[PATCH] drm/ttm: Fix accesses through vmas with only partial coverage

[Jakob Bornecrantz]

Looks good to me.

Cheers, Jakob.

----- Thomas Hellstrom <thellstrom at vmware.com> wrote:
> VMAs covering a bo but that didn't start at the same address space offset as
> the bo they were mapping were incorrectly generating SEGFAULT errors in
> the fault handler.
> 
> Reported-by: Joseph Dolinak <kanilo2 at yahoo.com>
> Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
> Cc: stable at vger.kernel.org
> ---
> drivers/gpu/drm/ttm/ttm_bo_vm.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index b249ab9..6440eea 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -169,9 +169,9 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
> 	}
> 
> 	page_offset = ((address - vma->vm_start) >> PAGE_SHIFT) +
> -	 drm_vma_node_start(&bo->vma_node) - vma->vm_pgoff;
> -	page_last = vma_pages(vma) +
> -	 drm_vma_node_start(&bo->vma_node) - vma->vm_pgoff;
> +		vma->vm_pgoff - drm_vma_node_start(&bo->vma_node);
> +	page_last = vma_pages(vma) + vma->vm_pgoff -
> +		drm_vma_node_start(&bo->vma_node);
> 
> 	if (unlikely(page_offset >= bo->num_pages)) {
> 		retval = VM_FAULT_SIGBUS;
> -- 
> 1.7.10.4