* flow_dissector test is flaky
@ 2020-09-24 1:48 Alexei Starovoitov
2020-09-24 2:05 ` Andrii Nakryiko
0 siblings, 1 reply; 3+ messages in thread
From: Alexei Starovoitov @ 2020-09-24 1:48 UTC (permalink / raw)
To: Stanislav Fomichev, bpf, Daniel Borkmann, Andrii Nakryiko
Hi Stanislav,
looks like flow_dissector selftest got quite unstable recently.
test_link_update_invalid_opts:FAIL:340
bpf_link_create(prog1): Argument list too long
#33/25 flow dissector link update invalid opts:FAIL
test_link_update_invalid_prog:FAIL:400
bpf_link_create(prog1): Argument list too long
#33/26 flow dissector link update invalid prog:FAIL
#33/27 flow dissector link update netns gone:OK
It's failing for me half of the time with a random number of failures.
Not sure what happened. I think it was stable in the past.
To reproduce:
test_progs -t flow_dissector
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: flow_dissector test is flaky
2020-09-24 1:48 flow_dissector test is flaky Alexei Starovoitov
@ 2020-09-24 2:05 ` Andrii Nakryiko
2020-09-24 2:21 ` Alexei Starovoitov
0 siblings, 1 reply; 3+ messages in thread
From: Andrii Nakryiko @ 2020-09-24 2:05 UTC (permalink / raw)
To: Alexei Starovoitov
Cc: Stanislav Fomichev, bpf, Daniel Borkmann, Andrii Nakryiko, Muchun Song
On Wed, Sep 23, 2020 at 6:49 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> Hi Stanislav,
>
> looks like flow_dissector selftest got quite unstable recently.
> test_link_update_invalid_opts:FAIL:340
> bpf_link_create(prog1): Argument list too long
> #33/25 flow dissector link update invalid opts:FAIL
> test_link_update_invalid_prog:FAIL:400
> bpf_link_create(prog1): Argument list too long
> #33/26 flow dissector link update invalid prog:FAIL
> #33/27 flow dissector link update netns gone:OK
>
I've seen similar flakiness for cgroup_link selftest that used to be
rock solid. And it just clicked when I saw this, that this patch might
be a culprit:
https://patchwork.ozlabs.org/project/netdev/patch/20200917074453.20621-1-songmuchun@bytedance.com/
It makes bpf_link detachment delayed, so now anything that relies on
the fact that bpf_link gets auto-detached immediately after the last
link FD was closed is flaky. But that is a pretty reasonable and
convenient assumption. So can we please revert that patch? It's a
really nice guarantee to have, while the benefits of the fix in that
patch is a bit ephemeral.
> It's failing for me half of the time with a random number of failures.
> Not sure what happened. I think it was stable in the past.
> To reproduce:
> test_progs -t flow_dissector
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: flow_dissector test is flaky
2020-09-24 2:05 ` Andrii Nakryiko
@ 2020-09-24 2:21 ` Alexei Starovoitov
0 siblings, 0 replies; 3+ messages in thread
From: Alexei Starovoitov @ 2020-09-24 2:21 UTC (permalink / raw)
To: Andrii Nakryiko
Cc: Stanislav Fomichev, bpf, Daniel Borkmann, Andrii Nakryiko, Muchun Song
On Wed, Sep 23, 2020 at 7:05 PM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Wed, Sep 23, 2020 at 6:49 PM Alexei Starovoitov
> <alexei.starovoitov@gmail.com> wrote:
> >
> > Hi Stanislav,
> >
> > looks like flow_dissector selftest got quite unstable recently.
> > test_link_update_invalid_opts:FAIL:340
> > bpf_link_create(prog1): Argument list too long
> > #33/25 flow dissector link update invalid opts:FAIL
> > test_link_update_invalid_prog:FAIL:400
> > bpf_link_create(prog1): Argument list too long
> > #33/26 flow dissector link update invalid prog:FAIL
> > #33/27 flow dissector link update netns gone:OK
> >
>
> I've seen similar flakiness for cgroup_link selftest that used to be
> rock solid. And it just clicked when I saw this, that this patch might
> be a culprit:
>
> https://patchwork.ozlabs.org/project/netdev/patch/20200917074453.20621-1-songmuchun@bytedance.com/
>
> It makes bpf_link detachment delayed, so now anything that relies on
> the fact that bpf_link gets auto-detached immediately after the last
> link FD was closed is flaky. But that is a pretty reasonable and
> convenient assumption. So can we please revert that patch? It's a
> really nice guarantee to have, while the benefits of the fix in that
> patch is a bit ephemeral.
Indeed. Reverted.
The usage of in_atomic() is fine there.
^ permalink raw reply [flat|nested] 3+ messages in thread
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