This is a note to let you know that I've just added the patch titled
drm/amdkfd: Fix a race condition of vram buffer unref in svm code
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-amdkfd-fix-a-race-condition-of-vram-buffer-unref.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit e4db7cf6fee4bbd787b1f5226535bd08781e0c87
Author: Xiaogang Chen <xiaogang.chen@xxxxxxx>
Date: Wed Sep 27 11:20:28 2023 -0500
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 <xiaogang.chen@xxxxxxx>
Reviewed-by: Philip Yang <Philip.Yang@xxxxxxx>
Reviewed-by: Jesse Zhang <Jesse.Zhang@xxxxxxx>
Tested-by: Jesse Zhang <Jesse.Zhang@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
index 86135ca33e5be..5ffbf9ab643b8 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
@@ -550,8 +550,15 @@ svm_range_vram_node_new(struct amdgpu_device *adev, struct svm_range *prange,
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 *
