drm/i915: Release vma when the handle is closed

In order to prevent a leak of the vma on shared objects, we need to
hook into the object_close callback to destroy the vma on the object for
this file. However, if we destroyed that vma immediately we may cause
unexpected application stalls as we try to unbind a busy vma - hence we
defer the unbind to when we retire the vma.

v2: Keep vma allocated until closed. This is useful for a later
optimisation, but it is required now in order to handle potential
recursion of i915_vma_unbind() by retiring itself.
v3: Comments are important.

Testcase: igt/gem_ppggtt/flink-and-close-vma-leak
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470293567-10811-26-git-send-email-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_drv.c

@@ -2578,6 +2578,7 @@ static struct drm_driver driver = {
 	.postclose = i915_driver_postclose,
 	.set_busid = drm_pci_set_busid,
 
+	.gem_close_object = i915_gem_close_object,
 	.gem_free_object = i915_gem_free_object,
 	.gem_vm_ops = &i915_gem_vm_ops,
 

drivers/gpu/drm/i915/i915_drv.h

@@ -3014,8 +3014,8 @@ struct drm_i915_gem_object *i915_gem_object_create(struct drm_device *dev,
 						  size_t size);
 struct drm_i915_gem_object *i915_gem_object_create_from_data(
 		struct drm_device *dev, const void *data, size_t size);
+void i915_gem_close_object(struct drm_gem_object *gem, struct drm_file *file);
 void i915_gem_free_object(struct drm_gem_object *obj);
-void i915_gem_vma_destroy(struct i915_vma *vma);
 
 /* Flags used by pin/bind&friends. */
 #define PIN_MAPPABLE	(1<<0)
@@ -3048,6 +3048,8 @@ int __must_check i915_vma_unbind(struct i915_vma *vma);
  * _guarantee_ VMA in question is _not in use_ anywhere.
  */
 int __must_check __i915_vma_unbind_no_wait(struct i915_vma *vma);
+void i915_vma_close(struct i915_vma *vma);
+void i915_vma_destroy(struct i915_vma *vma);
 
 int i915_gem_object_unbind(struct drm_i915_gem_object *obj);
 int i915_gem_object_put_pages(struct drm_i915_gem_object *obj);

drivers/gpu/drm/i915/i915_gem.c

@@ -2596,6 +2596,19 @@ out_rearm:
 	}
 }
 
+void i915_gem_close_object(struct drm_gem_object *gem, struct drm_file *file)
+{
+	struct drm_i915_gem_object *obj = to_intel_bo(gem);
+	struct drm_i915_file_private *fpriv = file->driver_priv;
+	struct i915_vma *vma, *vn;
+
+	mutex_lock(&obj->base.dev->struct_mutex);
+	list_for_each_entry_safe(vma, vn, &obj->vma_list, obj_link)
+		if (vma->vm->file == fpriv)
+			i915_vma_close(vma);
+	mutex_unlock(&obj->base.dev->struct_mutex);
+}
+
 /**
  * i915_gem_wait_ioctl - implements DRM_IOCTL_I915_GEM_WAIT
  * @dev: drm device pointer
@@ -2803,26 +2816,32 @@ static int __i915_vma_unbind(struct i915_vma *vma, bool wait)
 	if (active && wait) {
 		int idx;
 
+		/* When a closed VMA is retired, it is unbound - eek.
+		 * In order to prevent it from being recursively closed,
+		 * take a pin on the vma so that the second unbind is
+		 * aborted.
+		 */
+		vma->pin_count++;
+
 		for_each_active(active, idx) {
 			ret = i915_gem_active_retire(&vma->last_read[idx],
 						   &vma->vm->dev->struct_mutex);
 			if (ret)
-				return ret;
+				break;
 		}
 
+		vma->pin_count--;
+		if (ret)
+			return ret;
+
 		GEM_BUG_ON(i915_vma_is_active(vma));
 	}
 
 	if (vma->pin_count)
 		return -EBUSY;
 
-	if (list_empty(&vma->obj_link))
-		return 0;
-
-	if (!drm_mm_node_allocated(&vma->node)) {
-		i915_gem_vma_destroy(vma);
-		return 0;
-	}
+	if (!drm_mm_node_allocated(&vma->node))
+		goto destroy;
 
 	GEM_BUG_ON(obj->bind_count == 0);
 	GEM_BUG_ON(!obj->pages);
@@ -2855,7 +2874,6 @@ static int __i915_vma_unbind(struct i915_vma *vma, bool wait)
 	}
 
 	drm_mm_remove_node(&vma->node);
-	i915_gem_vma_destroy(vma);
 
 	/* Since the unbound list is global, only move to that list if
 	 * no more VMAs exist. */
@@ -2869,6 +2887,10 @@ static int __i915_vma_unbind(struct i915_vma *vma, bool wait)
 	 */
 	i915_gem_object_unpin_pages(obj);
 
+destroy:
+	if (unlikely(vma->closed))
+		i915_vma_destroy(vma);
+
 	return 0;
 }
 
@@ -3043,7 +3065,7 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
 
 		if (offset & (alignment - 1) || offset + size > end) {
 			ret = -EINVAL;
-			goto err_free_vma;
+			goto err_vma;
 		}
 		vma->node.start = offset;
 		vma->node.size = size;
@@ -3055,7 +3077,7 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
 				ret = drm_mm_reserve_node(&vm->mm, &vma->node);
 		}
 		if (ret)
-			goto err_free_vma;
+			goto err_vma;
 	} else {
 		if (flags & PIN_HIGH) {
 			search_flag = DRM_MM_SEARCH_BELOW;
@@ -3080,7 +3102,7 @@ search_free:
 			if (ret == 0)
 				goto search_free;
 
-			goto err_free_vma;
+			goto err_vma;
 		}
 	}
 	if (WARN_ON(!i915_gem_valid_gtt_space(vma, obj->cache_level))) {
@@ -3101,8 +3123,7 @@ search_free:
 
 err_remove_node:
 	drm_mm_remove_node(&vma->node);
-err_free_vma:
-	i915_gem_vma_destroy(vma);
+err_vma:
 	vma = ERR_PTR(ret);
 err_unpin:
 	i915_gem_object_unpin_pages(obj);
@@ -4051,21 +4072,18 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
 
 	trace_i915_gem_object_destroy(obj);
 
+	/* All file-owned VMA should have been released by this point through
+	 * i915_gem_close_object(), or earlier by i915_gem_context_close().
+	 * However, the object may also be bound into the global GTT (e.g.
+	 * older GPUs without per-process support, or for direct access through
+	 * the GTT either for the user or for scanout). Those VMA still need to
+	 * unbound now.
+	 */
 	list_for_each_entry_safe(vma, next, &obj->vma_list, obj_link) {
-		int ret;
-
+		GEM_BUG_ON(!vma->is_ggtt);
+		GEM_BUG_ON(i915_vma_is_active(vma));
 		vma->pin_count = 0;
-		ret = __i915_vma_unbind_no_wait(vma);
-		if (WARN_ON(ret == -ERESTARTSYS)) {
-			bool was_interruptible;
-
-			was_interruptible = dev_priv->mm.interruptible;
-			dev_priv->mm.interruptible = false;
-
-			WARN_ON(i915_vma_unbind(vma));
-
-			dev_priv->mm.interruptible = was_interruptible;
-		}
+		i915_vma_close(vma);
 	}
 	GEM_BUG_ON(obj->bind_count);
 
@@ -4129,22 +4147,6 @@ struct i915_vma *i915_gem_obj_to_ggtt_view(struct drm_i915_gem_object *obj,
 	return NULL;
 }
 
-void i915_gem_vma_destroy(struct i915_vma *vma)
-{
-	WARN_ON(vma->node.allocated);
-
-	/* Keep the vma as a placeholder in the execbuffer reservation lists */
-	if (!list_empty(&vma->exec_list))
-		return;
-
-	if (!vma->is_ggtt)
-		i915_ppgtt_put(i915_vm_to_ppgtt(vma->vm));
-
-	list_del(&vma->obj_link);
-
-	kmem_cache_free(to_i915(vma->obj->base.dev)->vmas, vma);
-}
-
 static void
 i915_gem_stop_engines(struct drm_device *dev)
 {

drivers/gpu/drm/i915/i915_gem_evict.c

@@ -182,8 +182,8 @@ found:
 				       struct i915_vma,
 				       exec_list);
 		if (drm_mm_scan_remove_block(&vma->node)) {
+			vma->pin_count++;
 			list_move(&vma->exec_list, &eviction_list);
-			i915_gem_object_get(vma->obj);
 			continue;
 		}
 		list_del_init(&vma->exec_list);
@@ -191,18 +191,14 @@ found:
 
 	/* Unbinding will emit any required flushes */
 	while (!list_empty(&eviction_list)) {
-		struct drm_i915_gem_object *obj;
-
 		vma = list_first_entry(&eviction_list,
 				       struct i915_vma,
 				       exec_list);
 
-		obj =  vma->obj;
 		list_del_init(&vma->exec_list);
+		vma->pin_count--;
 		if (ret == 0)
 			ret = i915_vma_unbind(vma);
-
-		i915_gem_object_put(obj);
 	}
 
 	return ret;

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -3342,6 +3342,31 @@ i915_vma_retire(struct i915_gem_active *active,
 		return;
 
 	list_move_tail(&vma->vm_link, &vma->vm->inactive_list);
+	if (unlikely(vma->closed && !vma->pin_count))
+		WARN_ON(i915_vma_unbind(vma));
+}
+
+void i915_vma_destroy(struct i915_vma *vma)
+{
+	GEM_BUG_ON(vma->node.allocated);
+	GEM_BUG_ON(i915_vma_is_active(vma));
+	GEM_BUG_ON(!vma->closed);
+
+	list_del(&vma->vm_link);
+	if (!vma->is_ggtt)
+		i915_ppgtt_put(i915_vm_to_ppgtt(vma->vm));
+
+	kmem_cache_free(to_i915(vma->obj->base.dev)->vmas, vma);
+}
+
+void i915_vma_close(struct i915_vma *vma)
+{
+	GEM_BUG_ON(vma->closed);
+	vma->closed = true;
+
+	list_del_init(&vma->obj_link);
+	if (!i915_vma_is_active(vma) && !vma->pin_count)
+		WARN_ON(__i915_vma_unbind_no_wait(vma));
 }
 
 static struct i915_vma *

drivers/gpu/drm/i915/i915_gem_gtt.h

@@ -189,6 +189,7 @@ struct i915_vma {
 #define LOCAL_BIND	(1<<1)
 	unsigned int bound : 4;
 	bool is_ggtt : 1;
+	bool closed : 1;
 
 	/**
 	 * Support different GGTT views into the same object.