[PATCH 3/3] drm/i915: Preallocate mm node for GTT mmap offset

[Chris Wilson <chris@chris-wilson.co.uk>]

As the shrinker may be invoked for the allocation, and it may reap
neighbouring objects in the offset range mm, we need to be careful in
the order in which we allocate the node, search for free space and then
insert the node into the mmap offset range manager.

Fixes i-g-t/gem_tiled_swapping

Reported-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c |   59 ++++++++++++++++++++++++++++++++-------
 1 file changed, 49 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d17f52d..3ab97c6 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1512,14 +1512,29 @@ i915_gem_get_unfenced_gtt_alignment(struct drm_device *dev,
 static int i915_gem_object_create_mmap_offset(struct drm_i915_gem_object *obj)
 {
 	struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
+	struct drm_gem_mm *mm = obj->base.dev->mm_private;
+	struct drm_map_list *list;
 	int ret;
 
-	if (obj->base.map_list.map)
+	list = &obj->base.map_list;
+	if (list->map)
 		return 0;
 
-	ret = drm_gem_create_mmap_offset(&obj->base);
-	if (ret != -ENOSPC)
-		return ret;
+	/* Set the object up for mmap'ing */
+	list->map = kzalloc(sizeof(struct drm_map_list), GFP_KERNEL);
+	if (!list->map)
+		return -ENOMEM;
+
+	list->map->type = _DRM_GEM;
+	list->map->size = obj->base.size;
+	list->map->handle = &obj->base;
+
+	/* Get a DRM GEM mmap offset allocated... */
+	list->file_offset_node = kzalloc(sizeof(struct drm_mm_node), GFP_KERNEL);
+	if (list->file_offset_node == NULL) {
+		ret = -ENOMEM;
+		goto out_free_list;
+	}
 
 	/* Badly fragmented mmap space? The only way we can recover
 	 * space is by destroying unwanted objects. We can't randomly release
@@ -1528,13 +1543,37 @@ static int i915_gem_object_create_mmap_offset(struct drm_i915_gem_object *obj)
 	 * offsets on purgeable objects by truncating it and marking it purged,
 	 * which prevents userspace from ever using that object again.
 	 */
-	i915_gem_purge(dev_priv, obj->base.size >> PAGE_SHIFT);
-	ret = drm_gem_create_mmap_offset(&obj->base);
-	if (ret != -ENOSPC)
-		return ret;
+	ret = drm_mm_insert_node(&mm->offset_manager, list->file_offset_node,
+				 obj->base.size / PAGE_SIZE, 0);
+	if (ret) {
+		i915_gem_purge(dev_priv, obj->base.size >> PAGE_SHIFT);
+		ret = drm_mm_insert_node(&mm->offset_manager, list->file_offset_node,
+					 obj->base.size / PAGE_SIZE, 0);
+	}
+	if (ret) {
+		i915_gem_shrink_all(dev_priv);
+		ret = drm_mm_insert_node(&mm->offset_manager, list->file_offset_node,
+					 obj->base.size / PAGE_SIZE, 0);
+	}
+	if (ret) {
+		kfree(list->file_offset_node);
+		goto out_free_list;
+	}
+
+	list->hash.key = list->file_offset_node->start;
+	ret = drm_ht_insert_item(&mm->offset_hash, &list->hash);
+	if (ret)
+		goto out_free_mm;
 
-	i915_gem_shrink_all(dev_priv);
-	return drm_gem_create_mmap_offset(&obj->base);
+	return 0;
+
+out_free_mm:
+	drm_mm_put_block(list->file_offset_node);
+out_free_list:
+	kfree(list->map);
+	list->map = NULL;
+
+	return ret;
 }
 
 static void i915_gem_object_free_mmap_offset(struct drm_i915_gem_object *obj)
-- 
1.7.10.4