On Wed, May 10, 2023 at 04:19:32PM +0200, Thomas Hellström wrote:
> If a vma was destroyed with the bo evicted, it might happen that we forget
> to remove it from the notifer::rebind_list. Fix to make sure that really
> happens.
>
> Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/xe/xe_vm.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index 5f93d78c2e58..f54b3b7566c9 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -978,6 +978,15 @@ static void xe_vma_destroy(struct xe_vma *vma, struct dma_fence *fence)
> } else {
> xe_bo_assert_held(vma->bo);
> list_del(&vma->bo_link);
> + /*
> + * TODO: We can do an advisory check for list link empty here,
> + * if this lock becomes too costly. Nobody can re-add to the
> + * bo to the vm::notifier::rebind_list at this point since we
> + * have the bo lock.
> + */
IMO grab isn't a big deal, not sure this is worth such a lengthly comment.
> + spin_lock(&vm->notifier.list_lock);
> + list_del(&vma->notifier.rebind_link);
Can you safe call list_del on an empty list? I thought that call blows
up hence we have a bunch of if (!list_empty()) checks before calling
list_del all over the driver.
Matt
> + spin_unlock(&vm->notifier.list_lock);
> if (!vma->bo->vm)
> vm_remove_extobj(vma);
> }
> --
> 2.39.2
>
