On Mon, Oct 12, 2015 at 10:31:35AM +0100, Chris Wilson wrote: > We basically need to clone the obj, move the pages and vma over and so > as the vma die the pages are unreferenced. All new use will be forced to > call gup and be fine. > > Ok, that smells ok, I'll see how doable that is. Hmm. If we take the vma-centric driver as granted (i.e. using the vma as the token when pinning, the vma holds fences etc), the tricky part if that we don't hold a reference from the pinned vma to the object. pin_display to the rescue! Initial sketch: static struct drm_i915_gem_object *steal_pages(struct drm_i915_gem_object *obj) { struct drm_i915_gem_object *clone; struct i915_vma *vma; int i; BUG_ON(obj->stolen); clone = i915_gem_object_alloc(obj->base.dev); if (clone == NULL) return clone; drm_gem_private_object_init(obj->base.dev, &clone->base, obj->base.size); i915_gem_object_init(clone, obj->ops); list_splice_init(&obj->vma_list, &clone->vma_list); list_for_each_entry(vma, &clone->vma_list, obj_link) vma->obj = clone; if (obj->pin_display) { clone->pin_display = obj->pin_display; while (obj->pin_display--) { drm_gem_object_reference(&clone->base); drm_gem_object_unreference(&obj->base); } } clone->bind_count = obj->bind_count; obj->bind_count = 0; /* vma_ht / vma_hashed */ for (i = 0; i < I915_NUM_RINGS; i++) { if (obj->last_read[i].request == NULL) continue; clone->last_read[i].request = obj->last_read[i].request; list_replace_init(&obj->last_read[i].link, &clone->last_read[i].link); clone->flags |= 1 << (i + I915_BO_ACTIVE_SHIFT); } if (obj->last_write.request) { clone->last_write.request = obj->last_write.request; list_replace_init(&obj->last_write.link, &clone->last_write.link); } clone->dirty = obj->dirty; obj->dirty = false; clone->tiling_mode = obj->tiling_mode; clone->stride = obj->stride; clone->pin_display = obj->pin_display; obj->pin_display = 0; clone->madv = I915_MADV_DONTNEED; clone->pages = obj->pages; clone->pages_pin_count = obj->pages_pin_count; clone->get_page = obj->get_page; clone->vmapping = obj->vmapping; obj->pages = NULL; obj->pages_pin_count = 0; obj->vmapping = NULL; clone->bit_17 = obj->bit_17; obj->bit_17 = NULL; i915_gem_release_mmap(obj); if (I915_BO_IS_ACTIVE(clone)) clone->active_reference = true; else drm_gem_object_unreference(&clone->base); return clone; } It does have the presumption that we have either an active reference or a pinned reference. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx