[LTP] [PATCH] cgroup_regression_test: Use unique names for hierarchies in each test

[Avinesh Kumar]

Hi all¸

I would like to ask if there are any other suggestions on how to address this
issue.
I tried a rather simpler approach (as suggested by Martin) of just adding a
delay using sleep after the umount call, which also seems to solve this issue
of incomplete unmounting.

--- a/testcases/kernel/controllers/cgroup/cgroup_regression_test.sh
+++ b/testcases/kernel/controllers/cgroup/cgroup_regression_test.sh
@@ -102,10 +102,11 @@ test1()
        cat cgroup/tasks > /dev/null
 
        kill -TERM $!
        wait $! 2>/dev/null
        umount cgroup/
+       sleep 2
        check_kernel_bug
 }

I will send this in the patch if we agree to use this approach instead of
unique names.

Thanks,
Avinesh

On Monday, July 14, 2025 1:56:51 PM CEST Andrea Cervesato wrote:
> On 7/11/25 3:15 PM, Michal Koutný wrote:
> > On Fri, Jul 11, 2025 at 02:41:18PM +0200, Andrea Cervesato <andrea.cervesato@suse.com> wrote:
> >> This git commit is part of cgroup v1 code and now in
> >> kernel/cgroup/cgroup-v1.c:cgroup1_root_to_use, but I don't see the same
> >> mechanism used by cgroup v2, which is our main version.
> > The patched tests use cgroup v1.
> >
> >> Is that something which might affect our system?
> > Since there's only one cgroup v2 (unified) hierarchy, it sort of lives
> > forever (statically alloc'd), so I wouldn't expect such residuals on v2
> > (with the current implementation).
> >
> > Michal
> 
> I bisected util-linux, but it doesn't seem to be the problem. On my 
> system (Tumbleweed), we are facing the same failure, no matter the 
> commit that is tested in util-linux between 2.39 and 2.41 versions.
> 
> I guess this issue might be caused by a specific setup of the Linux 
> kernel and its async nature, mixed with some services which are slowing 
> down the umount process.
> 
> I'm wondering how to proceed, since this is actually a soft-failure and 
> any fix to the test might hide future bugs.
> 
> - Andrea
> 
>