diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index 1fedb066f94c539..3732294c5848f02 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -969,7 +969,7 @@ async def _sock_sendfile_native(self, sock, file, offset, count):
             f"and file {file!r} combination")
 
     async def _sock_sendfile_fallback(self, sock, file, offset, count):
-        if offset:
+        if hasattr(file, 'seek'):
             file.seek(offset)
         blocksize = (
             min(count, constants.SENDFILE_FALLBACK_READBUFFER_SIZE)
@@ -1286,7 +1286,6 @@ async def sendfile(self, transport, file, offset=0, count=None,
             raise RuntimeError(
                 f"fallback is disabled and native sendfile is not "
                 f"supported for transport {transport!r}")
-
         return await self._sendfile_fallback(transport, file,
                                              offset, count)
 
@@ -1295,7 +1294,7 @@ async def _sendfile_native(self, transp, file, offset, count):
             "sendfile syscall is not supported")
 
     async def _sendfile_fallback(self, transp, file, offset, count):
-        if offset:
+        if hasattr(file, 'seek'):
             file.seek(offset)
         blocksize = min(count, 16384) if count else 16384
         buf = bytearray(blocksize)
diff --git a/Lib/asyncio/windows_events.py b/Lib/asyncio/windows_events.py
index 5f75b17d8ca649b..0bf7732136f1f8e 100644
--- a/Lib/asyncio/windows_events.py
+++ b/Lib/asyncio/windows_events.py
@@ -610,6 +610,9 @@ def sendfile(self, sock, file, offset, count):
         ov = _overlapped.Overlapped(NULL)
         offset_low = offset & 0xffff_ffff
         offset_high = (offset >> 32) & 0xffff_ffff
+        # TransmitFile ignores OVERLAPPED.Offset for handles not opened with
+        # FILE_FLAG_OVERLAPPED, so seek the CRT file pointer to match.
+        file.seek(offset)
         ov.TransmitFile(sock.fileno(),
                         msvcrt.get_osfhandle(file.fileno()),
                         offset_low, offset_high,
diff --git a/Lib/test/libregrtest/logger.py b/Lib/test/libregrtest/logger.py
index fa1d4d575c8fd4f..4e011ef06f8a913 100644
--- a/Lib/test/libregrtest/logger.py
+++ b/Lib/test/libregrtest/logger.py
@@ -1,5 +1,6 @@
 import os
 import time
+from typing import Callable
 
 from test.support import MS_WINDOWS
 from .results import TestResults
@@ -19,16 +20,27 @@ def __init__(self, results: TestResults, quiet: bool, pgo: bool):
         self._results: TestResults = results
         self._quiet: bool = quiet
         self._pgo: bool = pgo
+        self.get_mem_usage: Callable[[], int | None] | None = None
 
     def log(self, line: str = '') -> None:
         empty = not line
 
-        # add the system load prefix: "load avg: 1.80 "
+        # Add the memory usage: "mem: 1 GiB "
+        if self.get_mem_usage is not None:
+            mem = self.get_mem_usage()
+            if mem:
+                mib = mem / (1024*1024)
+                if mib >= 1024:
+                    line = f"mem: {mib / 1024:.1f} GiB {line}"
+                else:
+                    line = f"mem: {mib:.1f} MiB {line}"
+
+        # Add the system load prefix: "load avg: 1.80 "
         load_avg = self.get_load_avg()
         if load_avg is not None:
             line = f"load avg: {load_avg:.2f} {line}"
 
-        # add the timestamp prefix:  "0:01:05 "
+        # Add the timestamp prefix:  "0:01:05 "
         log_time = time.perf_counter() - self.start_time
 
         mins, secs = divmod(int(log_time), 60)
diff --git a/Lib/test/libregrtest/run_workers.py b/Lib/test/libregrtest/run_workers.py
index 424085a0050eb59..befdac7ee77f107 100644
--- a/Lib/test/libregrtest/run_workers.py
+++ b/Lib/test/libregrtest/run_workers.py
@@ -22,7 +22,7 @@
 from .single import PROGRESS_MIN_TIME
 from .utils import (
     StrPath, TestName,
-    format_duration, print_warning, count, plural)
+    format_duration, print_warning, count, plural, get_process_memory_usage)
 from .worker import create_worker_process, USE_PROCESS_GROUP
 
 if MS_WINDOWS:
@@ -452,6 +452,12 @@ def wait_stopped(self, start_time: float) -> None:
                 print_warning(f"Failed to join {self} in {format_duration(dt)}")
                 break
 
+    def get_mem_usage(self):
+        popen = self._popen
+        if popen is None:
+            return
+        return get_process_memory_usage(popen.pid)
+
 
 def get_running(workers: list[WorkerThread]) -> str | None:
     running: list[str] = []
@@ -473,6 +479,7 @@ def __init__(self, num_workers: int, runtests: RunTests,
                  logger: Logger, results: TestResults) -> None:
         self.num_workers = num_workers
         self.runtests = runtests
+        self.logger = logger
         self.log = logger.log
         self.display_progress = logger.display_progress
         self.results: TestResults = results
@@ -598,9 +605,21 @@ def _process_result(self, item: QueueOutput) -> TestResult:
 
         return result
 
+    def get_mem_usage(self):
+        usage = 0
+        main_mem = get_process_memory_usage(os.getpid())
+        if main_mem:
+            usage += main_mem
+        for worker in self.workers:
+            worker_mem = worker.get_mem_usage()
+            if worker_mem:
+                usage += worker_mem
+        return usage
+
     def run(self) -> None:
         fail_fast = self.runtests.fail_fast
         fail_env_changed = self.runtests.fail_env_changed
+        self.logger.get_mem_usage = self.get_mem_usage
 
         self.start_workers()
 
@@ -625,3 +644,4 @@ def run(self) -> None:
             # worker when we exit this function
             self.pending.stop()
             self.stop_workers()
+            self.logger.get_mem_usage = None
diff --git a/Lib/test/libregrtest/utils.py b/Lib/test/libregrtest/utils.py
index 00703d6c074855b..1b4cb96406d6f60 100644
--- a/Lib/test/libregrtest/utils.py
+++ b/Lib/test/libregrtest/utils.py
@@ -752,3 +752,26 @@ def display_title(title):
     print(title)
     print("#" * len(title))
     print(flush=True)
+
+
+def get_process_memory_usage(pid: int) -> int | None:
+    """
+    Read the private memory in bytes from /proc/pid/smaps.
+    """
+    try:
+        fp = open(f"/proc/{pid}/smaps", "rb")
+    except OSError:
+        return None
+
+    try:
+        total = 0
+        with fp:
+            for line in fp:
+                # Include both Private_Clean and Private_Dirty sections.
+                line = line.rstrip()
+                if line.startswith(b"Private_") and line.endswith(b'kB'):
+                    parts = line.split()
+                    total += int(parts[1]) * 1024
+        return total
+    except ProcessLookupError:
+        return None
diff --git a/Lib/test/test_asyncio/test_sendfile.py b/Lib/test/test_asyncio/test_sendfile.py
index dcd963b3355ef86..ae7a2e32c526873 100644
--- a/Lib/test/test_asyncio/test_sendfile.py
+++ b/Lib/test/test_asyncio/test_sendfile.py
@@ -228,6 +228,32 @@ def test_sock_sendfile_zero_size(self):
         self.assertEqual(ret, 0)
         self.assertEqual(self.file.tell(), 0)
 
+    def check_sock_sendfile_offset(self, data, offset, force_fallback=False):
+        sock, proto = self.prepare_socksendfile()
+        with tempfile.TemporaryFile() as f:
+            f.write(data)
+            f.flush()
+            self.assertEqual(f.tell(), len(data))
+
+            if force_fallback:
+                async def _sock_sendfile_fail(sock, file, offset, count):
+                    raise asyncio.exceptions.SendfileNotAvailableError()
+                with support.swap_attr(self.loop, '_sock_sendfile_native', _sock_sendfile_fail):
+                    ret = self.run_loop(self.loop.sock_sendfile(sock, f, offset, None))
+            else:
+                ret = self.run_loop(self.loop.sock_sendfile(sock, f, offset, None))
+            self.assertEqual(f.tell(), len(data))
+            sock.close()
+            self.run_loop(proto.wait_closed())
+            self.assertEqual(ret, len(data) - offset)
+
+    def test_sock_sendfile_offset(self):
+        data = b'abcdef'
+        for offset in (0, len(data) // 2, len(data)):
+            for force_fallback in (False, True):
+                with self.subTest(offset=offset, force_fallback=force_fallback):
+                    self.check_sock_sendfile_offset(data, offset, force_fallback)
+
     def test_sock_sendfile_mix_with_regular_send(self):
         buf = b"mix_regular_send" * (4 * 1024)  # 64 KiB
         sock, proto = self.prepare_socksendfile()
diff --git a/Lib/test/test_regrtest.py b/Lib/test/test_regrtest.py
index 02f6e0c74b5ce84..207b144d01d9255 100644
--- a/Lib/test/test_regrtest.py
+++ b/Lib/test/test_regrtest.py
@@ -41,7 +41,11 @@
 
 ROOT_DIR = os.path.join(os.path.dirname(__file__), '..', '..')
 ROOT_DIR = os.path.abspath(os.path.normpath(ROOT_DIR))
-LOG_PREFIX = r'[0-9]+:[0-9]+:[0-9]+ (?:load avg: [0-9]+\.[0-9]{2} )?'
+LOG_PREFIX = (
+    r'[0-9]+:[0-9]+:[0-9]+ '
+    r'(?:load avg: [0-9]+\.[0-9]{2} )?'
+    r'(?:mem: [0-9]+\.[0-9] (?:MiB|GiB) )?'
+)
 RESULT_REGEX = (
     'passed',
     'failed',
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-05-22-17-09-28.gh-issue-150107.GD72-D.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-05-22-17-09-28.gh-issue-150107.GD72-D.rst
new file mode 100644
index 000000000000000..a13f249e48cc021
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-05-22-17-09-28.gh-issue-150107.GD72-D.rst
@@ -0,0 +1,3 @@
+:mod:`asyncio`: ``sendfile()`` and ``sock_sendfile()`` event loop methods
+now call ``file.seek(offset)`` if *file* has a ``seek()`` method,
+even if *offset* is ``0`` (default value).
diff --git a/Misc/NEWS.d/next/Tests/2026-05-22-16-41-45.gh-issue-150114.UdMikH.rst b/Misc/NEWS.d/next/Tests/2026-05-22-16-41-45.gh-issue-150114.UdMikH.rst
new file mode 100644
index 000000000000000..a140bf921972ed9
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2026-05-22-16-41-45.gh-issue-150114.UdMikH.rst
@@ -0,0 +1,2 @@
+On Linux, regrtest now logs the total memory usage of all Python processes.
+Read the private memory in ``/proc/pid/smaps``. Patch by Victor Stinner.