From 50f35a907c4f9ed431fd3dbb8b871ef1cbb0718e Mon Sep 17 00:00:00 2001 From: Xiaogang Chen Date: Wed, 27 Sep 2023 11:20:28 -0500 Subject: [PATCH] drm/amdkfd: Fix a race condition of vram buffer unref in svm code [ Upstream commit 709c348261618da7ed89d6c303e2ceb9e453ba74 ] prange->svm_bo unref can happen in both mmu callback and a callback after migrate to system ram. Both are async call in different tasks. Sync svm_bo unref operation to avoid random "use-after-free". Signed-off-by: Xiaogang Chen Reviewed-by: Philip Yang Reviewed-by: Jesse Zhang Tested-by: Jesse Zhang Signed-off-by: Alex Deucher Signed-off-by: Sasha Levin --- drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c index d7e758c..6281d37 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c @@ -612,8 +612,15 @@ create_bo_failed: void svm_range_vram_node_free(struct svm_range *prange) { - svm_range_bo_unref(prange->svm_bo); - prange->ttm_res = NULL; + /* serialize prange->svm_bo unref */ + mutex_lock(&prange->lock); + /* prange->svm_bo has not been unref */ + if (prange->ttm_res) { + prange->ttm_res = NULL; + mutex_unlock(&prange->lock); + svm_range_bo_unref(prange->svm_bo); + } else + mutex_unlock(&prange->lock); } struct amdgpu_device * -- 2.7.4