Re: [PATCH] drm/amdgpu: Mark amdgpu_bo as invalid after moved

[Christian König <ckoenig.leichtzumerken@xxxxxxxxx>]

Yeah, completely agree. This patch doesn't really make sense.

Please explain why you would want to do this?

Regards,
Christian.

Am 11.07.24 um 13:56 schrieb Huang, Trigger:
> [AMD Official Use Only - AMD Internal Distribution Only]
>
> This patch seems to be wrong.
> Quite a lot of preparations have been done in amdgpu_bo_move_notify
> For example, amdgpu_bo_kunmap() will be called to prevent the BO from being accessed by CPU. If not called, the CPU may attempt to access the BO while it is being moved.
>
> Thanks,
> Trigger
>
> > -----Original Message-----
> > From: amd-gfx <amd-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of
> > YuanShang
> > Sent: Thursday, July 11, 2024 5:10 PM
> > To: amd-gfx@xxxxxxxxxxxxxxxxxxxxx
> > Cc: YuanShang Mao (River) <YuanShang.Mao@xxxxxxx>; YuanShang Mao
> > (River) <YuanShang.Mao@xxxxxxx>
> > Subject: [PATCH] drm/amdgpu: Mark amdgpu_bo as invalid after moved
> >
> > Caution: This message originated from an External Source. Use proper caution
> > when opening attachments, clicking links, or responding.
> >
> >
> > It leads to race condition if amdgpu_bo is marked as invalid before it is really
> > moved.
> >
> > Signed-off-by: YuanShang <YuanShang.Mao@xxxxxxx>
> > ---
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 10 +++++-----
> >   1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> > index 29e4b5875872..a29d5132ad3d 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> > @@ -519,8 +519,8 @@ static int amdgpu_bo_move(struct ttm_buffer_object
> > *bo, bool evict,
> >
> >          if (!old_mem || (old_mem->mem_type == TTM_PL_SYSTEM &&
> >                           bo->ttm == NULL)) {
> > -               amdgpu_bo_move_notify(bo, evict, new_mem);
> >                  ttm_bo_move_null(bo, new_mem);
> > +               amdgpu_bo_move_notify(bo, evict, new_mem);
> >                  return 0;
> >          }
> >          if (old_mem->mem_type == AMDGPU_GEM_DOMAIN_DGMA || @@ -
> > 530,8 +530,8 @@ static int amdgpu_bo_move(struct ttm_buffer_object *bo,
> > bool evict,
> >          if (old_mem->mem_type == TTM_PL_SYSTEM &&
> >              (new_mem->mem_type == TTM_PL_TT ||
> >               new_mem->mem_type == AMDGPU_PL_PREEMPT)) {
> > -               amdgpu_bo_move_notify(bo, evict, new_mem);
> >                  ttm_bo_move_null(bo, new_mem);
> > +               amdgpu_bo_move_notify(bo, evict, new_mem);
> >                  return 0;
> >          }
> >          if ((old_mem->mem_type == TTM_PL_TT || @@ -542,9 +542,9 @@ static
> > int amdgpu_bo_move(struct ttm_buffer_object *bo, bool evict,
> >                          return r;
> >
> >                  amdgpu_ttm_backend_unbind(bo->bdev, bo->ttm);
> > -               amdgpu_bo_move_notify(bo, evict, new_mem);
> >                  ttm_resource_free(bo, &bo->resource);
> >                  ttm_bo_assign_mem(bo, new_mem);
> > +               amdgpu_bo_move_notify(bo, evict, new_mem);
> >                  return 0;
> >          }
> >
> > @@ -557,8 +557,8 @@ static int amdgpu_bo_move(struct ttm_buffer_object
> > *bo, bool evict,
> >              new_mem->mem_type == AMDGPU_PL_OA ||
> >              new_mem->mem_type == AMDGPU_PL_DOORBELL) {
> >                  /* Nothing to save here */
> > -               amdgpu_bo_move_notify(bo, evict, new_mem);
> >                  ttm_bo_move_null(bo, new_mem);
> > +               amdgpu_bo_move_notify(bo, evict, new_mem);
> >                  return 0;
> >          }
> >
> > @@ -583,11 +583,11 @@ static int amdgpu_bo_move(struct
> > ttm_buffer_object *bo, bool evict,
> >                  return -EMULTIHOP;
> >          }
> >
> > -       amdgpu_bo_move_notify(bo, evict, new_mem);
> >          if (adev->mman.buffer_funcs_enabled)
> >                  r = amdgpu_move_blit(bo, evict, new_mem, old_mem);
> >          else
> >                  r = -ENODEV;
> > +       amdgpu_bo_move_notify(bo, evict, new_mem);
> >
> >          if (r) {
> >                  /* Check that all memory is CPU accessible */
> > --
> > 2.25.1