linux-kernel - Re: [PATCH v6 0/5] selftests/resctrl: Add non-contiguous CBMs in Intel CAT selftest

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Date: Mon, 26 Feb 2024 10:28:06 +0100
From: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
To: Shuah Khan <skhan@...uxfoundation.org>
CC: Reinette Chatre <reinette.chatre@...el.com>, <shuah@...nel.org>,
	<fenghua.yu@...el.com>, <linux-kselftest@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <ilpo.jarvinen@...ux.intel.com>
Subject: Re: [PATCH v6 0/5] selftests/resctrl: Add non-contiguous CBMs in
 Intel CAT selftest

Hi Shuah,

On 2024-02-23 at 15:37:11 -0700, Shuah Khan wrote:
>
>Hi Reinette,
>
>Okay ran a quick test. Why does this test leave "/sys/fs/resctrl"
>mounted when it exits. Can we fix this to unmount before the test
>exits?

I also wasn't able to reproduce this unmounting issue:
- with unmounted resctrl before test:

	[/root]# ls /sys/fs/resctrl/
	[/root]#
	[/root]# ./resctrl_tests -t L3_NONCONT_CAT
	TAP version 13
	# Pass: Check kernel supports resctrl filesystem
	# Pass: Check resctrl mountpoint "/sys/fs/resctrl" exists
	# resctrl filesystem not mounted
	# dmesg: [   12.502941] resctrl: L3 allocation detected
	# dmesg: [   12.507134] resctrl: MB allocation detected
	# dmesg: [   12.511315] resctrl: L3 monitoring detected
	1..1
	# Starting L3_NONCONT_CAT test ...
	# Mounting resctrl to "/sys/fs/resctrl"
	# Write schema "L3:1=3f" to resctrl FS
	# Write schema "L3:1=f0f" to resctrl FS # write() failed : Invalid argument
	# Non-contiguous CBMs not supported and write of non-contiguous CBM failed as expected
	ok 1 L3_NONCONT_CAT: test
	# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
	[/root]# ls /sys/fs/resctrl/
	[/root]#

And with mounted before test:

	[/root]# ls /sys/fs/resctrl/
	[/root]#
	[/root]# mount -t resctrl resctrl /sys/fs/resctrl
	[/root]# ls /sys/fs/resctrl/
	cpus  cpus_list  info  mode  mon_data  mon_groups  schemata  size  tasks
	[/root]# ./resctrl_tests -t L3_NONCONT_CAT
	TAP version 13
	# Pass: Check kernel supports resctrl filesystem
	# Pass: Check resctrl mountpoint "/sys/fs/resctrl" exists
	# resctrl filesystem is mounted
	# dmesg: [   12.502941] resctrl: L3 allocation detected
	# dmesg: [   12.507134] resctrl: MB allocation detected
	# dmesg: [   12.511315] resctrl: L3 monitoring detected
	1..1
	# Starting L3_NONCONT_CAT test ...
	# Mounting resctrl to "/sys/fs/resctrl"
	# Write schema "L3:1=3f" to resctrl FS
	# Write schema "L3:1=f0f" to resctrl FS # write() failed : Invalid argument
	# Non-contiguous CBMs not supported and write of non-contiguous CBM failed as expected
	ok 1 L3_NONCONT_CAT: test
	# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
	[/root]# ls /sys/fs/resctrl/
	[/root]#

Looking at the code there is an unmounting function called after each test (at
the end of run_single_test() inside of test_cleanup()). The non-contiguous test
also doesn't write any data into a temp file so no additional cleanup is
necessary.

-- 
Kind regards
Maciej Wieczór-Retman