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From: Roman Gushchin <guro@fb.com>
To: Yonghong Song <yhs@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
	"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Tejun Heo <tj@kernel.org>, Kernel Team <Kernel-team@fb.com>,
	"cgroups@vger.kernel.org" <cgroups@vger.kernel.org>,
	Stanislav Fomichev <sdf@fomichev.me>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 bpf-next 4/4] selftests/bpf: add auto-detach test
Date: Thu, 23 May 2019 17:58:40 +0000	[thread overview]
Message-ID: <20190523175833.GA7107@tower.DHCP.thefacebook.com> (raw)
In-Reply-To: <f7953267-8559-2f58-f39a-b2b0c3bf2e38@fb.com>

On Wed, May 22, 2019 at 10:47:24PM -0700, Yonghong Song wrote:
> 
> 
> On 5/22/19 4:20 PM, Roman Gushchin wrote:
> > Add a kselftest to cover bpf auto-detachment functionality.
> > The test creates a cgroup, associates some resources with it,
> > attaches a couple of bpf programs and deletes the cgroup.
> > 
> > Then it checks that bpf programs are going away in 5 seconds.
> > 
> > Expected output:
> >    $ ./test_cgroup_attach
> >    #override:PASS
> >    #multi:PASS
> >    #autodetach:PASS
> >    test_cgroup_attach:PASS
> > 
> > On a kernel without auto-detaching:
> >    $ ./test_cgroup_attach
> >    #override:PASS
> >    #multi:PASS
> >    #autodetach:FAIL
> >    test_cgroup_attach:FAIL
> 
> I ran this problem without both old and new kernels and
> both get all PASSes. My testing environment is a VM.
> Could you specify how to trigger the above failure?

Most likely you're running cgroup v1, so the memory controller
is not enabled on unified hierarchy. You need to pass
"cgroup_no_v1=all systemd.unified_cgroup_hierarchy=1"
as boot time options to run fully on cgroup v2.

But generally speaking, the lifecycle of a dying cgroup is
completely implementation-defined. No guarantees are provided.
So false positives are fine here, and shouldn't be considered as
something bad.

At the end all we want it to detach programs in a reasonable time
after rmdir.

Btw, thank you for the careful review of the patchset. I'll
address your comments, add acks and will send out v3.

Thanks!

  reply	other threads:[~2019-05-23 17:59 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-22 23:20 [PATCH v2 bpf-next 0/4] cgroup bpf auto-detachment Roman Gushchin
2019-05-22 23:20 ` [PATCH v2 bpf-next 1/4] bpf: decouple the lifetime of cgroup_bpf from cgroup itself Roman Gushchin
2019-05-23  5:33   ` Yonghong Song
2019-05-22 23:20 ` [PATCH v2 bpf-next 2/4] selftests/bpf: convert test_cgrp2_attach2 example into kselftest Roman Gushchin
2019-05-23  5:39   ` Yonghong Song
2019-05-22 23:20 ` [PATCH v2 bpf-next 3/4] selftests/bpf: enable all available cgroup v2 controllers Roman Gushchin
2019-05-23  5:45   ` Yonghong Song
2019-05-22 23:20 ` [PATCH v2 bpf-next 4/4] selftests/bpf: add auto-detach test Roman Gushchin
2019-05-23  5:47   ` Yonghong Song
2019-05-23 17:58     ` Roman Gushchin [this message]
2019-05-23 23:06       ` Yonghong Song
2019-05-23  5:52   ` Yonghong Song
2019-05-23  5:17 ` [PATCH v2 bpf-next 0/4] cgroup bpf auto-detachment Yonghong Song

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