partially reverted 76b40a5c

bitsandbytes/functional.py

@@ -571,9 +571,9 @@ def estimate_quantiles(A: Tensor, out: Tensor = None, offset: float = 1 / 512, n
 class QuantState:
     """container for quantization state components to work with Params4bit and similar clases"""
     valid_quant_types = ('fp4', 'nf4')
-    valid_qs_type_keys = [f"quant_state.bitsandbytes__{x}" for x in valid_quant_types]
-    valid_qs_keys = ['absmax', 'quant_map', 'nested_absmax', 'nested_quant_map', 'quant_state', 
-                     'quant_type', 'blocksize', 'dtype', 'shape', 'nested_blocksize', 'nested_dtype', 'nested_offset']
+    valid_qs_type_keys = [f"bitsandbytes__{x}" for x in valid_quant_types]
+    valid_qs_keys = ['absmax', 'quant_map', 'nested_absmax', 'nested_quant_map', 'quant_state', 'quant_type',
+                     'blocksize', 'dtype', 'shape', 'nested_blocksize', 'nested_dtype', 'nested_offset']
 
     def __init__(self, absmax, shape=None, code=None, blocksize=None, quant_type=None, dtype=None, offset=None, state2=None):
         self.absmax = absmax
@@ -611,16 +611,19 @@ class QuantState:
         """
 
         # unpacking tensor with non-tensor components
-        qs_key = [k for k, v in qs_dict.items() if k in cls.valid_qs_type_keys and isinstance(v, torch.Tensor)]
+        qs_key = [k for k, v in qs_dict.items() if "quant_state" in k and isinstance(v, torch.Tensor)]
         if not len(qs_key) and 'quant_type' not in qs_dict:
-            raise ValueError("Expected packed or unpacked quant_state items, found neither") 
-        elif len(qs_key) != 1:
-            raise ValueError(f"There should be exaclly one quant_state item with key from {cls.valid_qs_type_keys}. Detected {len(qs_key)} such items")
+            raise ValueError("Expected packed or unpacked quant_state items, found neither")
+        elif len(qs_key) != 1 or qs_key[0].split(".")[-1] not in cls.valid_qs_type_keys:
+            raise ValueError(f"There should be exactly one `quant_state` item with ending from {cls.valid_qs_type_keys}.\nDetected {qs_key}.")
 
         # unpacking minor and non-tensor quant state items if necessary
         if len(qs_key) == 1:
             qs_key = qs_key[0]
-            qs_dict |= unpack_tensor_to_dict(qs_dict.pop(qs_key))
+            qs_dict.update(unpack_tensor_to_dict(qs_dict.pop(qs_key)))
+
+        qs_dict = {k.split('.')[-1]: v for k, v in qs_dict.items()}  # strip prefixes
+        assert set(qs_dict.keys()).issubset(cls.valid_qs_keys)
 
         if 'nested_absmax' in qs_dict:
             offset = torch.tensor(float(qs_dict['nested_offset'])).to(device)
@@ -654,7 +657,7 @@ class QuantState:
             'quant_type': self.quant_type,
             'absmax': self.absmax,
             'blocksize': self.blocksize,
-            'quant_map': self.code,                      
+            'quant_map': self.code,
             'dtype': str(self.dtype).strip('torch.'),
             'shape': tuple(self.shape) if self.nested else None,
         }
@@ -677,6 +680,7 @@ class QuantState:
     def to(self, device):
         # make sure the quantization state is on the right device
         self.absmax = self.absmax.to(device)
+        self.offset = self.offset.to(device)
         if self.nested:
             self.offset = self.offset.to(device)
             self.state2.absmax = self.state2.absmax.to(device)

bitsandbytes/nn/modules.py

@@ -155,28 +155,38 @@ class Params4bit(torch.nn.Parameter):
         return self
 
     @classmethod
-    def from_state_dict(cls, state_dict, prefix="", requires_grad=False):
-        data = state_dict.pop(prefix.rstrip('.'))
-
-        # extracting components for QuantState from state_dict
-        qs_dict = {}
-        for k, v in state_dict.items():
-            if k.replace(prefix, '').split('.')[0] in QuantState.valid_qs_keys:
-                qs_dict[k] = v        
-        state_dict = {k: v for k, v in state_dict.items() if k not in qs_dict}
-        qs_dict = {k.replace(prefix, ''): v for k, v in qs_dict.items()}
-
-        if data.device.type != "cuda":
-            raise ValueError(f"`data.device.type` must be 'cuda', detected {data.device.type}")
-
-        cls.requires_grad = requires_grad
-        cls.quant_state = QuantState.from_dict(qs_dict=qs_dict, device=data.device)
-        cls.blocksize = cls.quant_state.blocksize             # this attribute can be deprecated - it duplicates same one in quant_state
-        cls.compress_statistics = cls.quant_state.nested      # this attribute can be deprecated - it duplicates quant_state.nested
-        cls.quant_type = cls.quant_state.quant_type           # this attribute can be deprecated - it duplicates same one in quant_state
-
-        self = torch.Tensor._make_subclass(cls, data=data.to(data.device))
-        return self, state_dict
+    def from_prequantized(cls, data, quantized_stats, requires_grad=False, device='cuda', **kwargs):
+        self = torch.Tensor._make_subclass(cls, data.to(device))
+        self.requires_grad = requires_grad
+        self.quant_state = QuantState.from_dict(qs_dict=quantized_stats, device=device)
+        self.blocksize = self.quant_state.blocksize
+        self.compress_statistics = self.quant_state.nested
+        self.quant_type = self.quant_state.quant_type
+        return self
+    
+    # @classmethod
+    # def from_state_dict(cls, state_dict, prefix="", requires_grad=False):
+    #     data = state_dict.pop(prefix.rstrip('.'))
+
+    #     # extracting components for QuantState from state_dict
+    #     qs_dict = {}
+    #     for k, v in state_dict.items():
+    #         if k.replace(prefix, '').split('.')[0] in QuantState.valid_qs_keys:
+    #             qs_dict[k] = v        
+    #     state_dict = {k: v for k, v in state_dict.items() if k not in qs_dict}
+    #     qs_dict = {k.replace(prefix, ''): v for k, v in qs_dict.items()}
+
+    #     if data.device.type != "cuda":
+    #         raise ValueError(f"`data.device.type` must be 'cuda', detected {data.device.type}")
+
+    #     cls.requires_grad = requires_grad
+    #     cls.quant_state = QuantState.from_dict(qs_dict=qs_dict, device=data.device)
+    #     cls.blocksize = cls.quant_state.blocksize             # this attribute can be deprecated - it duplicates same one in quant_state
+    #     cls.compress_statistics = cls.quant_state.nested      # this attribute can be deprecated - it duplicates quant_state.nested
+    #     cls.quant_type = cls.quant_state.quant_type           # this attribute can be deprecated - it duplicates same one in quant_state
+
+    #     self = torch.Tensor._make_subclass(cls, data=data.to(data.device))
+    #     return self, state_dict
 
     def cuda(self, device):
         w = self.data.contiguous().half().cuda(device)
@@ -251,17 +261,17 @@ class Linear4bit(nn.Linear):
             for k, v in self.weight.quant_state.as_dict(packed=True).items():
                 destination[prefix + "weight." + k] = v if keep_vars else v.detach()
 
-    def _load_from_state_dict(self, state_dict, prefix, local_metadata, strict,
-                              missing_keys, unexpected_keys, error_msgs):
-        # Note: super()._load_from_state_dict() is not called here intentionally.
-        if self.bias is not None:
-            bias_data = state_dict.pop(prefix + "bias", None)
-            self.bias.data = bias_data.to(self.bias.data.device)
-
-        self.weight, state_dict = bnb.nn.Params4bit.from_state_dict(
-                        state_dict, prefix=prefix + "weight" + ".", requires_grad=False
-                    )
-        unexpected_keys.extend(state_dict.keys())
+    # def _load_from_state_dict(self, state_dict, prefix, local_metadata, strict,
+    #                           missing_keys, unexpected_keys, error_msgs):
+    #     # Note: super()._load_from_state_dict() is not called here intentionally.
+    #     if self.bias is not None:
+    #         bias_data = state_dict.pop(prefix + "bias", None)
+    #         self.bias.data = bias_data.to(self.bias.data.device)
+
+    #     self.weight, state_dict = bnb.nn.Params4bit.from_state_dict(
+    #                     state_dict, prefix=prefix + "weight" + ".", requires_grad=False
+    #                 )
+    #     unexpected_keys.extend(state_dict.keys())
 
     def forward(self, x: torch.Tensor):
         # weights are cast automatically as Int8Params, but the bias has to be cast manually

tests/test_linear4bit.py

@@ -7,8 +7,6 @@ import pytest
 import torch
 
 import bitsandbytes as bnb
-from bitsandbytes import functional as F
-from bitsandbytes.nn.modules import Linear4bit
 
 
 @pytest.mark.skipif(not torch.cuda.is_available(), reason="this test requires a GPU")
@@ -41,7 +39,10 @@ def test_linear_serialization(quant_type, compress_statistics, bias):
 
     # saving to state_dict:
     sd = linear_q.state_dict()
-
+    # restoring from state_dict:
+    bias_data2 = sd.pop("bias", None)
+    weight_data2 = sd.pop("weight")
+    weight2 = bnb.nn.Params4bit.from_prequantized(quantized_stats=sd, data=weight_data2)
     # creating new layer with same params:
     linear_q2 = bnb.nn.Linear4bit(
         linear.in_features,
@@ -53,7 +54,9 @@ def test_linear_serialization(quant_type, compress_statistics, bias):
         device=device,                  # TODO create on meta device to save loading time
     )
     # loading weights from state_dict:
-    linear_q2.load_state_dict(sd)    
+    linear_q2.weight = weight2.to(device)
+    if bias:
+        linear_q2.bias = torch.nn.Parameter(bias_data2)
 
     # MATCHING
     a, b = linear_q.weight, linear_q2.weight
@@ -61,7 +64,7 @@ def test_linear_serialization(quant_type, compress_statistics, bias):
     assert a.device == b.device
     assert a.dtype == b.dtype
     assert torch.equal(a, b)
-    
+
     q0 = a.quant_state
     q1 = b.quant_state
     for attr in ('code', 'dtype', 'blocksize', 'absmax'):