Re: [PATCH] drm/amdgpu: move lockdep assert to the right place.

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On 2/4/2022 1:32 PM, Christian König wrote:
Am 04.02.22 um 19:12 schrieb Bhardwaj, Rajneesh:
[Sorry for top posting]

Hi Christian

I think you forgot the below hunk, without which the issue is not fixed completely on a multi GPU system.

No, that is perfectly intentional. While removing a bo_va structure it can happen that there are still mappings attached to it (for example because the application crashed).


OK. but for me, at boot time, I see flood of warning messages coming from  amdgpu_vm_bo_del so the previous patch doesn't help.



Because of this locking the VM before the remove is mandatory. Only while adding a bo_va structure we can avoid that.

Regards,
Christian.


diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index dcc80d6e099e..6f68fc9da56a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -2670,8 +2670,6 @@ void amdgpu_vm_bo_del(struct amdgpu_device *adev,
        struct amdgpu_vm *vm = bo_va->base.vm;
        struct amdgpu_vm_bo_base **base;

-       dma_resv_assert_held(vm->root.bo->tbo.base.resv);
-
        if (bo) {
                dma_resv_assert_held(bo->tbo.base.resv);
                if (bo->tbo.base.resv == vm->root.bo->tbo.base.resv)


If you chose to include the above hunk, please feel free to add

Reviewed-and-tested-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@xxxxxxx>

On 2/4/2022 11:27 AM, Felix Kuehling wrote:

Am 2022-02-04 um 03:52 schrieb Christian König:
Since newly added BOs don't have any mappings it's ok to add them
without holding the VM lock. Only when we add per VM BOs the lock is
mandatory.

Signed-off-by: Christian König <christian.koenig@xxxxxxx>
Reported-by: Bhardwaj, Rajneesh <Rajneesh.Bhardwaj@xxxxxxx>

Reviewed-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>


---
  drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index fdc6a1fd74af..dcc80d6e099e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -375,6 +375,8 @@ static void amdgpu_vm_bo_base_init(struct amdgpu_vm_bo_base *base,
      if (bo->tbo.base.resv != vm->root.bo->tbo.base.resv)
          return;
  + dma_resv_assert_held(vm->root.bo->tbo.base.resv);
+
      vm->bulk_moveable = false;
      if (bo->tbo.type == ttm_bo_type_kernel && bo->parent)
          amdgpu_vm_bo_relocated(base);
@@ -2260,8 +2262,6 @@ struct amdgpu_bo_va *amdgpu_vm_bo_add(struct amdgpu_device *adev,
  {
      struct amdgpu_bo_va *bo_va;
  - dma_resv_assert_held(vm->root.bo->tbo.base.resv);
-
      bo_va = kzalloc(sizeof(struct amdgpu_bo_va), GFP_KERNEL);
      if (bo_va == NULL) {
          return NULL;




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