From 9172be8cfcf3021e976e01b83f7afef563048afa Mon Sep 17 00:00:00 2001
From: pluesclues <136766175+pluesclues@users.noreply.github.com>
Date: Tue, 20 Jan 2026 00:04:27 -0500
Subject: [PATCH] Fix vllm ipykernel patch (#3907)

* Implement vLLM patch for notebook detection

Add patch for vLLM compatibility in notebook environments.

* Fix sys.stdout.fileno for vLLM compatibility

Patch sys.stdout.fileno for vLLM compatibility in notebooks.

* Add patch_vllm_for_notebooks to initialization

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Harden vLLM notebook stdout patch

* Use logger for vLLM notebook patch

* Clarify vLLM notebook patch log message

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: danielhanchen <danielhanchen@users.noreply.github.com>
---
 unsloth/__init__.py     |  3 +++
 unsloth/import_fixes.py | 59 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+)

diff --git a/unsloth/__init__.py b/unsloth/__init__.py
index 89824a25d1..d3093cf4c0 100644
--- a/unsloth/__init__.py
+++ b/unsloth/__init__.py
@@ -134,6 +134,7 @@ from .import_fixes import (
     patch_enable_input_require_grads,
     fix_openenv_no_vllm,
     fix_executorch,
+    patch_vllm_for_notebooks,
 )
 
 fix_xformers_performance_issue()
@@ -147,6 +148,7 @@ patch_datasets()
 patch_enable_input_require_grads()
 fix_openenv_no_vllm()
 fix_executorch()
+patch_vllm_for_notebooks()
 
 del fix_xformers_performance_issue
 del fix_vllm_aimv2_issue
@@ -159,6 +161,7 @@ del patch_datasets
 del patch_enable_input_require_grads
 del fix_openenv_no_vllm
 del fix_executorch
+del patch_vllm_for_notebooks
 
 # Torch 2.4 has including_emulation
 if DEVICE_TYPE == "cuda":
diff --git a/unsloth/import_fixes.py b/unsloth/import_fixes.py
index 27e5342e20..89d9d4bdba 100644
--- a/unsloth/import_fixes.py
+++ b/unsloth/import_fixes.py
@@ -204,6 +204,65 @@ def fix_xformers_performance_issue():
             logger.info(f"Unsloth: Failed patching Xformers with error = {str(e)}")
 
 
+def patch_vllm_for_notebooks():
+    import sys
+
+    ipython = None
+    try:
+        from IPython import get_ipython as _get_ipython
+    except Exception:
+        _get_ipython = None
+
+    if _get_ipython is not None:
+        try:
+            ipython = _get_ipython()
+        except Exception:
+            ipython = None
+
+    if ipython is None:
+        try:
+            import builtins
+
+            _get_ipython = getattr(builtins, "get_ipython", None)
+            if callable(_get_ipython):
+                ipython = _get_ipython()
+        except Exception:
+            ipython = None
+
+    if ipython is None:
+        return
+
+    try:
+        shell = ipython.__class__.__name__
+        is_notebook = shell == "ZMQInteractiveShell" or "google.colab" in str(
+            type(ipython)
+        )
+    except Exception:
+        return
+
+    if not is_notebook:
+        return
+
+    if not hasattr(sys.stdout, "fileno"):
+        return
+
+    needs_patch = False
+    try:
+        fd = sys.stdout.fileno()
+        if not isinstance(fd, int) or fd < 0:
+            needs_patch = True
+    except Exception:
+        needs_patch = True
+
+    if not needs_patch:
+        return
+
+    logger.info(
+        "Unsloth: Notebook detected - Patching sys.stdout.fileno for newer `vllm>=0.12.0` versions"
+    )
+    sys.stdout.fileno = lambda: 1
+
+
 # ValueError: 'aimv2' is already used by a Transformers config, pick another name.
 def fix_vllm_aimv2_issue():
     spec = importlib.util.find_spec("vllm")