mmap unload fix for lowvram

nodes.py

@@ -180,9 +180,32 @@ class GGUFModelPatcher(comfy.model_patcher.ModelPatcher):
         device_to = device_to if comfy.model_management.DISABLE_SMART_MEMORY else None
         return super().unpatch_model(device_to=device_to, unpatch_weights=unpatch_weights)
 
+    mmap_released = False
     def load(self, *args, force_patch_weights=False, **kwargs):
         # always call `patch_weight_to_device` even for lowvram
-        return super().load(*args, force_patch_weights=True, **kwargs)
+        super().load(*args, force_patch_weights=True, **kwargs)
+
+        # make sure nothing stays linked to mmap after first load
+        if not self.mmap_released:
+            linked = []
+            if kwargs.get("lowvram_model_memory", 0) > 0:
+                for n, m in self.model.named_modules():
+                    if hasattr(m, "weight"):
+                        device = getattr(m.weight, "device", None)
+                        if device == self.offload_device:
+                            linked.append((n, m))
+                            continue
+                    if hasattr(m, "bias"):
+                        device = getattr(m.bias, "device", None)
+                        if device == self.offload_device:
+                            linked.append((n, m))
+                            continue
+            if linked:
+                print(f"Attempting to release mmap ({len(linked)})")
+                for n, m in linked:
+                    # TODO: possible to OOM, find better way to detach
+                    m.to(self.load_device).to(self.offload_device)
+            self.mmap_released = True
 
     def clone(self, *args, **kwargs):
         n = GGUFModelPatcher(self.model, self.load_device, self.offload_device, self.size, weight_inplace_update=self.weight_inplace_update)