Re: [syzbot] [dri?] WARNING in drm_prime_destroy_file_private (3)

[Hillf Danton <hdanton@sina.com>]

> Date: Tue, 12 May 2026 12:56:33 -0700	[thread overview]
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    81d6f7807536 Merge tag 'v7.1-rc3-smb3-client-fixes' of git..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=159b10c8580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=59da38148f3a3d24
> dashboard link: https://syzkaller.appspot.com/bug?extid=d7c9eed171647e421013
> compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12332a73980000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=161a3dba580000

Test Edward's fix.

#syz test

--- x/drivers/gpu/drm/drm_gem.c
+++ y/drivers/gpu/drm/drm_gem.c
@@ -374,14 +374,8 @@ drm_gem_object_release_handle(int id, vo
 	if (obj->funcs->close)
 		obj->funcs->close(obj, file_priv);
 
-	mutex_lock(&file_priv->prime.lock);
-
 	drm_prime_remove_buf_handle(&file_priv->prime, id);
-
-	mutex_unlock(&file_priv->prime.lock);
-
 	drm_vma_node_revoke(&obj->vma_node, file_priv);
-
 	drm_gem_object_handle_put_unlocked(obj);
 
 	return 0;
@@ -401,13 +395,16 @@ drm_gem_handle_delete(struct drm_file *f
 {
 	struct drm_gem_object *obj;
 
+	mutex_lock(&filp->prime.lock);
 	spin_lock(&filp->table_lock);
 
 	/* Check if we currently have a reference on the object */
 	obj = idr_replace(&filp->object_idr, NULL, handle);
 	spin_unlock(&filp->table_lock);
-	if (IS_ERR_OR_NULL(obj))
+	if (IS_ERR_OR_NULL(obj)) {
+		mutex_unlock(&filp->prime.lock);
 		return -EINVAL;
+	}
 
 	/* Release driver's reference and decrement refcount. */
 	drm_gem_object_release_handle(handle, obj, filp);
@@ -416,6 +413,7 @@ drm_gem_handle_delete(struct drm_file *f
 	spin_lock(&filp->table_lock);
 	idr_remove(&filp->object_idr, handle);
 	spin_unlock(&filp->table_lock);
+	mutex_unlock(&filp->prime.lock);
 
 	return 0;
 }
@@ -1030,17 +1028,18 @@ int drm_gem_change_handle_ioctl(struct d
 		return -EINVAL;
 	handle = args->new_handle;
 
+	mutex_lock(&file_priv->prime.lock);
 	obj = drm_gem_object_lookup(file_priv, args->handle);
-	if (!obj)
+	if (!obj) {
+		mutex_unlock(&file_priv->prime.lock);
 		return -ENOENT;
+	}
 
 	if (args->handle == handle) {
 		ret = 0;
-		goto out;
+		goto out_unlock;
 	}
 
-	mutex_lock(&file_priv->prime.lock);
-
 	spin_lock(&file_priv->table_lock);
 
        /* When create_tail allocs an obj idr, it needs to first alloc as NULL,
@@ -1092,9 +1091,8 @@ int drm_gem_change_handle_ioctl(struct d
 	spin_unlock(&file_priv->table_lock);
 
 out_unlock:
-	mutex_unlock(&file_priv->prime.lock);
-out:
 	drm_gem_object_put(obj);
+	mutex_unlock(&file_priv->prime.lock);
 
 	return ret;
 }
@@ -1126,8 +1124,10 @@ drm_gem_open(struct drm_device *dev, str
 void
 drm_gem_release(struct drm_device *dev, struct drm_file *file_private)
 {
+	mutex_lock(&file_private->prime.lock);
 	idr_for_each(&file_private->object_idr,
 		     &drm_gem_object_release_handle, file_private);
+	mutex_unlock(&file_private->prime.lock);
 	idr_destroy(&file_private->object_idr);
 }
 
--