Add new tests to check the correctness of the `-overcommit memlock`
option (possible values: off, on, on-fault) by using
`/proc/{qemu_pid}/status` file to check in VmSize, VmRSS and VmLck
values:

* if `memlock=off`, then VmLck = 0;
* if `memlock=on`, then VmLck > 0 and almost all memory is resident;
* if `memlock=on-fault`, then VmLck > 0 and only few memory is resident.

Signed-off-by: Alexandr Moshkov <dtalexundeer@yandex-team.ru>
---
 tests/functional/meson.build     |  1 +
 tests/functional/test_memlock.py | 79 ++++++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+)
 create mode 100755 tests/functional/test_memlock.py

diff --git a/tests/functional/meson.build b/tests/functional/meson.build
index 52b4706cfe..13079f58b6 100644
--- a/tests/functional/meson.build
+++ b/tests/functional/meson.build
@@ -68,6 +68,7 @@ tests_generic_system = [
   'empty_cpu_model',
   'info_usernet',
   'version',
+  'memlock',
 ]
 
 tests_generic_linuxuser = [
diff --git a/tests/functional/test_memlock.py b/tests/functional/test_memlock.py
new file mode 100755
index 0000000000..83cb5394cd
--- /dev/null
+++ b/tests/functional/test_memlock.py
@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+#
+# Functional test that check overcommit memlock options
+#
+# Copyright (c) Yandex Technologies LLC, 2025
+#
+# Author:
+#  Alexandr Moshkov <dtalexundeer@yandex-team.ru>
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+import re
+
+from typing import Dict
+
+from qemu_test import QemuSystemTest
+from qemu_test import skipLockedMemoryTest
+
+
+STATUS_VALUE_PATTERN = re.compile(r'^(\w+):\s+(\d+) kB', re.MULTILINE)
+
+
+@skipLockedMemoryTest(2_097_152)  # 2GB
+class MemlockTest(QemuSystemTest):
+    """
+    Boots a Linux system with memlock options.
+    Then verify, that this options is working correctly
+    by checking the smaps of the QEMU proccess.
+    """
+
+    def common_vm_setup_with_memlock(self, memlock):
+        self.vm.add_args('-overcommit', f'mem-lock={memlock}')
+        self.vm.launch()
+
+    def test_memlock_off(self):
+        self.common_vm_setup_with_memlock('off')
+
+        status = self.get_process_status_values(self.vm.get_pid())
+
+        self.assertTrue(status['VmLck'] == 0)
+
+    def test_memlock_on(self):
+        self.common_vm_setup_with_memlock('on')
+
+        status = self.get_process_status_values(self.vm.get_pid())
+
+        # VmLck > 0 kB and almost all memory is resident
+        self.assertTrue(status['VmLck'] > 0)
+        self.assertTrue(status['VmRSS'] >= status['VmSize'] * 0.70)
+
+    def test_memlock_onfault(self):
+        self.common_vm_setup_with_memlock('on-fault')
+
+        status = self.get_process_status_values(self.vm.get_pid())
+
+        # VmLck > 0 kB and only few memory is resident
+        self.assertTrue(status['VmLck'] > 0)
+        self.assertTrue(status['VmRSS'] <= status['VmSize'] * 0.30)
+
+    def get_process_status_values(self, pid: int) -> Dict[str, int]:
+        result = {}
+        raw_status = self._get_raw_process_status(pid)
+
+        for line in raw_status.split('\n'):
+            if m := STATUS_VALUE_PATTERN.match(line):
+                result[m.group(1)] = int(m.group(2))
+
+        return result
+
+    def _get_raw_process_status(self, pid: int) -> str:
+        try:
+            with open(f'/proc/{pid}/status', 'r') as f:
+                return f.read()
+        except FileNotFoundError:
+            self.skipTest("Can't open status file of the process")
+
+
+if __name__ == '__main__':
+    MemlockTest.main()
-- 
2.34.1

On 25/05/2025 09.07, Alexandr Moshkov wrote:
> Add new tests to check the correctness of the `-overcommit memlock`
> option (possible values: off, on, on-fault) by using
> `/proc/{qemu_pid}/status` file to check in VmSize, VmRSS and VmLck
> values:
> 
> * if `memlock=off`, then VmLck = 0;
> * if `memlock=on`, then VmLck > 0 and almost all memory is resident;
> * if `memlock=on-fault`, then VmLck > 0 and only few memory is resident.
> 
> Signed-off-by: Alexandr Moshkov <dtalexundeer@yandex-team.ru>
> ---
>   tests/functional/meson.build     |  1 +
>   tests/functional/test_memlock.py | 79 ++++++++++++++++++++++++++++++++
>   2 files changed, 80 insertions(+)
>   create mode 100755 tests/functional/test_memlock.py
> 
> diff --git a/tests/functional/meson.build b/tests/functional/meson.build
> index 52b4706cfe..13079f58b6 100644
> --- a/tests/functional/meson.build
> +++ b/tests/functional/meson.build
> @@ -68,6 +68,7 @@ tests_generic_system = [
>     'empty_cpu_model',
>     'info_usernet',
>     'version',
> +  'memlock',
>   ]
>   
>   tests_generic_linuxuser = [
> diff --git a/tests/functional/test_memlock.py b/tests/functional/test_memlock.py
> new file mode 100755
> index 0000000000..83cb5394cd
> --- /dev/null
> +++ b/tests/functional/test_memlock.py
> @@ -0,0 +1,79 @@
> +#!/usr/bin/env python3
> +#
> +# Functional test that check overcommit memlock options
> +#
> +# Copyright (c) Yandex Technologies LLC, 2025
> +#
> +# Author:
> +#  Alexandr Moshkov <dtalexundeer@yandex-team.ru>
> +#
> +# SPDX-License-Identifier: GPL-2.0-or-later
> +
> +import re
> +
> +from typing import Dict
> +
> +from qemu_test import QemuSystemTest
> +from qemu_test import skipLockedMemoryTest
> +
> +
> +STATUS_VALUE_PATTERN = re.compile(r'^(\w+):\s+(\d+) kB', re.MULTILINE)
> +
> +
> +@skipLockedMemoryTest(2_097_152)  # 2GB
> +class MemlockTest(QemuSystemTest):
> +    """
> +    Boots a Linux system with memlock options.

Nit: I'd maybe change this into "Runs a guest with..." since it does not 
really boot a Linux here. I could change it while picking up the patch if 
you like.

Apart from that: Works for me now, and the patch looks much simpler, thanks!

Reviewed-by: Thomas Huth <thuth@redhat.com>
Tested-by: Thomas Huth <thuth@redhat.com>

On 5/27/25 11:13, Thomas Huth wrote:
> On 25/05/2025 09.07, Alexandr Moshkov wrote:
>> Add new tests to check the correctness of the `-overcommit memlock`
>> option (possible values: off, on, on-fault) by using
>> `/proc/{qemu_pid}/status` file to check in VmSize, VmRSS and VmLck
>> values:
>>
>> * if `memlock=off`, then VmLck = 0;
>> * if `memlock=on`, then VmLck > 0 and almost all memory is resident;
>> * if `memlock=on-fault`, then VmLck > 0 and only few memory is resident.
>>
>> Signed-off-by: Alexandr Moshkov <dtalexundeer@yandex-team.ru>
>> ---
>>   tests/functional/meson.build     |  1 +
>>   tests/functional/test_memlock.py | 79 ++++++++++++++++++++++++++++++++
>>   2 files changed, 80 insertions(+)
>>   create mode 100755 tests/functional/test_memlock.py
>>
>> diff --git a/tests/functional/meson.build b/tests/functional/meson.build
>> index 52b4706cfe..13079f58b6 100644
>> --- a/tests/functional/meson.build
>> +++ b/tests/functional/meson.build
>> @@ -68,6 +68,7 @@ tests_generic_system = [
>>     'empty_cpu_model',
>>     'info_usernet',
>>     'version',
>> +  'memlock',
>>   ]
>>     tests_generic_linuxuser = [
>> diff --git a/tests/functional/test_memlock.py 
>> b/tests/functional/test_memlock.py
>> new file mode 100755
>> index 0000000000..83cb5394cd
>> --- /dev/null
>> +++ b/tests/functional/test_memlock.py
>> @@ -0,0 +1,79 @@
>> +#!/usr/bin/env python3
>> +#
>> +# Functional test that check overcommit memlock options
>> +#
>> +# Copyright (c) Yandex Technologies LLC, 2025
>> +#
>> +# Author:
>> +#  Alexandr Moshkov <dtalexundeer@yandex-team.ru>
>> +#
>> +# SPDX-License-Identifier: GPL-2.0-or-later
>> +
>> +import re
>> +
>> +from typing import Dict
>> +
>> +from qemu_test import QemuSystemTest
>> +from qemu_test import skipLockedMemoryTest
>> +
>> +
>> +STATUS_VALUE_PATTERN = re.compile(r'^(\w+):\s+(\d+) kB', re.MULTILINE)
>> +
>> +
>> +@skipLockedMemoryTest(2_097_152)  # 2GB
>> +class MemlockTest(QemuSystemTest):
>> +    """
>> +    Boots a Linux system with memlock options.
>
> Nit: I'd maybe change this into "Runs a guest with..." since it does 
> not really boot a Linux here. I could change it while picking up the 
> patch if you like.
Yes, I don't mind. Thanks for review!

Best regards,

Alexandr