From 55caa6051d675148aba009c85618c6d3adf85091 Mon Sep 17 00:00:00 2001
From: tjp_zju <tanjianpingzju1990@gmail.com>
Date: Wed, 7 Jan 2026 14:42:20 +0800
Subject: [PATCH] refactor: find_loaded_library (#31866)

Signed-off-by: tjp_zju <tanjianpingzju1990@gmail.com>
Co-authored-by: Cyrus Leung <cyrus.tl.leung@gmail.com>
---
 vllm/device_allocator/cumem.py                | 28 +------------------
 .../device_communicators/cuda_wrapper.py      | 28 +------------------
 vllm/utils/system_utils.py                    | 27 ++++++++++++++++++
 3 files changed, 29 insertions(+), 54 deletions(-)

diff --git a/vllm/device_allocator/cumem.py b/vllm/device_allocator/cumem.py
index e9695698b..2f97288b6 100644
--- a/vllm/device_allocator/cumem.py
+++ b/vllm/device_allocator/cumem.py
@@ -19,37 +19,11 @@ import torch
 
 from vllm.logger import init_logger
 from vllm.utils.platform_utils import is_pin_memory_available
+from vllm.utils.system_utils import find_loaded_library
 
 logger = init_logger(__name__)
 
 
-def find_loaded_library(lib_name) -> str | None:
-    """
-    According to according to https://man7.org/linux/man-pages/man5/proc_pid_maps.5.html,
-    the file `/proc/self/maps` contains the memory maps of the process, which includes the
-    shared libraries loaded by the process. We can use this file to find the path of the
-    a loaded library.
-    """  # noqa
-    found_line = None
-    with open("/proc/self/maps") as f:
-        for line in f:
-            if lib_name in line:
-                found_line = line
-                break
-    if found_line is None:
-        # the library is not loaded in the current process
-        return None
-    # if lib_name is libcudart, we need to match a line with:
-    # address /path/to/libcudart-hash.so.11.0
-    start = found_line.index("/")
-    path = found_line[start:].strip()
-    filename = path.split("/")[-1]
-    assert filename.rpartition(".so")[0].startswith(lib_name), (
-        f"Unexpected filename: {filename} for library {lib_name}"
-    )
-    return path
-
-
 cumem_available = False
 try:
     from vllm.cumem_allocator import (
diff --git a/vllm/distributed/device_communicators/cuda_wrapper.py b/vllm/distributed/device_communicators/cuda_wrapper.py
index 6aadab33e..422991ca9 100644
--- a/vllm/distributed/device_communicators/cuda_wrapper.py
+++ b/vllm/distributed/device_communicators/cuda_wrapper.py
@@ -15,6 +15,7 @@ import torch  # noqa
 import vllm.envs as envs
 from vllm.logger import init_logger
 from vllm.platforms import current_platform
+from vllm.utils.system_utils import find_loaded_library
 
 logger = init_logger(__name__)
 
@@ -37,33 +38,6 @@ class Function:
     argtypes: list[Any]
 
 
-def find_loaded_library(lib_name) -> str | None:
-    """
-    According to according to https://man7.org/linux/man-pages/man5/proc_pid_maps.5.html,
-    the file `/proc/self/maps` contains the memory maps of the process, which includes the
-    shared libraries loaded by the process. We can use this file to find the path of the
-    a loaded library.
-    """  # noqa
-    found = False
-    with open("/proc/self/maps") as f:
-        for line in f:
-            if lib_name in line:
-                found = True
-                break
-    if not found:
-        # the library is not loaded in the current process
-        return None
-    # if lib_name is libcudart, we need to match a line with:
-    # address /path/to/libcudart-hash.so.11.0
-    start = line.index("/")
-    path = line[start:].strip()
-    filename = path.split("/")[-1]
-    assert filename.rpartition(".so")[0].startswith(lib_name), (
-        f"Unexpected filename: {filename} for library {lib_name}"
-    )
-    return path
-
-
 class CudaRTLibrary:
     exported_functions = [
         # ​cudaError_t cudaSetDevice ( int  device )
diff --git a/vllm/utils/system_utils.py b/vllm/utils/system_utils.py
index 76cac59c1..aa14b3951 100644
--- a/vllm/utils/system_utils.py
+++ b/vllm/utils/system_utils.py
@@ -267,3 +267,30 @@ def set_ulimit(target_soft_limit: int = 65535):
                 current_soft,
                 e,
             )
+
+
+def find_loaded_library(lib_name: str) -> str | None:
+    """
+    According to according to https://man7.org/linux/man-pages/man5/proc_pid_maps.5.html,
+    the file `/proc/self/maps` contains the memory maps of the process, which includes the
+    shared libraries loaded by the process. We can use this file to find the path of the
+    a loaded library.
+    """  # noqa
+    found_line = None
+    with open("/proc/self/maps") as f:
+        for line in f:
+            if lib_name in line:
+                found_line = line
+                break
+    if found_line is None:
+        # the library is not loaded in the current process
+        return None
+    # if lib_name is libcudart, we need to match a line with:
+    # address /path/to/libcudart-hash.so.11.0
+    start = found_line.index("/")
+    path = found_line[start:].strip()
+    filename = path.split("/")[-1]
+    assert filename.rpartition(".so")[0].startswith(lib_name), (
+        f"Unexpected filename: {filename} for library {lib_name}"
+    )
+    return path