On 2026-06-04 13:20, Yunxiang Li wrote:
amdgpu_amdkfd_gpuvm_free_memory_of_gpu() unpinned DOORBELL and MMIO
remap BOs (which are pinned at allocation time) before checking whether
the BO is still mapped to the GPU. When the BO is still mapped, the
function returns -EBUSY and leaves the BO alive, but it has already
been unpinned. The BO is then unpinned again when it is finally freed
during process teardown, triggering a ttm_bo_unpin() underflow warning:
WARNING: CPU: 18 PID: 15066 at ttm/ttm_bo.c:650 amdttm_bo_unpin+0x6d/0x80
[amdttm]
Workqueue: kfd_process_wq kfd_process_wq_release [amdgpu]
RIP: 0010:amdttm_bo_unpin+0x6d/0x80 [amdttm]
Call Trace:
amdgpu_bo_unpin+0x1a/0x90 [amdgpu]
amdgpu_amdkfd_gpuvm_unpin_bo+0x31/0xb0 [amdgpu]
amdgpu_amdkfd_gpuvm_free_memory_of_gpu+0x3bf/0x460 [amdgpu]
kfd_process_free_outstanding_kfd_bos+0xd4/0x170 [amdgpu]
kfd_process_wq_release+0x109/0x1b0 [amdgpu]
process_one_work+0x1e2/0x3b0
worker_thread+0x50/0x3a0
kthread+0xdd/0x100
ret_from_fork+0x29/0x50
Move the unpin after the mapped_to_gpu_memory check so it only happens
once we are committed to freeing the BO.
Fixes: d25e35bc26c3 ("drm/amdgpu: Pin MMIO/DOORBELL BO's in GTT domain")
Signed-off-by: Yunxiang Li <[email protected]>
Reviewed-by: Felix Kuehling <[email protected]>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index 7c01492e69ddd..5bb3e28441a5c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -1914,13 +1914,6 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
mutex_lock(&mem->lock);
- /* Unpin MMIO/DOORBELL BO's that were pinned during allocation */
- if (mem->alloc_flags &
- (KFD_IOC_ALLOC_MEM_FLAGS_DOORBELL |
- KFD_IOC_ALLOC_MEM_FLAGS_MMIO_REMAP)) {
- amdgpu_amdkfd_gpuvm_unpin_bo(mem->bo);
- }
-
mapped_to_gpu_memory = mem->mapped_to_gpu_memory;
is_imported = mem->is_imported;
mutex_unlock(&mem->lock);
@@ -1934,6 +1927,15 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
return -EBUSY;
}
+ /* At this point the BO is guaranteed to be freed, so unpin the
+ * MMIO/DOORBELL BOs that were pinned during allocation.
+ */
+ if (mem->alloc_flags &
+ (KFD_IOC_ALLOC_MEM_FLAGS_DOORBELL |
+ KFD_IOC_ALLOC_MEM_FLAGS_MMIO_REMAP)) {
+ amdgpu_amdkfd_gpuvm_unpin_bo(mem->bo);
+ }
+
/* Make sure restore workers don't access the BO any more */
mutex_lock(&process_info->lock);
if (!list_empty(&mem->validate_list))
