[PATCH] drm/ttm: Schedule out if possibe in bo delayed delete worker

[Christian König]

Am 09.04.20 um 03:31 schrieb xinhui pan:
> The delayed delete list is per device which might be very huge. And in
> a heavy workload test, the list might always not be empty. That will
> trigger any RCU stall warnings or softlockups in non-preemptible kernels
> Lets do schedule out if possible in that case.

Mhm, I'm not sure if that is actually allowed. This is called from a 
work item and those are not really supposed to be scheduled away.

Maybe rather change the while into while (!list_empty(&bdev->ddestroy) 
&& !should_reschedule(0)).

Christian.

>
> Signed-off-by: xinhui pan <xinhui.pan at amd.com>
> ---
>   drivers/gpu/drm/ttm/ttm_bo.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index 9e07c3f75156..b8d853cab33b 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -541,6 +541,7 @@ static bool ttm_bo_delayed_delete(struct ttm_bo_device *bdev, bool remove_all)
>   		}
>   
>   		ttm_bo_put(bo);
> +		cond_resched();
>   		spin_lock(&glob->lru_lock);
>   	}
>   	list_splice_tail(&removed, &bdev->ddestroy);