[PATCH] drm/ttm: fix busy memory to fail other user v3

[Koenig, Christian]

Am 26.04.19 um 11:07 schrieb zhoucm1:
> [SNIP]
>>> + spin_lock(&glob->lru_lock);
>>> +        for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
>>> +            if (list_empty(&man->lru[i]))
>>> +                continue;
>>> +            bo = list_first_entry(&man->lru[i],
>>> +                          struct ttm_buffer_object,
>>> +                          lru);
>>
>> You now need to check all BOs on the LRU, cause the first one where a 
>> trylock failed is not necessarily the first one on the list.
> Sorry, I don't get your opinion on this, Could you detail a bit how to 
> do that?
> I though after ww_mutex_lock, cs is done, then DC can pick up any of 
> them.

The first_bo is not necessarily the first BO of the LRU, but the first 
BO which failed in the trylock.

>
>>
>>> +
>>> +            break;
>>> +        }
>>> +        /* verify if BO have been moved */
>>> +        if (first_bo != bo) {

And in this case we would abort here without a good reason.

Christian.

>>> + spin_unlock(&glob->lru_lock);
>>> +            ww_mutex_unlock(&bo->resv->lock);
>>> +            return -EBUSY;
>>> +        }
>>> +        spin_unlock(&glob->lru_lock);
>>> +        /* ok, pick up first busy BO to wait to evict */
>>>       }
>>>         kref_get(&bo->list_kref);
>>> @@ -1784,7 +1819,10 @@ int ttm_bo_swapout(struct ttm_bo_global 
>>> *glob, struct ttm_operation_ctx *ctx)
>>>       spin_lock(&glob->lru_lock);
>>>       for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
>>>           list_for_each_entry(bo, &glob->swap_lru[i], swap) {
>>> -            if (ttm_bo_evict_swapout_allowable(bo, ctx, &locked)) {
>>> +            bool busy = false;
>>
>> Better make the parameter optional.
> Will do.
>
> -David
>>
>> Christian.
>>
>>> +
>>> +            if (ttm_bo_evict_swapout_allowable(bo, ctx, &locked,
>>> +                               &busy)) {
>>>                   ret = 0;
>>>                   break;
>>>               }
>>
>