Re: [PATCH] drm/test: drm_exec: use kzalloc() to allocate GEM objects

[Nirmoy Das]

On 29.08.25 09:55, Danilo Krummrich wrote:

Since commit e7fa80e2932c ("drm_gem: add mutex to drm_gem_object.gpuva")
it is possible for test_prepare_array() to exceed a stack frame size of
2048 bytes depending on the exact configuration of the kernel.

   drivers/gpu/drm/tests/drm_exec_test.c: In function ‘test_prepare_array’:
   drivers/gpu/drm/tests/drm_exec_test.c:171:1: error: the frame size of 2128 
bytes is larger than 2048 bytes [-Werror=frame-larger-than=]
     171 | }
         | ^
   cc1: all warnings being treated as errors
   make[6]: *** [scripts/Makefile.build:287: 
drivers/gpu/drm/tests/drm_exec_test.o] Error 1
   make[6]: *** Waiting for unfinished jobs....

In order to fix this, allocate the GEM objects in test_prepare_array()
with kzalloc(), rather than placing them on the stack.

Cc: Alice Ryhl <alicer...@google.com>
Cc: Christian König <christian.koe...@amd.com>
Fixes: e7fa80e2932c ("drm_gem: add mutex to drm_gem_object.gpuva")
Signed-off-by: Danilo Krummrich <d...@kernel.org>

Reviewed-by: Nirmoy Das <nirm...@nvidia.com>

---
  drivers/gpu/drm/tests/drm_exec_test.c | 26 +++++++++++++++++++-------
  1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/tests/drm_exec_test.c 
b/drivers/gpu/drm/tests/drm_exec_test.c
index d6c4dd1194a0..d59ec3baae1d 100644
--- a/drivers/gpu/drm/tests/drm_exec_test.c
+++ b/drivers/gpu/drm/tests/drm_exec_test.c
@@ -150,14 +150,22 @@ static void test_prepare(struct kunit *test)
  static void test_prepare_array(struct kunit *test)
  {
        struct drm_exec_priv *priv = test->priv;
-       struct drm_gem_object gobj1 = { };
-       struct drm_gem_object gobj2 = { };
-       struct drm_gem_object *array[] = { &gobj1, &gobj2 };
+       struct drm_gem_object *gobj1;
+       struct drm_gem_object *gobj2;
+       struct drm_gem_object *array[] = {
+               (gobj1 = kzalloc(sizeof(*gobj1), GFP_KERNEL)),
+               (gobj2 = kzalloc(sizeof(*gobj2), GFP_KERNEL)),
+       };
        struct drm_exec exec;
        int ret;

- drm_gem_private_object_init(priv->drm, &gobj1, PAGE_SIZE);

-       drm_gem_private_object_init(priv->drm, &gobj2, PAGE_SIZE);
+       if (!gobj1 || !gobj2) {
+               KUNIT_FAIL(test, "Failed to allocate GEM objects.\n");
+               goto out;
+       }
+
+       drm_gem_private_object_init(priv->drm, gobj1, PAGE_SIZE);
+       drm_gem_private_object_init(priv->drm, gobj2, PAGE_SIZE);

drm_exec_init(&exec, DRM_EXEC_INTERRUPTIBLE_WAIT, 0);

        drm_exec_until_all_locked(&exec)
@@ -166,8 +174,12 @@ static void test_prepare_array(struct kunit *test)
        KUNIT_EXPECT_EQ(test, ret, 0);
        drm_exec_fini(&exec);

- drm_gem_private_object_fini(&gobj1);

-       drm_gem_private_object_fini(&gobj2);
+       drm_gem_private_object_fini(gobj1);
+       drm_gem_private_object_fini(gobj2);
+
+out:
+       kfree(gobj1);
+       kfree(gobj2);
  }

static void test_multiple_loops(struct kunit *test)

base-commit: 0b6da6d3a8d5391ff9da2358ac5afd8b7badd943