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

[Christian König <ckoenig.leichtzumerken@xxxxxxxxx>]

Reviewed-by: Christian König <christian.koenig@xxxxxxx>

Am 17.06.19 um 20:21 schrieb Tom St Denis:

ping?

On Fri, Jun 14, 2019 at 12:51 PM StDenis, Tom <Tom.StDenis@xxxxxxx> 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@xxxxxxx>
---
 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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