[PATCH] drm/amd/amdgpu: cast mem->num_pages to 64-bits when shifting

[Tom St Denis]

ping?

On Fri, Jun 14, 2019 at 12:51 PM StDenis, Tom <Tom.StDenis at amd.com> wrote:

> On 32-bit hosts mem->num_pages is 32-bits and can overflow
> when shifted.  Add a cast to avoid this.
>
> Signed-off-by: Tom St Denis <tom.stdenis at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> index c963ad86072e..31895d3c33de 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> @@ -279,14 +279,16 @@ static int amdgpu_vram_mgr_new(struct
> ttm_mem_type_manager *man,
>         uint64_t vis_usage = 0;
>         unsigned i;
>         int r;
> +       uint64_t mem_bytes;
>
>         lpfn = place->lpfn;
>         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);
> +       mem_bytes = (u64)mem->num_pages << PAGE_SHIFT;
> +       if (atomic64_add_return(mem_bytes, &mgr->usage) >
> adev->gmc.mc_vram_size) {
> +               atomic64_sub(mem_bytes, &mgr->usage);
>                 mem->mm_node = NULL;
>                 return 0;
>         }
> @@ -308,7 +310,7 @@ 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) {
> -               atomic64_sub(mem->num_pages << PAGE_SHIFT, &mgr->usage);
> +               atomic64_sub(mem_bytes, &mgr->usage);
>                 return -ENOMEM;
>         }
>
> --
> 2.21.0
>
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