[PATCH] drm/ttm: update bulk move object of ghost BO

[Christian König]

Am 01.09.22 um 13:11 schrieb Christian König:
> Am 01.09.22 um 11:29 schrieb ZhenGuo Yin:
>> [Why]
>> Ghost BO is released with non-empty bulk move object. There is a
>> warning trace:
>> WARNING: CPU: 19 PID: 1582 at ttm/ttm_bo.c:366 
>> ttm_bo_release+0x2e1/0x2f0 [amdttm]
>> Call Trace:
>>    amddma_resv_reserve_fences+0x10d/0x1f0 [amdkcl]
>>    amdttm_bo_put+0x28/0x30 [amdttm]
>>    amdttm_bo_move_accel_cleanup+0x126/0x200 [amdttm]
>>    amdgpu_bo_move+0x1a8/0x770 [amdgpu]
>>    ttm_bo_handle_move_mem+0xb0/0x140 [amdttm]
>>    amdttm_bo_validate+0xbf/0x100 [amdttm]
>>
>> [How]
>> The resource of ghost BO should be moved to LRU directly, instead of
>> using bulk move. The bulk move object of ghost BO should set to NULL
>> before function ttm_bo_move_to_lru_tail_unlocked.
>>
>> Fixed:·5b951e487fd6bf5f·("drm/ttm:·fix·bulk·move·handling·v2")
>> Signed-off-by: ZhenGuo Yin <zhenguo.yin at amd.com>
>
> Good catch, but the fix is not 100% correct. Please rather just NULL 
> the member while initializing the BO structure.
>
> E.g. something like this:
>
>  ....
>  fbo->base.pin_count = 0;
> +fbo->base.bulk_move= NULL;
>  if (bo->type != ttm_bo_type_sg)
>  ....

On the other hand thinking about it that won't work either.

You need to set bulk_move to NULL manually in an else clauses or 
something like this.

Regards,
Christian.

>
> Thanks,
> Christian.
>
>> ---
>>   drivers/gpu/drm/ttm/ttm_bo_util.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c 
>> b/drivers/gpu/drm/ttm/ttm_bo_util.c
>> index 1cbfb00c1d65..a90bbbd91910 100644
>> --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
>> +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
>> @@ -238,6 +238,7 @@ static int ttm_buffer_object_transfer(struct 
>> ttm_buffer_object *bo,
>>         if (fbo->base.resource) {
>>           ttm_resource_set_bo(fbo->base.resource, &fbo->base);
>> +        ttm_bo_set_bulk_move(&fbo->base, NULL);
>>           bo->resource = NULL;
>>       }
>