diff --git a/unsloth/kernels/fast_lora.py b/unsloth/kernels/fast_lora.py index 60d0c318c3..f1c0e298d9 100644 --- a/unsloth/kernels/fast_lora.py +++ b/unsloth/kernels/fast_lora.py @@ -379,9 +379,22 @@ class LoRA_QKV(torch.autograd.Function): ): dtype = X.dtype - Q = matmul_lora(X, QW, QW_quant, QA, QB, QS) - K = matmul_lora(X, KW, KW_quant, KA, KB, KS) - V = matmul_lora(X, VW, VW_quant, VA, VB, VS) + # bitsandbytes 8-bit matmul expects 2D inputs. + # TorchInductor/AOTAutograd fails on 3D tensors during backward, + # so we explicitly flatten the sequence dimension. + orig_shape = X.shape + X_for_matmul = X + if X.dim() == 3: + X_for_matmul = X.view(-1, X.shape[-1]) + Q = matmul_lora(X_for_matmul, QW, QW_quant, QA, QB, QS) + K = matmul_lora(X_for_matmul, KW, KW_quant, KA, KB, KS) + V = matmul_lora(X_for_matmul, VW, VW_quant, VA, VB, VS) + + # Restore original shape after matmul + if len(orig_shape) == 3: + Q = Q.view(orig_shape[0], orig_shape[1], -1) + K = K.view(orig_shape[0], orig_shape[1], -1) + V = V.view(orig_shape[0], orig_shape[1], -1) ctx.custom_saved_tensors = ( QW,