Re: [PATCH v3 3/6] drm/amdgpu: delay the use of amdgpu_vm_set_task_info

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On 24/09/2024 09:23, Christian König wrote:
Am 23.09.24 um 12:25 schrieb Tvrtko Ursulin:

On 20/09/2024 10:06, Pierre-Eric Pelloux-Prayer wrote:
At this point the vm is locked so we safely modify it without risk of
concurrent access.

To which particular lock this is referring to and does this imply previous placement was unsafe?

We use the root PDs dma_resv object as VM lock to protect most field inside the VM structure, only a few are protected by an additional spinlock.

And yes, previously it was possible that you got a mangled process/task name because no lock was protecting the task_info structure.

Got it, thanks Christian!

In this case I only suggest to be more explicit in the commit message and clearly say it is fixing an existing bug. Like it stands I wasn't sure if it was that, or the movement was just enabling the changes which come later in the series.

Regards,

Tvrtko

Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@xxxxxxx>
---
  drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 6 +++---
  1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
index 1e475eb01417..891128ecee6d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
@@ -309,9 +309,6 @@ static int amdgpu_cs_pass1(struct amdgpu_cs_parser *p,
          p->gang_leader->uf_addr = uf_offset;
      kvfree(chunk_array);
  -    /* Use this opportunity to fill in task info for the vm */
-    amdgpu_vm_set_task_info(vm);
-
      return 0;
    free_all_kdata:
@@ -1180,6 +1177,9 @@ static int amdgpu_cs_vm_handling(struct amdgpu_cs_parser *p)
          job->vm_pd_addr = amdgpu_gmc_pd_addr(vm->root.bo);
      }
  +    /* Use this opportunity to fill in task info for the vm */
+    amdgpu_vm_set_task_info(vm);
+
      if (adev->debug_vm) {
          /* Invalidate all BOs to test for userspace bugs */
          amdgpu_bo_list_for_each_entry(e, p->bo_list) {




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