Re: [Intel-gfx] [PATCH 2/4] drm/i915/ttm: only fault WILLNEED objects

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

On Wed, 2022-01-05 at 14:58 +0000, Matthew Auld wrote:
> Don't attempt to fault and re-populate purged objects. By some fluke
> this passes the dontneed-after-mmap IGT, but for the wrong reasons.
> 
> Fixes: cf3e3e86d779 ("drm/i915: Use ttm mmap handling for ttm bo's.")
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>

Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> index 923cc7ad8d70..8d61d4538a64 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> @@ -883,6 +883,11 @@ static vm_fault_t vm_fault_ttm(struct vm_fault
> *vmf)
>         if (ret)
>                 return ret;
>  
> +       if (obj->mm.madv != I915_MADV_WILLNEED) {
> +               dma_resv_unlock(bo->base.resv);
> +               return VM_FAULT_SIGBUS;
> +       }
> +
>         if (drm_dev_enter(dev, &idx)) {
>                 ret = ttm_bo_vm_fault_reserved(vmf, vmf->vma-
> >vm_page_prot,
>                                               
> TTM_BO_VM_NUM_PREFAULT);