Am 2023-05-09 um 18:17 schrieb Alex Deucher:
From: Xiaogang Chen <xiaogang.chen@xxxxxxx>
mmu notifier does not always hold mm->sem during call back. That causes
a race condition between kfd userprt buffer mapping and mmu notifier
which leds to gpu shadder or SDMA access userptr buffer before it has been
mapped to gpu VM. Always map userptr buffer to avoid that though it may make
some userprt buffers mapped two times.
Suggested-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Signed-off-by: Xiaogang Chen <xiaogang.chen@xxxxxxx>
Reviewed-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
This patch is no longer needed and should not be applied. It was
originally applied to amd-staging-drm-next as patch
fcf00f8d29f2fc6bf00531a1447be28b99073cc3 in November 2022. This fixed a
race condition due to incorrect assumptions about the mmap lock and MMU
notifiers. This hunk was added back by my later patch f95f51a4c335
("drm/amdgpu: Add notifier lock for KFD userptrs") in December, using
our own notifier lock that doesn't suffer from those races.
Regards,
Felix
---
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 10 ----------
1 file changed, 10 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index 58a774647573..40078c0a5585 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -1942,16 +1942,6 @@ int amdgpu_amdkfd_gpuvm_map_memory_to_gpu(
*/
mutex_lock(&mem->process_info->lock);
- /* Lock notifier lock. If we find an invalid userptr BO, we can be
- * sure that the MMU notifier is no longer running
- * concurrently and the queues are actually stopped
- */
- if (amdgpu_ttm_tt_get_usermm(bo->tbo.ttm)) {
- mutex_lock(&mem->process_info->notifier_lock);
- is_invalid_userptr = !!mem->invalid;
- mutex_unlock(&mem->process_info->notifier_lock);
- }
-
mutex_lock(&mem->lock);
domain = mem->domain;
