Re: [PATCH v3 06/25] drm/xe: Add XE_BO_FLAG_PUT_VM_ASYNC

[Francois Dugast <francois.dugast@intel.com>]

On Fri, Feb 27, 2026 at 05:34:42PM -0800, Matthew Brost wrote:
> Add XE_BO_FLAG_PUT_VM_ASYNC, which indicates that an async BO put must
> also drop an additional reference to the BO’s VM. This is useful when a
> kernel BO, one that does not normally hold a VM reference, needs to be
> put asynchronously, ensuring the shared dma-resv object does not
> disappear before the BO.
> 
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_bo.c | 8 +++++++-
>  drivers/gpu/drm/xe/xe_bo.h | 1 +
>  2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
> index 8ff193600443..d4c8ef8ff2c3 100644
> --- a/drivers/gpu/drm/xe/xe_bo.c
> +++ b/drivers/gpu/drm/xe/xe_bo.c
> @@ -3567,8 +3567,14 @@ void xe_bo_put_commit(struct llist_head *deferred)
>  	if (!freed)
>  		return;
>  
> -	llist_for_each_entry_safe(bo, next, freed, freed)
> +	llist_for_each_entry_safe(bo, next, freed, freed) {
> +		struct xe_vm *vm = bo->vm;
> +		bool async = bo->flags & XE_BO_FLAG_PUT_VM_ASYNC;
> +
>  		drm_gem_object_free(&bo->ttm.base.refcount);
> +		if (async)
> +			xe_vm_put(vm);
> +	}
>  }
>  
>  static void xe_bo_dev_work_func(struct work_struct *work)
> diff --git a/drivers/gpu/drm/xe/xe_bo.h b/drivers/gpu/drm/xe/xe_bo.h
> index bf284ed47325..14be9c1bb09d 100644
> --- a/drivers/gpu/drm/xe/xe_bo.h
> +++ b/drivers/gpu/drm/xe/xe_bo.h
> @@ -52,6 +52,7 @@
>  #define XE_BO_FLAG_CPU_ADDR_MIRROR	BIT(24)
>  #define XE_BO_FLAG_FORCE_USER_VRAM	BIT(25)
>  #define XE_BO_FLAG_NO_COMPRESSION	BIT(26)
> +#define XE_BO_FLAG_PUT_VM_ASYNC		BIT(27)

If I understand correctly, this flag should only be used in the deferred
path, which is why it is ignored in the non-deferred path. Maybe it would
be good to add an assert there to make sure we are not mistakenly leaking
a VM reference.

Francois

>  
>  /* this one is trigger internally only */
>  #define XE_BO_FLAG_INTERNAL_TEST	BIT(30)
> -- 
> 2.34.1
>