[PATCH] drm/ttm: once more fix ttm_bo_bulk_move_lru_tail

[Christian König]

Am 13.09.2018 um 16:25 schrieb Alex Deucher:
> On Wed, Sep 12, 2018 at 3:25 PM Christian König
> <ckoenig.leichtzumerken at gmail.com> wrote:
>> While cutting the lists we sometimes accidentally added a list_head from
>> the stack to the LRUs, effectively corrupting the list.
>>
>> Remove the list cutting and use explicit list manipulation instead.
>>
>> Signed-off-by: Christian König <christian.koenig at amd.com>
> Can you apply this patch first and then do the clean up as a later
> series or temporarily disable the feature?  I want to send out a -next
> pull this week and I don't want to leave this broken.

Yeah, that should work as well.

Christian.

>
> Alex
>
>> ---
>>   drivers/gpu/drm/ttm/ttm_bo.c | 51 ++++++++++++++++++++++++++------------------
>>   1 file changed, 30 insertions(+), 21 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
>> index 138c98902033..b2a33bf1ef10 100644
>> --- a/drivers/gpu/drm/ttm/ttm_bo.c
>> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
>> @@ -247,23 +247,18 @@ void ttm_bo_move_to_lru_tail(struct ttm_buffer_object *bo,
>>   }
>>   EXPORT_SYMBOL(ttm_bo_move_to_lru_tail);
>>
>> -static void ttm_bo_bulk_move_helper(struct ttm_lru_bulk_move_pos *pos,
>> -                                   struct list_head *lru, bool is_swap)
>> +static void ttm_list_move_bulk_tail(struct list_head *list,
>> +                                   struct list_head *first,
>> +                                   struct list_head *last)
>>   {
>> -       struct list_head *list;
>> -       LIST_HEAD(entries);
>> -       LIST_HEAD(before);
>> +       first->prev->next = last->next;
>> +       last->next->prev = first->prev;
>>
>> -       reservation_object_assert_held(pos->last->resv);
>> -       list = is_swap ? &pos->last->swap : &pos->last->lru;
>> -       list_cut_position(&entries, lru, list);
>> +       list->prev->next = first;
>> +       first->prev = list->prev;
>>
>> -       reservation_object_assert_held(pos->first->resv);
>> -       list = is_swap ? pos->first->swap.prev : pos->first->lru.prev;
>> -       list_cut_position(&before, &entries, list);
>> -
>> -       list_splice(&before, lru);
>> -       list_splice_tail(&entries, lru);
>> +       last->next = list;
>> +       list->prev = last;
>>   }
>>
>>   void ttm_bo_bulk_move_lru_tail(struct ttm_lru_bulk_move *bulk)
>> @@ -271,23 +266,33 @@ void ttm_bo_bulk_move_lru_tail(struct ttm_lru_bulk_move *bulk)
>>          unsigned i;
>>
>>          for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
>> +               struct ttm_lru_bulk_move_pos *pos = &bulk->tt[i];
>>                  struct ttm_mem_type_manager *man;
>>
>> -               if (!bulk->tt[i].first)
>> +               if (!pos->first)
>>                          continue;
>>
>> -               man = &bulk->tt[i].first->bdev->man[TTM_PL_TT];
>> -               ttm_bo_bulk_move_helper(&bulk->tt[i], &man->lru[i], false);
>> +               reservation_object_assert_held(pos->first->resv);
>> +               reservation_object_assert_held(pos->last->resv);
>> +
>> +               man = &pos->first->bdev->man[TTM_PL_TT];
>> +               ttm_list_move_bulk_tail(&man->lru[i], &pos->first->lru,
>> +                                       &pos->last->lru);
>>          }
>>
>>          for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
>> +               struct ttm_lru_bulk_move_pos *pos = &bulk->vram[i];
>>                  struct ttm_mem_type_manager *man;
>>
>> -               if (!bulk->vram[i].first)
>> +               if (!pos->first)
>>                          continue;
>>
>> -               man = &bulk->vram[i].first->bdev->man[TTM_PL_VRAM];
>> -               ttm_bo_bulk_move_helper(&bulk->vram[i], &man->lru[i], false);
>> +               reservation_object_assert_held(pos->first->resv);
>> +               reservation_object_assert_held(pos->last->resv);
>> +
>> +               man = &pos->first->bdev->man[TTM_PL_VRAM];
>> +               ttm_list_move_bulk_tail(&man->lru[i], &pos->first->lru,
>> +                                       &pos->last->lru);
>>          }
>>
>>          for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
>> @@ -297,8 +302,12 @@ void ttm_bo_bulk_move_lru_tail(struct ttm_lru_bulk_move *bulk)
>>                  if (!pos->first)
>>                          continue;
>>
>> +               reservation_object_assert_held(pos->first->resv);
>> +               reservation_object_assert_held(pos->last->resv);
>> +
>>                  lru = &pos->first->bdev->glob->swap_lru[i];
>> -               ttm_bo_bulk_move_helper(&bulk->swap[i], lru, true);
>> +               ttm_list_move_bulk_tail(lru, &pos->first->swap,
>> +                                       &pos->last->swap);
>>          }
>>   }
>>   EXPORT_SYMBOL(ttm_bo_bulk_move_lru_tail);
>> --
>> 2.14.1
>>
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