RE: [PATCH] drm/amdgpu: fix Null pointer dereference error in amdgpu_device_recover_vram

["Xu, Feifei" <Feifei.Xu@xxxxxxx>]

[AMD Official Use Only - General]

Acked-by: Feifei Xu <Feifei.Xu@xxxxxxx>

-----Original Message-----
From: Horatio Zhang <Hongkun.Zhang@xxxxxxx>
Sent: Tuesday, May 30, 2023 2:53 AM
To: amd-gfx@xxxxxxxxxxxxxxxxxxxxx
Cc: Xu, Feifei <Feifei.Xu@xxxxxxx>; Yao, Longlong <Longlong.Yao@xxxxxxx>; Zhang, Horatio <Hongkun.Zhang@xxxxxxx>; Pan, Xinhui <Xinhui.Pan@xxxxxxx>
Subject: [PATCH] drm/amdgpu: fix Null pointer dereference error in amdgpu_device_recover_vram

Use the function of amdgpu_bo_vm_destroy to handle the resource release of shadow bo. During the amdgpu_mes_self_test, shadow bo released, but
vmbo->shadow_list was not, which caused a null pointer reference error
in amdgpu_device_recover_vram when GPU reset.

Fixes: cd7050908070 ("drm/amdgpu: Fix vram recover doesn't work after whole GPU reset (v2)")
Signed-off-by: xinhui pan <xinhui.pan@xxxxxxx>
Signed-off-by: Horatio Zhang <Hongkun.Zhang@xxxxxxx>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 10 ++++------  drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c  |  1 -
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index 46f249912b67..4e46f8f1b3de 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -79,9 +79,10 @@ static void amdgpu_bo_user_destroy(struct ttm_buffer_object *tbo)  static void amdgpu_bo_vm_destroy(struct ttm_buffer_object *tbo)  {
        struct amdgpu_device *adev = amdgpu_ttm_adev(tbo->bdev);
-       struct amdgpu_bo *bo = ttm_to_amdgpu_bo(tbo);
+       struct amdgpu_bo *shadow_bo = ttm_to_amdgpu_bo(tbo), *bo;
        struct amdgpu_bo_vm *vmbo;

+       bo = shadow_bo->parent;
        vmbo = to_amdgpu_bo_vm(bo);
        /* in case amdgpu_device_recover_vram got NULL of bo->parent */
        if (!list_empty(&vmbo->shadow_list)) { @@ -711,11 +712,6 @@ int amdgpu_bo_create_vm(struct amdgpu_device *adev,
                return r;

        *vmbo_ptr = to_amdgpu_bo_vm(bo_ptr);
-       INIT_LIST_HEAD(&(*vmbo_ptr)->shadow_list);
-       /* Set destroy callback to amdgpu_bo_vm_destroy after vmbo->shadow_list
-        * is initialized.
-        */
-       bo_ptr->tbo.destroy = &amdgpu_bo_vm_destroy;
        return r;
 }

@@ -732,6 +728,8 @@ void amdgpu_bo_add_to_shadow_list(struct amdgpu_bo_vm *vmbo)

        mutex_lock(&adev->shadow_list_lock);
        list_add_tail(&vmbo->shadow_list, &adev->shadow_list);
+       vmbo->shadow->parent = amdgpu_bo_ref(&vmbo->bo);
+       vmbo->shadow->tbo.destroy = &amdgpu_bo_vm_destroy;
        mutex_unlock(&adev->shadow_list_lock);
 }

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
index cc3b1b596e56..dea1a64be44d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
@@ -573,7 +573,6 @@ int amdgpu_vm_pt_create(struct amdgpu_device *adev, struct amdgpu_vm *vm,
                return r;
        }

-       (*vmbo)->shadow->parent = amdgpu_bo_ref(bo);
        amdgpu_bo_add_to_shadow_list(*vmbo);

        return 0;
--
2.34.1