Added is_available_triton guard to Triton SwitchBackLinear.

bitsandbytes/nn/triton_based_modules.py

@@ -3,6 +3,8 @@ import torch.nn as nn
 import time
 from functools import partial
 
+from bitsandbytes.triton.triton_utils import is_triton_available
+
 from bitsandbytes.triton.dequantize_rowwise import dequantize_rowwise
 from bitsandbytes.triton.quantize_rowwise import quantize_rowwise
 from bitsandbytes.triton.quantize_columnwise_and_transpose import quantize_columnwise_and_transpose
@@ -160,6 +162,10 @@ class SwitchBackLinear(nn.Linear):
         ):
         super().__init__(in_features, out_features, bias, device, dtype)
 
+        if not is_triton_available:
+            raise ImportError('''Could not import triton. Please install triton to use SwitchBackLinear.
+                               Alternatively, you can use bnb.nn.SwitchBackLinearBnb, but it will be slower''')
+
         # By default, we use the global quantization.
         self.vectorize = vectorize
         if self.vectorize: