drm/i915: Protect private gem objects from truncate (such as imported dmabuf)

If the object has no backing shmemfs filp, then we obviously cannot
perform a truncation operation upon it.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 1ec5f7ef2cc2..eb54a6d81517 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1385,6 +1385,11 @@ i915_gem_object_truncate(struct drm_i915_gem_object *obj)
 {
         struct inode *inode;
 
+        i915_gem_object_free_mmap_offset(obj);
+
+        if (obj->base.filp == NULL)
+                return;
+
         /* Our goal here is to return as much of the memory as
          * is possible back to the system as we are called from OOM.
          * To do this we must instruct the shmfs to drop all of its
@@ -1393,8 +1398,6 @@ i915_gem_object_truncate(struct drm_i915_gem_object *obj)
         inode = obj->base.filp->f_path.dentry->d_inode;
         shmem_truncate_range(inode, 0, (loff_t)-1);
 
-        i915_gem_object_free_mmap_offset(obj);
-
         obj->madv = __I915_MADV_PURGED;
 }