[PATCH 2/4] drm/ttm: add bit flag TTM_OPT_FLAG_FORCE_ALLOC

[Christian König]

Am 08.02.2018 um 10:05 schrieb Roger He:
> set TTM_OPT_FLAG_FORCE_ALLOC when we are servicing for page
> fault routine.
>
> for ttm_mem_global_reserve if in page fault routine, allow the gtt
> pages reservation always. because page fault routing already grabbed
> system memory and the allowance of this exception is harmless.
> Otherwise, it will trigger OOM killer.
>
> the subsequent patche will use this.
>
> v2: keep original behavior except ttm bo with flag no_retry
>
> Signed-off-by: Roger He <Hongbo.He at amd.com>
> ---
>   drivers/gpu/drm/ttm/ttm_bo_vm.c          | 6 ++++--
>   drivers/gpu/drm/ttm/ttm_page_alloc_dma.c | 1 -
>   include/drm/ttm/ttm_bo_api.h             | 4 +++-
>   3 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index 716e724..f10b8a0 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -224,7 +224,7 @@ static int ttm_bo_vm_fault(struct vm_fault *vmf)
>   		cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
>   						cvma.vm_page_prot);
>   	} else {
> -		struct ttm_operation_ctx ctx = {
> +		struct ttm_operation_ctx ttm_opt_ctx = {
>   			.interruptible = false,
>   			.no_wait_gpu = false
>   		};
> @@ -233,8 +233,10 @@ static int ttm_bo_vm_fault(struct vm_fault *vmf)
>   		cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
>   						cvma.vm_page_prot);
>   
> +		if (ttm->page_flags & TTM_PAGE_FLAG_NO_RETRY)
> +			ttm_opt_ctx.flags |= TTM_OPT_FLAG_FORCE_ALLOC;

Can't we always set the TTM_OPT_FLAG_FORCE_ALLOC flag here?

I don't see a reason why we should ever not set it.

Christian.

>   		/* Allocate all page at once, most common usage */
> -		if (ttm->bdev->driver->ttm_tt_populate(ttm, &ctx)) {
> +		if (ttm->bdev->driver->ttm_tt_populate(ttm, &ttm_opt_ctx)) {
>   			ret = VM_FAULT_OOM;
>   			goto out_io_unlock;
>   		}
> diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
> index b122f6e..354e0e1 100644
> --- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
> +++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
> @@ -944,7 +944,6 @@ int ttm_dma_populate(struct ttm_dma_tt *ttm_dma, struct device *dev,
>   	i = 0;
>   
>   	type = ttm_to_type(ttm->page_flags, ttm->caching_state);
> -
>   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>   	if (ttm->page_flags & TTM_PAGE_FLAG_DMA32)
>   		goto skip_huge;
> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> index 872ff6c..2142639 100644
> --- a/include/drm/ttm/ttm_bo_api.h
> +++ b/include/drm/ttm/ttm_bo_api.h
> @@ -278,7 +278,9 @@ struct ttm_operation_ctx {
>   };
>   
>   /* Allow eviction of reserved BOs */
> -#define TTM_OPT_FLAG_ALLOW_RES_EVICT	0x1
> +#define TTM_OPT_FLAG_ALLOW_RES_EVICT		0x1
> +/* when serving page fault or suspend, allow alloc anyway */
> +#define TTM_OPT_FLAG_FORCE_ALLOC		0x2
>   
>   /**
>    * ttm_bo_reference - reference a struct ttm_buffer_object