On 2019-06-12 4:08, StDenis, Tom wrote:
> (v2): Return 0 and set mem->mm_node to NULL.
> (v3): Use atomic64_add_return instead.
>
> Signed-off-by: Tom St Denis <tom.stde...@amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 17 ++++++++++++-----
>   1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> index 8aea2f21b202..c963ad86072e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> @@ -276,7 +276,7 @@ static int amdgpu_vram_mgr_new(struct 
> ttm_mem_type_manager *man,
>       struct drm_mm_node *nodes;
>       enum drm_mm_insert_mode mode;
>       unsigned long lpfn, num_nodes, pages_per_node, pages_left;
> -     uint64_t usage = 0, vis_usage = 0;
> +     uint64_t vis_usage = 0;
>       unsigned i;
>       int r;
>   
> @@ -284,6 +284,13 @@ static int amdgpu_vram_mgr_new(struct 
> ttm_mem_type_manager *man,
>       if (!lpfn)
>               lpfn = man->size;
>   
> +     /* bail out quickly if there's likely not enough VRAM for this BO */
> +     if (atomic64_add_return(mem->num_pages << PAGE_SHIFT, &mgr->usage) > 
> adev->gmc.mc_vram_size) {
> +             atomic64_sub(mem->num_pages << PAGE_SHIFT, &mgr->usage);

On 32-bit systems mem->num_pages is only 32-bit (unsigned long) and the 
<< PAGE_SHIFT may overflow. You probably want to cast this to u64 
explicitly before the shift.

Regards,
   Felix


> +             mem->mm_node = NULL;
> +             return 0;
> +     }
> +
>       if (place->flags & TTM_PL_FLAG_CONTIGUOUS) {
>               pages_per_node = ~0ul;
>               num_nodes = 1;
> @@ -300,8 +307,10 @@ static int amdgpu_vram_mgr_new(struct 
> ttm_mem_type_manager *man,
>   
>       nodes = kvmalloc_array((uint32_t)num_nodes, sizeof(*nodes),
>                              GFP_KERNEL | __GFP_ZERO);
> -     if (!nodes)
> +     if (!nodes) {
> +             atomic64_sub(mem->num_pages << PAGE_SHIFT, &mgr->usage);
>               return -ENOMEM;
> +     }
>   
>       mode = DRM_MM_INSERT_BEST;
>       if (place->flags & TTM_PL_FLAG_TOPDOWN)
> @@ -321,7 +330,6 @@ static int amdgpu_vram_mgr_new(struct 
> ttm_mem_type_manager *man,
>               if (unlikely(r))
>                       break;
>   
> -             usage += nodes[i].size << PAGE_SHIFT;
>               vis_usage += amdgpu_vram_mgr_vis_size(adev, &nodes[i]);
>               amdgpu_vram_mgr_virt_start(mem, &nodes[i]);
>               pages_left -= pages;
> @@ -341,14 +349,12 @@ static int amdgpu_vram_mgr_new(struct 
> ttm_mem_type_manager *man,
>               if (unlikely(r))
>                       goto error;
>   
> -             usage += nodes[i].size << PAGE_SHIFT;
>               vis_usage += amdgpu_vram_mgr_vis_size(adev, &nodes[i]);
>               amdgpu_vram_mgr_virt_start(mem, &nodes[i]);
>               pages_left -= pages;
>       }
>       spin_unlock(&mgr->lock);
>   
> -     atomic64_add(usage, &mgr->usage);
>       atomic64_add(vis_usage, &mgr->vis_usage);
>   
>       mem->mm_node = nodes;
> @@ -359,6 +365,7 @@ static int amdgpu_vram_mgr_new(struct 
> ttm_mem_type_manager *man,
>       while (i--)
>               drm_mm_remove_node(&nodes[i]);
>       spin_unlock(&mgr->lock);
> +     atomic64_sub(mem->num_pages << PAGE_SHIFT, &mgr->usage);
>   
>       kvfree(nodes);
>       return r == -ENOSPC ? 0 : r;
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