[PATCH 01/15] drm/xe/vm: Don't use a pin the vm_resv during validation

[Matthew Brost]

On Wed, Aug 13, 2025 at 12:51:07PM +0200, Thomas Hellström wrote:
> The pinning has the odd side-effect that unlocking *any* resv
> during validation triggers an "unlocking pinned lock" warning.
> 

So this is a cross process thing then - right? e.g., Process A pins a
dma-resv lock, Process B unlock a dma-resv lock and boom lockdep
warning? Just want to make sure I am understandinf the problem
correctly.

Matt 

> Cc: Matthew Brost <matthew.brost at intel.com>
> Fixes: 9d5558649f68 ("drm/xe: Rework eviction rejection of bound external bos")
> Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> ---
>  drivers/gpu/drm/xe/xe_bo.c |  5 ++---
>  drivers/gpu/drm/xe/xe_vm.h | 15 ++-------------
>  2 files changed, 4 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
> index 6fea39842e1e..11eaf3b06766 100644
> --- a/drivers/gpu/drm/xe/xe_bo.c
> +++ b/drivers/gpu/drm/xe/xe_bo.c
> @@ -2468,7 +2468,6 @@ int xe_bo_validate(struct xe_bo *bo, struct xe_vm *vm, bool allow_res_evict)
>  		.no_wait_gpu = false,
>  		.gfp_retry_mayfail = true,
>  	};
> -	struct pin_cookie cookie;
>  	int ret;
>  
>  	if (vm) {
> @@ -2479,10 +2478,10 @@ int xe_bo_validate(struct xe_bo *bo, struct xe_vm *vm, bool allow_res_evict)
>  		ctx.resv = xe_vm_resv(vm);
>  	}
>  
> -	cookie = xe_vm_set_validating(vm, allow_res_evict);
> +	xe_vm_set_validating(vm, allow_res_evict);
>  	trace_xe_bo_validate(bo);
>  	ret = ttm_bo_validate(&bo->ttm, &bo->placement, &ctx);
> -	xe_vm_clear_validating(vm, allow_res_evict, cookie);
> +	xe_vm_clear_validating(vm, allow_res_evict);
>  
>  	return ret;
>  }
> diff --git a/drivers/gpu/drm/xe/xe_vm.h b/drivers/gpu/drm/xe/xe_vm.h
> index 2f213737c7e5..2ecb417c19a2 100644
> --- a/drivers/gpu/drm/xe/xe_vm.h
> +++ b/drivers/gpu/drm/xe/xe_vm.h
> @@ -315,22 +315,14 @@ void xe_vm_snapshot_free(struct xe_vm_snapshot *snap);
>   * Register this task as currently making bos resident for the vm. Intended
>   * to avoid eviction by the same task of shared bos bound to the vm.
>   * Call with the vm's resv lock held.
> - *
> - * Return: A pin cookie that should be used for xe_vm_clear_validating().
>   */
> -static inline struct pin_cookie xe_vm_set_validating(struct xe_vm *vm,
> -						     bool allow_res_evict)
> +static inline void xe_vm_set_validating(struct xe_vm *vm, bool allow_res_evict)
>  {
> -	struct pin_cookie cookie = {};
> -
>  	if (vm && !allow_res_evict) {
>  		xe_vm_assert_held(vm);
> -		cookie = lockdep_pin_lock(&xe_vm_resv(vm)->lock.base);
>  		/* Pairs with READ_ONCE in xe_vm_is_validating() */
>  		WRITE_ONCE(vm->validating, current);
>  	}
> -
> -	return cookie;
>  }
>  
>  /**
> @@ -338,17 +330,14 @@ static inline struct pin_cookie xe_vm_set_validating(struct xe_vm *vm,
>   * @vm: Pointer to the vm or NULL
>   * @allow_res_evict: Eviction from @vm was allowed. Must be set to the same
>   * value as for xe_vm_set_validation().
> - * @cookie: Cookie obtained from xe_vm_set_validating().
>   *
>   * Register this task as currently making bos resident for the vm. Intended
>   * to avoid eviction by the same task of shared bos bound to the vm.
>   * Call with the vm's resv lock held.
>   */
> -static inline void xe_vm_clear_validating(struct xe_vm *vm, bool allow_res_evict,
> -					  struct pin_cookie cookie)
> +static inline void xe_vm_clear_validating(struct xe_vm *vm, bool allow_res_evict)
>  {
>  	if (vm && !allow_res_evict) {
> -		lockdep_unpin_lock(&xe_vm_resv(vm)->lock.base, cookie);
>  		/* Pairs with READ_ONCE in xe_vm_is_validating() */
>  		WRITE_ONCE(vm->validating, NULL);
>  	}
> -- 
> 2.50.1
>