[Intel-gfx] [PATCH v2 10/16] drm/i915: Make i915_gem_evict_vm work correctly for already locked objects

[Matthew Auld]

On Mon, 29 Nov 2021 at 13:58, Maarten Lankhorst
<maarten.lankhorst at linux.intel.com> wrote:
>
> i915_gem_execbuf will call i915_gem_evict_vm() after failing to pin
> all objects in the first round. We are about to remove those short-term
> pins, but even without those the objects are still locked. Add a special
> case to allow i915_gem_evict_vm to evict locked objects as well.
>
> This might also allow multiple objects sharing the same resv to be evicted.
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>

Reviewed-by: Matthew Auld <matthew.auld at intel.com>

Do we need similar treatment for stuff like evict_for_node etc?

> ---
>  drivers/gpu/drm/i915/i915_gem_evict.c | 23 ++++++++++++++++++++++-
>  1 file changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_evict.c b/drivers/gpu/drm/i915/i915_gem_evict.c
> index 24f5e3345e43..f502a617b35c 100644
> --- a/drivers/gpu/drm/i915/i915_gem_evict.c
> +++ b/drivers/gpu/drm/i915/i915_gem_evict.c
> @@ -410,21 +410,42 @@ int i915_gem_evict_vm(struct i915_address_space *vm, struct i915_gem_ww_ctx *ww)
>         do {
>                 struct i915_vma *vma, *vn;
>                 LIST_HEAD(eviction_list);
> +               LIST_HEAD(locked_eviction_list);
>
>                 list_for_each_entry(vma, &vm->bound_list, vm_link) {
>                         if (i915_vma_is_pinned(vma))
>                                 continue;
>
> +                       /*
> +                        * If we already own the lock, trylock fails. In case the resv
> +                        * is shared among multiple objects, we still need the object ref.
> +                        */
> +                       if (ww && (dma_resv_locking_ctx(vma->obj->base.resv) == &ww->ctx)) {
> +                               __i915_vma_pin(vma);
> +                               list_add(&vma->evict_link, &locked_eviction_list);
> +                               continue;
> +                       }
> +
>                         if (!i915_gem_object_trylock(vma->obj, ww))
>                                 continue;
>
>                         __i915_vma_pin(vma);
>                         list_add(&vma->evict_link, &eviction_list);
>                 }
> -               if (list_empty(&eviction_list))
> +               if (list_empty(&eviction_list) && list_empty(&locked_eviction_list))
>                         break;
>
>                 ret = 0;
> +               /* Unbind locked objects first, before unlocking the eviction_list */
> +               list_for_each_entry_safe(vma, vn, &locked_eviction_list, evict_link) {
> +                       __i915_vma_unpin(vma);
> +
> +                       if (ret == 0)
> +                               ret = __i915_vma_unbind(vma);
> +                       if (ret != -EINTR) /* "Get me out of here!" */
> +                               ret = 0;
> +               }
> +
>                 list_for_each_entry_safe(vma, vn, &eviction_list, evict_link) {
>                         __i915_vma_unpin(vma);
>                         if (ret == 0)
> --
> 2.34.0
>