linux-kernel - Re: [PATCH testsuite] tests/task_setscheduler: add cgroup v2 case for moving proc to root cgroup

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <55390a1e-5994-465a-a5c5-94f3370259c3@huawei.com>
Date: Sat, 27 Jul 2024 10:54:30 +0800
From: Gong Ruiqi <gongruiqi1@...wei.com>
To: Ondrej Mosnacek <omosnace@...hat.com>
CC: Paul Moore <paul@...l-moore.com>, Stephen Smalley
	<stephen.smalley.work@...il.com>, <selinux@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Wang Weiyang <wangweiyang2@...wei.com>
Subject: Re: [PATCH testsuite] tests/task_setscheduler: add cgroup v2 case for
 moving proc to root cgroup

On 2024/07/26 21:43, Ondrej Mosnacek wrote:
> On Thu, Jul 18, 2024 at 2:34 PM Gong Ruiqi <gongruiqi1@...wei.com> wrote:
>>
>>
>> On 2024/07/18 0:17, Paul Moore wrote:
>>> ...
>>>
>>> Where (what distribution, version, etc.) did you see this problem?
>>
>> The problem occurred when I ran the testsuite on Fedora 40 with v6.6
>> kernel, and it was the only failed testcase.
> 
> Sorry for the delay... For some reason the test passes for me even
> with cgroup v2 only and without the patch (also when run from a
> regular user account with sudo). Do you happen to know what
> circumstances are needed for it to fail when the cgroup is not
> switched?
> 

As the comment in the script says, a process need to be in the root
cgroup in order to switch its scheduler policy to SCHED_{RR,FIFO}. So
maybe in your case the shell process is already in the root cgroup?

In my case I need to ssh to a Fedora VM, and that makes my shell process
to be in a sub cgroup called /user.slice/.../XXX.scope (looks like some
systemd stuff). And since /sys/fs/cgroup/cpu/tasks doesn't exit in the
system with cgroup v2 only, the script skips moving the target process
to the root cgroup, and therefore the subsequent test fails.