drm/amdgpu: improve HMM error -ENOMEM and -EBUSY handling

Under memory pressure, hmm_range_fault may return error code -ENOMEM
or -EBUSY, change pr_info to pr_debug to remove unnecessary kernel log
message because we will retry restore again.

Call get_user_pages_done if TTM get user pages failed will have
WARN_ONCE kernel calling stack dump log.
Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c

@@ -1731,35 +1731,17 @@ static int update_invalid_user_pages(struct amdkfd_process_info *process_info,
 		ret = amdgpu_ttm_tt_get_user_pages(bo->tbo.ttm,
 						   bo->tbo.ttm->pages);
 		if (ret) {
-			bo->tbo.ttm->pages[0] = NULL;
-			pr_info("%s: Failed to get user pages: %d\n",
+			pr_debug("%s: Failed to get user pages: %d\n",
 				__func__, ret);
-			/* Pretend it succeeded. It will fail later
-			 * with a VM fault if the GPU tries to access
-			 * it. Better than hanging indefinitely with
-			 * stalled user mode queues.
-			 */
-		}
-	}
-
-	return 0;
-}
 
-/* Remove invalid userptr BOs from hmm track list
- *
- * Stop HMM track the userptr update
- */
-static void untrack_invalid_user_pages(struct amdkfd_process_info *process_info)
-{
-	struct kgd_mem *mem, *tmp_mem;
-	struct amdgpu_bo *bo;
+			/* Return error -EBUSY or -ENOMEM, retry restore */
+			return ret;
+		}
 
-	list_for_each_entry_safe(mem, tmp_mem,
-				 &process_info->userptr_inval_list,
-				 validate_list.head) {
-		bo = mem->bo;
 		amdgpu_ttm_tt_get_user_pages_done(bo->tbo.ttm);
 	}
+
+	return 0;
 }
 
 /* Validate invalid userptr BOs
@@ -1841,13 +1823,6 @@ static int validate_invalid_user_pages(struct amdkfd_process_info *process_info)
 		list_move_tail(&mem->validate_list.head,
 			       &process_info->userptr_valid_list);
 
-		/* Stop HMM track the userptr update. We dont check the return
-		 * value for concurrent CPU page table update because we will
-		 * reschedule the restore worker if process_info->evicted_bos
-		 * is updated.
-		 */
-		amdgpu_ttm_tt_get_user_pages_done(bo->tbo.ttm);
-
 		/* Update mapping. If the BO was not validated
 		 * (because we couldn't get user pages), this will
 		 * clear the page table entries, which will result in
@@ -1946,7 +1921,6 @@ static void amdgpu_amdkfd_restore_userptr_worker(struct work_struct *work)
 	}
 
 unlock_out:
-	untrack_invalid_user_pages(process_info);
 	mutex_unlock(&process_info->lock);
 	mmput(mm);
 	put_task_struct(usertask);