ static int amdgpu_cs_vm_handling(struct 
>> amdgpu_cs_parser *p)
>>           job->vm_pd_addr = amdgpu_gmc_pd_addr(vm->root.bo);
>>       }
>>   +    /* Use this opportunity to fill in task info for the vm */
>> +    amdgpu_vm_set_task_info(vm);
>> +
>>       if (adev->debug_vm) {
>>           /* Invalidate all BOs to test for userspace bugs */
>>           amdgpu_bo_list_for_each_entry(e, p->bo_list) {