Hi
Am 15.07.25 um 16:01 schrieb Alex Deucher:
On Tue, Jul 15, 2025 at 4:38 AM Thomas Zimmermann <[email protected]> wrote:
This reverts commit 515986100d176663d0a03219a3056e4252f729e6.
The dma_buf field in struct drm_gem_object is not stable over the
object instance's lifetime. The field becomes NULL when user space
releases the final GEM handle on the buffer object. This resulted
in a NULL-pointer deref.
Workarounds in commit 5307dce878d4 ("drm/gem: Acquire references on
GEM handles for framebuffers") and commit f6bfc9afc751 ("drm/framebuffer:
Acquire internal references on GEM handles") only solved the problem
partially. They especially don't work for buffer objects without a DRM
framebuffer associated.
Hence, this revert to going back to using .import_attach->dmabuf.
Signed-off-by: Thomas Zimmermann <[email protected]>
Acked-by: Alex Deucher <[email protected]>
Can I take this patch into drm-misc-fixes?
Best regards
Thomas
---
drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 2 +-
drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 3 ++-
drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 2 +-
3 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
index ff98c87b2e0b..5743ebb2f1b7 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
@@ -514,7 +514,7 @@ bool amdgpu_dmabuf_is_xgmi_accessible(struct amdgpu_device
*adev,
return false;
if (drm_gem_is_imported(obj)) {
- struct dma_buf *dma_buf = obj->dma_buf;
+ struct dma_buf *dma_buf = obj->import_attach->dmabuf;
if (dma_buf->ops != &amdgpu_dmabuf_ops)
/* No XGMI with non AMD GPUs */
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index 6626a6e64ff5..d1ccbfcf21fa 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -317,7 +317,8 @@ static int amdgpu_gem_object_open(struct drm_gem_object
*obj,
*/
if (!vm->is_compute_context || !vm->process_info)
return 0;
- if (!drm_gem_is_imported(obj) || !dma_buf_is_dynamic(obj->dma_buf))
+ if (!drm_gem_is_imported(obj) ||
+ !dma_buf_is_dynamic(obj->import_attach->dmabuf))
return 0;
mutex_lock_nested(&vm->process_info->lock, 1);
if (!WARN_ON(!vm->process_info->eviction_fence)) {
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index af0f655dfd5b..b9b4f7d9186e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -1272,7 +1272,7 @@ int amdgpu_vm_bo_update(struct amdgpu_device *adev,
struct amdgpu_bo_va *bo_va,
struct drm_gem_object *obj = &bo->tbo.base;
if (drm_gem_is_imported(obj) && bo_va->is_xgmi) {
- struct dma_buf *dma_buf = obj->dma_buf;
+ struct dma_buf *dma_buf = obj->import_attach->dmabuf;
struct drm_gem_object *gobj = dma_buf->priv;
struct amdgpu_bo *abo = gem_to_amdgpu_bo(gobj);
--
2.50.0
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
