drm/i915: Do not mis-classify clean objects as purgeable

Whilst cleaning up the patches for submission, I mis-classified non-dirty
objects as purgeable. This was causing the backing pages for those
objects to be evicted under memory-pressure, discarding valid and
unreplaceable texture data.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index c8ecc75..c69f1fa 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1530,6 +1530,23 @@ i915_gem_object_move_to_flushing(struct drm_gem_object *obj)
        obj_priv->last_rendering_seqno = 0;
 }
 
+/* Immediately discard the backing storage */
+static void
+i915_gem_object_truncate(struct drm_gem_object *obj)
+{
+    struct inode *inode;
+
+    inode = obj->filp->f_path.dentry->d_inode;
+    if (inode->i_op->truncate)
+           inode->i_op->truncate (inode);
+}
+
+static inline int
+i915_gem_object_is_purgeable(struct drm_i915_gem_object *obj_priv)
+{
+       return obj_priv->madv == I915_MADV_DONTNEED;
+}
+
 static void
 i915_gem_object_move_to_inactive(struct drm_gem_object *obj)
 {
@@ -2018,17 +2035,14 @@ i915_gem_object_unbind(struct drm_gem_object *obj)
        if (!list_empty(&obj_priv->list))
                list_del_init(&obj_priv->list);
 
+       if (i915_gem_object_is_purgeable(obj_priv))
+               i915_gem_object_truncate(obj);
+
        trace_i915_gem_object_unbind(obj);
 
        return 0;
 }
 
-static inline int
-i915_gem_object_is_purgeable(struct drm_i915_gem_object *obj_priv)
-{
-       return !obj_priv->dirty || obj_priv->madv == I915_MADV_DONTNEED;
-}
-
 static struct drm_gem_object *
 i915_gem_find_inactive_object(struct drm_device *dev, int min_size)
 {
@@ -2041,7 +2055,8 @@ i915_gem_find_inactive_object(struct drm_device *dev, int min_size)
        list_for_each_entry(obj_priv, &dev_priv->mm.inactive_list, list) {
                struct drm_gem_object *obj = obj_priv->obj;
                if (obj->size >= min_size) {
-                       if (i915_gem_object_is_purgeable(obj_priv) &&
+                       if ((!obj_priv->dirty ||
+                            i915_gem_object_is_purgeable(obj_priv)) &&
                            (!best || obj->size < best->size)) {
                                best = obj;
                                if (best->size == min_size)
@@ -4808,19 +4823,6 @@ void i915_gem_release(struct drm_device * dev, struct drm_file *file_priv)
        mutex_unlock(&dev->struct_mutex);
 }
 
-/* Immediately discard the backing storage */
-static void
-i915_gem_object_truncate(struct drm_gem_object *obj)
-{
-    struct inode *inode;
-
-    inode = obj->filp->f_path.dentry->d_inode;
-
-    mutex_lock(&inode->i_mutex);
-    truncate_inode_pages(inode->i_mapping, 0);
-    mutex_unlock(&inode->i_mutex);
-}
-
 static int
 i915_gem_shrink(int nr_to_scan, gfp_t gfp_mask)
 {
@@ -4866,10 +4868,7 @@ i915_gem_shrink(int nr_to_scan, gfp_t gfp_mask)
                                         &dev_priv->mm.inactive_list,
                                         list) {
                        if (i915_gem_object_is_purgeable(obj_priv)) {
-                               struct drm_gem_object *obj = obj_priv->obj;
-                               i915_gem_object_unbind(obj);
-                               i915_gem_object_truncate(obj);
-
+                               i915_gem_object_unbind(obj_priv->obj);
                                if (--nr_to_scan <= 0)
                                        break;
                        }
@@ -4878,6 +4877,8 @@ i915_gem_shrink(int nr_to_scan, gfp_t gfp_mask)
                spin_lock(&shrink_list_lock);
                mutex_unlock(&dev->struct_mutex);
 
+               would_deadlock = 0;
+
                if (nr_to_scan <= 0)
                        break;
        }
@@ -4896,11 +4897,7 @@ i915_gem_shrink(int nr_to_scan, gfp_t gfp_mask)
                                         &dev_priv->mm.inactive_list,
                                         list) {
                        if (nr_to_scan > 0) {
-                               struct drm_gem_object *obj = obj_priv->obj;
-                               i915_gem_object_unbind(obj);
-                               if (i915_gem_object_is_purgeable(obj_priv))
-                                       i915_gem_object_truncate(obj);
-
+                               i915_gem_object_unbind(obj_priv->obj);
                                nr_to_scan--;
                        } else
                                cnt++;